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Development of a "new" shelf-stable salsa with microwave vacuum (MIVAC) dehydrated cilantro

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ABSTRACT
DEVELOPMENT OF A “NEW” SHELF-STABLE SALSA WITH
MICROWAVE VACUUM (MIVAC)
DEHYDRATED CILANTRO
A new shelf-stable salsa was developed using microwave vacuum (MTVAC)
dehydrated cilantro. It was predicted that the MTVAC dehydration process would
retain the fresh characteristics of the herb when added to a processed product and
would be preferred by consumers. A standardized formulation without cilantro was
developed as a control. An affective test was used for consumer acceptance.
Analytical testing was used to reformulate the control and determine an “optimum”
level of MTVAC dehydrated cilantro to add to the control. An affective test was
conducted to determine if the reformulation with cilantro was preferred. The first
affective test showed a 93% acceptance of the control recipe. The “optimum” amount
of MTVAC dehydrated cilantro was determined to be at a 0.5% concentration level by
a group recognition threshold. The second affective test showed a slight preference
for the reformulation with cilantro, but no significant statistical preference was
measured.
Karla Marie Carlsen
May 1997
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DEVELOPMENT OF A “NEW” SHELF-STABLE SALSA WITH
MICROWAVE VACUUM (MTVAC)
DEHYDRATED CILANTRO
by
Karla Marie Carlsen
A thesis
submitted in partial
fulfillment of the requirements for the degree of
Master o f Science in Agriculture
in the School of Agricultural Sciences and Technology
California State University, Fresno
May 1997
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UMI Number: 13 86269
UMI Microform 1386269
Copyright 1997, by UMI Company. All rights reserved.
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APPROVED
For the Department of Enology, Food Science, and Nutrition:
ft & (-^
L;_____________________________
Dennis A. Ferris (Chair)
Enology, Food Science, and Nutrition
N. Joamfe Caid
Enology, Food Science, and Nutrition
J)n
,nAj-£j <A,Udby
Sandra S. Witte
Enology, Food Science, and Nutrition
For the Graduate Committee:
Dean, Division of Graduate Studies
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AUTHORIZATION FOR REPRODUCTION
OF MASTER'S THESIS
K ^
I grant authorization for the reproduction of this thesis in part or
in its entirety without further authorization from me, on the
condition that the person or agency requesting reproduction
absorbs the cost and provides proper acknowledgment of
authorship.
________
Permission to reproduce this thesis in part or in its entirety must
be obtained from me.
Signature of thesis writer: ‘Ktf.iCi. ^
Cl.
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ACKNOWLEDGMENTS
I would like to thank my major professor, Dr. Dennis Ferris, for guidance,
support, and patience throughout this project; and Dr. Sandra Witte and Mrs.
Joanne Caid who served on my committee and encouraged me to further my
education.
I am grateful to the California Tomato Research Institute for funding this
study as well as other opportunities for students at California State University,
Fresno.
And last, but not least, I would like to thank my husband, Carl, and my
children, Peter, Kelly, and Bridget, for their steadfast love and support during my
many hours of unavailability; and my parents for volunteering countless hours of
child care and household maintenance.
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TABLE OF CONTENTS
Page
LIST OF T A B L E S ............................................................................................ vii
LIST OF F I G U R E S ........................................................................................... viii
IN TROD U CTION ...........................................................................................
1
REVIEW OF LITER A TU R E..........................................................................
4
C ila n tr o .................................................................................................
5
Microwave Vacuum ( M T V A C ) .........................................................
6
Sensory E valuation................................................................................
7
METHODOLOGY.................................................................................................. 10
Phase 1-Control Formulation and Consumer Acceptance Testing .
10
Phase 2-Reformulation of Control Salsa and Analytical Testing
14
. .
Phase 3-Affective Consumer T estin g .......................................................... 22
RESULTS AND D IS C U S S IO N ........................................................................... 25
Results o f Phase 1 .......................................................................................25
Results o f Phase 2
.......................................................................................27
Results o f Phase 3 .......................................................................................34
C O N C L U S IO N S ..................................................................................................37
Phase 1-Control Formulation and Consumer Acceptance Testing
.
37
Phase 2-Analytic-Discriminative T esting.................................................... 39
Phase 3-Affective Consumer Testing
Consumer Preference T e s t i n g .................................................... 44
REFEREN CES........................................................................................................45
A PP E N D IC E S ........................................................................................................50
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VI
APPENDIX
Page
A. CONSENT WAIVER F O R M ....................................................
51
B. TEST SCORE SHEETS...............................................................
54
C. RAW DATA INCLUDING
OPEN-ENDED COM M ENTS...............................................
58
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LIST OF TABLES
Table
Page
1.
Triangle Test results for groups 1 and 2
.......................................... 28
2.
Recognition threshold scores: Number correct
out o f three sample s e t s ................................................................ 30
3.
Converted data for individual recognition threshold:
% correct above chance for each p a n e lis t ....................................32
4.
Calculated individual and group t h r e s h o l d s .................................... 32
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LIST OF FIGURES
Figure
Page
1.
Affective test for consumer a c c e p t a n c e .......................................... 26
2.
Estimate of approximate threshold levels for individual judges .
3.
Affective test for consumer preference................................................35
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33
INTRODUCTION
Of all new food products introduced on supermarket shelves in the last
year, 3,698 were condiments (Domblaser, 1996). Salsas have shown the most
growth in this category, replacing catsup, as the number one selling condiment in
the United States today (Cousminer, 1996). According to a Neilsen Consumer
Survey, the average household purchases 5.3 containers of salsa per year,
compared with only 4.2 containers of catsup. This translates to salsa sales of over
$600 million dollars per year (Mogelonsky, 1995; Charlet, 1994).
One reason that accounts for the rapid growth and acceptance o f salsa is the
changing demographics as the Hispanic population of the United States expands.
An increase in the number and popularity of Mexican restaurants has exposed
consumers to hot, spicy and bold flavors (Toops and Kevin, 1996). Another
reason is the fashionable trend called “fusion cuisine” gaining notoriety among
chefs from coast to coast. This fusion, or mixture of ingredients, flavors or
cooking techniques of two or more cultures is the result of increased interest in
ethnic and novel foods among consumers who want "something different." Still
another reason is salsa’s low fat composition, which provides additional benefits
to the consumer perception of “freshness” associated with vegetable products and
disease prevention (Hollingsworth, 1996).
While tomato is the basis for traditional salsa, variations with fruits and
vegetables are now being served as an accompaniment to main dishes on a variety
of restaurant menus. One traditional ingredient, the herb cilantro, is borrowed
from both Mexican and Oriental cuisine, and is readily adaptable, offering new
and exciting flavor to many dishes.
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Because salsa is often offered as an accompaniment to tortilla chips, there is
a connection to the salty snack market, which is also rapidly growing in popularity
(Mogelonsky, 1995). Due to the growing demand for salsa and other products
containing fresh herbs, it is advantageous to the food processing industry to
produce a shelf-stable, processed product that contains cilantro, or other herbs,
without losing the volatile compounds that give salsa its fresh flavor appeal.
The purpose of this study was to develop a "new" consumer-acceptable,
processed, shelf-stable salsa that contains microwave vacuum (MTVAC)
dehydrated cilantro. Microwave vacuum dehydration allows for food products to
achieve a very low moisture content, while retaining attributes, such as flavor,
color and texture, which are compromised during conventional dehydration
processes. Using MTVAC technology preserves cilantro and imparts the
characteristic flavor and odor of cilantro to the processed salsa.
The study was completed in three phases. Phase 1 was the product
development stage. The objectives of this phase were: (1) to develop a
standardized formulation for salsa without MTVACed cilantro to use as a control
and (2) to use affective testing to verify consumer acceptance of the control
formulation. Phase 2 was the determination of an “optimum” amount of cilantro
to add to the control using analytical testing. The objectives in Phase 2 were: (1)
to use a Triangle Test to screen subjects to serve on a trained panel and (2) to use
this panel to verify a recognition threshold o f MTVACed cilantro added to the
control formulation. Phase 3 was the determination of a preference between the
control formulation without cilantro and the formulation with MTVACed cilantro.
The objective of Phase 3 was to determine consumer preference through affective
testing.
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3
The null hypothesis is that the target market, identified as customers at
California State University, Fresno, Farm Market, will prefer a standardized salsa
formulation made with MTVACed cilantro to the same formulation without
MTVACed cilantro. The alternate hypothesis is that the same target market will
not prefer a standardized salsa formulation made with MTVACed cilantro to a
standardized salsa formulation without cilantro.
The resulting standardized salsa formulation produced will be considered
for eventual scale-up at the Center for Food Science and Nutrition Research Food
Processing Laboratory. Surveys conducted at the California State University,
Fresno, Farm Market over the past 3 years have indicated a 17% increase in
interest in salsa, with a shelf-stable product preferred over a refrigerated product
(Carlsen, 1995; Ferris, 1997). After scale-up, the finished product will be sold at
the California State University, Fresno, Farm Market.
University product development research often generates interest among food
industry representatives. The use of MTVAC dehydrated cilantro in salsa is novel
and has application in many other condiment or sauce formulations (Ferris, 1996).
It is also hoped that this interest can lead to a collaborative working relationship
between the food industry and the university as they realize the position that
university facilities can serve in benchtop and scale-up operations.
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REVIEW OF LITERATURE
Salsas are a combination of chopped vegetables and/or fruits to which any
o f a variety of different herbs, such as cilantro, are added. The high degree of
versatility of salsa includes use as a cooking sauce, a condiment or garnish for
meats, poultry, eggs or fish, a dressing for salads and grains, and as an appetizer
with chips or vegetables. In most formulations, tomatoes, cilantro, hot peppers
and onions are key flavor components. The combined ingredients are not a puree,
but are distinct pieces and are often uncooked (Cousminer, 1996).
Tomato salsa can be made as a fresh product that needs to be refrigerated and
used within a day or two. In order to prolong the shelf life beyond this time, the
salsa must be processed to destroy any microorganisms responsible for spoilage.
Because it is considered a high-acid food (Cousminer, 1996), tomato salsa can be
produced using a high-pressure retort system at low (195-212°F) temperature or
the "Hot-Fill-Hold" method (Ronsivalli and Vieira, 1992). The "Hot-Fill-Hold"
method is preferred because it does not "over-process" the product, retaining firm
texture and shape of the individual ingredients. Processing specifications using the
Hot-Fill-Hold Method require time and temperature parameters to insure safety,
while preserving quality of the finished product. According to current standards,
minimum heat treatment required for high acid foods is 190° to 200°F in the
coldest point (Rodrigo et al., 1990). Thermo-resistant bacteria, such as Bacillus
coagulans, are found to be controlled in a tomato product at pH 4.5 and below
when processed at 185° - 225°F for 2.56 minutes (Rodrigo et al., 1990). While
tomatoes can withstand the temperatures reached under this type o f minimal
processing without a loss o f flavor or texture, cilantro can undergo an undesirable
flavor change (Giese, 1994).
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Cilantro
Traditionally, the herb cilantro (Coriandrum sativum L.) is used to impart a
flavor which is characteristic in Mexican cuisine. Cilantro is the green, leafy
portion of the coriander plant also known as Chinese parsley (Labensky and
Hause, 1995) and is similar to the parsley family (Carum petroselinum)
(Ockerman, 1978; Rosengarten, 1969). It is normally used in its fresh state as a
seasoning or garnish. A study by Potter (1996) showed a significant difference in
leaf oil during five distinct stages of growth, from the vegetative period to fruit set.
An increase in (E)-2-Decenal was found to be present at the bud formation and
blooming stages of the plant. (E)-2-Decenal is an irritant which may add an
objectionable flavor. These oil compositional differences underscore the need to
obtain cilantro which has been harvested at an early stage of growth, prior to fruit
set, when levels of (E)-2-Decenal are low (Potter, 1996).
The cilantro plant is delicate and the volatiles that produce the odor and
flavor in this herb are easily vaporized (Giese, 1994). Under normal heat
processing conditions o f canning, the color, flavor and aroma characteristics of
fresh cilantro undergo changes or can be lost. Many processed salsas on the
market today do not include cilantro in their ingredients because o f these
undesirable qualities.
Because the flavor and aroma o f cilantro is widely associated with fresh
salsa, incorporation o f this herb was considered an important objective. Due to the
problems associated with adding fresh cilantro during the processing stage, it was
believed that adding the herb produced using MTVAC technology would achieve
the desired flavor. In addition, the low moisture content o f the dehydrated product
would retard growth of naturally occurring yeasts and molds (Blumenthal, 1990).
Attributes desired in any dehydrated product include minimum change from fresh
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6
product character, lower final moisture content, and reconstituted character similar
to fresh in terms of flavor, color and texture (Clary, 1996). Common dehydration
processes, such as air convection and freeze drying, result in a product that may
retain some of these qualities, but is lacking in others. Air convection employs
heated air which removes moisture from a product by evaporation or vaporization.
However, the high heat may result in a loss o f color or browning effect. Flavor
may be affected as well if temperatures reached cause volatile oils to evaporate or
undergo heat-related reactions. Similarly, the freeze drying process, while
utilizing low pressure and low temperature to remove moisture without volatile
loss, may cause cell damage due to expansion and rupture of cells upon freezing.
The result of this damage is loss of texture upon re-hydration (Clary, 1996).
Cilantro can be dehydrated in the Dried Foods Technology Laboratory at
California State University, Fresno, using MTVAC technology. MTVAC
technology is described below.
Microwave Vacuum (MTVAC)
The patented MTVAC dehydration process allows fresh fruits, vegetables,
and herbs to be dried to low moisture levels with minimal loss of their volatile
components through the combined microwave vacuum dehydration process,
(McKinney and Wear, 1987; McKinney et al., 1983). Within the MTVAC
chamber, foods are exposed to radiant microwave energy at wavelengths
approximately 300 MHz as generated by a magnetron tube (Clary, 1994). As the
food absorbs the microwave energy, the polar water molecules attempt to rotate
while sodium and chloride ions naturally present in the food product move in a
linear fashion. This molecular movement within the food product produces heat,
which drives the moisture from the inside of the food to the outside where it
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7
vaporizes (Clary, 1994). This is opposite to other dehydration processes, which
remove moisture from the product from the outside to the center through osmosis
(Clary, 1996). Some of the factors that affect the rate of mass transfer of moisture
include surface area, vacuum/pressure, time and temperature (Clary, 1996).
Because the MTVAC chamber operates without pressure, the boiling point of water
is lowered and moisture loss is achieved at a much lower temperature (Clary,
1996). The MTVAC process combines low atmospheric pressure and microwave
energy resulting in relatively quick, low temperature dehydration of a product with
little or no loss of volatile oils or heat damage to the plant cell walls (Clary, 1996).
The MTVAC process has already been successfully used to produce dehydrated
cilantro that retains its fresh appearance when reconstituted (Clary, 1996).
Sensory Evaluation
Sensory evaluation methods gather information through the use of reliable
and valid testing of products in order to make decisions (Meilgaard et al., 1991).
Four key factors are crucial: definition of the problem, test design,
instrumentation, and interpretation of the test results (Meilgaard et al., 1991). A
clear definition of the problem includes both project and test objectives, allowing
the researcher to select the testing methods which will generate suggested
solutions to the problem (Lawless and Claassen, 1993; Meilgaard et al. 1991).
This is especially important in food product development, where multiple
objectives, i.e., information regarding a food or ingredient characteristic and
consumer perception, may be common goals (O’Mahony, 1986). Since the
“instruments” many times are human subjects, the researcher is required to
maximize efforts to control variability and bias (Meilgaard et al., 1991).
Consumer testing has increased in use and, when used properly, has been found to
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8
be very effective in product development, maintenance, and improvement
(Meilgaard et al., 1991).
Types o f Tests
The diverse tests used in sensory evaluation can be divided into two major
groups, affective and analytical-discriminative. Dependent on the primary goal,
affective tests fall into two categories: acceptance or preference. Both tests seek to
evaluate a general personal response (acceptance and/or preference) by a
representative sample of potential consumers (Meilgaard et al., 1991). Acceptance
testing determines the “affective status” of a product, i.e., how much a product is
liked/accepted. Assessment by means o f a hedonic rating scale, preferably
balanced with equal number of positive and negative choices in increments of
equal size, results in more useful information (Meilgaard et al., 1991). Preference
testing requires the subject to make a forced choice between two or more products,
but may not indicate whether the product is liked. Training may be used for
acceptance or preference tests; however, testing usually occurs on a large scale
using untrained subjects (Sensory Evaluation Division o f the Institute of Food
Technologists (SED, IFT, 1981).
Analytical-discriminative tests are usually administered in a laboratory
using trained, experienced testers. Similar to chemical or physical analysis, the
goal is to obtain precise and reproducible results (Lawless and Claasen, 1993).
Analytical-discriminative tests can further be broken down into difference and
sensitivity. The objective is to identify and quantify food attributes based on
difference or similarity (SED, IFT, 1981). Subjects must be experienced in
methodology and possess the ability to identify, recognize, and recall sensory
characteristics to assure repeatable results (Meilgaard et al., 1991). The validity of
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9
the results depends on individual subject sensitivity and reproducibility; the
environment in which the test occurs; and control over physical and psychological
influences (Amerine et al., 1965).
Panel training is an important aspect in analytical testing. Orientation prior
to the actual test should include familiarizing the subjects with the test procedure
and scoring, and explaining product characteristics (Meilgaard et al., 1991). The
researcher provides only enough information necessary to instruct the subjects
without introducing bias (Meilgaard et al., 1991).
The Triangle Test for difference is frequently used for panel selection based
on the ability to make a distinction between three samples (Amerine et al., 1965).
The subject must choose the odd sample from three in which two are identical and
one is different.
The Recognition Threshold Test for sensitivity is used to determine a
concentration at which trained panelists identify and recognize a certain substance.
This threshold is higher than the absolute threshold, which is the lowest possible
concentration which is detectable (Meilgaard et al., 1991). Thresholds are among
the most difficult data to obtain and define. Results are difficult to reproduce,
even given the same panel on a given day (Meilgaard et al., 1991; Blumenthal,
1990).
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METHODOLOGY
Phase 1-Control Formulation and Consumer
Acceptance Testing
The first objective of Phase 1 was to develop and standardize a formulation
for a new salsa. The purpose of standardization was to establish a formula that
would “yield a known quantity of a known quality at a known cost” (Knight and
Kotschevar, 1989). Careful weighing or measurement of ingredients; attention to
correct ingredient ratio; and documented handling, preparation and yield ensure
reproducibility of a control formulation.
The second objective in Phase 1 was to use affective consumer testing to
determine acceptance of the control salsa formulation, using a single sample and a
nine-point hedonic rating scale (Meilgaard et al., 1991). The purpose was to
establish consumer acceptance of the control formulation for salsa prior to
reformulation in Phase 2 to include the MIVACed cilantro.
Formulation
The basic formulation for the tomato-based salsa was as follows:
Tomatoes, Toma-Tek, aseptic in foil bag, 3/4"cut
779.0 grams
(77.5%)
Onions, white, cut I/2"dice
155.8 grams
(15.5%)
70.4 grams
(7.0%)
Jalapeno peppers, Cal-Compack, brined, l/4"dice
Use of a preprocessed tomato assisted in the standardization of color, size
of cut, and pH. Initially, tomatoes were provided by TomaTek, Inc. in 15-lb.
aseptic lined, foil sample bags. The processed tomatoes were steam peeled and
diced in a 3/4" x 3/4" cut. Calcium chloride (CaCl2) at 800 to 900 ppm was added
for firmness. Citric acid was included to adjust the acidity level to a pH between
3.7 to 4.2. The tomatoes were processed aseptically and packaged in a lined foil
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11
pouch. Tomatoes were removed from the foil pouch and weighed by difference on
a top loading Ohaus electronic balance, model #GT4000.
Use of a brined product assisted in the standardization of the capsaicin
(heat) level in the jalapeno peppers. In this way, a “medium” salsa was produced
with assurance of a standardized heat level that was consistent batch to batch.
Jalapeno peppers were purchased through Whole Herb Company, Sonoma,
California, and packed by Cal-Compack Foods, Inc., Santa Ana, California. The
jalapeno peppers were cut into a 1/4" x 1/8" dice, standardized to a pungency level
in the range of 100 - 200 ASTA Heat Units (ppm) and packed in brine containing
13-14% sodium chloride (NaCl) and 2.5-3.5% acetic acid, with a pH in the range
of 2.8 - 3.7. The jalapeno peppers were drained in a wire strainer for 10 minutes,
then weighed by difference as above.
Since seasonal variation is not as great, it was felt that fresh onions would
better match competing salsa brand ingredients. White onions were purchased
from Save Mart supermarket in the Fresno, California area. They were peeled,
diced into 1/2" pieces, then weighed by difference as above.
Tomato solids and juice, onions, and jalapeno peppers were combined in a
3-quart saucepan and brought to "Hot-Fill-Hold" temperature (195-210°F), stirred
occasionally, and held at this temperature for 10 minutes (Ronsivalli and Vieira,
1992). The pH of the mixture was taken and recorded prior to heating. The salsa
was packed in 11-ounce clear, glass canning jars at the end of the holding time.
Jars were washed and dried prior to filling. New fids were held in hot (180°F)
water for a minimum of 10 minutes until jars were filled. The filled jars were
inverted and held no longer than 5 minutes, then cooled in a refrigerator (35 40°F). After cooling, pH and salsa yield were measured and recorded. In order to
limit microbiological activity and insure a safe product, a calibrated Oakton pH
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12
meter, model #WD-35615-62, was used to test representative samples to assure the
salsa was below pH 4.2.
Consumer Acceptance Testing
A Simple Acceptance Test of the control salsa without cilantro was
conducted using a nine-point Hedonic Rating Scale. The objective was to
determine overall acceptability of the control formulation. Scale ratings were
converted to numerical scores: 9, like extremely; 8, like very much; 7, like
moderately; 6, like slightly; 5, neither like nor dislike; 4, dislike slightly; 3, dislike
moderately; 2, dislike very much; 1, dislike extremely (Amerine et al., 1965). The
mean and median of the total responses were required to be equal to or greater
than 6 in order to accept the control formulation (Amerine et al., 1965;
O’Mahony, 1986).
Participant Selection
Thirty untrained volunteers were recruited among shoppers at the California
State University, Fresno Farm Market, to best estimate the preference of the target
market (Meilgaard et al., 1991). Participants were selected on the basis of an
affirmative answer to the question, “Do you eat salsa?” (ASTM, 1995c; Meilgaard
et al., 1991; SED, EFT, 1981). A Human Subject Review Committee determined
the participants associated with this experiment to be “at minimal risk.” The
consent waiver forms (see Appendix A),which include subjects signed consents to
participate in the study, will be stored, on file, in the office of Dr. Dennis Ferris,
Department of Enology, Food Science and Nutrition, California State University,
Fresno, for 5 years. Testing occurred over a 1-week period.
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13
Sample Preparation
Salsa was prepared according to the standardized control formulation on
page 10 in the test kitchen, Sensory Laboratory, Family and Food Science Building
at California State University, Fresno. One tablespoon of control salsa was placed
in 2-ounce white paper portion control cups at 35-40° F. A single sample was
presented to each panelist on a tray with a plastic spoon, score sheet and pencil. A
cup of tepid water was offered to cleanse the palate before tasting.
Testing Procedure
The testing was held in the California State University, Fresno, Farm Market.
A storage cabinet was used to hold samples, and provide a place for participants to
write on score sheets. Opened jars o f salsa were kept chilled in a cooler during the
testing process to maintain temperature control.
A single sample appropriate for determining acceptability of a new product
was presented (SED, IFT, 1981). Participants were asked to taste the salsa and
mark their response on the score sheet using a nine-point Hedonic Rating Scale to
describe their opinion (Appendix B). Comments regarding what in particular was
liked or disliked about the product were solicited at the bottom of the score sheet.
Statistical Analysis
The Consumer Acceptance Test was analyzed using a one-tailed, one
sample T-test. The results of the T-test were compared to Table T4, page 329 of
Sensory Evaluation Techniques (Meilgaard et al., 1991). Results of the Consumer
Acceptance Test were also presented graphically (SED,IFT, 1981; Meilgaard et
al., 1991).
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14
Phase 2 - Reformulation of Control Salsa
and Analytical Testing
When the control formulation for salsa was found to be acceptable by
affective testing of the consumer group, the control formulation was modified to
include MTVAC dehydrated cilantro. One purpose of Phase 2 was to provide a
basis for determining the “optimum” amount of MTVACed cilantro to be added to
the control formulation. A Triangle Test was used as a screening to select a panel
of judges to measure the Recognition Threshold of cilantro added to the control
salsa. This panel of judges were trained to participate in an analytical
discriminative Recognition Threshold test.
Reformulation of Control Salsa
The reformulated salsa was as follows:
Tomatoes, San Benito brand, canned T'dice
779.0 grams
(77.1%)
Jalapeno peppers, Cal-Compack, brined, sliced
155.8 grams
(15.4%)
70.4 grams
(7.0%)
5.0 grams
(0.5%)
Onions, white, cut l/2"dice
MTVACed cilantro, stem and leaves, chopped
Toma-Tek, Inc. was no longer able to supply 3/4" size, aseptically
processed tomatoes in the amounts necessary for the remainder of the study and
for future scale-up. The new ingredient supplier, S.E. Rykoff, provided San
Benito brand canned tomatoes; however, they were only available in a T' size cut.
The canning process and increase in size of cut were two unavoidable changes.
Other ingredient specifications, color and pH, were maintained as well as calcium
chloride and citric acid levels.
Tomatoes, white onions and jalapeno peppers were weighed using the same
procedure as stated in Phase 1 on page 11; ingredients were combined in a 3-quart
saucepan; and brought to “Hot-Fill- Hold” temperature for 7 minutes before the
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15
MTVAC cilantro was added. A pH reading was recorded prior to heating, using
the same instrument and method as previously stated.
The cilantro for use in this trial was preprocessed in the Viticulture and
Enology Research Center MTVAC Food Processing Laboratory located on the
California State University, Fresno, campus in March, 1996. Cilantro stems and
leaves were washed, dried, soaked in citric acid at pH 3 for 1 hour to retard
enzymatic activity, then chopped to process the stems and leaves separately. The
cilantro was processed in the MTVAC at 130°F for 70 minutes and 3,000 watts.
After dehydration, the cilantro was vacuum packed in lined foil pouches to limit
exposure to light, air, and moisture. Desiccant pouches were added to stabilize
moisture levels. The pouches were opened to remove the cilantro and then closed
by folding over the top and taping shut using masking tape.
The cilantro leaves were crumbled and the stems were chopped by hand to
approximately 1/4" size. The MTVACed cilantro was weighed by difference using
the same balance as before and added to the control salsa formulation in a 0.5%
concentration by weight. This concentration was selected based on former
experiments (Duran-Guiterrez, 1995).
The MTVACed cilantro was added to the control salsa formulation and the
temperature was maintained for 3 more minutes. The researcher reasoned that the
added cilantro would come up to “Hot-Fill-Hold” temperature in the salsa without
prolonged exposure to heat.
Condition 1 - Panel Selection
for Discriminative Tests
A Triangle Test was used to determine if a participant could detect a
difference between control samples and those containing MTVACed cilantro. This
was a screening process for serving on the threshold panel (Meilgaard et al.,
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16
1991). This screening of subjects is useful during recruitment because a subject is
eliminated early on if they are unable to discriminate between a sample with the
desired ingredient and a sample that does not contain this ingredient (Meilgaard et
al., 1991). Fatigue during testing due to the chemical irritant properties of the
capsaicin present in jalapeno peppers was an important consideration. In order to
minimize the trigeminal effects of this stimulus, the smallest required number of
repetitions for each testing situation was adopted (Amerine et al., 1965). This
panel was assembled and trained to determine a recognition threshold for the
“optimum” addition of cilantro to the control salsa formulation.
Panel Selection
Panel selection for the Triangle Test was based on the ability to recognize
and identify the flavor of the herb cilantro when added to the control salsa.
Participants were recruited from faculty and experienced students of the California
State University, Fresno, Department of Enology, Food Science, and Nutrition;
Food Services department; Viticulture and Enology Research Center Dried Foods
Technology Laboratory; and other professionals from the food industry. Criteria
included commitment to the testing schedule, general good health, and ability to
discriminate flavor and aroma accurately. Fourteen individuals participated in the
Triangle Testing, 6 men and 8 women ranging in age from 20 to 60. The
participants were provided with the same consent waiver form described in Phase
1 (Appendix A).
Panelist Training
Panelists were trained in two separate groups. Both groups were
familiarized with the test method and scoring procedure (Rutledge, 1992).
Training for the first group of 9 panelists was held in Room 105 of the Family and
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17
Food Science Building in a group setting. Seating for this training session was
provided at tables and chairs arranged in a U-shape (Meilgaard et al., 1991;
Rutledge, 1992). Training for the second group of 5 panelists was held in Room
118 of the Family and Food Science Building in a group setting. Seating for this
session was round table style, commonly used in focus or smaller group settings
(Meilgaard et al., 1991; Rutledge, 1990).
Both groups of panelists viewed sample score sheets (see Appendix B) and
were given scoring instructions. Panelists were instructed that samples would be
presented in sets of three; to taste all samples from left to right; and indicate on the
score sheet which sample was different. Panelists were allowed to return to the
samples in a given set to re-taste if necessary. Instructions for the Forced-Choice
Method were described during training: if a panelist could not tell the difference
between samples, they must guess (Meilgaard et al., 1991; SED, EFT, 1981).
Sample Preparation
Samples of the reformulated control salsa were prepared in the same test
kitchen using the “new” formulation on page 14. One tablespoon of control salsa
without cilantro and 1 tablespoon reformulated salsa were placed in individual 2ounce clear plastic portion control cups. The cups were coded using random
numbers from a random number chart (Meilgaard et al., 1991). The salsa was
served at 35 - 40°F.
Testing Procedure
Sensory testing for the first group o f 9 panelists was performed in the
individual testing booths in the Sensory Laboratory in the Food and Family
Science Building, which accommodates up to 5 panelists at one time. Each booth
is equipped with a water fountain and a pass-through door for presentation of
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18
samples. The booths are arranged side by side and are divided by 4-foot panels to
insure privacy (Meilgaard et al., 1991). The panelists entered and exited the
tasting booth area o f the laboratory from the outside hallway. Red lighting was
used to attempt to mask appearance differences between samples (Meilgaard et al.,
1991).
Testing for the second group of 5 subjects occurred in Room 118 of the
Family and Food Science Building. Tepid water in cups was provided and
samples were held covered until presentation. Available fluorescent lighting was
used.
Panelists were instructed to rinse their mouth with water prior to tasting the
samples and rinse between samples. Unsalted crackers were provided for panelists
to eat between sample sets (Gillette et al., 1984).
Samples were arranged on trays in sets of three. In each set, 2 samples
were identical and 1 was different. Six possible combinations were prepared.
Samples were presented in balanced order so that the chance of panelists receiving
an identical sample order was minimized (ABB, BAA, AAB, BBA, ABA, BAB)
(Meilgaard et al., 1991). Each of the 14 participants received 3 sets o f samples for
a total of 42 sample sets. Panelists were instructed to taste 3 samples in one set,
then circle the number on the score sheet corresponding to the sample that was
different. Testing occurred on 2 different days.
Statistical Analysis
The Triangle test was analyzed using Table T7 Triangle Test for
Difference: Critical Number (Minimum) o f Correct Answers (Meilgaard et al.,
1991). Each panelist group was analyzed separately. The results were presented
separately in one table.
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19
Condition 2-Recognition
Threshold Test
A panelist’s ability to recognize the MTVACed cilantro sample correctly in
three sets of three samples served in the Triangle Test was the criterion for serving
on a Recognition Threshold panel. Panelists who met this criterion were asked to
return to serve on the threshold panel. This panel was trained to determine a
Recognition Threshold level of cilantro in the control salsa. This threshold was
used to determine a guideline for adding an “optimum” level of cilantro to the
standardized control formulation. The researcher reasoned that a concentration
higher than that detected by a trained panel would be necessary for an untrained
group to recognize. One concentration step above the established group threshold
was selected to be appropriate and yet cost effective.
Recognition Threshold Test
A Recognition Threshold Test was used to determine the concentration at
which the MTVACed cilantro could be recognized by a trained panel. The purpose
of this test was to establish a guideline for adding an “optimum” level of cilantro
to the control salsa formulation. According to ASTM, 1995, method E1432, the
recognition threshold was defined as “the lowest concentration of a substance in a
medium relating to the lowest physical intensity at which a stimulus is recognized
by an individual panelist 50% of the time” (Meilgaard et al., 1991). The
Recognition Threshold o f each individual judge was determined by the BestEstimate Threshold criterion (BET) using a trained panel (ASTM, 1995b). The
group threshold concentration was determined based on the geometric mean of the
individual threshold levels (ASTM, 1995b; Meilgaard et al., 1991). It was
assumed that a one step higher concentration of cilantro will be recognized by
50% of the corresponding population (Meilgaard et al., 1991).
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20
Panelist Selection
Five panelists were selected, based on their ability to perceive a difference
in three out of three samples in the Triangle Test and availability. The panelists
included 3 men and 2 women, approximately 20 to 45 years of age, experienced in
sensory testing. The panel was retrained for familiarity with the new test
procedures and with the cilantro stimulus using the re-hydrated cilantro to
calibrate panelists.
Panel Training
Training was provided at the California State University, Fresno, Sensory
Laboratory in the Family and Food Science Building to familiarize the panelists
with the format o f the test, the task involved and the evaluation procedure
(Meilgaard et al., 1991). The panelists were made familiar with the sample of
control salsa; the sample of reformulated salsa; as well as a sample cup containing
re-hydrated MTVACed cilantro.
Panelists were instructed to rinse their mouth with water before tasting the
first sample and between sets. Unsalted crackers were provided to eat between
sample sets (Gillette et al., 1984). Samples were tasted from left to right. As in
the Triangle Test, the Forced Choice Method was used: if a panelist could not tell
which was different, they were instructed to guess. Panelists were allowed to
return to each sample within a sample set in order to choose the sample in which
the odor or flavor of cilantro was recognized (ASTM, 1995a).
Sample Preparation
Samples were prepared in the California State University, Fresno test kitchen
described above by adding MTVACed cilantro to the control salsa formulation on
page 10 in a series of concentration steps. The lowest concentration increments of
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21
the substance began well below the level that the most sensitive panelist was
expected to recognize (ASTM, 1995a). The ingredients, tomato, white onion, and
jalapeno pepper, were weighed by difference using the same scale as before and
placed into five individual 3-quart saucepans. Using the same instrument and
method as before, a pH reading was taken for each of the five saucepans of salsa.
Each of the saucepans were brought to “Hot-Fill-Hold” temperature and held for
seven minutes (Ronsivalli and Vieira, 1992). MTVACed cilantro was weighed by
difference using the same balance at 0.05%, 0.1%, 0.3%, 0.5%, and 0.7% (by
weight) concentrations and was added to each of the saucepans. After the addition
of the MTVACed cilantro, temperature was maintained for 3 more minutes. One
tablespoon o f salsa at each concentration was placed in a 2-ounce clear plastic
portion control cup and served at 35-40° F. All samples were coded using random
numbers.
Testing Procedures
The test procedure used for the Recognition Threshold test was the 3Altemate Forced Choice (3-AFC) Method. If the panelist could not make a
choice, they were instructed to guess (ASTM, 1995a,b). Each designated set of
three samples contained one sample with cilantro and two samples without cilantro
(blanks). Beginning with the lowest concentration of cilantro, the panelists were
asked to identify the samples which contained the taste and odor of cilantro and
record the results on the score sheet provided (Appendix B).
Nine samples were presented on a tray at each concentration step, arranged
in three rows of three, with the sample containing cilantro in randomized leftcenter-right position to eliminate bias. Testing continued until all sets were
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22
evaluated, or until a panelist correctly identified all three sets at two consecutive
concentration steps (ASTM, 1995a).
Sensory testing was performed in the individual testing booths in the
California State University, Fresno Sensory Laboratory. Green lighting was used
in the booths to mask visual differences between samples (Meilgaard et al., 1991).
Statistical Analysis
Results o f the Recognition Threshold test were analyzed using the Best
Estimate Threshold calculation in Appendix X -l of the ASTM test for
Determination of Odor and Taste Thresholds By a Forced-Choice Ascending
Concentration Series Method of Limits (ASTM, 1995a). Individual thresholds
were determined by converting data into percent correct above chance values and
presented graphically. The group threshold was accepted to be the geometric
mean of the individual thresholds (ASTM, 1995a,b).
Phase 3-Affective Consumer Testing
After the optimum amount of MTVACed cilantro was added to the control
formulation, a second affective test was administered to determine if a consumer
preference existed between the two salsa formulations. A Consumer Preference
Test using Paired Preference was performed to determine if there was a preference
for the reformulated salsa with cilantro over the control formulation. A One-Sided
Comparison test was used to answer the original null hypothesis. To best
approximate the preference of the target market, the test was conducted on 6
randomly selected days over a 2 week period.
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23
Participant Selection
Participants were recruited from customers at the California State
University, Fresno, Farm Market. One hundred and two customers were asked to
taste the two salsa formulation samples. Panelists were asked to sign a consent
waiver form (Appendix A) prior to tasting.
Training
Training was minimal. Participants were asked to taste both samples and
record the sample number they preferred. Participants were allowed to choose
which sample to try first, reducing bias. Although rinsing between samples was
not practical in this setting, a cup of tepid water and unsalted crackers were
offered to each participant with the samples and score sheet.
Sample Preparation
Samples were prepared using the control and reformulation recipes as
described on pages 10 and 14 in Sensory Laboratory test kitchen at California
State University, Fresno. One tablespoon of each salsa, control and reformulated,
was placed in two clear, 2-ounce clear plastic portion control cups and served at
35 - 40° F. Samples were tasted with a plastic spoon. Jars of opened salsa used in
the test were kept in a cooler throughout the testing period to control serving
temperature. Random numbers were used to identify each sample.
Testing Procedure
The same storage cabinet in the Farm Market as described in the Consumer
Acceptance Test was used to hold samples and provide a space for writing on the
score sheets (see Appendix B). Panelists were presented with two coded samples
at the same time, the control salsa and reformulated salsa with cilantro. The
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24
samples were placed side by side, in random order. The chance a panelist would
taste one formulation before the other was random.
Statistical Analysis
The Consumer Preference Test was analyzed using Table T8 for
Comparison Test Difference: Critical Number (Minimum) of Correct Answers
with the results presented graphically (SED, EFT, 1981; Meilgaard et al., 1991).
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RESULTS AND DISCUSSION
Results of Phase 1
Formulation
A standardized control salsa formulation was produced. This formulation
was found to be acceptable by means of a Consumer Acceptance Test. No further
modification to the control formulation was necessary.
Consumer Acceptance Test
Nominal scores for the Consumer Acceptance Test were converted to
numeric values in order to determine a mean value of 7.1, a median value of 7 and
a standard deviation of 1.16. The mean score o f 7.1 was compared to the criteria
for acceptance score of 6 using a T-test resulting in a value of 5.19, which is
greater than the tabular value of 1.697 required for significance at 0.05%
confidence level.
The median measure of central tendency is often used when the data are
skewed by extreme values (O’Mahony, 1986). The results of the affective test for
consumer acceptance are illustrated in Figure I. Although positively skewed, a
normal distribution was suggested by the data. The largest percent of scores fall in
the 7, “like moderately” (46.7%) and 8, “like very much” (40%) range. Criteria
for acceptance of the control formulation was a mean score of 6, “like slightly”, or
above. The mean value was 7.1 and median value was 7 , which are both above
the score criteria for acceptance, 6 “like slightly”. The variance was 1.334. Based
on the 7.1 mean value rating among the consumers tested, research proceeded
without any changes to the formulation. It should be noted that this test was based
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26
Consumer Acceptance Test Results
Frequency
16
■■■-
dislike
extremely
dislike very
m uch
1
2
dislike
moderately
3
■
dislike
slightly
neither like
nor dislike
4
5
like
slightly
6
.
like
m oderately
7
8
like very
much
like
extrem ely
9
Numeric Scale of Scores
Figure 1-Affective test for consumer acceptance
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27
on a small sample o f customers (n = 30), which was referred to as a rough
screening, common in benchtop studies (Fuller, 1994; SED,IFT, 1981). Raw
scores including opened-ended comments are in Appendix C.
Results of Phase 2
Reformulation o f Control Salsa
The reformulation used the acceptable control formula producing a “new”
formulation with a 0.5% concentration (by weight) o f MTVACed cilantro added.
This amount was determined through discriminative recognition threshold testing
of concentration levels above and below the 0.5% concentration.
Triangle Test
The scores for both groups of individual judges participating in the Triangle
Test used for panel selection appear separately in Table 1. Scores for individual
judges as well as overall scores were analyzed by Table T7 Triangle Test for
Difference: Critical Number (Minimum) of Correct Answers (Meilgaard et al.,
1991). Due to the difference in test conditions, the two panels must be considered
independently, with raw scores reported in Appendix C (Meilgaard et al., 1991).
O f the first group, 56%, or 5 out of 9 subjects, were able to correctly
identify three out of three samples containing cilantro at the 5% significance level.
In the second group, 40%, or 2 out of 5 subjects, were able to correctly identify
three out of three samples containing cilantro at the 5% significance level.
The second group, tested under fluorescent fighting, should have been able
to visually detect the sample with cilantro, yet only 2 panelists out o f 5 scored
correctly three out of three times. This suggests that perhaps there was an
unaccounted factor influencing the panelists’ response; more training is needed;
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28
Table 1 - Triangle Test results for groups 1 and 2
Triangle Test - Group 1
Panelist
1
2
3
4
5
6
7
8
9
# Correct/# Possible
3 out of 3
3 out of 3
3 out of 3
0 out of 3
2 out of 3
1 out of 3
1 out of 3
3 out of 3
3 out of 3
Will Serve on Threshold Panel
Y
Y
Y
19
27
Total Correct Responses
Total Possible
Triangle Test - Group 2
Panelist
10
11
12
13
14
# Correct/# Possible
2 out of 3
3 out of 3
1 out of 3
2 out of 3
3 out of 3
Will Serve on Threshold Panel
Y
Y
Total Correct Responses
11
Total Possible
15
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29
or that cilantro at a 0.5% concentration in salsa is not perceptible to this group of
subjects, even with visual clues.
One possible reason that the first group scored higher than the second group
involves the use o f colored lighting in the sensory booths. It was assumed that
using red lighting would mask differences between the samples, but in actuality,
the reverse was true. During testing, two judges reported that the red lights caused
the samples containing cilantro to appear to have black particles. According to
Meilgaard, theater gels or low-pressure sodium lamps which emit light at one
wavelength are alternatives which remove colors, but do not eliminate differences
in color intensity (Meilgaard et al., 1991). What is also interesting is that, while
the red lighting effect provided a visual difference between samples with and
without cilantro, there was still only 50% recognition by the judges. This could be
explained by the psychological effects of stimulus error, in which irrelevant data
causes error (Meilgaard et al., 1991). The panelists who reported the visual
difference wondered if the test was purposely designed to “trick” them. To control
this factor, blue and green lighting were tested (Meilgaard et al., 1991). Green
lighting was found to be more effective in masking differences between the salsa
samples with and without cilantro.
From the two groups participating in the Triangle Test, seven panelists
scores met the criteria for the threshold test, however only five were able to return
to serve on the Recognition Threshold panel. Judges were selected based on their
ability to correctly identify samples containing cilantro in the Triangle Test.
Recognition Threshold Testing
The “best-estimate” value of the individual panelists was calculated from
each individual’s correct/incorrect responses; the group threshold is the geometric
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30
mean of all the individual responses (ASTM, 1991a,b). Scores for the individual
judges at each concentration step are shown in Table 2, representing correct
choices in three sets. For example, if the judge scored correctly all three times, the
overall score for that concentration step would be 3, with the probability of 1/3
that the correct choice was by chance alone. These data are then converted
according to ASTM methods to represent the percent correct above chance, using
the formula: % correct above chance = 100(3C-N)/2N, where N = the number of
tests presented per panelist and concentration, and C = the number o f correct
choices.
Table 2-Recognition threshold scores: Number correct out of three sample sets
Number Correct
Panelist Number
Concentration
Steps
1
2
3
4
5
0.05%
0
1
2
1
0
0.10%
0
1
1
0
2
0.20%
0
1
1
3
2
0.30%
2
0
2
0
3
0.40%
2
1
1
3
3
0.50%
3
3
2
3
0.60%
3
3
2
0.70%
3
3
I
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31
The converted scores are shown in Table 3, as indicated in ASTM Method
E 1432-91, using the formula appearing below the table. After conversion, the
scores are transformed so that 100% is plotted as 99.5%, 0% as 0.5%, and less
than 0 as 0.1%. A best fit line is plotted through the points and the threshold is
read as the concentration corresponding to 50% probability (ASTM, 1995b).
Individual thresholds are the mean of the concentration step values at which the
judge correctly identified the sample containing MTVACed cilantro at 50% above
chance.
Calculated threshold levels for each judge using the regression formula
appearing on each graph is shown in Table 4. The estimate o f approximate
threshold levels by individual judges is represented graphically in Figure 2. Using
these calculated individual threshold values, the group mean is calculated to be the
geometric mean o f the individual threshold means.
Because this test required so many repetitions, fatigue and chemical
irritation due to capsaicin levels in the samples were a concern. Capsaicin, a
pungent amide o f vanillylamide present in jalapeno peppers, stimulates pain
receptors in the mouth and throat, and causes an intense burning sensation
(Amerine etal., 1965; Krajewska and Powers, 1988). Free nerve endings, usually
mucosal membranes, are known as the trigeminal receptors (Amerine et al., 1965).
Other physical responses that are common include tearing in the eyes and nasal
secretion (Krajewska and Powers, 1988). Capsaicin does not impart a detectable
flavor or odor to a food product; however, individuals have a wide range o f
sensitivity to the substance (Krajewska and Powers, 1988). To control this
problem, panelists were required to drink water and eat unsalted crackers between
sample sets to cleanse the palate and prevent capsaicin build-up inside the mouth
(Krajewska and Powers, 1988).
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32
Table 3-Converted data for individual recognition threshold: % correct above
chance for each panelist at each concentration
Panelist Number
4
5
Cone.
Steps
50.00
0.50
0.10
0.05%
0.50
0.50
0.10
50.00
0.10%
0.10
0.50
0.50
99.50
50.00
0.20%
2.52
50.00
0.10
50.00
0.10
99.50
0.30%
2.40
50.00
0.50
0.50
99.50
99.50
0.40%
2.30
99.50
99.50
50.00
99.50
2.22
99.50
99.50
50.00
0.60%
2.15
99.50
99.50
0.50
0.70%
1
2
3
3.30
0.10
0.50
3.00
0.10
2.70
Log of
Cone. Levels
0.50%
Data converted per formula:
% Correct above Chance = 100(3C-N)/2N
N = number of tests presented per panelist and concentration (in this study, 3)
C = number of correct choices
(ASTM, 1995b)
Table 4-Calculated individual and group thresholds
Panelist Number
1
0.36
2
0.42
3
*
4
0.26
5
0.17
Group Threshold
0.29
* no threshold established for panelist #3
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33
Individual Threshold Judge 1
Individual Threshold Judge 2
150.00
150.00
<D
O
c
to
g
c
.e
0
100.00
©
1<
8
oo
*
i
50.00
mm
■1
50.00
i
0.00
3.30 3.00
05%
100.00
>
t
0.00
7 7 0 7 5 2 7 4 0 7 3 0 7 2 2 715
20% 30% 40% .50% .60% 70%
3.30 3.00 7 7 0 7 5 2 7 4 0 730 7 2 2 7 1 5
05% 10% .20% 30% 40% 50% 60% 70%
Concentration Steps
10^fconcenlitration Steps
y= 17 683X-42
y = 17 75x- 30.025
Individual Threshold Judge 3
0O)
Individual Threshold Judge 4
150.00
150.00
100.00
O 100.00
c
<0
5
aj
50.00
0.00
mm
50.00
3 30 3.00 7 7 0 7 5 2 7 4 0 7 3 0 7 2 2 7 1 5
05% 10% 20% 30% 40% 50% .60% 70%
Concentration Steps
3.30 3.00 7 7 0 7 5 2 7 40 7 3 0 7 2 2 7 1 5
05% .10% .20% 30% .40% 50% .60% 70%
Concentration Steps
y = 19.823X -19.513
Individual Threshold Judge 5
150.00
0<D 100.00
1<
lO
50.00
O
0.00
3.30 3.00 7 7 0 7 5 2 7 4 0 730 7 2 2 7 1 5
05% 10% 20% 30% 40% 50% 60% 70%
y = 24.83x - 14.67 Concentration Steps
Figure 2-Estimate of approximate threshold levels by individual judges
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34
The error of expectation is a common problem in threshold testing. This
error occurs when panelist anticipate the stimulus being tested and report it before
it is actually perceived (Meilgaard et al., 1991). The error o f central tendency,
where the odd sample is detected more often in the middle position of a set of
three, and the pattern effect, where panelists try to detect a pattern in presentation,
were also considered in the test design (Meilgaard et al., 1991). To control these
factors, the method of presentation included random sample code numbers and
random order of presentation and the Three-Alternate Forced Choice (3-AFC)
method for scoring was adopted (Amerine et al., 1965, Meilgaard et al., 1991).
While it would be expected that an increase in recognition as the
concentration increased, judge 3 was inconsistent in recognition response to
cilantro. Four judges scored were able to detect cilantro in the samples (50%
correct recognition above chance at or below). Judge 3 was unable to score a
threshold value. These data support a group recognition threshold of 0.29 (%
concentration MTVACed cilantro), as shown in Table 4, at the 0.5% concentration
level, based on the mean score for percent correct above chance (ASTM, 1995b).
It can be inferred from these results that adding cilantro to the control formulation
at 0.5% concentration will result in a product in which the flavor and odor of
cilantro will be recognized by a large percentage of the population.
Results of Phase 3
Consumer Preference Test
The results of the affective test for consumer preference appear in a
frequency chart in Figure 3. According to Table T8 Two-Sided Paired
Comparison Test for Difference: Critical Number (Minimum) of Correct Answers,
for a sample size n - 102, 61 participants would have had to have chosen the
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35
Consumer Preference Test Results
60
•
Control
Cilantro
Control vs Cilantro Formulations
Figure 3 - Affective test for consumer preference
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36
reformulated salsa with cilantro in order to show a significant preference at the 5%
confidence level. A Two-Sided Test is used to measure the responses that agree
with the direction of interest, namely, a preference for the formulation containing
cilantro (Meilgaard et al., 1991). This test, also conducted at the California State
University, Fresno, Farm Market, compared the control salsa to the reformulated
salsa with MTVACed cilantro. Of the 102 persons participating, 49% preferred the
control, while 52% preferred the formulation with cilantro.
To account for these results, at least two explanations can be offered.
During the tasting session, there were occasions where more than one person was
scoring the samples. This may introduce bias in the form of mutual suggestion,
where one participant is influenced by the other participant, through words, facial
expressions or gestures (Meilgaard et al., 1991). This can be controlled when
using a panel format, but is more difficult to control in a consumer setting.
Another factor that can influence response is the error of expectation, where the
participant is given information about the sample which may affect a response
based on preconception (Meilgaard et al., 1991). Based on some of the
commentary responses, some participants may have anticipated that one sample
was “hotter” than the other, when indeed the only difference between sample was
the addition of cilantro (see Appendix C). Subjects were only given instructions to
taste the two samples and indicate a preference. Because so many comments
mentioned a heat (pungency) difference between the two samples, the subjects
may have believed that this characteristic was the one under study.
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CONCLUSIONS
Phase 1-Control Formulation and Consumer
Acceptance Testing
Formulation
The high ratings resulting from the Consumer Acceptance rough screening
were well within limits of overall acceptance of the basic control formulation.
Beside overall acceptance of the formulation, an assumption was made that the
heat level was within an acceptable range. There are no recommended changes at
this time.
Recommendations for Further Study
One factor that may be a problem in the scale-up of this formulation is the
1" size of the tomato cut. While this size yields the desirable chunky appearance
and retains shape and texture during the salsa cooking time, it may be too large for
the pump to accommodate at the California State University, Fresno Food
Processing Laboratory. Finding an ingredient supplier that produces a product
with the same specifications other than size will be important.
The tomatoes used in the Consumer Acceptance Test were supplied by
Toma-Tek, Inc., Firebaugh, California. Toma-Tek, Inc. was unable to supply the
same aseptically processed tomatoes in the quantities needed for the other sensory
tests required for this study, as well as the scale up process. To complete the
sensory testing necessary, canned tomatoes packed by San Benito Foods and
supplied by S.E. Rykoff were used. The decision to change tomato suppliers at
this point was based on availability, cost, and quality. The variables introduced by
this change included the use o f can processing instead of aseptic packaging and an
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38
increase in cut from 3/4" to 1" in size. Visually, the tomatoes appeared chunkier;
however, the color and flavor were comparable. All other specifications, including
citric acid, sodium chloride, pH and yield, were maintained.
Using a pre-processed tomato product enables a standardized color and Brix
level of the tomato. If the formulation were changed to utilize fresh tomatoes,
these parameters would have to be standardized and controlled.
The white onions were purchased at a local supermarket and hand cut into
1/2" pieces. For scale-up processing, a standardized, mechanical process is
necessary. A cost analysis study comparing the financial and time-saving benefits
of a vertical or Buffalo chopper for manual processing, or a pre-cut onion product
should be conducted for larger scale production.
The jalapeno-pepper ingredient was selected to assure a standardized heat
level. Because this product is packaged in a brine, there may be a salty or metallic
aftertaste present. Future study should include investigation as to the
objectionable qualities that this aftertaste may present over time.
Consumer Acceptance Test
Phase 1 cumulative scores o f the Consumer Acceptance Test show that 93%
of the respondents rated the salsa with a score of 6, “like slightly,” or above, which
satisfied the criteria for acceptance of the salsa formulation. Statistical analysis
using a t-test showed that the sample mean value of 7.1 was significantly different
than the value of 6 required for acceptance. From this information, the researcher
inferred that the target market, defined as customers at the California State
University, Fresno, Farm Market liked the control salsa.
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39
Recommendation for Future Studies
The subjective nature of sensory testing makes reproducibility and
quantification difficult (Amerine et al., 1965; O’Mahony, 1986; Meilgaard et al.,
1991). Due to time or budget limitations, often too few subjects or trials are used
(Roessler, 1984). For the Consumer Acceptance Test, 30 subjects represents the
lower limits required for such a test. However, due to the favorable results of the
subsequent Consumer Preference tests, the researcher feels that the target
population has been adequately represented. A larger sample may be required in
future studies, perhaps to break out segments of the market that prefer a hotter or
milder formulation. For this study, the high level of acceptance justified
continuation to the next phase.
Phase 2-Analvtic-Discriminative Testing
Re-formulation of Control Salsa
The basic salsa formulation produced for the discriminative testing portion
of the study included the addition of MTVAC dehydrated cilantro. The cilantro
used was produced approximately 1 year prior and packaged in vacuum foil bags.
Upon opening, the dry cilantro began equilibrating immediately, and upon
rehydration in (room temperature) water had surprisingly bright green color,
regained flavor and aroma. The dry leaf portion was crushed by hand and the stem
portion cut. The handling of the dry cilantro stems was very awkward and
recommendations for future treatment should include chopping prior to drying.
Furthermore, to maintain the optimum dry state prior to addition to the salsa
formulation, cilantro should be packaged in batch weight so that an entire
packaged portion would be used at one time.
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40
Recommendation for Future Studies
Further comparison tests should be conducted to determine if there is a
detectable difference between the MTVACed cilantro, conventional air dried and
freeze dried when used in the salsa formulation. Parameters should include flavor,
aroma, color, texture, availability, cost and microbiological testing.
Additional sensory testing is necessary after scale-up to insure that the
standardized formulation maintains acceptable parameters. Shelf life studies are a
prime consideration to maintain safety and acceptability of product characteristics.
It is not known how the chemical composition of cilantro leaf oil, as well as the
capsaicin present in the jalapeno peppers, will degrade over time. These
components have the potential to develop off flavors or change into undesirable
irritants. Possible interactions should be studied. While a clear glass jar allows
the customer to view the product and lends marketability and safe packaging, it
also allows light to interact with the product which will cause damage over time
(Clary, 1996).
A critical control point is the addition of the dehydrated cilantro to the
tomato mixture. In the future, testing to determine yeast and mold counts which
conform to standardized limits will be important because the cilantro is added at
the end of the heating time.
Other testing should include determining soluble solids, water activity,
color measurement, and perhaps rheological properties. These tests could be used
to establish processing parameters needed for full processing (Resurreccion and
Shewfelt, 1985; Lopez et al., 1986; Rodrigo et al., 1990).
Some of the consumer comments suggested that smaller tomato chunks or a
thicker salsa is desirable. Smaller tomato dice or the addition of tomato paste may
be alternatives to the original formulation. Other comments suggested that the
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41
control sample (without cilantro) seemed hotter and the cilantro sample seemed
sweeter. Because both formulations were made on the same day, with the same
ingredient specifications, one explanation is there may be some interaction
between the cilantro and the capsaicin responsible for the heat sensation. The
cilantro may have a potentiating effect on the sweetness of the tomato or onion or
a masking effect on the jalapeno. These effects are certainly worth further
investigation and if found to be true, adjustments should be made to the
formulation.
Triangle Test
The Triangle Test was correctly used to screen potential subjects based on
their ability to discriminate a given difference (Meilgaard et al., 1991). Out o f the
14 panelists participating in the Triangle Test in Phase 2, only 7 met the criteria of
three out of three correct scores required to serve on the Recognition Threshold
panel. Out of that 7, only 5 would commit to continue to serve on the Recognition
Threshold panel, which allowed for the minimum amount of data needed to
establish a group threshold.
In the first group of 9 panelists, red lighting was selected to mask
differences among samples. In this study, it had the opposite effect, as reported by
2 panelists. According to the 2 panelists, the samples containing cilantro were
identifiable by dark specks, causing bias, yet only 5 of the 9 panelists scored three
out of three correct. This suggests that not all of the 9 panelists noticed the
difference caused by the lighting effects. It more importantly suggests that the
panelists who observed the difference due to lighting may have scored according
to visual clues rather than flavor or odor discrimination. This would allow for a
panelist to meet the objective of the Triangle Test (ability to distinguish MTVACed
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42
cilantro), but not possess the sensitivity to flavor and odor necessary to serve on a
threshold panel. In this sense, the Triangle Test failed to correctly screen panelists
for the sensory abilities needed for threshold testing.
The panelists that were unable to distinguish a difference between samples
were either unfamiliar with the characteristic flavor and odor of cilantro, in spite
of training, or perhaps not sensitive to it at the 0.5% concentration level used for
the Triangle Test. Consequently, more panelists were recruited to be screened so
that a large enough pool would be available for the Recognition Threshold test.
The sensory laboratory was not available to test the second group of 5
panelists for the Triangle Test. Testing occurred in a group rather than individual
setting under different lighting conditions. The group setting may have allowed
for bias as panelists could observe facial expressions, though no speaking was
allowed. The fluorescent lighting allowed for visual clues between samples, yet
only 2 of the 5 panelists detected a difference in three out of three sets. Again, this
suggests that the visual difference was not noticed by some panelists.
Recommendation for Future Studies
For future studies, more training of the panelists to insure complete
understanding of test objectives and scoring methods is recommended.
Assessment of the reproducibility of results for an individual judge may require
repeating the test over more than one day. This may be necessary to calibrate a
panel within a narrower confidence range.
To account for fatigue encountered due to the trigeminal response to the
salsa, testing should be conducted over more than one day, under identical test
conditions. If possible within budgetary and time constraints, a larger number of
subjects should be tested so that a larger pool could be obtained.
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43
Because the green lighting was later found to be effective in masking the
MIVACed cilantro added to the control formulation, it is recommended that this be
used for any analytical-discriminative testing.
Recognition Threshold Test
Out of the 5 panelists who met the criteria for panel selection through
screening, judge 3 scored inconsistently and was unable to detect the MIVACed
cilantro in the salsa sample even at the highest concentration. No threshold was
established for this judge. Higher concentrations should be introduced to this
judge to establish an individual threshold; however, time constraints and
availability of judge 3 prevented further testing during this trial. Further, this
judge was in the first group of panelist screen using the red lighting in the sensory
booth. It is the opinion of this researcher that this judge correctly identified
MTVAC cilantro visually, rather than by flavor and odor, during the Triangle Test.
If this is the case, this judge did not meet screening criteria as required by the
Triangle Test objectives. This could be verified through repeating the Triangle test
screening for this judge under green lighting conditions.
Recommendation for Future Studies
If this test were to be repeated, several factors should be investigated. One,
determine if the screening procedure is adequate for determining that a subject can
correctly identify a substance. Two, if time and budget permit, recruit a larger
panel for threshold testing to better represent the population (Morrison, 1982).
According to Brown, a panel of 25 or more is necessary to offset the variation
between individual subjects (Brown et al., 1978). Three, because the effects o f
fatigue and trigeminal response are factors due to the pungency o f this product,
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44
perhaps a sample without jalapeno peppers would be an alternative to assist the
subjects in correctly identifying the stimulus of interest, cilantro.
Phase 3-Affective Consumer Testing
Consumer Preference Testing
While it was concluded that the Alternative Hypothesis must be accepted
for this study, Meilgaard suggests that a “failure to prove significant difference
does not mean that proof o f similarity has been obtained”(Meilgaard et al., 1991).
Results of the Consumer Preference Test showed only a slightly greater preference
for the salsa with cilantro; however, there was no statistical difference in
preference for that sample. These results may be explained by some of the
psychological factors influencing sensory tests such as the error of expectation and
mutual suggestion. The test location has several effects on the results obtained
(Meilgaard et al., 1991). While less control can be obtained at a central location
than a laboratory, the respondents are truly representative of the targeted
population which lends validity to the results (Meilgaard et al., 1991).
Finally, although no statistical difference was determined by the Consumer
Preference testing, both salsa formulations were very well received. Based on
these findings, it would be worth investigating the feasibility o f producing both
formulations for sale at the California State University, Fresno Farm Market.
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REFERENCES
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REFERENCES
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for the production of dried grapes. Ph.D Dissertation, Michigan State University
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Ferris, D.A. 1996. California State University, Fresno revised tomato salsa project
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Ferris, D A. 1995, 1997. California State University, Fresno farm market survey.
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Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
APPENDICES
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APPENDIX A
CONSENT WAIVER FORM
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CONSENT FORM
CALIFORNIA STATE UNIVERSITY, FRESNO
DEPARTMENT OF ENOLOGY, FOOD SCIENCE AND NUTRITION
CONSENT TO PARTICIPATE IN THE FOLLOWING STUDY
I, (please print)___________________________________________ hereby willingly
and voluntarily consent to participate as a subject in the research project entitled
“Development of “Fresh Flavor” in a Mildly Processed Tomato-Based Salsa”
conducted by Dennis Ferris, Ph.D. and Karla Carlsen at the California State University,
Fresno. The California State University, Fresno Committee on the Protection of Human
Subjects has reviewed and approved the procedures for this research, which is determined
to be of minimal risk to participants.
I understand the procedures for participating in the project are as follows:
I will taste a sample of tomato-based salsa (recipe appears below) and record my
results on an accompanying score sheet. To the best of my knowledge, I have no known
allergies to any of the ingredients listed in the recipe.
I understand that the results of the study will be kept on file at California State University,
Fresno for five years in the office of Dr. Dennis Ferris and will be kept confidential.
I understand that my participation in this study does not in any way affect my relationship
with California State University, Fresno.
I understand that I may quit or decline to participate in the study at any time.
The salsa contains the following ingredients:
Tomatoes
jalapeno chili peppers
White onion
Dehydrated cilantro
I fiilly understand the terms of my consent and agree to participate in the study.
Signed
Date
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APPENDIX B
TEST SCORE SHEETS
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Consumer Acceptance Test
Name______________________
Date___
Type of Sample: Tomato Salsa
•
Please rinse your mouth before starting.
Evaluate the product in front of you by looking at it and tasting it.
Considering ALL characteristics (APPEARANCE, FLAVOR, and PUNGENCY)
indicate your overall opinion by checking one box [ S ].
__
1
Dislike
Extremely
LJ
Dislike
Very Much
u
□
□
a
i
__
i
!
!
Dislike
Dislike
Neither
Like
Like
Like
Moderately
Slightly
like nor
Slightly
Moderately
Very Much
Like
dislike
(nl/nd)
Comments: Please indicate WHAT in particular you liked or disliked about this
product. (USE WORDS NOT SENTENCES).
LIKED
DISLIKED
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55
Triangle Test
Taster N o._______
Name_____________________________
Date
Type o f Sample: Tomato Salsa
Instructions:
•
Rinse with water before starting.
•
Taste the samples on the tray from left to right.
Two samples are identical; one is different. Determine which is the odd/different
sample. Circle the code of the odd sample. If no difference is apparent, you must
guess. After completing one set, rinse palate with cracker and water before starting
on the next set.
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56
Threshold Test
Name___________________________ Date___
Type of Sample:
Tomato Salsa
Instructions:
•
Rinse with water before starting.
•
Please taste the samples on the tray from left to right.
Two samples are identical; one is different. Determine which is the odd/different sample.
Circle the code of the odd sample. If no difference is apparent, you must guess. After
completing one set, rinse palate with cracker and water before starting on the next set.
Circle the odd sample
Set 1
____
_____
_____
Set 2
____
_____
_____
Set 3
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57
Consumer Preference Test
Name______________________ Date
Type of Sample: Tomato Salsa
Please taste both products.
Which sample do you prefer?
Please circle your choice.
451
862
Why do you prefer this sample?
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APPENDIX C
RAW DATA INCLUDING OPEN-ENDED COMMENT
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59
Consumer Preference Test Comments: 451 Preferred
451 = Control Formulation without Cilantro
right degree of heat
seemed fresher, more interesting mix of flavors
tastier, warm, not too hot
862 needs smaller (cut) veggies
needs more spices ('Mexican') more chile
not as hot as the other
tastes better
fresh tasting
it tastes more fresh; 862 tasted roasted and a little salty
tasted more spicy
better flavor
texture and taste, more tomato taste
good bite, both are good, I'd buy both
862 has too much cilantro, 451 is hotter,more vinegar, tangy
not as spicy, good overall flavor
fresh tasting
tastes zestier
seems to be less spicy, less onion (in sample)
less spicy, richer, more vegetable-like
because it's hot
I like the hot stuff!
taste is lighter, more tangy, better flavor, but not as chunky
862 tasted sweeter, 451 is not too hot, nor was it bland, good blend
spicy, appealing, liked both, but 451 a bit better
sweeter, crunchier, fresher
flavor is slightly different
better taste
because it's spicier
not quite as hot as the second (862) one
better smell and taste, looks more fresh (color)
sharper taste, onions, crisper, heat level medium to hot, brings out flavor
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60
Consumer Preference Test Comments: 832 Preferred
862 = Control Formulation without Cilantro
right degree of heat
seemed fresher, more interesting mix of flavors
tastier, warm, not too hot
862 needs smaller (cut) veggies
needs more spices ('Mexican') more chile
not as hot as the other
tastes better
fresh tasting
it tastes more fresh; 862 tasted roasted and a little salty
tasted more spicy
better flavor
texture and taste, more tomato taste
good bite, both are good, I'd buy both
862 has too much cilantro, 451 is hotter,more vinegar, tangy
not as spicy, good overall flavor
fresh tasting
tastes zestier
seems to be less spicy, less onion (in sample)
less spicy, richer, more vegetable-like
because it's hot
I like the hot stuff!
taste is lighter, more tangy, better flavor, but not as chunky
862 tasted sweeter, 451 is not too hot, nor was it bland, good blend
spicy, appealing, liked both, but 451 a bit better
sweeter, crunchier, fresher
flavor is slightly different
better taste
because it's spicier
not quite as hot as the second (862) one
better smell and taste, looks more fresh (color)
sharper taste, onions, crisper, heat level medium to hot, brings out flavor
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