close

Вход

Забыли?

вход по аккаунту

?

j.foodhyd.2018.08.034

код для вставкиСкачать
Accepted Manuscript
Characterization and functional evaluation of oat protein isolate-Pleurotus ostreatus
β-glucan conjugates formed via Maillard reaction
Lei Zhong, Ning Ma, Yiliang Wu, Liyan Zhao, Gaoxing Ma, Fei Pei, Qiuhui Hu
PII:
S0268-005X(18)31261-X
DOI:
10.1016/j.foodhyd.2018.08.034
Reference:
FOOHYD 4615
To appear in:
Food Hydrocolloids
Received Date: 10 July 2018
Revised Date:
16 August 2018
Accepted Date: 19 August 2018
Please cite this article as: Zhong, L., Ma, N., Wu, Y., Zhao, L., Ma, G., Pei, F., Hu, Q., Characterization
and functional evaluation of oat protein isolate-Pleurotus ostreatus β-glucan conjugates formed via
Maillard reaction, Food Hydrocolloids (2018), doi: 10.1016/j.foodhyd.2018.08.034.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please
note that during the production process errors may be discovered which could affect the content, and all
legal disclaimers that apply to the journal pertain.
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
ACCEPTED MANUSCRIPT
Characterization and functional evaluation of oat protein isolate-Pleurotus
2
ostreatus β-glucan conjugates formed via Maillard reaction
3
Lei Zhonga, Ning Mab, Yiliang Wub, Liyan Zhaoa, Gaoxing Maa, Fei Peib, Qiuhui
4
Hua*
5
a
6
Nanjing, 210095, China*.
7
qiuhuihu@njau.edu.cn*
8
zhonglei1116@163.com
9
zhlychen@njau.edu.cn
RI
PT
1
M
AN
U
SC
College of Food Science and Technology, Nanjing Agricultural University,
10
magaoxing90@163.com
11
b
12
Economics, Nanjing, 210023, China.
13
mning1978@sina.com
14
512670135@qq.com
15
feipei87@163.com
16
*Corresponding author
19
20
21
TE
D
EP
18
AC
C
17
College of Food Science and Engineering, Nanjing University of Finance and
22
23
24
25
1
ACCEPTED MANUSCRIPT
26
Abstract
28
Oat protein isolate is nutritious but with poor processing functionality. Pleurotus
29
ostreatus β-glucan with good processing functionality can be conjugated with oat
30
protein isolate via Maillard reaction, leading to an improved utilization of protein in
31
food industry. Therefore, we produced conjugate with oat protein isolate and
32
Pleurotus ostreatus β-glucan via Maillard reaction under controlled dry-heating
33
conditions. The formation of conjugates with high molecular weight was identified by
34
a new band of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The
35
analysis of amino acid composition showed that cysteine and lysine were the
36
dominant Maillard reaction sites of oat protein isolate and Pleurotus ostreatus
37
β-glucan. Changes in spatial configuration of conjugates caused reduction in their
38
surface hydrophobicity of proteins and intrinsic fluorescence intensity. Fourier
39
transform infrared spectroscopy analysis of conjugates suggested that Maillard
40
reaction could cause the C=O stretching vibration, as well as the C-H and N-H
41
deformation vibration. Circular dichroism analysis indicated that the secondary
42
structure of conjugates was altered by decreasing the contents of α-helix and β-sheet
43
and increasing the contents of β-turn and random coil. The surface structure of
44
conjugates was loose and porous using scanning electron microscope. Furthermore,
45
Maillard reaction could improve the solubility, emulsifying property and thermal
46
stability of oat protein isolate. Our findings confirm the potential of protein-
47
carbohydrate conjugate formed by Maillard reaction, to improve the application of
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
27
2
ACCEPTED MANUSCRIPT
48
instable but valuable proteins in food industry.
49
Keywords: Oat protein isolate, Processing functionality, Pleurotus ostreatus β-glucan,
50
Conjugate, Maillard reaction.
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
51
3
ACCEPTED MANUSCRIPT
1. Introduction
53
Oats with better nutrition are superior sources of low-cost dietary proteins (ranging
54
from12 to 20%, w/w) among cereals (Mohamed et al., 2009; Grigg, 1995). Oat
55
protein isolate has abundant essential amino acids such as lysine (Klose & Arendt,
56
2012). It can be used as a promising food ingredient for human consumption (Zhang
57
et al., 2015). However, the poor functional properties of oat protein isolate, such as
58
solubility, emulsibility, foamability and gel property, can restrict its application in
59
food products (Ma, 1985). Therefore, it is necessary to improve the functionality of
60
oat protein isolate for an effective utilization by some modification techniques.
61
Physical, chemical and enzymatic modifications of oat protein isolates are generally
62
used to improve their functional properties for wider application (Zhao et al., 2017).
63
Most food proteins modified by chemical treatment have potential health risks (Guo
64
& Xiong, 2013). Physical treatment is mostly destructive by extrusion or ultrasound
65
(Tian, Chen, & Small, 2011). Enzymatic treatment is mostly time-consuming and
66
expensive, as well as off-flavor caused by protein hydrolysates (Galazka, Dickinson,
67
& Ledward, 2000). In contrast, under controlled conditions, Maillard reaction is easy
68
to perform without the addition of chemical reagents and the generation of harmful
69
secondary compounds (Oliver, Melton, & Stanley, 2006; Zhuo et al., 2013). It can
70
combine the functionalities of protein and polysaccharide to prepare a novel protein–
71
polysaccharide conjugate for more industrial applications (Akhtar & Ding, 2017). In
72
food processing, such conjugates with stable structure can serve as important food
73
ingredients, leading to improved techno-functional properties of food proteins and
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
52
4
ACCEPTED MANUSCRIPT
changes in the texture, taste, flavor and colour of food products (de Oliveira et al.,
75
2016). The quality of final food products that can be accepted by consumers depended
76
on functionalities of their proteins. Moreover, conjugates are also used as supporters
77
of active ingredients to enhance the bioavailability of ingredients in gastrointestinal
78
tract. Thus, food industry has growing interest in converting proteins into excellent
79
functional conjugates via Maillard reaction.
80
Pleurotus ostreatus is an important edible mushroom for its active compounds, such
81
as polysaccharides, phenols and lactones (Julita & Marek, 2007). P. ostreatus is rich
82
in β-glucan containing a linear glucose polymer formed by β (1-3) and β (1-6)
83
linkages and P. ostreatus β-glucan can be linked to proteins by some modification
84
techniques (De Silva et al., 2013). P. ostreatus β-glucan has been approved for a novel
85
food ingredient by the European Food Safety Authority due to its excellent
86
functionalities, such as water-holding capacity, emulsibility and swelling power
87
(Singh, 2015; Thammakiti et al., 2004). During the Maillard reaction, P. ostreatus
88
β-glucan can prevent the polymerization of protein and the formation of advanced
89
glycation end products due to its steric hindrance, which could be conducive to
90
enhance the covalent binding of P. ostreatus β-glucan to protein (de Oliveira et al.,
91
2016). Taken together, P. ostreatus β-glucan can be a good candidate for improving
92
the functionalities of oat protein isolate via Maillard reaction.
93
Under controlled conditions of Maillard reaction, the structural properties of food
94
protein can be considerably altered and these changes are helpful to enhance the
95
functional properties of protein, such as solubility, emulsibility and thermal stability
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
74
5
ACCEPTED MANUSCRIPT
(Liu, Ru, & Ding, 2012; Usui et al., 2017; Sheng et al., 2017; Jimenez-Castano,
97
Villamiel, & Lopez-Fandino, 2007; Kim & Shin, 2015). For example, Qu et al. (2018)
98
found that the improved solubility and emulsifying property of rapeseed protein
99
isolate-dextran conjugates are related to their loose surface structure and more
RI
PT
96
hydrophilic groups. Pirestani et al. (2018) showed that canola protein isolate
101
(CPI)-gum arabic conjugates with extended secondary structure have higher thermal
102
stability than CPI alone via Maillard reaction. Mu et al. (2011) suggested that soy
103
protein isolate (SPI)-acacia gum conjugates have higher emulsion stability than SPI
104
alone and SPI-acacia gum mixture because acacia gum in the conjugates can provide
105
a steric hindrance layer around the oil droplets. Therefore, to understand these
106
structural properties of conjugates better can allow their application in the food
107
processing as components to enhance functionalities of final products.
108
In the study, we prepared conjugates between oat protein isolate and P. ostreatus
109
β-glucan under optimized dry-heating conditions. The structural and functional
110
properties of conjugates were further studied to compare with oat protein isolate,
111
heated oat protein isolate and the mixture of oat protein isolate-P. ostreatus β-glucan.
AC
C
EP
TE
D
M
AN
U
SC
100
6
ACCEPTED MANUSCRIPT
2. Materials and methods
113
2.1. Materials
114
Oats were purchased from the local supermarket in Nanjing, Jiangsu, China.
115
Pleurotus ostreatus was purchased from Zhiqingtang Bio-Technique Co., Ltd.
116
(Yancheng, Jiangsu Province, China). Mixed amino acids standard solution and
117
potassium bromide (spectral purity) were purchased from Sigma-Aldrich (Shanghai,
118
China). All other analytical reagents were purchased from Sinopharm Chemical
119
Regent Co., Ltd (Shanghai, China).
M
AN
U
120
SC
RI
PT
112
2.2. Extraction of oat protein isolate
122
Oat protein isolate was extracted as reported earlier with some modifications (Zhang
123
et al., 2015). Fat-free oat powders were dissolved in distilled water (10%, w/v) and
124
pH was adjusted to 9.5 with 1 mol/L NaOH before centrifugation at 3500 × g for 15
125
min. The obtained supernatant was kept at pH 4.5 and then centrifuged under the
126
same condition. Precipitates were washed three times with distilled water and then
127
freeze-dried. The purity of protein in oat protein isolate was about 90.15% determined
128
by the Kjeldahl method (Jung, et al., 2003).
EP
AC
C
129
TE
D
121
130
2.3. Extraction of P. ostreatus β-glucan
131
To remove soluble impurities, the powder of P. ostreatus was washed with 80%
132
ethanol (v/v) for 8 h and extracted with boiling water for further preparation as
133
reported earlier with some modifications (Szwengiel & Stachowiak, 2016). Before
7
ACCEPTED MANUSCRIPT
centrifugation at 3500 × g for 20 min, the hot aqueous extractions were concentrated
135
to a reduced volume by rotary evaporator, followed by precipitation using excess 95%
136
ethanol. The obtained precipitates were dialyzed for 48 h (12-14 kDa) and then
137
freeze-dried. After re-dissolving into ultrapure water, the soluble fractions of β-glucan
138
were purified for further study (Khan et al., 2015). The purity of P. ostreatus β-glucan
139
was 90.36% using yeast and mushroom β-glucan enzymatic assay kit (Megazyme
140
International Ireland Ltd., Wicklow, Ireland).
142
2.4. Preparation of oat protein isolate-P. ostreatus β-glucan conjugates
143
Oat protein isolate and P. ostreatus β-glucan in various proportion of 1:1, 1:2, 1:3, 1:4
144
and 1:5 (w/w) were dissolved in 0.05 mol/L sodium phosphate buffer (pH 7.0)
145
containing 0.02% sodium azide. After completely hydration at 4 °C overnight, the
146
mixture was adjusted to desired pH of 4, 6, 8, 10 and 12 using 0.1 mol/L NaOH or
147
HCI and then freeze-dried. The obtained lyophilized powders were incubated at 60 °C,
148
75% relative humidity for 1, 3, 5, 7 and 9 days. Oat protein isolate, heated oat protein
149
isolate and the mixture of oat protein isolate-P. ostreatus β-glucan were treated as
150
comparison samples in the same way.
TE
D
EP
AC
C
151
M
AN
U
141
SC
RI
PT
134
152
2.5. Evaluation of the extent of Maillard reaction
153
The degree of graft (DG) and browning index were considered as major indicators to
154
evaluate the extent of Maillard reaction. DG was measured by spectrophotometry as
155
reported earlier with some modifications (Snyder & Sobocinski, 1975). Diluted
8
ACCEPTED MANUSCRIPT
sample was mixed with 1.5 mL trinitrobenzene sulfonic acid (0.1 mg/L) and 3 mL
157
sodium phosphate buffer (0.2 mol/L, pH 8.0) containing 1 mg/mL sodium dodecyl
158
sulfate, followed by dark-incubation at 55 °C. After an hour, the reaction was
159
terminated by adding 1.2 mL Na2SO3 (0.1 mol/L). The absorbance of the sample was
160
measured at 420 nm after cooling at room temperature for 15 min. A control with
161
distilled water instead of the sample was treated under the same condition. The
162
content of free amino groups was calculated from the standard curve of L-leucine at
163
420 nm and the formula is given below:
C1 -Ct
C1
M
AN
U
DG =
SC
RI
PT
156
Where C1 is the content of free amino groups of oat protein isolate and Ct is the
165
content of free amino groups of conjugates after reacting for t (min).
166
The browning index was measured at 420 nm as reported earlier with some
167
modifications (Lertittikul, Benjakul, & Tanaka, 2007). Before the measurement, the
168
conjugate was diluted to the concentration of 5 mg/mL with distilled water.
EP
169
TE
D
164
2.6. Confirmation of oat protein isolate-P. ostreatus β-glucan conjugates
171
SDS-PAGE was performed using 5% stacking gel and 12% separating gel (Zhang et
172
al., 2015). After the sample solution and standard protein (11-180 kDa) were loaded
173
into corresponding well, migration was conducted at 90 V and then at constant
174
voltage of 120 V. Gels were dyed by Coomassie blue R250 and then faded with 10%
175
acetic acid and 10% ethanol.
AC
C
170
176
9
ACCEPTED MANUSCRIPT
2.7. Characterization of oat protein isolate-P. ostreatus β-glucan conjugates
178
2.7.1. Fourier transform infrared spectroscopy (FT-IR) analysis
179
Sample (1 mg) was mixed with 200 mg KBr and measured at the wavelength of
180
4000-400 cm-1 using FT-IR as reported earlier with some modifications (Mohsin et al.,
181
2018) (Bruker tensor 27, Bruker Corporation, Karlsruhe, Germany).
182
RI
PT
177
2.7.2. Determination of intrinsic fluorescence emission
184
Samples containing 0.1 mg protein/mL were dissolved in 0.05 mol/L phosphate buffer
185
(pH 7.0). The emission wavelength ranged from 300 to 420 nm at the excitation
186
wavelength of 280 nm with a scanning speed of 1200 nm/min (Sheng et al., 2017).
M
AN
U
SC
183
187
2.7.3. Determination of the surface hydrophobicity of proteins
189
The fluorescence intensity of samples was determined at the excitation wavelength of
190
370 nm with the emission wavelength ranging from 300 to 650 nm as reported earlier
191
with some modifications (Kato et al., 1990). Protein solutions (4 mL) in 0.04 mg/mL
192
increments from 0 to 0.16 mg/mL were mixed with 20 µL 8.0 mmol/L
193
1-anilinonaphthalene-8-sulfonic acid. The function could be established between the
194
concentration of protein and its fluorescence intensity. The slope of this function
195
indicated the surface hydrophobicity of proteins.
AC
C
EP
TE
D
188
196
197
2.7.4. Scanning electron microscopy (SEM) analysis
198
The sample was placed on the conductive adhesive and covered with gold of 10 nm.
10
ACCEPTED MANUSCRIPT
199
The surface structure of the sample was observed in different magnifications (×300, ×
200
600, ×1200, ×2000) and in secondary electron mode at 15.0 kV using a scanning
201
electron microscope (TM-3000, Hitachi Corporation, Tokyo, Japan) (Qu et al., 2018).
RI
PT
202
2.7.5 Circular dichroism (CD) analysis
204
As reported earlier with some modifications, the secondary structure of protein
205
samples with different treatment was determined using CD spectrometer (a model
206
J-1500, JASCO Corporation, Tokyo, Japan) (Pirestani et al., 2017). The sample
207
containing 0.2 mg/mL protein was dissolved in 0.05 mol/L phosphate buffer (pH 7.0)
208
and then scanned between 190 and 260 nm with the band-width of 1 nm. The contents
209
of secondary structures including α-helix, β-sheet, β-turn and random coil, were
210
determined using the JASCO software.
TE
D
M
AN
U
SC
203
211
2.7.6. Determination of amino acid composition
213
All the samples were treated with 6 mol/L HCl at 110 °C for 12 h and the amino acid
214
composition was determined as reported earlier with some modifications (Fang et al.,
215
2017). The acidolysis products were analyzed by automatic amino-acid analyzer
216
(Hitachi L 8800, Hitachi Ltd., Tokyo, Japan).
AC
C
217
EP
212
218
2.8. Functional properties of conjugates
219
2.8.1. Solubility
220
The sample was dissolved in the solution (1 mg/mL) with different pH at 3 to 11 and
11
ACCEPTED MANUSCRIPT
then stirred at room temperature for 2 h. After centrifugation at 4000 × g for 20 min,
222
the content of protein in the supernatants was determined according to the earlier
223
report with some modifications (Qu et al., 2018). The solubility was showed as the
224
content of protein in supernatants per 100 g of protein.
225
RI
PT
221
2.8.2. Emulsifying activity and emulsion stability
227
The emulsifying activity and emulsion stability were measured by the turbidimetric
228
method as reported earlier with some modifications (Wang, Zhao, & Jiang, 2007). To
229
prepare the emulsion, 5 mL soybean oil was mixed with 20 mL 0.1% (w/v) sample
230
solution with different pH (3 to 11) by mechanical homogenizer (Ultra-Turrax T25,
231
IKA, Staufen, Germany) at 12000 rpm for 3 min separately. The emulsion (100 µL)
232
was diluted with 9.9 mL sodium dodecyl sulfate solution (0.1%, w/v). The
233
emulsifying activity and emulsion stability were calculated using the following
234
formula.
TE
D
M
AN
U
SC
226
235
2×2.303×A0 ×D
EP
Emulsifying activity ( m2 ⁄g )=
AC
C
Emulsion stability (min)=
C×V×W×104
A0 ×15
A0 -A15
236
Where A0 and A15 are the absorbance of emulsion at 500 nm after 0 min and 15 min.
237
D is dilution factor (D=100), C is the concentration of protein, V is the ratio of oil in
238
the emulsion (V=0.2). W is the width of optical path (W=0.01 m).
239
240
2.8.3. Differential scanning calorimetry analysis in thermal property
12
ACCEPTED MANUSCRIPT
Protein samples were accurately injected into aluminum pans and subjected to
242
differential scanning calorimetry analysis (25 to 120 °C) with the heating rate of 10
243
°C/min (PE-8000, Perkin Elmer Ltd., Waltham, MA) (Kamboj et al., 2015).
244
Denaturation temperature (Td) and enthalpy changes of denaturation (∆H) were
245
calculated by Pyris software (Version 9.0, Perkin Elmer Ltd., Waltham, MA).
RI
PT
241
246
2.9. Statistical analysis
248
Data are represented as means ± standard deviation for three replications using SPSS
249
software (Vision 22.0, SPSS Inc., Chicago, Illinois). Differences were considered to
250
be significant at p < 0.05 according to Duncan’s Multiple Range Test.
M
AN
U
251
SC
247
3. Results and discussions
253
3.1. Selection of Maillard reaction conditions
254
As shown in Fig. 1, the degree of graft and browning index of conjugates increased
255
first and then decreased as the increase in proportion of oat protein isolate and P.
256
ostreatus β-glucan, reaction time and pH. Under controlled conditions, the reaction
257
could form covalent bonds between protein and polysaccharide, meanwhile inhibiting
258
the formation of melanoidins at later reaction stage and achieving the desired
259
conjugate with excellent functionality finally (Hofmann, 1998; Hong et al., 2010).
260
Native oat protein isolates could react with few polysaccharides, while denatured oat
261
protein isolates could bind to more carbonyl groups of P. ostreatus β-glucan at the
262
proportion of 1:2 due to more exposure of lysine residues (de Oliveira et al., 2016).
AC
C
EP
TE
D
252
13
ACCEPTED MANUSCRIPT
However, the increased proportion of oat protein isolate and P. ostreatus β-glucan
264
from 1:3 to 1:5 could not cause an improved production of such conjugates because
265
the steric hindrance of polysaccharides limited the extent of Maillard reaction (Oliver,
266
Melton, & Stanley, 2006). As reaction time passed (from 1 to 5 days), the ε-amino
267
groups of lysine residues are gradually exposed on the surface of oat protein isolate,
268
leading to the formation of more conjugates. However, as the extension of reaction
269
time, the cross-link formed between oat protein isolate molecules could decrease the
270
content of their available free amino groups, leading to lower conjugation (Martins,
271
Jongen, & Majs, 2000). Therefore, the reaction time of 5 days was chosen as a
272
standard condition for the formation of conjugates. In addition, the formation of final
273
conjugates also depended on acid-base environment. As the increase of pH (from 4 to
274
8), the protonated ε-amino groups of lysine residues converted to active electrophile,
275
which is helpful to form more conjugates (Kato, 2002). However, higher pH (pH > 8)
276
could impel the conversion of Amadori compounds into advanced glycation end
277
products, leading to the poor functionality of oat protein isolate (Lertittikul, Benjakul,
278
& Tanaka, 2007).
279
Taken together, the desired conjugate was formed at pH 8.0, at the proportion of 1:2
280
(oat protein isolate to P. ostreatus β-glucan) and for 5 days (60 °C and 75% relative
281
humidity). Under this optimum condition, the degree of graft and browning index of
282
conjugates reached 26.27% and 0.45, respectively.
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
263
283
284
3.2. Evidence for the formation of oat protein isolate-P. ostreatus β-glucan conjugates
14
ACCEPTED MANUSCRIPT
As shown in Fig. 2, 2 feature bands of lane A (25-35 kDa and 48-63 kDa) were related
286
to globulins. They were major fraction of oat protein isolate (Mirmoghtadaie, Kadivar,
287
& Shahedi, 2009). A new band of lane B appeared at about 135 kDa when oat protein
288
isolate was heated under the optimum condition. The cross-link formed by heat
289
treatment was between oat protein isolate molecules, leading to the formation of
290
dimmers (Chakraborti et al., 2010; Yadav et al., 2010). This phenomenon agreed with
291
the result in 3.1. The obvious band of the mixture (lane C) was similar to that of the
292
oat protein isolate (lane A) and this result was consistent with the previous study (Kim
293
& Shin, 2015). A characteristic band of lane D was visible on the top of the stacking
294
gel, indicating the covalent bond had formed between the amino groups of oat protein
295
isolate and carbonyl groups of P. ostreatus β-glucan. This phenomenon was consistent
296
with previous reports and the increased molecular weight of protein was considered as
297
a key indicator for the formation of conjugates after Maillard reaction
298
(Ledesma-Osuna et al., 2010; Xu et al., 2010; Sheng et al., 2017). Compared with
299
heated oat protein isolate (lane B), the obvious band of conjugate (lane D) at about
300
135 kDa did not disappear completely because part of oat protein isolates could
301
participate in the formation of cross-link. To some extent, it suggested that P.
302
ostreatus β-glucan could suppress the dimerization of oat protein isolate via Maillard
303
reaction (Bi et al., 2017; Loveday, 2016).
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
285
304
305
3.3. Characterization of oat protein isolate-P. ostreatus β-glucan conjugates
306
Protein-polysaccharide conjugate is a complex polymer and various conjugates can be
15
ACCEPTED MANUSCRIPT
produced under different conditions (Maria et al., 2013). Recent reports focused on
308
studying the characterization of conjugates according to changes in the structure of
309
protein, including functional groups, micro-environment of tryptophan, hydrophobic
310
interaction, amino acid composition, secondary structure and microstructure (Alvarez
311
et al., 2012; Bund et al., 2012; Ledesma-Osuna et al., 2010).
312
RI
PT
307
3.3.1. FT-IR analysis in functional groups of conjugates
314
As shown in Fig. 3, in the region between 3500 and 3000 cm-1, O-H stretching
315
vibration caused the appearance of absorption peaks of 4 samples. The absorption
316
peaks of oat protein isolate and heated oat protein isolate in the region of 1360-1310
317
cm-1 resulted from C-N stretching vibration. The C-O stretching vibration of 4
318
samples caused the appearance of absorption peaks at 1200-1000 cm-1. The absorption
319
peaks between 1470 and 1430 cm-1 corresponded to the CH3 deformation vibration of
320
the oat protein isolate and mixture. FT-IR could be used for an effective analysis of
321
protein-polysaccharide conjugate (Van Der Ven, et al., 2002). When the modifications
322
of functional groups occurred at a molecular level via Maillard reaction, FT-IR spectra
323
displayed new peaks and changes of the position or intensity (Deygen & Kudryashova,
324
2016). After covalent binding with the carbonyl group of P. ostreatus β-glucan, oat
325
protein isolate displayed a new absorption peak at 2880 cm-1 caused by C-H
326
stretching vibration. This characteristic peak also appeared in Maillard reaction
327
pattern of glucose and alanine (Mohsin et al., 2018). The characteristic absorption
328
peaks of conjugates at 1707 cm-1 and 1595 cm-1 were attributed to the C=O stretching
AC
C
EP
TE
D
M
AN
U
SC
313
16
ACCEPTED MANUSCRIPT
vibration and N-H deformation vibration. In the region between 985 and 995 cm-1, the
330
absorption peak of conjugate at 992 cm-1 resulted from the C-H deformation vibration
331
of oat protein isolate side chains (Gu et al., 2010). The absorption peak at 765 cm-1 in
332
the mixture was considered as the characteristic of glucose residues (Zhu, Xue, &
333
Zhang, 2016). Oat protein isolate, heated oat protein isolate and the mixture have
334
broad peaks at 812 cm-1, resulting from the products of protein degradation (Synytsya
335
et al., 2009). Otherwise, the similar phenomena observed above were proven in many
336
other studies (Chang & Tanaka, 2002; Du et al., 2013; Gu et al., 2010; Su et al.,
337
2010).
M
AN
U
SC
RI
PT
329
338
3.3.2. Intrinsic fluorescence analysis of the micro-environment of tryptophan in
340
conjugates
341
As shown in Fig. 4A, compared with oat protein isolate, the fluorescence intensity of
342
heated oat protein isolate increased, while conjugate exhibited the lowest intensity
343
among groups. Fluorescence emission of tryptophan was extremely sensitive to
344
changes of the surrounding environment. It could be described as a great indicator for
345
monitoring the conformational transition of protein (Broersen et al., 2004). The
346
conformation of oat protein isolate turned from tight to extensional state after heat
347
treatment, causing that its internal tryptophan residues were gradually exposed to the
348
surface (Laura, Villamiel, & Rosina, 2007; Renard et al., 1998). We speculated that
349
heated oat protein isolate existed as a molten-globule state with a packed hydrophobic
350
core, causing its increased surface hydrophobicity (Kim & Shin, 2015). Compared
AC
C
EP
TE
D
339
17
ACCEPTED MANUSCRIPT
with the oat protein isolate, a slight increase exhibited in the fluorescence intensity of
352
mixture, indicating that hydrophobic environment could be more inclined to surround
353
the tryptophan residues of mixture than that of oat protein isolate (Choi et al., 2005).
354
After covalent binding with P. ostreatus β-glucan, the fluorescence intensity of oat
355
protein isolate decreased but no shift exhibited in such conjugate compared with
356
heated oat protein isolate. The long-chain P. ostreatus β-glucan had an effect of
357
steric-hindrance and could block the fluorescent signal of tryptophan residues from
358
oat protein isolate (Hattori et al., 1997; Jimenez et al., 2005). These results were
359
consistent with the previous studies (Ledesma-Osuna et al., 2010; Sheng et al., 2017).
M
AN
U
SC
RI
PT
351
360
3.3.3. Surface hydrophobicity of proteins in conjugates
362
As shown in Fig. 4B, in comparison with oat protein isolate, the surface
363
hydrophobicity of heated oat protein isolates increased to 2361 and the conjugate
364
decreased to 1207 significantly (p < 0.05). However, no significant difference
365
exhibited in surface hydrophobicity of proteins between the oat protein isolate and
366
mixture (p > 0.05). The surface hydrophobicity indicated the amount of hydrophobic
367
groups exposed on the surface of a protein molecule was used to evaluate the
368
conformational changes of protein. In the native state, most nonpolar amino acids
369
were served as hydrophobic core and polar amino acids often distributed on the
370
surface of protein (Sheng et al., 2017). The heat treatment increased the exposure of
371
native hydrophobic peptides, leading to an increased surface hydrophobicity of oat
372
protein isolate (Pirestani et al., 2017). It was consistent with the result of 3.3.2. The
AC
C
EP
TE
D
361
18
ACCEPTED MANUSCRIPT
conjugate had the lowest surface hydrophobicity of proteins due to the steric
374
hindrance of P. ostreatus β-glucan (Liu, Ru, & Ding, 2012). In addition, the
375
introduction of P. ostreatus β-glucan increased the amount of hydrophilic groups
376
exposed on the surface of conjugates via Maillard reaction, also leading to the
377
decreased surface hydrophobicity of oat protein isolates in conjugate (Mu et al., 2010).
378
This result could also explain that the improved solubility and emulsibility of oat
379
protein isolate after Maillard reaction.
SC
RI
PT
373
M
AN
U
380
3.3.4. Amino acid composition of conjugates
382
As shown in table 1, the content of hydrophilic amino acids among groups were
383
higher than that of hydrophobic amino acids. The covalently binding to protein with
384
polysaccharide caused the decrease of several amino acids after Maillard reaction
385
(Chen et al., 2013). Compared with other groups, the contents of Cys and Lys in
386
conjugate significantly decreased to 0.138% and 3.037% (p < 0.05), suggesting that
387
Cys and Lys were the dominant binding sites of oat protein isolate and P. ostreatus
388
β-glucan (Thorpe & Baynes, 2003). The content of His in conjugate significantly
389
increased to 3.883% compared with other groups (p < 0.05) but changes in the content
390
of total amino acids were not significant (p > 0.05). The reason was that the increase
391
in the exposure of other unfolded amine groups could counteract the decrease of
392
amines via modification (Guo & Xiong, 2013). In addition, the conformational
393
changes around Lys residues could influence the reaction efficiency between other
394
amino groups and P. ostreatus β-glucan, and affect the content of amino groups
AC
C
EP
TE
D
381
19
ACCEPTED MANUSCRIPT
eventually (Chen et al., 2013).
396
3.3.5. Circular dichroism analysis in the secondary structure of conjugates
397
Fig. 5 shows circular dichroism spectrum of oat protein isolate, heated oat protein
398
isolate, the mixture and conjugation of oat protein isolate-P. ostreatus β-glucan in the
399
far-UV region of 190 to 260 nm. The spectrum reflected the structure of peptide in
400
protein cytoskeleton. The α-helical structure of four samples in the spectrogram had a
401
positive band around 192 nm and a negative band at 208 nm and 222 nm. A negative
402
band around 216 nm and a positive band ranging from 190 to 200 nm indicated the
403
existence of β-sheet. A positive band at about 206 nm suggested β-turn.
404
As shown in table 2, all samples contained four kinds of secondary structures. α- helix
405
and β-sheet are the dominant proportion in oat protein isolate (34.4% α- helix and
406
34.1% β-sheet) and conjugate (26.4% α- helix and 31.3% β-sheet). As for heated oat
407
protein isolate, the primary secondary structure is random coil (31.6%) and β-sheet
408
(30.8%). However, α-helix (34.7%) and random coil (26.9%) accounted for the
409
dominant proportion in mixture. Compared with oat protein isolate, heated oat protein
410
isolate and conjugate had the lower content of α-helix and β-sheet structure, indicating
411
that heat treatment could disturb hydrogen bonds in these two structures and forces
412
between oat protein isolate molecules (Sheng et al., 2017; Pirestani et al., 2017). The
413
mixture had higher contents of β-turn and random coil than oat protein isolate due to
414
the interaction between polysaccharide and protein (Li et al., 2014). Compared with
415
mixture (11.3% β-turn and 25.4% β-sheet), the significant increase showed in the
416
content of β-turn and β-sheet of conjugate (p < 0.05). This was because covalent
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
395
20
ACCEPTED MANUSCRIPT
binding with P. ostreatus β-glucan could enhance the intermolecular interaction
418
between neighboring protein molecules via Maillard reaction (Mangavel et al., 2001).
419
In addition, the conjugate had higher random coil and lower α-helix than oat protein
420
isolate. The reason was that Maillard reaction caused oat protein isolate to unscrew
421
and transform into random coil (Li et al., 2014; Mangavel et al., 2001). These results
422
indicated that Maillard reaction could affect the extended secondary structure of oat
423
protein isolate (Qu et al., 2018). It was consistent with the result of the previous study
424
(Mu et al., 2010).
M
AN
U
SC
RI
PT
417
425
3.3.6. SEM analysis in the microstructure of conjugates
427
As shown in Fig. 6A, due to its sunken surface structure, oat protein isolate tended to
428
aggregate in an aqueous model system, leading to the decrease of solubility. After heat
429
treatment, oat protein isolate with the smooth particle had a crumblier structure and
430
appeared some visible cracks. This phenomenon was similar to structural changes of
431
bull serum albumin induced by heat treatment (Semasaka et al., 2018). The mixture
432
had similar surface structure to oat protein isolate. However, the surface structure of
433
conjugates became looser and more porous than that of other three samples and this
434
result was consistent with the previous finding (Mu et al., 2010). On the one hand, it
435
indicated that oat protein isolate was combined with P. ostreatus β-glucan molecules
436
firmly, leading to the formation of inhomogeneous and accumulated structure
437
(Boostani et al., 2017). On the other hand, this structure could be beneficial to
438
improve the efficiency of Maillard reaction. As confirmed by the results of intrinsic
AC
C
EP
TE
D
426
21
ACCEPTED MANUSCRIPT
439
fluorescence and circular dichroism analysis in 3.3.2 and 3.3.5, after covalent binding
440
with P. ostreatus β-glucan, oat protein isolate with the extended structure also caused
441
its loose and porous surface structure.
RI
PT
442
3.4. Functional properties of oat protein isolate-P. ostreatus β-glucan conjugates
444
Functional properties of proteins, including solubility, emulsibility and thermal
445
stability, played a vital role in determining the quality of final products (Liu, Ru, &
446
Ding, 2012). The emulsibility and thermal stability contributed to food texture and
447
flavor. Furthermore, among these properties, solubility was a crucial property in food
448
industry because it directly affected other techno-functional properties (de Oliveira et
449
al., 2016).
M
AN
U
SC
443
TE
D
450
3.4.1. Solubility
452
As shown in table 3, the solubility of heated oat protein isolate decreased as the
453
increase of pH compared with that of oat protein isolate. Heat treatment could
454
increase the surface hydrophobicity of oat protein isolate as confirmed in the result of
455
3.3.3, leading to the decrease of its solubility. Furthermore, the zeta-potential of oat
456
protein isolate, heated oat protein isolate and the mixture was 0 mV where pH was
457
around 4.7 (Fig. S1), suggesting that the isoelectric point of these three samples was
458
about 4.7. Therefore, their solubility was relatively low when pH (pH 4.0 and 5.0)
459
was near the isoelectric point. After covalent binding with P. ostreatus β-glucan, the
460
solubility of oat protein isolate could be greatly improved. On the one hand, it is due
AC
C
EP
451
22
ACCEPTED MANUSCRIPT
to that the introduction of P. ostreatus β-glucan could increase the amount of
462
hydrophilic groups and enhance the steric stabilization of oat protein isolate
463
(Jimenez-Castano, Villamiel, & Lopez-Fandino, 2007; Mu et al., 2010). On the other
464
hand, Maillard reaction could shift the isoelectric point of oat protein isolate to a more
465
acidic region (Fig. S1), causing that the solubility of conjugate could increase in a
466
broad range of pH. In addition, the limited extent of Maillard reaction could increase
467
the solubility of oat protein isolate due to the restricted attack of hydrophilic
468
polysaccharide residues to the protein (de Oliveira et al., 2016). The previous study
469
confirmed that the lowest solubility exhibited in whey protein isolate and whey
470
protein isolate-maltodextrin conjugate at pH 5.0 and pH 4.0, respectively
471
(Martinez-Alvarenga et al., 2014). However, egg white protein-pectin conjugate was
472
reported to have lower solubility than original egg white protein as the increase of
473
reaction time (Al-Hakkak & Al-Hakkak, 2010). This contradiction resulted from the
474
biochemical complexity of reacting proteins and polysaccharide (Oliver, Melton, &
475
Stanley, 2006). In addition, the increased heat time promoted the development of
476
advanced stage of Maillard reaction, then leading to the lower solubility of protein. It
477
suggested that the controlled conditions in our study could prevent the formation of
478
advanced glycation end products.
SC
M
AN
U
TE
D
EP
AC
C
479
RI
PT
461
480
3.4.2. Emulsifying activity and emulsion stability
481
As shown in Fig. 6B-1, heated oat protein isolate had lower emulsifying activity than
482
oat protein isolate as the increase of pH. The reason was that heat treatment could
23
ACCEPTED MANUSCRIPT
decrease the solubility of oat protein isolate as confirmed by the result of 3.4.1,
484
causing that few oat protein isolates could be adsorbed on the oil-water interface
485
(Zhang et al., 2015). In addition, the emulsifying activity of mixture increased
486
compared with that of oat protein isolate in a broad range of pH. However, after
487
covalent binding with P. ostreatus β-glucan, the emulsifying activity of oat protein
488
isolate could be considerably improved. The macromolecular P. ostreatus β-glucan in
489
conjugate could form long range steric repulsion between the surface of emulsion
490
droplets. In addition, it could also promote the formation of a stable membrane around
491
the oil droplets, which was conducive to increase the emulsifying activity of oat
492
protein isolate (Dickinson, 2009; Guo & Xiong, 2013; Qi et al., 2010). More
493
hydrophilic groups of conjugates could increase their solubility as confirmed by the
494
result of 3.4.1, leading to an improved emulsifying activity of conjugate.
495
As shown in Fig. 6B-2, except from conjugate, the emulsion stability of samples went
496
up first but then it went down as the increase of pH. Compared with oat protein isolate
497
(31.921 min) at pH 7, the highest emulsion stability of heated oat protein isolate
498
decreased to 28.77 min due to its lower solubility. In addition, mixture had the highest
499
emulsion stability (41.84 min) at pH 8.0, indicating that the addition of P. ostreatus
500
β-glucan could improve the emulsibility of original oat protein isolate and this result
501
was consistent with the previous study (Pirestani et al., 2017). Compared with the
502
mixture, the emulsion stability of conjugate arrived at 50.186 min at pH 8.0 owing to
503
its excellent solubility. After covalent binding with P. ostreatus β-glucan, oat protein
504
isolates were adsorbed on the oil-water interface and could be protected against the
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
483
24
ACCEPTED MANUSCRIPT
instability in the acid environment. On the other hand, conjugate could saturate the
506
surface layer because its surface was much more active than that of the protein or
507
polysaccharide, leading to an improved emulsibility of oat protein isolate.
508
Furthermore, as confirmed by the result of SEM in 3.3.6, the incompact structure on
509
the surface of conjugate could also contribute to the adsorption of protein to the
510
oil-water interface.
RI
PT
505
SC
511
3.4.3. Thermal property
513
As shown in Fig. 6C, the negative peak at 101.387 °C was a main decalescence peak
514
of oat protein isolate as well as one endothermic transition of heated oat protein
515
isolate at 102.75 °C. However, the denaturation temperature of the conjugate (105.645
516
°C) was significantly higher than that of the mixture (103.091 °C) (p < 0.05). Protein
517
denaturation indicated the non-covalent interactions maintaining the tertiary structure
518
were destroyed, including Van der Waals force, hydrogen bond, hydrophobic and
519
disulfide bond (Boye & Alli, 2000). The result revealed that Maillard reaction could
520
enhance the thermal stability of oat protein isolate through the differential interactions
521
and a combination of excluded volume (Timasheff, 1998). In addition, the
522
introduction of P. ostreatus β-glucan could increase the steric exclusion and
523
electrostatic repulsion of conjugates, preventing the aggregation of oat protein isolate
524
at the high temperature (Robitaille & Ayers, 1995). It was consistent with the
525
extended secondary structure as confirmed from the results of FT-IR and circular
526
dichroism in 3.3.1 and 3.3.5. The result also suggested that oat protein isolate had the
AC
C
EP
TE
D
M
AN
U
512
25
ACCEPTED MANUSCRIPT
lowest denaturation temperature among these samples, indicating that it may be easier
528
to expose more available lysine residues during heat treatment (Liu et al., 2012).
529
Enthalpy value (∆H) was related to the ordered structure content, which determined
530
the requirement of energy to overcome these non-covalent interactions during the
531
denaturation of protein (Choi, Mine, & Ma, 2006). As shown in table 4, conjugate had
532
the lowest ∆H of 2.598 J/g and the mixture had the highest enthalpy value, causing the
533
disruption of intramolecular force in oat protein isolate. These results suggested that
534
oat protein isolate modified by P. ostreatus β-glucan maintained thermally stable. It
535
was related to the decreased content of α-helix and β-sheet of conjugates as confirmed
536
in the result of 3.3.5.
M
AN
U
SC
RI
PT
527
537
Conclusions
539
The conjugate was mainly formed between the carbonyl group of P. ostreatus
540
β-glucan and lysine and cysteine of oat protein isolate via Maillard reaction, leading
541
to the stretching and deformation vibration of functional groups. After covalent
542
binding with P. ostreatus β-glucan, the incompact surface structure and decreased
543
surface hydrophobicity of oat protein isolate caused its increased solubility and
544
emulsibility. The introduction of P. ostreatus β-glucan enhanced the thermal stability
545
of oat protein isolate due to its extended secondary structure induced by Maillard
546
reaction. Under the controlled condition, Maillard reaction was an effective way to
547
improve the application potentials of oat protein isolate in food processing. This study
548
established a framework that can be used to achieve excellent functionalities in other
AC
C
EP
TE
D
538
26
ACCEPTED MANUSCRIPT
modification of proteins and polysaccharides.
550
Acknowledgements
551
This work was supported by the State Key Research and Development Plan "Modern
552
food processing, storage and transportation technology and equipment (No.
553
2017YFD0400205), and a project funded by the Priority Academic Program
554
Development of Jiangsu Higher Education Institutions (PAPD).
RI
PT
549
SC
555
M
AN
U
556
557
558
559
563
564
565
566
567
EP
562
AC
C
561
TE
D
560
568
569
570
27
ACCEPTED MANUSCRIPT
571
Reference
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
Al-Hakkak, J., & Al-Hakkak, F. (2010). Functional egg white-pectin conjugates
prepared by controlled Maillard reaction. Journal of Food Engineering, 100(1),
152-159.
Akhtar, M., & Ding, R. (2017). Covalently cross-linked proteins & polysaccharides:
Formation, characterisation and potential applications. Current Opinion in
Colloid & Interface Science, 28, 31-36.
Alvarez, C., Garcia, V., Rendueles, M., & Diaz, M. (2012). Functional properties of
isolated porcine blood proteins modified by Maillard's reaction. Food
Hydrocolloids, 28(2), 267-274.
Bi, B., Yang, H., Fang, Y., Nishinari, K., & Phillips, G. O. (2017). Characterization
and emulsifying properties of beta-lactoglobulin-gum Acacia seyal conjugates
prepared via the Maillard reaction. Food Chemistry, 214, 614-621.
Boye, J. I., & Alli, I. (2000). Thermal denaturation of mixtures of alpha-lactalbumin
and beta-lactoglobulin: A differential scanning calorimetric study. Food
Research International, 33(8), 673-682.
Boostani, S., Aminlari, M., Moosavi-nasab, M., Niakosari, M., & Mesbahi, G. (2017).
Fabrication and characterisation of soy protein isolate-grafted dextran
biopolymer: A novel ingredient in spray-dried soy beverage formulation.
International Journal of Biological Macromolecules, 102, 297-307.
Broersen, K., Voragen, A. G. J., Hamer, R. J., & de Jongh, H. H. J. (2004).
Glycoforms of beta-lactoglobulin with improved thermostability and
preserved structural packing. Biotechnology and Bioengineering, 86(1), 78-87.
Bund, T., Allelein, S., Arunkumar, A., Lucey, J. A., & Etzel, M. R. (2012).
Chromatographic purification and characterization of whey protein-dextran
glycation products. Journal of Chromatography A, 1244, 98-105.
Chakraborti, S., Chatterjee, T., Joshi, P., Poddar, A., Bhattacharyya, B., Singh, S. P.,
Gupta, V., & Chakrabarti, P. (2010). Structure and activity of lysozyme on
binding to ZnO nanoparticles. Langmuir: the ACS Journal of Surfaces and
Colloids, 26(5), 3506-3513.
Chang, M. C., & Tanaka, J. (2002). FT-IR study for hydroxyapatite/collagen
nanocomposite cross-linked by glutaraldehyde. Biomaterials, 23(24),
4811-4818.
Chen, H., Wang, P., Wu, F., Xu, J., Tian, Y., Yang, N., Cissouma, A. I., Jin, Z., &
Xu, X. (2013). Preparation of phosvitin-dextran conjugates under high
temperature in a liquid system. International Journal of Biological
Macromolecules, 55, 258-263.
Choi, Kim, H. J., Park, K. H., & Moon, T. W. (2005). Molecular characteristics of
ovalbumin-dextran conjugates formed through the Maillard reaction. Food
Chemistry, 92(1), 93-99.
Choi, S., Mine, Y., & Ma, C. (2006). Characterization of heat-induced aggregates of
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
572
28
ACCEPTED MANUSCRIPT
EP
TE
D
M
AN
U
SC
RI
PT
globulin from common buckwheat (Fagopyrum esculentum Moench).
International Journal of Biological Macromolecules, 39(4-5), 201-209.
de Oliveira, F. C., dos Reis Coimbra, J. S., de Oliveira, E. B., Giraldo Zuniga, A. D.,
& Garcia Rojas, E. E. (2016). Food protein-polysaccharide conjugates
obtained via the Maillard reaction: A review. Critical Reviews in Food Science
and Nutrition, 56(7), 1108-1125.
De Silva, D. D., Rapior, S., Sudarman, E., Stadler, M., Xu, J., Alias, S. A., & Hyde,
K. D. (2013). Bioactive metabolites from macrofungi: ethnopharmacology,
biological activities and chemistry. Fungal Diversity, 62(1), 1-40.
Deygen, I. M., & Kudryashova, E. V. (2016). New versatile approach for analysis of
PEG content in conjugates and complexes with biomacromolecules based on
FTIR spectroscopy. Colloids and Surfaces B-Biointerfaces, 141, 36-43.
Dickinson, E. (2009). Hydrocolloids as emulsifiers and emulsion stabilizers. Food
Hydrocolloids, 23, 1473–1482.
Du, Y., Shi, S., Jiang, Y., Xiong, H., Woo, M. W., Zhao, Q., Bai, C., Zhou, Q., &
Sun, W. (2013). Physicochemical properties and emulsion stabilization of rice
dreg glutelin conjugated with kappa-carrageenan through Maillard reaction.
Journal of the Science of Food and Agriculture, 93(1), 125-133.
Fang, D., Yang, W., Kimatu, B. M., Zhao, L., An, X., & Hu, Q. (2017). Comparison
of flavour qualities of mushrooms (Flammulina velutipes) packed with
different packaging materials. Food Chemistry, 232, 1-9.
Galazka, V. B., Dickinson, E., & Ledward, D. A. (2000). Influence of high pressure
processing on protein solutions and emulsions. Current Opinion in Colloid &
Interface Science, 5(3-4), 182-187.
Grigg, D. (1995). The pattern of world protein consumption. Geoforum, 26, 1-17.
Gu, F.-L., Kim, J. M., Abbas, S., Zhang, X.-M., Xia, S.-Q., & Chen, Z.-X. (2010).
Structure and antioxidant activity of high molecular weight Maillard reaction
products from casein-glucose. Food Chemistry, 120(2), 505-511.
Guo, X., & Xiong, Y. L. (2013). Characteristics and functional properties of
buckwheat protein-sugar schiff base complexes. Lwt-Food Science and
Technology, 51(2), 397-404.
Hattori, M., Ogino, A., Nakai, H., & Takahashi, K. (1997). Functional improvement
of beta-lactoglobulin by conjugating with alginate lyase-lysate. Journal of
Agricultural and Food Chemistry, 45(3), 703-708.
Hofmann, T. (1998). Characterization of the chemical structure of novel colored
Maillard reaction products from furan-2-carboxaldehyde and amino acids.
Journal of Agricultural and Food Chemistry, 46(3), 932-940.
Hong, J. H., Jung, D. W., Kim, Y. S., Lee, S. M., & Kim, K. O. (2010). Impacts of
glutathione Maillard reaction products on sensory characteristics and
consumer acceptability of beef soup. Journal of Food science, 75(8), 427-434.
Jimenez, C. L., Lopez-Fandino, R., Olano, A., & Villamiel, M. (2005). Study on
beta-lactoglobulin glycosylation with dextran: Effect on solubility and heat
stability. Food Chemistry, 93(4), 689-695.
Jimenez-Castano, L., Villameil, M., & Lopez-Fandino, R. (2007). Glycosylation of
AC
C
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
29
ACCEPTED MANUSCRIPT
EP
TE
D
M
AN
U
SC
RI
PT
individual whey proteins by Maillard reaction using dextran of different
molecular mass. Food Hydrocolloids, 21, 433-443.
Julita, R., & Marek, S. (2007). Dried shiitake (Lentinulla edodes) and oyster
(Pleurotus ostreatus) mushrooms as a good source of nutrient. Acta
Scientiarum Polonorum Technologia Alimentaria, 6(4), 339-343.
Jung, S., Rickert, D. A., Deak, N. A., Aldin, E. D., Recknor, J., Johnson, L. A., &
Murphy, P. A. (2003). Comparison of Kjeldahl and Dumas methods for
determining protein contents of soybean products. Journal of the American Oil
Chemists Society, 80(12), 1169-1173.
Kamboj, S., Singh, K., Tiwary, A. K., & Rana, V. (2015). Optimization of microwave
assisted Maillard reaction to fabricate and evaluate corn fiber gum-chitosan
IPN films. Food Hydrocolloids, 44, 260-276.
Kato, A. (2002). Industrial applications of Maillard-type protein-polysaccharide
conjugates. Food Science and Technology Research, 8(3), 193-199.
Kato, A., Sasaki, Y., Furuta, R., & Kobayashi, K. (1990). Functional protein
polysaccharide conjugate prepared by controled dry-heating of ovalbumin
dextran mixtures. Agricultural and Biological Chemistry, 54(1), 107-112.
Khan, A. A., Gani, A., Shah, A., Masoodi, F. A., Hussain, P. R., Wani, I. A., &
Khanday, F. A. (2015). Effect of gamma-irradiation on structural, functional
and antioxidant properties of beta-glucan extracted from button mushroom
(Agaricus bisporus). Innovative Food Science & Emerging Technologies, 31,
123-130.
Kim, D.-Y., & Shin, W.-S. (2015). Characterisation of bovine serum albuminfucoidan conjugates prepared via the Maillard reaction. Food Chemistry, 173,
1-6.
Klose, C., & Arendt, E. K. (2012). Proteins in oats; their synthesis and changes during
germination: A review. Critical Reviews in Food Science and Nutrition, 52(7),
629-639.
Laura, J. C., Villamiel, M., & Rosina, L.-F. (2007). Glycosylation of individual whey
proteins by Maillard reaction using dextran of different molecular mass. Food
Hydrocolloids, 21(3), 433-443.
Ledesma-Osuna, A. I., Ramos-Clamont, G., Guzman-Partida, A. M., &
Vazquez-Moreno, L. (2010). Conjugates of bovine serum albumin with chitin
oligosaccharides prepared through the Maillard Reaction. Journal of
Agricultural and Food Chemistry, 58(22), 12000-12005.
Lertittikul, W., Benjakul, S., & Tanaka, M. (2007). Characteristics and antioxidative
activity of Maillard reaction products from a porcine plasma protein–glucose
model system as influenced by pH. Food Chemistry, 100(2), 669-677.
Li, C., Xue, H., Chen, Z., Ding, Q., & Wang, X. (2014). Comparative studies on the
physicochemical properties of peanut protein isolate-polysaccharide
conjugates prepared by ultrasonic treatment or classical heating. Food
Research International, 57, 1-7.
Liu, Y., Zhao, G., Zhao, M., Ren, J., & Yang, B. (2012). Improvement of functional
properties of peanut protein isolate by conjugation with dextran through
AC
C
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
30
ACCEPTED MANUSCRIPT
EP
TE
D
M
AN
U
SC
RI
PT
Maillard reaction. Food Chemistry, 131, 901-906.
Liu, J., Ru, Q., & Ding, Y. (2012). Glycation a promising method for food protein
modification: Physicochemical properties and structure, A review. Food
Research International, 49(1), 170-183.
Loveday, S. M. (2016). Beta-lactoglobulin heat denaturation: a critical assessment of
kinetic modelling. International Dairy Journal, 52, 92-100.
Ma, C. Y. (1985). Functional properties of oat concentrate treated with linoleate
ortrypsin. Canadian Institute of Food Science and Technology Journal, 18,
79–84.
Mangavel, C., Barbot, J., Popineau, Y., & Gueguen, J. (2001). Evolution of wheat
gliadins conformation during film formation: A fourier transform infrared
study. Journal of Agricultural and Food Chemistry, 49(2), 867-872.
Martinez-Alvarenga, M. S., Martinez-Rodriguez, E. Y., Garcia-Amezquita, L. E.,
Olivas, G. I., Zamudio-Flores, P. B., Acosta-Muniz, C. H., & Sepulveda, D. R.
(2014). Effect of Maillard reaction conditions on the degree of glycation and
functional properties of whey protein isolate-Maltodextrin conjugates. Food
Hydrocolloids, 38, 110-118.
Maria, J. S., Perduca, M. J., Piagentini, A., Santiago, L. G., Rubiolo, A. C., & Carrara,
C. R. (2013). Gel mechanical properties of milk whey protein-dextran
conjugates obtained by Maillard reaction. Food Hydrocolloids, 31(1), 26-32.
Martins, S., Jongen, W. M. F., & Majs, v. B. (2000). A review of Maillard reaction in
food and implications to kinetic modelling. Trends in Food Science &
Technology, 11(9-10), 364-373.
Mirmoghtadaie, L., Kadivar, M., & Shahedi, M. (2009). Effects of succinylation and
deamidation on functional properties of oat protein isolate. Food Chemistry,
114(1), 127-131.
Mohamed, A., Biresaw, G., Xu, J., Hojilla-Evangelista, M. P., & Rayas-Duarte, P.
(2009). Oats protein isolate: thermal, rheological, surface and functional
properties. Food Research International, 42(1), 107-114.
Mohsin, G. F., Schmitt, F.-J., Kanzler, C., Epping, J. D., Flemig, S., & Hornemann,
A. (2018). Structural characterization of melanoidin formed from D-glucose
and L-alanine at different temperatures applying FTIR, NMR, EPR, and
MALDI-ToF-MS. Food Chemistry, 245, 761-767.
Mu, L., Zhao, H., Zhao, M., Cui, C. and Liu, L. (2011). Physicochemical properties
of soy protein isolates-acacia gum conjugates. Czech Journal of Food
Sciences, 29(2), 129-136.
Mu, L., Zhao, M., Yang, B., Zhao, H., Cui, C., & Zhao, Q. (2010). Effect of ultrasonic
treatment on the graft reaction between soy protein isolate and gum acacia and
on the physicochemical properties of conjugates. Journal of Agricultural and
Food Chemistry, 58(7), 4494-4499.
Oliver, C. M., Melton, L. D., & Stanley, R. A. (2006). Creating proteins with novel
functionality via the Maillard reaction: A review. Critical Reviews in Food
Science and Nutrition, 46(4), 337-350.
Pirestani, S., Nasirpour, A., Keramat, J., & Desobry, S. (2017). Preparation of
AC
C
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
31
ACCEPTED MANUSCRIPT
EP
TE
D
M
AN
U
SC
RI
PT
chemically modified canola protein isolate with gum Arabic by means of
Maillard reaction under wet-heating conditions. Carbohydrate Polymers, 155,
201-207.
Pirestani, S., Nasirpour, A., Keramat, J., Desobry, S., & Jasniewski, J. (2018).
Structural properties of canola protein isolate-gum Arabic Maillard conjugate
in an aqueous model system. Food Hydrocolloids, 79, 228-234.
Qi, J.-r., Liao, J.-s., Yin, S.-w., Zhu, J., & Yang, X.-q. (2010). Formation of
acid-precipitated soy protein-dextran conjugates by Maillard reaction in liquid
systems. International Journal of Food Science and Technology, 45(12),
2573-2580.
Qu, W., Zhang, X., Han, X., Wang, Z., He, R., & Ma, H. (2018). Structure and
functional characteristics of rapeseed protein isolate dextran conjugates. Food
Hydrocolloids, 82, 329-337.
Renard, D., Lefebvre, J., Griffin, M. C. A., & Griffin, W. G. (1998). Effects of pH
and salt environment on the association of beta-lactoglobulin revealed by
intrinsic fluorescence studies. International Journal of Biological
Macromolecules, 22(1), 41-49.
Robitaille, G., & Ayers, C. (1995). Effects of kappa-casein glycosylation on heat
stability of milk. Food Research International, 28, 17-21.
Sheng, L., Su, P., Han, K., Chen, J., Cao, A., Zhang, Z., Lin, Y., & Ma, M. (2017).
Synthesis and structural characterization of lysozyme-pullulan conjugates
obtained by the Maillard reaction. Food Hydrocolloids, 71, 1-7.
Singh, A. S. S. (2015). Physicochemical, thermal, rheological and morphological
characteristics of starch from three indian lotus root (Nelumbo Nucifera
Gaertn) cultivars. Journal of Food Processing & Technology, 06(2), 1-8.
Snyder, S. L., & Sobocinski, P. Z. (1975). An improved 2,4,6-trinitrobenzenesulfonic
acid method for the determination of amines. Analytical Biochemistry, 64(1),
284-288.
Su, J.-F., Huang, Z., Yuan, X.-Y., Wang, X.-Y., & Li, M. (2010). Structure and
properties of carboxymethyl cellulose/soy protein isolate blend edible films
crosslinked by Maillard reactions. Carbohydrate Polymers, 79(1), 145-153.
Synytsya, A., Mickova, K., Synytsya, A., Jablonsky, I., Spevacek, J., Erban, V.,
Kovarikova, E., & Copikova, J. (2009). Glucans from fruit bodies of
cultivated mushrooms Pleurotus ostreatus and Pleurotus eryngii: Structure
and potential prebiotic activity. Carbohydrate Polymers, 76(4), 548-556.
Szwengiel, A., & Stachowiak, B. (2016). Deproteinization of water-soluble
beta-glucan during acid extraction from fruiting bodies of Pleurotus ostreatus
mushrooms. Carbohydrate Polymers, 146, 310-319.
Semasaka, C., Mhaske, P., Buckow, R., & Kasapis, S. (2018). Modeling water
partition in composite gels of BSA with gelatin following high pressure
treatment. Food Chemistry, 265, 32-38.
Thammakiti, S., Suphantharika, M., Phaesuwan, T., & Verduyn, C. (2004).
Preparation of spent brewer's yeast β-glucans for potential applications in the
food industry. International Journal of Food Science & Technologies, 39, 21–
AC
C
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
32
ACCEPTED MANUSCRIPT
EP
TE
D
M
AN
U
SC
RI
PT
29.
Thorpe, S. R., & Baynes, J. W. (2003). Maillard reaction products in tissue proteins:
New products and new perspectives. Amino Acids, 25(3-4), 275-281.
Tian, S., Chen, J., & Small, D. M. (2011). Enhancement of solubility and emulsifying
properties of soy protein isolates by glucose conjugation. Journal of Food
Processing and Preservation, 35(1), 80-95.
Timasheff, S. N. (1998). Control of protein stability and reactions by weakly
interacting cosolvents: the simplicity of the complicated. Advances in Protein
Chemistry, 51, 355-432.
Usui, M., Tamura, H., Nakamura, K., Ogawa, T., Muroshita, M., Azakami, H.,
Kanuma, S., & Kato, A. (2004). Enhanced bactericidal action and masking of
allergen structure of soy protein by attachment of chitosan through
Maillard-type protein-polysaccharide conjugation. Nahrung-Food, 48(1),
69-72.
Van Der Ven, C., Muresan, S., Gruppen, H., de Bont, D. B., Merck, K. B., &
Voragen, A. G. (2002). FTIR spectra of whey and casein hydrolysates in
relation to their functional properties. Journal of Agricultural and Food
Chemistry, 50(24), 6943–6950.
Wang, J. S., Zhao, M. M., & Jiang, Y. M. (2007). Effects of wheat gluten
hydrolysateand its ultrafiltration fractions on dough properties and bread
quality. Food Technology and Biotechnology, 45, 410–414.
Xu, C.-h., Yu, S.-j., Yang, X.-q., Qi, J.-r., Lin, H., & Zhao, Z.-g. (2010). Emulsifying
properties and structural characteristics of beta-conglycinin and dextran
conjugates synthesised in a pressurised liquid system. International Journal of
Food Science and Technology, 45(5), 995-1001.
Yadav, M. P., Parris, N., Johnston, D. B., Onwulata, C. I., & Hicks, K. B. (2010).
Corn fiber gum and milk protein conjugates with improved emulsion stability.
Carbohydrate Polymers, 81(2), 476-483.
Zhang, B., Guo, X., Zhu, K., Peng, W., & Zhou, H. (2015). Improvement of
emulsifying properties of oat protein isolate-dextran conjugates by glycation.
Carbohydrate Polymers, 127, 168-175.
Zhao, C.-B., Zhang, H., Xu, X.-Y., Cao, Y., Zheng, M.-Z., Liu, J.-S., & Wu, F.
(2017). Effect of acetylation and succinylation on physicochemical properties
and structural characteristics of oat protein isolate. Process Biochemistry, 57,
117-123.
Zhu, W., Xue, X., & Zhang, Z. (2016). Ultrasonic-assisted extraction, structure and
antitumor activity of polysaccharide from polygonum multiflorum.
International Journal of Biological Macromolecules, 91, 132-142.
Zhuo, X.-Y., Qi, J.-R., Yin, S.-W., Yang, X.-Q., Zhu, J.-H., & Huang, L.-X. (2013).
Formation of soy protein isolate-dextran conjugates by moderate Maillard
reaction in macromolecular crowding conditions. Journal of the Science of
Food and Agriculture, 93(2), 316-323.
AC
C
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
33
ACCEPTED MANUSCRIPT
832
833
Figure caption
835
Fig. 1. Effect of different reaction conditions on the degree of graft and browning
836
index from Maillard reaction products. A: effect of the proportion of OPI and GPO
837
(heated at pH 6.0 and for 5 d); B: effect of reaction time (heated at pH 6.0 with OPI to
838
GPO proportion of 1:3); C: Effect of pH (heated for 5 d with OPI to GPO proportion
839
of 1:3); OPI: oat protein isolate; GPO: β-glucan from P. ostreatus.
840
Fig. 2. SDS-PAGE of OPI, heated OPI, the mixture of OPI-GPO and OPI-GPO
841
conjugate (A). Marker (11-180 kDa); lane A: OPI; lane B: Heated OPI; lane C: The
842
mixture of OPI-GPO; lane D: OPI-GPO conjugate. OPI: oat protein isolate; Heated
843
OPI: heated oat protein isolate; The mixture of OPI-GPO: the mixture of oat protein
844
isolate and β-glucan from P. ostreatus; OPI-GPO conjugate: oat protein isolate and
845
β-glucan from P. ostreatus conjugate.
846
Fig. 3. The fourier transform infrared spectroscopy of OPI, heated OPI, the mixture of
847
OPI-GPO and OPI-GPO conjugate. OPI: oat protein isolate; heated OPI: heated oat
848
protein isolate; The mixture of OPI-GPO: the mixture of oat protein isolate and
849
β-glucan from P. ostreatus; OPI-GPO conjugate: oat protein isolate and β-glucan from
850
P. ostreatus conjugate.
851
Fig. 4. The intrinsic fluorescence of OPI, heated-OPI, the mixture of OPI-GPO and
852
OPI-GPO conjugate (A). Surface hydrophobicity of OPI, heated OPI, the mixture of
853
OPI-GPO and OPI-GPO conjugate (B). OPI: oat protein isolate; heated OPI: heated
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
834
34
ACCEPTED MANUSCRIPT
oat protein isolate; The mixture of OPI-GPO: the mixture of oat protein isolate and
855
β-glucan from P. ostreatus; OPI-GPO conjugate: oat protein isolate and β-glucan from
856
P. ostreatus conjugate.
857
Fig. 5. The far-UV CD of OPI, heated OPI, the mixture of OPI-GPO and OPI-GPO
858
conjugate. OPI: oat protein isolate; heated OPI: heated oat protein isolate; The
859
mixture of OPI-GPO: the mixture of oat protein isolate and β-glucan from P. ostreatus;
860
OPI-GPO conjugate: oat protein isolate and β-glucan from P. ostreatus conjugate.
861
Fig. 6. The surface structure of OPI, heated OPI, the mixture of OPI-GPO, OPI-GPO
862
conjugate (A). The emulsifying activity (B-1) and emulsion stability (B-2) of OPI,
863
heated OPI, the mixture of OPI-GPO, OPI-GPO conjugate. The thermal property of
864
OPI, heated OPI, the mixture of OPI-GPO, OPI-GPO conjugate (C). OPI: oat protein
865
isolate; heated OPI: heated oat protein isolate; The mixture of OPI-GPO: the mixture
866
of oat protein isolate and β-glucan from P. ostreatus; OPI-GPO conjugate: oat protein
867
isolate and β-glucan from P. ostreatus conjugate.
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
854
35
ACCEPTED MANUSCRIPT
Table 1. Analysis of amino acid composition of OPI, heated OPI, the mixture of OPI-GPO and
OPI-GPO conjugate.
Content (%)
The mixture of
OPI-GPO
OPI-GPO conjugate
5.668 ± 0.492 a
5.908 ± 0.421 a
5.780 ± 0.237 a
1.377 ± 0.122 a
4.102 ± 0.393 a
8.901 ± 0.567 a
6.706 ± 0.530 a
4.782 ± 0.461 a
43.224 ± 3.892 a
5.692 ± 0.321 a
5.951 ± 0.443 a
5.660 ± 0.312 a
1.452 ± 0.018 a
3.967 ± 0.226 a
8.667 ± 0.619 a
6.766 ± 0.471 a
4.821 ± 0.365 a
42.975 ± 2.197 a
5.387 ± 0.476 a
5.892 ± 0.413 a
5.721 ± 0.404 a
1.342 ± 0.053 a
4.021 ± 0.271 a
8.762 ± 0.61 a
6.692 ± 0.482 a
4.679 ± 0.371 a
42.496 ± 4.109 a
5.591 ± 0.344 a
5.677 ± 0.314 a
5.881 ± 0.437 a
1.313 ± 0.084 a
3.895 ± 0.198 a
8.950 ± 0.501 a
6.610 ± 0.182 a
4.721 ± 0.329 a
42.638 ± 1.491 a
5.536 ± 0.128 a
4.612 ± 0.363 a
21.706 ± 1.138 a
5.048 ± 0.282 a
2.325 ± 0.183 a
4.516 ± 0.189 a
0.696 ± 0.051 b
5.115 ± 0.409 a
7.223 ± 0.537 a
56.776 ± 3.98 a
5.870 ± 0.342 a
4.494 ± 0.355 a
21.617 ± 1.828 a
4.889 ± 0.364 a
2.303 ± 0.176 a
4.063 ± 0.29 a
0.629 ± 0.011 b
4.879 ± 0.357 a
7.280 ± 0.618 a
57.025 ± 3.196 a
5.652 ± 0.427 a
4.772 ± 0.374 a
22.012 ± 2.129 a
5.128 ± 0.330 a
2.350 ± 0.205 a
4.492 ± 0.357 a
0.895 ± 0.059 b
5.021 ± 0.243 a
7.182 ± 0.705 a
57.504 ± 5.161 a
5.741 ± 0.439 a
4.878 ± 0.119 a
22.471 ± 1.86 a
5.228 ± 0.183 a
0.138 ± 0.09 b
4.609 ± 0.372 a
3.883 ± 0.277 a
3.037 ± 0.301 b
7.376 ± 0.62 a
57.362 ± 3.811 a
SC
RI
PT
Heated OPI
M
AN
U
Hydrophobicity
Thr
Ala
Val
Met
Ile
Leu
Phe
Pro
Total
Hydrophile
Asp
Ser
Glu
Gly
Cys
Tyr
His
Lys
Arg
Total
OPI
TE
D
Amino acid
EP
Values were expressed as mean ± standard deviation values (n=3). Different letters within the
AC
C
same amino acid component showed a significant difference (p < 0.05). OPI: oat protein isolate;
Heated OPI: Heated oat protein isolate; The mixture of OPI-GPO: The mixture of oat protein
isolate and β-glucan from P. ostreatus; OPI-GPO conjugate: Oat protein isolate and β-glucan from
P. ostreatus conjugate.
ACCEPTED MANUSCRIPT
Table 2. Calculation of secondary structures of OPI, heated OPI, the mixture of OPI-GPO and
OPI-GPO conjugate.
Secondary structure (%)
OPI
Heated OPI
The mixture of OPI-GPO
OPI-GPO conjugate
α-Helix
34.4 ± 2.6 a
23.9 ± 2.1 c
34.7 ± 3.5 a
26.4 ± 2.5 b
β-Sheet
34.1 ± 1.6 a
30.8 ± 3.3 b
25.4 ± 1.5 c
31.3 ± 2.5 b
β-Turn
10.1 ± 0.9 c
11.7 ± 1.3 b
11.3 ± 1.4 b
17.6 ± 1.5 a
Random coil
19.7 ± 1.4 d
31.6 ± 2.8 a
26.9 ± 1.5 b
24.0 ± 1.2 c
RI
PT
Sample
Values were expressed as mean ± standard deviation values (n=3). Different letters indicated
SC
significant difference (p < 0.05) in the same column. OPI: oat protein isolate; Heated OPI: heated
M
AN
U
oat protein isolate; The mixture of OPI-GPO: the mixture of oat protein isolate and β-glucan from
P. ostreatus; OPI-GPO conjugate: oat protein isolate and β-glucan from P. ostreatus conjugate.
Table 3. The solubility of OPI, heated OPI, the mixture of OPI-GPO and OPI-GPO conjugate.
Solubility (%)
73.871 ± 2.012 b
5.511 ± 0.124 c
10.25 ± 0.621 c
51.762 ± 1.98 c
60.821 ± 1.071 c
64.982 ± 2.581 c
69.125 ± 1.231 c
74.092 ± 1.401 c
82.812 ± 1.012 b
AC
C
3
4
5
6
7
8
9
10
11
Heated OPI
TE
D
OPI
73.481 ± 1.708 b
5.012 ± 0.582 c
10.071 ± 1.209 c
45.201 ± 1.922 d
56.095 ± 1.210 d
60.704 ± 2.058 d
64.652 ± 2.567 d
68.805 ± 1.668 d
79.102 ± 1.291 d
EP
pH
The mixture of
OPI-GPO
76.023 ± 1.019 a
10.768 ± 2.062 b
26.672 ± 1.585 b
57.177 ± 1.296 b
68.965 ± 1.56 b
70.529 ± 2.456 b
71.991 ± 2.178 b
80.208 ± 1.339 b
84.931 ± 1.316 c
OPI-GPO conjugate
25.943 ± 0.873 c
38.621 ± 1.087 a
50.846 ± 1.119 a
65.823 ± 2.942 a
75.616 ±1.896 a
80.101 ± 2.628 a
83.291 ± 1.397 a
85.209 ± 2.073 a
87.287 ± 1.306 a
Values were expressed as mean ± standard deviation values (n=3). Different letters within the
same line showed a significant difference (p < 0.05). OPI: oat protein isolate; Heated OPI: Heated
oat protein isolate; The mixture of OPI-GPO: The mixture of oat protein isolate and β-glucan from
P. ostreatus; OPI-GPO conjugate: Oat protein isolate and β-glucan from P. ostreatus conjugate.
ACCEPTED MANUSCRIPT
Table 4. Denaturation temperature (Td) and enthalpy value (∆H) of samples obtained by
differential scanning calorimeter.
Td (°C)
∆H (J/g)
OPI
101.387 ± 8.271 c
6.504 ± 0.429 b
Heated OPI
102.750 ± 7.329 b
5.285 ± 0.435 c
The mixture of OPI
103.091 ± 9.387 b
7.593 ± 0.903 a
OPI-GPO conjugate
105.645 ± 3.302 a
2.598 ± 0.729 d
RI
PT
Sample
SC
Values were expressed as mean ± standard deviation values (n=3). Different letters indicated
M
AN
U
significant difference (p < 0.05) in the same column. OPI: oat protein isolate; Heated OPI: heated
oat protein isolate; The mixture of OPI-GPO: the mixture of oat protein isolate and β-glucan from
AC
C
EP
TE
D
P. ostreatus; OPI-GPO conjugate: oat protein isolate and β-glucan from P. ostreatus conjugate.
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
Fig. 1
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
Fig. 2
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
Fig. 3
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
Fig. 4
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
Fig. 5
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
Fig. 6
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
ACCEPTED MANUSCRIPT
•
•
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
•
Oat protein isolate-Pleurotus ostreatus β-glucan conjugates with high grafting
degree were prepared by dry-heating for the first time.
After Maillard reaction, changes in structural properties of oat protein isolate
improved its solubility, emulsifying property and thermal stability.
Maillard reaction could enhance the utilization value of oat protein isolate in
food industry under controlled dry-heating conditions.
Документ
Категория
Без категории
Просмотров
0
Размер файла
1 607 Кб
Теги
034, foodhyd, 2018
1/--страниц
Пожаловаться на содержимое документа