Physical quality and in vitro starch digestibility of biscuits as affected by addition of soluble dietary fiber from defatted rice bran

Physical quality and in vitro starch digestibility of biscuits as affected by addition of soluble dietary fiber from defatted rice bran

Food Hydrocolloids 99 (2020) 105349 Contents lists available at ScienceDirect Food Hydrocolloids journal homepage: www.elsevier.com/locate/foodhyd ...

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Food Hydrocolloids 99 (2020) 105349

Contents lists available at ScienceDirect

Food Hydrocolloids journal homepage: www.elsevier.com/locate/foodhyd

Physical quality and in vitro starch digestibility of biscuits as affected by addition of soluble dietary fiber from defatted rice bran

T

Mengyun Jiaa, Qiang Yua,∗, Jiajun Chena, Zhicheng Heb, Yi Chena, Jianhua Xiea, Shaoping Niea, Mingyong Xiea a

State Key Laboratory of Food Science and Technology, China-Canada Joint Lab of Food Science and Technology (Nanchang), Nanchang University, 235 Nanjing East Road, Nanchang, 330047, China b School of Food Science and Technology, Nanchang University, Nanchang, 330031, China

A R T I C LE I N FO

A B S T R A C T

Keywords: Biscuits Soluble dietary fiber Physical quality In vitro starch digestibility Sensory evaluation

The increasing demand for functional foods has boosted up the food industry to produce fiber-enriched products. The purpose of this study was to investigate the effects of soluble dietary fiber from defatted rice bran (DRB) obtained through Trichoderma viride fermentation (F-SDF) on the physical properties and starch digestion characteristics of biscuits. Rheological analysis results showed that the addition of F-SDF delayed the gelatinization of starch. Texture profile analysis (TPA) results demonstrated that the addition of F-SDF reduced the hardness, springiness, cohesiveness, gumminess, chewiness and resilience of the biscuits. The scanning electron microscopy (SEM) results showed that F-SDF hindered the formation of the gluten network structure in the biscuits, making the biscuits loose. Meanwhile, X-ray diffraction (XRD) revealed the addition of F-SDF reduced the area of the crystallization zone. In addition, F-SDF led to a significant reduction of predicted glycemic index (pGI) of reformulated biscuits. Sensory evaluation results indicated that the effects of F-SDF addition on the odor, color and taste of the biscuits were relatively small, while the biscuits with highest texture and acceptability score were obtained by incorporating 6% of F-SDF in the formulation. In summary, adding the proper amount of F-SDF could improve the physical properties of the biscuits and exhibit potential to decrease the postprandial blood glucose level resulted by biscuits.

1. Introduction Biscuits are widely consumed around the world due to the pleasant taste, ready-to-eat property and affordable cost(Sulieman et al., 2019). However, part of nutritional values of biscuit is not suitable for the modern population. In particular, some biscuits belong to the high glycemic index food (GI > 70), which limits the choice of obese, middle-aged and other consumer groups. Recently, emerging studies focus on adding different ingredients into baking products to reduce GI value and improve the quality. The quality of biscuits is affected by many factors, including quality and level of raw materials used, mixing, resting and moulding of the doughs, and baking and cooling conditions of the biscuits(Manohar & Rao, 2002). Sensory evaluation of food, such as appearance, color, taste, smell, uniformity, etc. are the most intuitive indicators to describe and judge food quality. Scientific and reasonable sensory indicators of food can reflect the characteristic and quality requirements of food. However, due to subjectivity of sensory evaluation, instrumental



analyses are used to make more assessments. Texture profile analysis (TPA) is a technique by which the instrument simulates a person's chewing action. It simulates compression and stretching actions of the tooth twice, then records and plots the relationship between force and time, and obtains the parameters corresponding to the human sensory evaluation, including hardness, springiness, cohesiveness, gumminess, chewiness and resilience(Carr, L., Tandini, & C., 2003). Starch is one of the main ingredients in biscuits. The relationship between starch digestibility and human health is mainly measured by the digestion rate of starch and the blood sugar response of human body. The glycemic index (GI) characterizes the carbohydrates consumed in different types of foods on the basis of postprandial level of blood glucose(D. J. Jenkins et al., 1982). Long-term intake of low GI foods are reported to associate with the reduced incidence and prevalence of heart disease, diabetes, and also some forms of cancer(BrandMiller, 2007; A. L.; Jenkins, 2007; Roberts, 2000; Wolever & Christine, 2002). By reducing the glycemic index in food by certain means, it is beneficial for the prevention of chronic diseases.

Corresponding author. State Key Laboratory of Food Science and Technology, Nanchang University, 235 Nanjing East Road, Nanchang, 330047, China. E-mail address: [email protected] (Q. Yu).

https://doi.org/10.1016/j.foodhyd.2019.105349 Received 8 July 2019; Received in revised form 24 August 2019; Accepted 28 August 2019 Available online 10 September 2019 0268-005X/ © 2019 Elsevier Ltd. All rights reserved.

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Fig. 1. Rheological properties of the doughs containing different levels of F-SDF. (A): Storage modulus of dough added with different content of F-SDF; (B): Loss modulus of dough added with different content of F-SDF; (C): Loss angle of dough added with different content of F-SDF.

could provide theoretical and practical basis for the development of biscuits with beneficial properties.

Preceding studies have reported several factors that may alter the GI of food, including food structure, amylose/amylopectin ratio(Sasaki et al., 2009), food processing level (Senay, Maribel, Kristin, & BelloPérez, 2012), and the presence of nutrients such as fat, protein and dietary fiber(Cleary & Brennan, 2006). In recent years, there has been an increasing interest in DF due to its health-promoting features (Liu et al., 2019;; Zhuang et al., 2018). Especially, many studies have documented the relationship between increased fiber consumption and decreased glycemic response in diabetics(Chau, Chen, & Lin, 2004). Regand et al. found that the higher the molecular weight and solution concentration of oat β-glucan, the better the effect of delaying starch digestion((Regand et al., 2011)). In our previous study, we obtained soluble dietary fiber from defatted rice bran (DRB) through Trichoderma viride fermentation, named as F-SDF. DRB is a residue of rice bran extract oil that contains large amounts of nutrients, including dietary fiber (DF) and other ingredients. F-SDF was composed of fucose, galactose, glucose, mannose, fructose, galacturonic acid and glucuronic acid with the molar ratio of 1.07: 2.12: 1.00: 78.36: 2.29: 25.41: 0.48. It had four components, and the relative weight average molecular weights were calculated to be 982.8 kDa, 119.6 kDa, 25.1 kDa and 1.8 kDa, successively. Moreover, FSDF exhibited higher water-holding capacity (WHC), oil-holding capacity (OHC), water solubility (WS) and cholesterol absorption capacity (CAC). In this study, different proportions of F-SDF were added to the flour to make biscuits, and the effect of F-SDF on the physical properties and starch digestion characteristics of biscuits were investigated, which

2. Materials and methods 2.1. Materials and reagents Defatted rice bran (DRB) was obtained from Jiangxi Tianyu Oil Co., Ltd. (Jiangxi, China). Low-gluten flour, butter, milk, salt and other raw materials were obtained from a local supermarket. Trichoderma viride (GIM: 3.597) was purchased from Guangdong Microbial Culture Center. Heat-stable α-amylase and papain were purchased from Aladdin Biotechnology Co., Ltd (Shanghai, China) and Nanning Pangbo Bioengineering Co., Ltd (Guizhou, China), respectively. Pancreatin (8 USP/mg) from porcine pancreas was purchased from Sigma Co., Ltd (USA), and saccharifying enzyme (10000 U/mL) was purchased from Shanghai Aladdin Biotechnology Co., Ltd. 2.2. Preparation of F-SDF F-SDF was prepared according to the method described by Jia et al. (Jia et al., 2019). In briefly, potato dextrose agar media (PDA) of Trichoderma viride was used in the seed medium at their active sporulating stage. Next, Trichoderma viride was utilized to ferment the DRB on a reciprocal shaker under the conditions (inoculum size = 10%, pH = 5.8 and time = 41 h). The fermented DRB was incubated with the 2

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thermostable α-amylase and papain continuously and centrifuged. Thereafter, 95% ethanol was added to the supernatant and centrifuged to obtain F-SDF. The F-SDF was then freeze dried. 2.3. Biscuits-making procedure Biscuits as a food vehicle model for F-SDF were prepared using basic ingredients: low-gluten flour (starch content is 73%), butter (36% of low-gluten flour quality), milk (42 mL/g), salt (3% of low-gluten flour quality) and F-SDF (0, 1.2%, 3.6%, 6%, 8.4%, and 10.8% of low-gluten flour quality). The doughs were prepared by uniformly stirring the raw materials and were sheeted using a rolling pin. Next, the doughs were cut into a fixed shape by the mold and was placed on a perforated tray and baked in a conventional oven for 10 min at 180 °C. Dough samples (sampling about 0.25 cm2, thickness 2–3 mm) were lyophilized, and stored at dry plastic containers for further analysis.

*For each analysis, Mean ± SD, results are the average of six replicates; Values in the same column with different letters are significantly (p < 0.05) different.

Resilience

0.593 ± 0.101a

0.448 ± 0.073b

7589.855 ± 2992.358bc 0.371 ± 0.095bc 10954.343 ± 4838.310ab Chewiness

Gumminess

Cohesiveness

14257.693 ± 4437.976a

6452.485 ± 1841.334c 0.340 ± 0.046cd

4529.449 ± 2067.218c 0.323 ± 0.080cd

17587.302 ± 5800.444c 0.593 ± 0.032b 0.433 ± 0.068d 7846.929 ± 3196.104c 47.798 ± 7.041c 0.271 ± 0.059d 21046.999 ± 5606.924bc 0.592 ± 0.051b 0.493 ± 0.061cd 10593.986 ± 4299.560c 23572.395 ± 4479.169abc 0.582 ± 0.052b 0.533 ± 0.090bc 12759.130 ± 3975.091b 25838.284 ± 6663.010ab 0.665 ± 0.064a 0.609 ± 0.063b 16064.278 ± 5645.271ab Hardness Springiness

27942.800 ± 4032.556a 0.687 ± 0.077a 0.727 ± 0.076a 20465.666 ± 4651.634a

21561.454 ± 3858.500bc 0.591 ± 0.033b 0.501 ± 0.055cd 10851.834 ± 2618.646c

10.8% 3.6% 1.2% 0

Table 1 Effect of F-SDF content on texture properties of biscuits.

6%

8.4%

M. Jia, et al.

2.4. Water-holding capacity (WHC) of biscuits The WHC was determined in triplicate according to the method described Raghavendra et al. with minor modification(Raghavendra, Rastogi, Raghavarao, & Tharanathan, 2004). The biscuits (0.5 g) were dissolved with 10 mL distilled water respectively, and equilibration at 37 °C for 1 h. After centrifugation at 4800 r/min for 10 min, and the sediment was weighed (as wet weight) and dried to constant weight (as dry weight) in a forced-air oven (110 °C). WHC was defined as follow Eqn (1): WHC (g/g) = (WW − WD)/ WD

(1)

where WW is the wet weight and WD is the dry weight. 2.5. Rheological behavior measurement of the doughs The rheological properties of the doughs were measured using strain controlled ARES rheometer (TA Instruments, New Castle, USA) equipped with parallel plate (40 mm diameter, gap 1 mm)(Wang, Jiang, Ren, Shen, & Xie, 2019). A gelvent trap cover was applied to limit evaporation and mitigate interference. Before each measurement, samples were equilibrated for 5 min. Storage modulus (G′), loss modulus (G") and loss angle (tanδ = G"/G′) of samples were measured at a constant frequency of 1 Hz and a fixed strain of 0.5%. The test temperature was 45 °C–120 °C, and the heating rate was 5 °C/min. 2.6. Texture profile analysis (TPA) Texture profile analysis (TPA) of biscuits were performed using a texture analyzer (TA-XT plus, Stable Co., England)(Deng, Wu, & Li, 2006). The measurement conditions of biscuits were: P/30R probe, PreTest Speed: 2.0 mm/s, Test Speed: 1.0 mm/s, Post-Test Speed: 2.0 mm/ s, Compression Degree: 30%. Each group was tested six times. 2.7. Scanning electron microscopy (SEM) The doughs and biscuits samples (both taking the fracture surface) were subjected to SEM analysis and the micrographs were digitally recorded using JSM 6701F scanning electron microscope (Jeol Ltd. Japan). 2.8. X-ray diffraction (XRD) The XRD profiles of biscuits were collected by using a diffractometer (D8 Advance, Bruker, Germany) at the operating voltage and current of 30 kV and 20 mA, respectively. The diffraction intensities were swept on the biscuits between 5 and 55° (2θ angle range). 3

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Fig. 2. SEM micrographs of biscuits (100 × ). (A): Biscuits with 0% F-SDF added; (B): Biscuits with 1.2% F-SDF added; (C): Biscuits with 6% F-SDF added; (D): Biscuits with 8.4% F-SDF added.

2.10. Sensory evaluation of biscuits

2.9. Starch digestion in vitro and calculation of predicted glycemic index (pGI)

The sensory analysis of biscuits were carried out as follows: biscuits samples were presented in a sealed pouch coded with different numbers to six experienced judges by assigning a score for each quality attribute, such as color, texture, taste, odor, overall acceptability. The sensory quality attribute of each biscuit had a score of 5.

In vitro starch digestibility of biscuits was analyzed according to the methods described by Englyst et al.(Englyst, Kingman, & Cummings, 1992) with minor modifications. Biscuits samples (0.5 g) were suspended in 10 mL sodium acetate buffer (0.2 M, pH = 5.2), and 3 glass beads were added to prevent agglomeration. The enzyme mixture containing 10 mL pancreatin (320 U/L) and 40 μL saccharifying enzyme (10000 U/mL) was added to each tube and tubes were placed in a 37 °C constant temperature shaking water bath to incubate at 170 r/min. Aliquots (1 mL) were taken every 30 min up to 120 min, and then mixed with 4 mL of absolute ethanol to stop the enzyme reaction. The glucose content of samples was detected using the 3.5-dinitrosalicylic acid (DNS) method (Foschia, Peressin, Sensidoni, Brennan, & Brennan, 2015), and glucose release was plotted against time and area under the curve (AUC) was calculated by dividing the graph into trapezoids as described (Foschia, Peressini, Sensidoni, Brennan, & Brennan, 2015).

2.11. Color measurement of biscuits The values of surface color of biscuits were measured using the colorimeter (Labscan, XE, Hunter Lab. Inc., USA), and expressed as L* (L* = 0 [black] and L* = 100 [white]), a* (−a* = greenness and +a* = redness), and b* (−b* = blueness and +b* = yellowness). (Alongi, Melchior, & Anese, 2019). Average of six values was taken for each set of samples.

4

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Fig. 3. SEM micrographs of doughs (100 × ). (A): Biscuits with 0% F-SDF added; (B): Biscuits with 1.2% F-SDF added; (C): Biscuits with 6% F-SDF added; (D): Biscuits with 8.4% F-SDF added.

Fig. 5. Glucose release curves of F-SDF-enriched biscuits during in vitro starch digestion.

Fig. 4. XRD pattern of biscuits with different contents of F-SDF.

5

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León, & Ribotta, 2019); F-SDF interacted with the starch, enveloping the starch or forming a barrier that prevented enzymatic hydrolysis; In addition, the F-SDF could capture more water contained in the doughs. Consequently, during biscuits baking, starch gelatinization would be partially prevented. At the same time, the addition of F-SDF diluted the starch content of the biscuits as one of the possible reasons. 3.3. Texture of biscuits The texture analysis results of biscuits were shown in Table 1. The results showed that adding F-SDF reduced the hardness, springiness, cohesiveness, gumminess, chewiness and resilience of the biscuits. There was a class of water-insoluble proteins in low-gluten flour, including glutenin and gliadin. The glutenin determined the elasticity and structural strength of the doughs and the gliadin determined the viscosity and fluidity of the doughs. The combination of gliadin and glutenin formed a soft gel of a special network structure that was elastic, viscous and extensible, ie, gluten. F-SDF competitively absorbed water and wrapped starch granules distributed in the gluten network structure, which prevented many protein molecules from being firmly intertwined and hinders the formation of a spatial network. Moreover, gluten protein was diluted by adding F-SDF to the flour, which destroyed the formation of the gluten network structure. The hardness of biscuits is determined by composite matrix of protein aggregates, lipids, and sugars embedded within ungelatinized starch granules(Chevallier, Colonna, Buléon, & Valle, 2000). If the hardness of biscuits was too high, it will affect the taste and make the biscuits not crisp enough. If the hardness of the biscuits was too small, the biscuits will be easily broken. The reduction in the gluten network structure in the biscuits reduces the hardness of the biscuits. Meanwhile, because the water holding capacity of F-SDF was strong, more moisture was retained in the biscuits, resulting in a decrease in the hardness of the biscuits. The biscuits with F-SDF added had a relatively high porosity and a looser structure. Studies have shown hardness may also be affected by the porosity of the biscuits(Umesha, Manohar, Indiramma, Akshitha, & Naidu, 2015). Chewiness refers to the energy required to turn a biscuit into a state in which can be swallowed. The experimental results have demonstrated that if chewing is too large or too small, it will not be conducive to the taste of biscuits. Cohesiveness refers to the amount of internal binding force required to form a sample, reflecting the strength of the interaction between molecules within the sample or between various structural elements. Therefore, it also reflects the ability of the sample to resist damage and maintain its integrity. With the addition of F-SDF, the cohesiveness of the biscuits was reduced, causing the biscuits with horny edges, excessively crisp, easily broken and difficult to be transported and stored.

Fig. 6. Sensory evaluation of investigated biscuits with different F-SDF content. 5-point scale was used (5-corresponds to meeting the demands for certain characteristic completely; 1-implies major qualitative deficiencies of the product).

2.12. Data analysis Data analysis of results was performed with IBM SPSS statistical software (version 21.0, SPSS Inc., Chicago, IL, USA) and Design Expert 8.0. Data were analyzed by analysis of variance (ANOVA) and expressed as mean ± standard deviation (S.D.). P < 0.05 was considered to be statistically significant. Origin 8.0 was used for construction of graphs and figures and for data processing. 3. Results and discussion 3.1. WHC of biscuits WHC is defined as the amount of water retained by a known weight of hydrocolloid after the application of external forces (Raghavendra et al., 2004). The experimental results showed that when the addition amount of F-SDF was 0%, 1.2%, 3.6%, 6%, 8.4%, and 10.8%, WHC was 1.70 ± 0.02, 1.78 ± 0.03, 1.83 ± 0.01, 1.83 ± 0.02, 1.85 ± 0.01, 1.86 ± 0.01 respectively, suggesting that F-SDF could capture water contained in the doughs, and change the water distribution in the biscuits, which had a certain influence on the gelatinization properties of the starch in the doughs and the texture properties of the biscuits. 3.2. Rheological analysis Fig. 1 showed that the G′, G" values and tanδ of doughs with different concentrations of F-SDF added. In all of the analyzed samples, as the F-SDF content increased, a decrease in G′ and an increase in G" were observed. At the same time, the increase of F-SDF made the tanδ of the dough showing an upward trend. These results indicated that F-SDF could increase the viscous ratio of dough system and increase the fluidity of dough. In addition, the gradual increase of temperature corresponding to the peak value in rheology indicated that the addition of F-SDF hindered the gelatinization of starch. The effect of F-SDF on starch rheology may be mainly manifested in several aspects: F-SDF and starch formed complex through hydrogen bond and van der Waals force, which changed the viscosity and the expansion of starch(Canalis,

3.4. SEM The microstructure of the biscuits and doughs performed by SEM was shown in Fig. 2 and Fig. 3, respectively. There was many starch granules observed in biscuits and doughs without F-SDF. The starch granules were covered with gluten and butter, and the gluten network was relatively uniform and firm. As the amount of F-SDF added increase, the starch granules in the doughs and biscuits were still wrapped, and the structure of the gluten network was continuous, but

Table 2 Appearance properties of biscuit samples containing different levels of F-SDF. 0% L* a* b*

1.2% a

87.5 ± 0.1 1.2 ± 0.1d 11.8 ± 0.1bc

3.6% b

87.7 ± 0.2 1.2 ± 0.0cd 11.9 ± 0.1cd

6% b

87.7 ± 0.2 1.2 ± 0.1bc 12.0 ± 0.1d

8.4% a

87.5 ± 0.1 1.1 ± 0.0ab 11.8 ± 0.0ab

10.8% ab

87.6 ± 0.1 1.1 ± 0.0a 11.8 ± 0.1ab

87.6 ± 0.1 a 1.1 ± 0.1b 11.7 ± 0.1a

*For each analysis, Mean ± SD, results are the average of six replicates; Values in the same column with different letters are significantly (p < 0.05) different. 6

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with some slack and small voids. Meanwhile, F-SDF was filled in the network structure, covering the surface of starch granules and hindering the network structure of gluten. When the addition of F-SDF reached 6%, the microstructure of the biscuits and doughs appeared to be acceptable, with integrated gluten network and less cracks. However, the biscuits added 8.4% F-SDF were partially torn, the microstructure of the biscuits and doughs with 10.8% F-SDF added was too loose (data not shown).

to 6%, the texture score increased from 3.5 to 4.3. With the increasing of F-SDF added, the texture score decreased rapidly, the texture score of 10.8% F-SDF added biscuit was even lower than that of without F-SDF. Moreover, the surface color of biscuits in terms of L*, a*, and b* values was showed in Table 2. Although there was a significant difference in the value of L*, a*, and b*, the difference between the values was so small that the results of sensory evaluation were not significant. 4. Conclusion

3.5. XRD analysis The present study demonstrated that the addition of F-SDF could delay the gelatinization of starch in doughs, and reduce the hardness, springiness, cohesiveness, gumminess, chewiness and resilience of the biscuits. Moreover, F-SDF hindered the formation of the gluten network structure, and reduced the area of the crystallization zone of the biscuits. Meanwhile, the pGI value of the biscuits was decreased by the addition of F-SDF. However, the addition of F-SDF had less effect on the color, smell and taste of the biscuits. Furthermore, biscuits with 6% FSDF added got the highest acceptability and texture score. In summary, the present study will be helpful regarding the development of functional foods enriched with soluble dietary fiber.

XRD was used in this study to investigate changes in crystallinity of biscuits with different levels of F-SDF. Crystallinity is an important indicator for evaluating the physical properties of foods. Food with large crystallization zone has dense structure and is not easy to be influenced by external forces and chemical reagents. Meanwhile, crystallinity controls the digestibility by affecting the properties of foods (Dona, Pages, Gilbert, & Kuchel, 2010). To examine the influence of amount of F-SDF on the crystal structure of the biscuits, X-ray diffraction analysis was carried out. The different addition amounts of F-SDF corresponding to the XRD spectra were given in Fig. 4. It can be seen from the X-ray diffraction pattern of the doughs that there were obvious peaks at 2θ of 15°, 17°, 18°, 20°, and 23°. The diffraction peak without F-SDF was the highest, and the crystalline region was intact, indicating that the crystal content of the doughs was high. The X-ray diffraction patterns of doughs with F-SDF were similar to those of dough without FSDF, but the peak area decreased significantly with the increase of FSDF content, and some of the peaks disappeared. The results showed that the addition of F-SDF changed the crystalline area of doughs and affected the quality of biscuits.

Declaration of interests The authors declare no conflict of interest in this work. Acknowledgements This work was supported by the Key Research and Development Program of Jiangxi Province of China (20171BBF60041), National Natural Science Foundation of China (31701603), and Research Project of State Key Laboratory of Food Science and Technology (SKLF-ZZA201611).

3.6. In vitro digestion rate of starch and prediction of glycemic index Conventional and F-SDF-containing biscuits were in vitro digested to assess the effect of reformulation on the pGI (Fig. 5). As expected, the maximum glucose concentration was recorded in white bread. The biscuit with 1.2% F-SDF added had a pGI of 73.69 and was therefore classified as a high predicted glycemic index food. The pGI of biscuits with 6% and 10.8% F-SDF was reduced to 66.72 and 62.47, respectively, which ranked the product as a medium glycemic index food. Dietary fiber affects digestion by changing the physical and chemical properties of the starch system. Besides, SDF can increase matrix viscosity at gastrointestinal level, contributing to the formation of a gel. Moreover SDF can envelop starch grains, and protect them from the amylolytic activity of digestive enzymes and thus impinge the release of free glucose, resulting in a reduced glycemic response(Juvonen et al., 2009). Viscous dietary fiber may prolong the absorption time of nutrients and regulate blood nutrient levels during digestion(Goni, Valdivieso, & Gudiel-Urbano, 2002). Dartois et al. studied the effect of guar gum on the in vitro digestibility of starch, and found that the presence of guar gum increased the viscosity of the system and inhibited the action of the enzyme(Dartois, Singh, Kaur, & Singh, 2010). The experimental results showed that the addition of F-SDF could inhibit the in vitro digestion and hydrolysis of starch to a certain extent, thereby reducing the pGI value and starch hydrolysis rate of biscuits, and the pGI value gradually decreased as the amount of addition increased.

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3.7. Effect of F-SDF on sensory and color in biscuits Sensory evaluation results of biscuits were shown in Fig. 6. The results showed that acceptability and texture score of biscuits was most popular when adding 6% F-SDF. The effect of the amount added on the odor, taste and color of the biscuits were relatively small, indicating that the addition of F-SDF will not affect the deliciousness of the biscuit. In addition, when the amount of F-SDF added to the biscuits increased 7

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