Effects of whey protein on the in vitro digestibility and physicochemical properties of potato starch

Effect of hydrocolloids on starch digestion: A review

Rapidly digestible starch can increase postprandial blood sugar rapidly, which can be overcome by hydrocolloids. The paper aims to review the effect of hydrocolloids on starch digestion. Hydrocolloids used to reduce starch digestibility are mostly polysaccharides like xanthan gum, pectin, β-glucan, and konjac glucomannan. Their effectiveness is related to their source and structure, mixing mode of hydrocolloid/starch, physical treatment, and starch processing. The mechanisms of hydrocolloid action include increased system viscosity, inhibition of enzymatic activity, and reduced starch accessibility to enzymes. Reduced starch accessibility to enzymes involves physical barrier and structural orderliness. In the future, physical treatments and intensity used for stabilizing hydrocolloid/starch complex, risks associated with different doses of hydrocolloids, and the development of related clinical trials should be focused on. Besides, investigating the effect of hydrocolloids on starch should be conducted in the context of practical commercial applications rather than limited to the laboratory level.

Role of pea protein isolate in modulating pea starch digestibility: insights from physicochemical and microstructural analysis

BACKGROUND

Understanding the interactions between protein and starch is crucial in revealing the mechanisms by which protein influences starch digestibility. The present study investigated the impact of different contents of pea protein isolate (PPI) on the physicochemical properties and digestibility of pea starch (PS).

RESULTS

The results demonstrated that as the content of PPI increased from 0% to 12%, and the digestion of PS decreased by 12.3%. Rheological analysis indicated that PPI primarily interacted with molecular chains of PS through hydrogen bonds. Increasing the content of PPI resulted in a 30.6% decrease in the hardness of the composite gels, accompanied by a 10% reduction in the short-ordered structure of PS. This hindered the formation of molecular aggregation and resulted in a loose and disordered gel network structure. The microstructure confirmed that the attachment of PPI to PS served as a physical barrier, impeding starch digestibility.

CONCLUSION

In summary, the primary mechanism by which PPI inhibited PS digestion involved steric hindrance exerted by PPI and its interaction with PS via hydrogen bonds. These findings contribute to a better understanding of the interaction mechanisms between PS and PPI and offer insights for the optimal utilization of pea resources. © 2024 Society of Chemical Industry.

Impact of Whey Protein Isolate and Xanthan Gum on the Functionality and in vitro Digestibility of Raw and Cooked Chestnut Flours

Due to the limitations of the properties of chestnut flour, its applications have been restricted. The objective of this study is to investigate the impact of whey protein isolate (WPI) and xanthan gum (XG) on the functional and digestive properties of chestnut flour, specifically focusing on gel texture, solubility and swelling power, water absorption capacity, freeze-thaw stability and starch digestibility. The addition of both WPI and XG reduced the gel hardness, gumminess and chewiness of the co-gelatinized and physically mixed samples. Furthermore, the inclusion of physically mixed WPI and XG led to an increase in the solubility (from 58.2 to 75.0%) and water absorption capacity (from 3.11 to 5.45 g/g) of chestnut flour. The swelling power of the chestnut flour was inhibited by both additives. WPI was superior to XG at maintaining freeze-thaw stability, by reducing the syneresis from 71.9 to 68.1%. Additionally, WPI and XG contributed to the inhibition of starch hydrolysis in the early stage of digestion, resulting in a lower starch digestibility of chestnut flours. This research provides insights into the interaction mechanisms between WPI, XG, and chestnut flour, offering valuable information for the development of chestnut flour products with enhanced properties.

Including protein hydrolysates during thermal processing mitigates the starch digestion of resulted starch-based binary matrix

Staple foods with starch and protein components are usually consumed after thermal processing. To date, how including protein hydrolysates (with varied hydrolysis degrees) tailors the structure and digestion features of starch-based matrix with thermal processing has not yet been sufficiently understood. Here, corn starch (CS), soy protein isolate (SPI), and soy protein isolate hydrolysates (SPIH) with different hydrolysis time (5-60 min) were used to prepare starch-based binary matrices. With the addition of SPI or SPIH during thermal processing, the resultant binary systems exhibited higher thermal stability (breakdown visibility was increased by 1.9-10.8 times), denser networks, and fewer short-range orders (R995/1022 was decreased by up to 15.3 %). These structural changes allowed an inhibited starch digestion within the binary system, especially with increased SPI or SPIH content. Compared with CS, the content of resistant starch (RS) for CS-SPI binary complex (10:3 w/w) increased from 9.89 % to 16.69 %. Compared to SPI, SPIH inclusion displayed a stronger inhibitory effect on starch digestion since the reduced molecule size of SPIH probably enhanced its interplays with starch or amylase. For instance, the 10:3 w/w starch-SPIH 60 binary matrix possessed the highest RS content (19.07 %).

Effects of Wheat Oligopeptide on the Baking and Retrogradation Properties of Bread Rolls: Evaluation of Crumb Hardness, Moisture Content, and Starch Crystallization

Delaying the deterioration of bakery goods is necessary in the food industry. The objective of this study was to determine the effects of wheat oligopeptide (WOP) on the qualities of bread rolls. The effects of WOP on the baking properties, moisture content, and starch crystallization of rolls during the storage process were investigated in this study. The results showed that WOP effectively improved the degree of gluten cross-linking, thereby improving the specific volume and the internal structure of rolls. The FTIR and XRD results showed that the addition of WOP hindered the formation of the starch double helix structure and decreased its relative crystallinity. The DSC results revealed a decrease in the enthalpy change (ΔH) from 0.812 to 0.608 J/g after 7 days of storage with 1.0% WOP addition, further indicating that WOP reduced the availability of water for crystal lattice formation and hindered the rearrangement of starch molecules. The addition of WOP also improved the microstructure of the rolls that were observed using SEM analysis. In summary, WOP is expected to be an effective natural additive to inhibit starch staling and provide new insights into starchy food products.

Impact of red kidney bean protein on starch digestion and exploring its underlying mechanism

This study aimed to investigate the effect of different proportions of red kidney bean protein (RKP) on the digestibility of co-gelatinized wheat starch (WS) and corn starch (CS), as well as explore the potential underlying mechanisms. The results showed a significant reduction in both the rate and extent of digestion for WS and CS after adding the RKP during co-gelatinization. Furthermore, incorporating RKP at 0 % to 20 % levels increased the content of resistant starch (RS) by 34.89 % and 14.43 % in the digested systems of wheat starch and maize starch, respectively, while decreasing the concentration of rapidly digestible starch (RDS) by 12.24 % and 20.39 %, respectively. Furthermore, RKP was found to inhibit α-amylase in a dose-dependent and non-competitive manner. Its interaction with starch occurred through hydrogen bonds and hydrophobic interactions, resulting in a modification of the short-range ordered structure of starch and ultimately leading to inhibition of starch digestion. The physical barrier effect of RKP on starch digestion also contributed to its inhibitory action. Considering the health-related delay in the rate and extent of postprandial starch digestion, Our findings have important inspirational value for the use of red kidney bean protein in hypoglycemic foods.

Effect of Starch on the Solubility of Quinoa Protein Isolates during Heat Treatment

There is increasing interest in developing quinoa products due to their unique nutritional value. Starch and protein are the primary components in quinoa, and the interaction between them affects the quality of quinoa products. This study extracted the starch and protein from quinoa and simulated the thermal processing of quinoa to investigate the effects of starch on the solubility and structure of quinoa protein isolates during heat treatment. The structure of quinoa protein isolates was characterized by fluorescence spectroscopy, Fourier transform infrared spectroscopy, laser particle size analysis, and scanning electron microscopy. The results showed that starch decreased protein solubility, and the maximum solubility was obtained after heating for 5 min. After starch addition during heat treatment, the surface charge distribution of protein changed, the degree of protein aggregation increased, the particle size of proteins increased, the thermal stability increased, and the β-sheet ratio of the proteins increased, suggesting that the protein structure is more ordered, which is the structural foundation of protein solubility decreasing. The research about the interaction between starch and protein and the effects on the solubility of protein could provide a reference for quinoa products processing.

Study on the mechanism of various exogenous proteins with different inhibitions on wheat starch digestion: From the distribution behaviors of protein in the starch matrix

This study aimed to compare the effect of various exogenous proteins on wheat starch (WS) digestion and assess the relevant mechanisms based on the distribution behaviors of exogenous proteins in the starch matrix. Rice protein (RP), soy protein isolate (SPI), and whey protein isolate (WPI) all effectively suppressed the rapid digestion of WS but with different modes. RP increased the slowly digestible starch content, while SPI and WPI increased the resistant starch content. Fluorescence images showed that RP aggregated and competed for effective space with starch granules, while SPI and WPI formed continuous network structures among the starch matrix. These distribution behaviors endowed different reductions in starch digestion by influencing the gelatinization and ordered structure of starch. Pasting and water mobility results suggested all exogenous proteins inhibited the water migration and swelling of starch. Simultaneously, X-ray diffraction and Fourier transform infrared spectroscopy analysis showed that exogenous proteins improved the ordered structures of starch. RP had a more significant effect on the long-term ordered structure, while SPI and WPI had a more effective effect on the short-term ordered structure. These findings will enrich the theory of exogenous protein inhibiting starch digestion and inspire the applications in low-glycemic index food.

Mechanism of synergistic stabilization of emulsions by amorphous taro starch and protein and emulsion stability

Amorphous taro starch (TS)/whey protein isolate (WPI) mixtures were prepared using pasting treatment. The TS/WPI mixtures and their stabilized emulsions were characterized to determine the emulsion stability and the mechanism of synergistic stabilization of emulsions. As WPI content increased from 0% to 13%, the paste final viscosity and retrogradation ratio of the TS/WPI mixture gradually decreased from 3683 cP to 2532 cP and from 80.65% to 30.51%, respectively. As the WPI content increased from 0% to 10%, the emulsion droplet size decreased gradually from 96.81 μm to 10.32 μm, and the storage modulus G' and stabilities of freeze-thaw, centrifugal, and storage increased gradually. Confocal laser scanning microscopy revealed that WPI and TS were mainly distributed at the oil-water interface and droplet interstice, respectively. Thermal treatment, pH, and ionic strength had little influence on the appearance but had different influences on the droplet size and G', and the rates of droplet size and G' increase under storage varied with different environmental factors.

Effect of starch-protein interaction on regulating the digestibility of waxy rice starch under radio frequency treatment with added CaCl2

This study investigated the effect of starch-protein interaction on regulating the digestibility of waxy rice starch under radio frequency (RF) treatment with added salts. The results showed that starch-protein interactions could significantly reduce the digestibility of waxy rice starch (WRS) under synergetic Ca²⁺-RF treatment. With the increase of Ca²⁺ content (0-2 %), the resistant starch content of WRS-WPI, WRS-SPI and WRS-PPI increased from 35.53 %, 36.12 % and 38.78 % to 51.05 %, 52.82 % and 55.93 %, respectively. The addition of appropriate Ca²⁺ content could increase the short-range ordered structure and lamella structure and form a more compact and uniform microstructure. In addition, the interaction between WRS and protein was mainly through hydrogen bonding and hydrophobic interactions during RF treatment. Furthermore, the presence of Ca²⁺ could improve the distribution and mobility of water molecules and regulate the rheological properties of WRS-protein complexes. This study offers theoretical guidance for the design and production of rice starch-based products with lower digestibility.

Effects of rice protein, soy isolate protein, and whey concentrate protein on the digestibility and physicochemical properties of extruded rice starch

Protein, as the second major component in starchy foods, is crucial for its influence on the physicochemical properties and digestibility of starch. However, the effect of different sources of protein on starch digestibility is still unclear. In this paper, the effects of different sources of proteins (rice protein: RP, soybean isolate protein: SPI, and whey concentrate protein: WPC) on structural features, digestibility, and enzyme activity of extruded rice starch were investigated. The addition of all three proteins reduced the starch digestibility of extrudates. Native SPI and WPC suppressed amyloglucosidase activity, and all three proteins exhibited stronger amyloglucosidase inhibition when hydrolyzed. The rheological properties and Fourier transform infrared spectroscopy results revealed the exogenous proteins and starch interacted through non-covalent bonds and improved the ordered structures in the extrudates. The extrusion process also facilitated the formation of a V-type structure. The sum of SDS and RS content of extrudates was negatively correlated with the content of leached amylose and positively correlated with the ratio of 1047/1022 cm^-1 . These findings suggest that the inclusion of exogenous proteins during extrusion can affect starch digestibility through mechanisms such as the interaction with starch molecules, as well as the inhibition of amylase activity. PRACTICAL APPLICATION: This result indicated that the addition of protein during extrusion not only increased the nutritional value of the extrudate, but also decreased the starch digestibility. Extrusion technology can efficiently produce extruded products with protein, expanding further applications of protein in food and providing new healthy staple food options for special populations, such as diabetic and overweight people.

Physicochemical and functional properties of the protein-starch interaction in Chinese yam

Protein-starch interaction has an important impact on the properties of starchy foods rich in protein, but the contribution of the interaction to Chinese yam still remains unclear. This study aimed to characterize the physicochemical and functional properties related to the possible interaction between starch and protein in Chinese yam. Differential scanning calorimetry and rapid viscosity analyzer results revealed that the gelatinization temperature increased in protein and starch cross-linked powder, while the peak viscosity and the setback viscosity decreased. The swelling power and solubility at 80°C and 95°C decreased with increasing protein ratio in the powder. In vitro starch digestibility test indicated that a high protein ratio could rapidly reduce digestible starch, but increase both slowly digestible starch and resistant starch. Protein could act as the physical barrier toward starch against heating and digestion to exert the influence on starch properties. Fourier transform infrared spectroscopy test revealed the interaction between protein and starch. These results revealed the role of protein-starch interaction and provided beneficial information for the utilization of Chinese yam.

Insight into the effect of garlic peptides on the physicochemical and anti-staling properties of wheat starch

The staling of wheat starch in storage seriously damages the quality of starch-based foods, and how to delay the staling has become a topic focus. To solve the problem, this study analyzed the effect of garlic peptides on the physical and retrogradation behaviors of wheat starch during storage. The rheological, pasting, swelling properties, molecular order, water migration, and microstructure of wheat starch gels were evaluated. Our results showed that garlic peptides effectively reduced the storage and loss modulus of wheat starch. The physical properties indicated that garlic peptides suppressed the swelling and gelatinization of starch, which exhibited higher water holding capacity and lower water migration. In addition, garlic peptides incorporated wheat starch exhibited the lowest gel hardness during storage. X-ray diffraction and Fourier Transform Infrared Spectroscopy analysis indicated that garlic peptides could reduce the crystallinity and inhibit the formation of ordered structures in wheat starch gel. The microstructure observation showed that the gel with garlic peptides maintained the integrity of the network structure. Consequently, garlic peptides are expected to be an effective natural additive to inhibit starch staling and provide new insights for starch-based foods.

Different nitrogen fertilizer application in the field affects the morphology and structure of protein and starch in rice during cooking

Nitrogen fertilization is one of the most important cultivation practices that affects the eating quality of rice. During the cooking process, nitrogen fertilizer application in the field changed the structure of protein and starch during cooking, which eventually reduced the rice eating quality. However, the morphology and structure of rice during cooking under high nitrogen fertilizer application in the field have not been explored. The relationship between the morphological and structural changes of rice protein and starch during cooking and the rice eating quality has not been studied. In this study, we conducted field trials at two nitrogen fertilizer levels (0 N and 350 N), and the rice was cooked after harvest. Our results showed that the peak viscosity of rice flour was 3326 cp and 2453 cp at 0 N and 350 N, respectively, and the peak viscosity of rice starch was 3424 cp and 3378 cp, respectively. Rice proteins played an important role in the starch gelatinization properties and thermodynamic properties. High nitrogen fertilizer application increased the protein content of rice from 5.97 % to 11.32 %, and more protein bodies adhered to the surface of amyloplasts eventually inhibiting starch gelatinization. The rice proteins could bind to amylose-lipid complexes during cooking, promoting the formation of V-type diffraction peaks. What is more, under high nitrogen fertilizer, rice protein had more β-sheets, which slowed the entry of water into the interior of starch molecules and prevented the destruction of the short-range ordered structure of starch. Our study provides the possibility to further improve the eating quality of rice under nitrogen fertilizer treatment.

Mechanisms Underlying the Formation of Amylose- Lauric Acid-β-Lactoglobulin Complexes: Experimental and Molecular Dynamics Studies

The aim of the present study was to reveal the mechanisms underlying the formation of ternary complexes with a model system of amylose (AM), lauric acid (LA), and β-lactoglobulin (βLG) using experimental studies and molecular dynamics (MD) simulations. Experimental analyses showed that hydrophobic interactions and hydrogen bonds contributed more than electrostatic forces to the formation of the AM-LA-βLG complex. MD simulations indicated that interactions between AM and βLG through electrostatic forces and hydrogen bonds, and to a less extent van der Waals forces, and interactions between AM and LA through van der Waals forces, were mostly responsible for complex formation. The combination of experimental results and MD simulations has provided new mechanistic insights and led us to conclude that hydrophobic interactions, van der Waals forces between AM and LA, and van der Waals forces and hydrogen bonds between AM and βLG were the main driving forces for the formation of the AM-LA-βLG complex.