Effects of endogenous proteins and lipids on structural, thermal, rheological, and pasting properties and digestibility of adlay seed (Coix lacryma-jobi L.) starch

Strategic exploration of whole grain cereals in modulating the glycaemic response

In the current context, diabetes presents itself as a widespread and complex global health issue. This study explores the significant influence of food microstructure and food matrix components interaction (protein, lipid, polyphenols, etc.) on the starch digestibility and the glycaemic response of post-prandial glycemia, focusing on the potential effectiveness of incorporating bioactive components from whole grain cereals into dietary strategies for the management and potential prevention of diabetes. This study aims to integrate the regulation of postprandial glycaemic homeostasis, including the complexities of starch digestion, the significant potential of bioactive whole grain components and the impact of food processing, to develop a comprehensive framework that combines these elements into a strategic approach to diabetes nutrition. The convergence of these nutritional strategies is analyzed in the context of various prevalent dietary patterns, with the objective of creating an accessible approach to mitigate and prevent diabetes. The objective remains to coalesce these nutritional paradigms into a coherent strategy that not only addresses the current public health crisis but also threads a preventative approach to mitigate future prevalence and impact.

Effects of adding proteins from different sources during heat-moisture treatment on corn starch structure, physicochemical and in vitro digestibility

Proteins impact starch digestion, but the specific mechanism under heat-moisture treatment remains unclear. This study examined how proteins from various sources-white kidney bean, soybean, casein, whey-altered corn starch's structure, physicochemical properties, and digestibility during heat-moisture treatment (HMT). HMT and protein addition could significantly reduce starch's digestibility. The kidney bean protein-starch complex under HMT had the highest resistant starch at 19.74 %. Most proteins effectively inhibit α-amylase, with kidney bean being the most significantly (IC50 = 1.712 ± 0.085 mg/mL). HMT makes starch obtain a more rigid structure, limits its swelling ability, and reduces paste viscosity and amylose leaching. At the same time, proteins also improve starch's short-range order, acting as a physical barrier to digestion. Rheological and low-field NMR analyses revealed that protein enhanced the complexes' shear stability and water-binding capacity. These findings enrich the understanding of how proteins from different sources affect starch digestion under HMT, aiding the creation of nutritious, hypoglycemic foods.

Effects of protein morphological structures on the cereal processing, sensorial property and starch digestion: a review

In cereals, the protein body and protein matrix are usually two morphological protein structures. However, processing treatments can affect protein structures, change protein bodies into the matrix, or induce a change in the matrix structure; therefore, the processing-induced matrix was listed as the third morphological structure of the protein. Previous research on the effect of proteins was mainly based on protein content and composition, but these studies arrived at different conclusions. Studying the effect of protein morphological structures on sensorial property and starch digestion can provide a theoretical basis for selecting cultivars with high sensorial property and help produce low-glycemic index foods for people with diabetes, controlling their postprandial blood sugar. This study aimed to review the distribution and structure of protein bodies, protein matrices, and processing-induced matrices, as well as their influence on cereal sensorial property and starch digestion. Therefore, we determined the protein morphological structures in different cereal cultivars and summarized its impact. Protein bodies mainly have steric stabilization effects on starch gelatinization, whereas the protein matrix serves as a physical barrier surrounding the starch to inhibit water absorption and α-amylase. Processing can change protein morphological structures, enabling protein bodies to act as a physical matrix barrier.

A review of endogenous non-starch components in cereal matrix: spatial distribution and mechanisms for inhibiting starch digestion

As compared with exogenous components, non-starch components (NSCS), such as proteins, lipids, non-starch polysaccharides (NSPs), and polyphenols, inherently present in cereals, are more effective at inhibiting starch digestibility. Existing research has mostly focused on complex systems but overlooked the analysis of the in-situ role of the NSCS. This study reviews the crucial mechanisms by which endogenous NSCS inhibit starch digestion, emphasizing the spatial distribution-function relationship. Starch granules are filled with pores/channels-associated proteins and lipids, embedding in the protein matrix, and maintained by endosperm cell walls. The potential starch digestion inhibition of endogenous NSCS is achieved by altering starch gelatinization, molecular structure, digestive enzyme activity, and accessibility. Starch gelatinization is constrained by endogenous NSCS, particularly cell wall NSPs and matrix proteins. The stability of the starch crystal structure is enhanced by the proteins and lipids distributed in the starch granule pores and channels. Endogenous polyphenols greatly inhibit digestive enzymes and participate in the cross-linking of NSPs in the cell wall space, which together constitute a physical barrier that hinders amylase diffusion. Additionally, the spatial entanglement of NSCS and starch under heat and non-heat processing conditions reduces starch accessibility. This review provides novel evidence for the health benefits of whole cereals.

Effect of oleic acid-rich rapeseed oil on the physicochemical, rheological, and structural characteristics of wheat dough

Some wheat-based foods require different doses of oil to moderate quality of dough during processing and the influence mechanisms remain unclear. Therefore, the effect of rapeseed oil addition on physicochemical characteristics and fine structure of dough and underlying mechanism were elucidated by rheometer, scanning microscope and molecular spectroscopic method. Results showed that compared with native dough (without exogenous rapeseed oil), the addition of rapeseed oil changed the fine structure, improved extensibility, but reduced viscoelasticity of the dough. Moreover, high addition especially 20 wt% oil (based on wheat flour) significantly changed gelatinization and retrogradation behaviors of the dough, whilst disrupted gluten network and increased random coil content (32.1%) of dough except that decreased its α-helix (21.2%), β-sheet (23.1%), disulfide bond (7.9 μmol/g) compared with native dough which were 16.3%, 29.2%, 33.1%, 11.0 μmol/g, respectively. Results in the study could provide a certain understanding for application of vegetable oils in wheat-based products.

Influence of gelatinized octenyl succinic anhydride-modified waxy adlay seed starch on the properties of astaxanthin-loaded emulsions: Emulsion properties, stability and in vitro digestion properties

Octenyl succinic anhydride (OSA)-modified starch is a commonly used food emulsifier and its emulsifying properties are positively correlated with the degree of substitution (DS). However, the maximum concentration of OSA in starch approved by the FDA and the China National Food Safety Standards is 3%. This study aims to enhance the emulsifying properties of OSA-modified waxy adlay seed starch by gelatinization under a limited DS and investigate its use in preparing delivery systems. The gelatinized OSA starch exhibited a more flexible macromolecular structure and better emulsifying activity (20.19 m2/g). The gelatinized OSA starch-stabilized astaxanthin-loaded emulsions showed high retention of astaxanthin (>50%) and long-term stability (56 days). In vitro digestion, the emulsion system showed a protective effect on astaxanthin, and the bioaccessibility of astaxanthin was increased to 16.32%. This study indicated that gelatinization could enhance the emulsifying properties of OSA starch, and this starch-stabilized emulsion was an effective system for astaxanthin.

In vitro digestibility of starch and protein in cooked wheat and oat whole flours: A comparative study

Whole grains have garnered significant attention in the food industry due to their retained abundant nutrients when compared to refined grains. However, limited knowledge exists regarding the digestive behavior of starch and protein. This study compared the physicochemical properties and in vitro starch and protein digestibility of cooked whole wheat flour (WF) and naked oat flour (NOF), and evaluated the impact of endogenous components (protein, lipid, β-glucan, and polyphenol) on the physicochemical properties and digestibility of WF and NOF. The result indicated that the final hydrolysis rate of WF samples (starch: 23.2 %∼46.3 %; protein: 23.1 %∼63.0 %) was lower than that of NOF samples (starch: 32.1 %∼61.0 %; protein: 32.3 %∼63.6 %). The removal of different endogenous components led to improved digestibility of starch and protein in both WF and NOF. This study contributes to the understanding of the starch and protein digestibility of whole grains, consequently facilitating the development of whole grain products.

Effects of cold plasma pretreatment combined with sodium periodate on property enhancement of dialdehyde starch prepared using native maize starch

This study represents the inaugural investigation into the effect of cold plasma (CP) pretreatment combined with sodium periodate on the preparation of dialdehyde starch (DAS) from native maize starch and its consequent effects on the properties of DAS. The findings indicate that the maize starch underwent etching by the plasma, leading to an increase in the particle size of the starch, which in turn weakened the rigid structure of the starch and reduced its crystallinity. Concurrently, the plasma treatment induced cleavage of the starch molecular chain, resulting in a decrease in the viscosity of the starch and an enhancement of its fluidity. These alterations facilitated an increased contact area between the starch and the oxidising agent sodium periodate, thereby augmenting the efficiency of the DAS preparation reaction. Consequently, the aldehyde group content was elevated by 9.98 % compared to the conventional DAS preparation methodology. Therefore, CP could be an efficient and environmentally friendly non-thermal processing method to assist starch oxidation for DAS preparation and property enhancement.

Effect of endogenous protein and lipid removal on the physicochemical and digestion properties of sand rice (Agriophyllum squarrosum) flour

The study investigated the effect of removing protein and/or lipid on the physicochemical characteristics and digestibility of sand rice flour (SRF). Morphological images showed that protein removal had a greater impact on exposing starch granules, while lipids acted as an adhesive. The treatment altered starch content in SRF samples, leading to increased starch crystallinity, denser semi-crystalline region, lower onset gelatinization temperature (To), higher peak viscosity and gelatinization enthalpy (ΔH), where Protein removal showed a more pronounced effect on altering physicochemical properties compared to lipid removal. The research revealed a positive correlation between rapidly digestible starch (RDS), maximum degree of starch hydrolysis (C∞), digestion rate constant (k) values and 1047/1022 cm-1 ratio, showing a strong connection between short-range structure and starch digestibility. The presence of endogenous proteins and lipids in SRF hinder digestion by restricting starch swelling and gelatinization, and physically obstructing enzyme-starch interaction. Lipids had a greater impact on starch digestibility than proteins, possibly due to their higher efficacy in reducing digestibility, higher lipid content with greater potential to form starch-lipid complexes. This study provides valuable insights into the interaction between starch and proteins/lipids in the sand rice seed matrix, enhancing its applicability in functional and nutritional food products.

A review of the effects of fermentation on the structure, properties, and application of cereal starch in foods

Fermentation is one of the oldest food processing techniques known to humans and cereal fermentation is still widely used to create many types of foods and beverages. Starch is a major component of cereals and the changes in its structure and function during fermentation are of great importance for scientific research and industrial applications. This review summarizes the preparation of fermented cereals and the effects of fermentation on the structure, properties, and application of cereal starch in foods. The most important factors influencing cereal fermentation are pretreatment, starter culture, and fermentation conditions. Fermentation preferentially hydrolyzes the amorphous regions of starch and fermented starches have a coarser appearance and a smaller molecular weight. In addition, fermentation increases the starch gelatinization temperature and enthalpy and reduces the setback viscosity. This means that fermentation leads to a more stable and retrogradation-resistant structure, which could expand its application in products prone to staling during storage. Furthermore, fermented cereals have potential health benefits. This review may have important implications for the modulation of the quality and nutritional value of starch-based foods through fermentation.

The impact of different soluble endogenous proteins and their combinations with β-glucan on the in vitro digestibility, microstructure, and physicochemical properties of highland barley starch

The impacts of protein types and its interaction with β-glucan on the in vitro digestibility of highland barley starch were investigated through analyzing physicochemical and microstructural properties of highland barley flour (HBF) after sequentially removing water- (WP), salt- (SP), alcohol- (AP) and alkali-soluble (AlkP) proteins. Resistant starch (RS) increased significantly in HBF after removing WP and SP, and RS of HBF was lower than that of without β-glucan. After removing WP, SP and AP, swelling powers of HBF without β-glucan (9.33-9.77) were higher than those of HBF (12.09-15.95). Trends of peak viscosity and peak temperature (thermal degradation temperature) were similar as swelling power, and HBF without AP showed the highest peak temperature (310.33 °C). Removals of different proteins improved the crystalline structure and short-range order of starch. There was a blue shift in T2 values and an opposite change in free water proportion. The matrix on starch surface was mainly formed by AP and AlkP, which could be aggregated by β-glucan. But, the inhibitory effect of AP or AlkP was stronger than that of proteins combined with β-glucan. These results help in the development of starch-based foods with different digestive properties by combining different protein types with β-glucan.

Combined effect of heat moisture and ultrasound treatment on the physicochemical, thermal and structural properties of new variety of purple rice starch

The advantages of physically modifying starch are evident: minimal environmental impact, no by-products, and straightforward control. The impact of dual modification on starch properties is contingent upon modification conditions and starch type. Herein, we subjected purple rice starch (PRS) to heat-moisture treatment (HMT, 110 °C, 4 h) with varying moisture content, ultrasound treatment (UT, 50 Hz, 30 min) with different ultrasonic power, and a combination of HMT and UT. Our findings reveal that UT following HMT dispersed starch granules initially aggregated by HMT and resulted in a rougher granule surface. Rheological analysis showcased a synergistic effect of HMT and UT, enhancing the fluidity of PRS and reinforcing its resistance to deformation in paste form. The absorbance ratio R1047/1015 indicates that increased moisture content during HMT and high ultrasound power for UT reduced the short-range order degree (1.69). However, the combined HMT-UT exhibited an increased R1047/1015 (1.38-1.64) compared to HMT alone (1.29-1.45), likely due to short-chain rearrangement. Notably, the A-type structure of PRS remained unaltered, but overall crystallinity significantly decreased (23.01 %-28.56 %), consistent with DSC results. In summary, physical modifications exerted significant effects on PRS, shedding light on the mechanisms governing the transformation of structural properties during HMT-UT.

Influence of starch-protein interactions on the digestibility and chemical properties of a 3D-printed food matrix based on salmon by-product proteins

This study evaluated the influence of starch-protein interactions on the chemical properties and digestibility of a 3D-printed gel based on salmon by-product protein. Changes in the starch-protein interactions of the stable cornstarch (CS, 15%) and salmon protein isolate (SPI, 4%-12%) printable gels during the in vitro gastrointestinal digestion process were studied by principal component analysis. Protein-rich printed gels increased resistant starch content by 18.05%. Changes in chemical properties and the starch-protein concentration of the gels during the digestion process were highly correlated. The CS-SPI gels in the gastric and intestinal phases exhibited lower α-helix/β-sheet ratio and fluorescence intensity values, whereas surface hydrophobicity increased. This resulted in more ordered structures with a high level of molecular interaction that inhibited enzymatic hydrolysis. This study provides crucial information about the transformations of starch-protein interactions during the digestibility of 3D-printed food matrices as an alternative source of nutrients with a high nutritional quality.

Effect of starch and protein on eating quality of japonica rice in Yangtze River Delta

This study examined four types of japonica rice from Yangtze River Delta, categorized based on amylose content (AC) and protein content (PC): high AC with high PC, high AC with low PC, low AC with high PC, and low AC with low PC. It systematically explored the effect of starch, protein and their interactions on eating quality of japonica rice. Rheological analysis revealed that increased amylose, long chains amylopectin or protein levels during cooking strengthen starch-protein interactions (hydrogen bonding), forming a firm gel network. Scanning electron microscopy showed that increased amylose, long chains amylopectin or protein levels made protein and starch more stable in combination during cooking, limiting starch structure cleavage. Therefore, the eating quality of high AC in similar PC japonica rice and high PC in similar AC japonica rice were poor. Further, correlation and random-forest analysis (RFA) identified amylose as the most influential factor in starch-protein interactions affecting rice eating quality, followed by amylopectin and protein. RFA also revealed that in high AC japonica rice, the interactions of Fb3 and albumin with amylose were more conducive to forming good eating quality. In low AC japonica rice, the interactions of Fb2 and prolamin with amylose were more beneficial.

New Insight into the Effects of Endogenous Protein and Lipids on the Enzymatic Digestion of Starch in Sorghum Flour

The effects of endogenous lipids and protein in sorghum flour on starch digestion were studied following the depletion of lipids and/or protein and after the reconstitution of separated fractions. The removal of protein or lipids moderately increases the digestibility of starch in raw (uncooked) sorghum flour to values close to those for purified starch. Rapid Visco Analyzer data (as a model for the cooking process) show that cooked sorghum flours with lipids have a lower starch digestibility than those without lipids after RVA processing, due to the formation of starch-lipid complexes as evidenced by their higher final viscosity and larger enthalpy changes. Additionally, the formation of a starch-lipid-protein ternary complex was identified in cooked sorghum flour, rather than in a reconstituted ternary mixture, according to the unique cooling stage viscosity peak and a greater enthalpy of lipid complexes. After heating, the sorghum flour showed a lower digestibility than the depleted flours and the reconstituted flours. The results indicate that the natural organization of components in sorghum flour is an important factor in facilitating the interactions between starch, lipids, and protein during RVA processing and, in turn, reducing the starch digestion.

Reduction of starch granule surface lipids alters the physicochemical properties of crosslinked maize starch

Normal and waxy maize starches with and without removal of starch granule surface lipids (SGSLs) were crosslinked by POCl3 (0.01 %, 0.1 % and 1 %). Crosslinked starches showed lower swelling power and solubility, but higher pasting viscosity, pseudoplasticity, thixotropy, storage modulus and loss modulus. Crosslinking increased the double helical structure but decreased the crystallinity for waxy maize starch. The phosphorus content of crosslinked waxy maize starches after SGSLs removal increased, indicating SGSLs removal promoted crosslinking. SGSLs removal increased G' and G" for crosslinked waxy maize starches. SGSLs removal increased SP and solubility and decreased pasting and rheological parameters of starches. With increased POCl3 dosage, the effect of SGSLs removal on starch properties was gradually suppressed by crosslinking. Waxy and normal maize starches showed significantly different changes with crosslinking and SGSLs removal, and the presence of amylose seemed to impede the effect of crosslinking and SGSLs removal. The removal of SGSLs could extend the application of crosslinked starch in frozen foods, drinks, and canned foods as thickener and stabilizer, due to its better hydrophilicity and viscous liquid-like rheological properties. The study will assist carbohydrate chemists and food processors in developing new food products.

Effect of non-starch components on the structural properties, physicochemical properties and in vitro digestibility of waxy highland barley starch

Highland barley (HB) endosperm with an amylose content of 0-10 % is called waxy HB (WHB). WHB is a naturally slow-digesting grain, and the interaction between its endogenous non-starch composition and the WHB starch (WHBS) has an important effect on starch digestion. This paper focuses on the mechanisms by which the components of β-glucan, proteins and lipids affect the molecular, granular, crystalline structure and digestive properties of WHBS. After eliminating the main nutrients except for starch, the estimated glycemic index (eGI) of the samples rose from 62.56 % to 92.93 %, and the rapidly digested starch content increased from 60.81 % to 98.56 %, respectively. The resistant starch (RS) content, in contrast, dropped from 38.61 % to 0.13 %. Comparatively to lipids, β-glucan and protein contributed more to the rise in eGI and decline in RS content. The crystalline characteristics of starch were enhanced in the decomposed samples. The samples' gelatinization properties improved, as did the order of the starch molecules. Protein and β-glucan form a dense matrix on the surface of WHBS particles to inhibit WHBS digestion. In summary, this study revealed the mechanism influencing the digestibility of WHBS from the perspective of endogenous non-starch composition and provided a theoretical basis to develop slow-digesting foods.

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.

A review of starch swelling behavior: Its mechanism, determination methods, influencing factors, and influence on food quality

Swelling behavior involves the process of starch granules absorbing enough water to swell and increase the viscosity of starch suspension under hydrothermal conditions, making it one of the important aspects in starch research. The changes that starch granules undergo during the swelling process are important factors in predicting their functional properties in food processing. However, the factors that affect starch swelling and how swelling, in turn, affects the texture and digestion characteristics of starch-based foods have not been systematically summarized. Compared to its long chains, the short chains of amylose easily interact with amylopectin chains to inhibit starch swelling. Generally, reducing the swelling of starch could increase the strength of the gel while limiting the accessibility of digestive enzymes to starch chains, resulting in a reduction in starch digestibility. This article aims to conduct a comprehensive review of the mechanism of starch swelling, its influencing factors, and the relationship between swelling and the pasting, gelling, and digestion characteristics of starch. The role of starch swelling in the edible quality and nutritional characteristics of starch-based foods is also discussed, and future research directions for starch swelling are proposed.

Modulating the glycemic response of starch-based foods using organic nanomaterials: strategies and opportunities

Traditionally, diverse natural bioactive compounds (polyphenols, proteins, fatty acids, dietary fibers) are used as inhibitors of starch digestive enzymes for lowering glycemic index (GI) and preventing type 2 diabetes mellitus (T2DM). In recent years, organic nanomaterials (ONMs) have drawn a great attention because of their ability to overcome the stability and solubility issues of bioactive. This review aimed to elucidate the implications of ONMs in lowering GI and as encapsulating agents of enzymes inhibitors. The major ONMs are presented. The mechanisms underlying the inhibition of enzymes, the stability within the gastrointestinal tract (GIT) and safety of ONMs are also provided. As a result of encapsulation of bioactive in ONMs, a more pronounced inhibition of enzymes was observed compared to un-encapsulated bioactive. More importantly, the lower the size of ONMs, the higher their inhibitory effects due to facile binding with enzymes. Additionally, in vivo studies exhibited the potentiality of ONMs for protection and sustained release of insulin for GI management. Overall, regulating the GI using ONMs could be a safe, robust and viable alternative compared to synthetic drugs (acarbose and voglibose) and un-encapsulated bioactive. Future researches should prioritize ONMs in real food products and evaluate their safety on a case-by-case basis.

The effect of heat-moisture treatment changed the binding of starch, protein and lipid in rice flour to affect its hierarchical structure and physicochemical properties

This study investigated the effect of removing proteins, lipids and starch on the structure, physicochemical properties and digestion properties of rice flour (with 30% moisture) treated with heat moisture treatment (HMT). According to the results, HMT caused the adhesion and agglomeration of the rice flour, promoted the binding between starch, protein and lipid molecular chains and led to the formation of complexes (especially starch-lipid complexes), which hindered the removal of non-starch components. Compared to the untreated rice flour, the HMT treated lipid-removal rice flour had small changes in their crystallinity, gelatinization temperature and viscosity property. After removing protein, the crystallinity, peak viscosity, final viscosity, breakdown and starch digestibility were sharply increased. In particular, the peak viscosity increased from 811 cP to 1746 cP and the enthalpy change increased from 5.33 J/g to 10.18 J/g. These findings are helpful in understanding the contribution of removing endogenous proteins and lipids to the physicochemical changes of HMT treated rice flour during its heating process and thus can be helpful in controlling the quality of rice flour through HMT.

DPP-IV Inhibitory Peptides from Coix Seed Prolamins: Release, Identification, and Analysis of the Interaction between Key Residues and Enzyme Domains

Dipeptidyl peptidase IV (DPP-IV) inhibitory peptides can regulate type 2 diabetes by inhibiting the cleavage of glucagon-like peptide-1 and prolonging its half-life. The development of DPP-IV inhibitory peptides is still a hot topic. The primary structure of coix seed prolamins contains peptide sequence fragments that potentially inhibit DPP-IV; however, limited information is available regarding the extraction of peptides from coix seeds and the analysis of their conformational relationships. In this study, novel coix seed prolamin-derived peptides were obtained through single hydrolysis and double-enzyme stepwise hydrolysis. The inhibitory activity of these peptides against DPP-IV was evaluated to explore new functional properties of coix seeds. The results evidenced that the step-by-step enzymolysis (papain and alcalase) compared to single enzymolysis promoted the secondary structure disruption of the hydrolysates, enhanced the β-turn structure, significantly increased the content of peptides below 1 kDa, and exhibited a substantial increase in DPP-IV inhibitory activity (97% inhibition). Three nontoxic DPP-IV inhibitory peptides, namely, LPFYPN, TFFPQ, and ATFFPQ (IC50 = 70.24, 176.87, 268.31 μM), were isolated and identified. All three peptides exhibited strong interactions with DPP-IV (all KA values >103). LPFYPN exhibited competitive inhibition, while TFFPQ and ATFFPQ demonstrated mixed competitive-noncompetitive inhibition. Hydrogen bonding and hydrophobic interactions were the main contributors to the coix seed prolamin peptides binding to DPP-IV. The central residue was a key amino acid in the parent peptide sequence, forming a more stable π-π stacking with residues in the active pocket, which may facilitate peptide activity. This study provides theoretical support for the development of coix seed-derived hypoglycemic peptides.

Effect of protein on the gelatinization behavior and digestibility of corn flour with different amylose contents

The effects of endogenous proteins on the gelatinization behavior and digestibility of waxy corn flour (WCF), normal corn flour (NCF) and high amylose corn flour (HCF) were systematically investigated. Microscopic characteristics showed that the proteins surrounded multiple starch granules, which led to an increase in the particle size of the corn flour, but no significant change in the relative crystallinity. Small angle x-ray scattering experiments during pasting revealed that the starch granules of NCF remained compact, while WCF and HCF were relatively loose. Carbon-13 nuclear magnetic resonance spectroscopy (13C NMR) showed that the proteins retained the helical structure of starch allowing NCF to have a higher Resistant starch(RS) content. The presence of protein led to a decrease in swelling power, viscosity, and in vitro digestibility of starch, and a noticeable increase in gelatinization temperature and thermal stability. RS increased most significantly in NCF from 3.86 % to 15.27 %. The effect of protein on the water activity of starch with different amylose contents after pasting was also inconsistent. This study will contribute to the understanding of the interaction between starch and protein in corn flours with different amylose contents and contribute to the development of corn flours.

Effect of oil extraction on physicochemical and structural properties of starch isolated from acorn (Quercus brantii)

Acorn (Quercus brantii) is a rich source of starch. Since the presence of lipids affects the physicochemical properties of starch and the extraction of nutritious acorn oil and its starch is economical, it's essential to study the acorn starch characteristics before and after oil extraction. Firstly, the best condition for reaching the maximum extraction yield of acorn starch (AS) was determined, and defatted acorn starch (DAS) was extracted in the same conditions. Then the physicochemical properties of both samples were compared. The structural properties were investigated by Scanning Electron Microscopy images. The maximum yield of AS was obtained in a 1:10 ratio (acorn flour: water) at 45 °C and 180 min. Results demonstrated significant differences between color parameters and fat content (0.65 ± 0.04 and 12 ± 0.02) of AS and DAS. Also, DAS had higher swelling power, solubility, and lower turbidity than AS. The X-ray diffraction pattern showed that AS was C-type with relative crystallinity of 27.77 %. Pasting, thermal, and textural properties reflected the higher viscosity, gelatinization, retrogradation, and hardness for DAS compared to AS. Consequently, all of these analyses exhibited structural changes in acorn starch by removing lipids from acorn flour and provided essential information for further applications of acorn starch in different industries.

Analysis of Hormone Regulation on Seed Germination of Coix Based on Muli-Omics Analysis

Seed germination is an important stage of growth and reproduction and plays an important role in the life cycle of spermatophyte. It is co-determined by both genetic and environmental factors, and plant hormone regulation may be a highly conservative mechanism. Coix lachryrma-jobi (coix) is a grain with balanced nutrition for medicine and food and has substantial production value. It is an important part of agricultural production, and the efficiency of seed germination after sowing is a key link. In this study, coix species "small white shell Xingren" was used as the experimental material, and changes in gene expression levels and metabolite enrichment in seeds were identified by transcriptome and metabonomic analysis before and after seed germination. A total of 599 metabolites, including those from amino acid metabolism, sugar metabolism, and fatty acid metabolism, were significantly increased in germinating coix. Simultaneously, 10,929 differentially expressed genes (DEGs) were identified, and functional clusters of genes were also significantly clustered in hormone-signaling and glucose and fatty acid metabolism. In addition, this study found that a considerable number of hormone-signaling genes were significantly up-regulated during seed germination, activating multiple metabolic processes. The results of our conjoint analysis of multi omics showed that glucose and fatty acid metabolism played an important role in seed germination under hormone regulation.

Improving the emulsification performance of adlay seed starch by esterification combined with ultrasonication and enzymatic treatment

In this study, superior modified starch was prepared using ultrasonic and enzymatic treatments to confirm the potential of using adlay seed starch (ASS) in Pickering emulsions. Octenyl succinic anhydride (OSA)-modified starches, such as OSA-UASS, OSA-EASS, and OSA-UEASS, were prepared using ultrasonic, enzymatic, and combined ultrasonic and enzymatic treatments, respectively. The effects of these treatments on the structure and properties of ASS were evaluated to elucidate their influence on starch modification. Ultrasonic and enzymatic treatments improved the esterification efficiency of ASS by changing its external and internal morphological characteristics and the crystalline structure to provide more binding sites for esterification. The degree of substitution (DS) of ASS modified by these pretreatments was 22.3-51.1 % higher than that of the OSA-modified starch without pretreatment (OSA-ASS). Fourier transform infrared and X-ray photoelectron spectroscopy results confirmed the esterification. Small particle size and near-neutral wettability indicated that OSA-UEASS was the promising emulsification stabilizer. The emulsion prepared using OSA-UEASS exhibited better emulsifying activity and emulsion stability and long-term stability for up to 30 days. These amphiphilic granules with improved structure and morphology were used to stabilize a Pickering emulsion.

Effects of the degree of substitution of octenyl succinic anhydride on the physicochemical characteristics of adlay starch

Impact of octenyl succinic anhydride (OSA) esterification on the structural, thermal, pasting, and emulsifying characteristics of adlay starch was investigated. The degree of substitution (DS) increased significantly from 0.008 to 0.025 with increasing OSA quantity, and the bands intensity at 1724 cm^-1 and 1572 cm^-1 in Fourier transform infrared spectroscopy increased with increasing DS. OSA modified starch showed unaltered orthorhombic diffraction pattern and morphological structure in native adlay starch, but gelatinization temperatures and enthalpy decreased significantly. Higher DS values lowered iodine binding capacity (from 1.37 to 0.77) and a shift in the maximum absorbance wavelength toward the shortwave direction was observed (from 530 nm to 510 nm). Significant increases were observed in peak, through, breakdown and final viscosities upon OSA esterification, while the pasting temperature decreased. Furthermore, contact angles increased significantly from 27.4° to 73.4° with increasing DS, and OSA-starch exhibited superior emulsion stability. Therefore, esterification with OSA effectively modified adlay starch to meet industrial demands and enhance its functional properties.

Factors influencing the starch digestibility of starchy foods: A review

Starchy foods are a major energy source of the human diet, their digestion is closely related to human health. Most foods require lots of processing before eating, therefore, many factors can influence starch digestibility. The factors that affect the digestibility of starches have been widely discussed previously, but the extracted starches in those studies were different from those present within the actual food matrix. This review summarizes the factors influencing the starch digestibility in starchy foods. Endogenous non-starch components hinder the starch digestive process. Food ingredients and additives decrease starch digestibility by inhibiting the activity of digestive enzymes or hindering the contact between starch and enzymes. Storage induce the retrogradation of starch, decreasing the digestibility of foods. Therefore, preparing starchy foods with whole grains, processing them as little as possible, using food additives reasonably, and storage conditions may all be beneficial measures for the production of low GI foods.

Effect of the Amylose Nanoscale Polymerization Index on the Digestion Kinetics and Mechanism of Recombinant Chinese Seedless Breadfruit Starch Triadic Complexes

The demand for multicomponent foods to meet human energy and nutritional needs has been increasing; however, few studies have addressed the theoretical basis for their preparation. We investigated the effect of the nanoscale polymerization index (DPw) of amylose on the logarithm of slope plot-based kinetics and the mechanism of digestion of starch-lauric acid-β-lactoglobulin protein complexes. Amylose from each of the five Chinese seedless breadfruit species was mixed with breadfruit amylopectin with the highest resistant starch (RS) content to form starch ternary complexes with various amylose DPws. All five complexes exhibited V-type crystalline diffraction and rod-like molecular configuration. Characteristic X-ray diffraction peaks and Fourier transform-infrared spectra of the ternary complexes revealed similar molecular configurations. As the amylose DPw increased, the complexing index, relative crystallinity, short-range order, weight-average molar mass, molecular density index, gelatinization temperature, decomposition temperature, RS, slowly digestible starch (SDS), and speed rate constants at the second hydrolysis stage (k₂) increased, whereas the semicrystalline lamellae thickness, mass fractal structure parameter, average characteristic crystallite unit length, radius of gyration, fractal dimension and cavities of granule surface microstructure, final viscosity, interval speed rate from SDS to RS, equilibrium concentration, and glycemic index decreased. The digestion kinetics exhibited highly significant variation according to the physiochemical properties and multiscale supramolecular structure (r > 0.99 or r < -0.99, p < 0.01). Together, these results identify amylose DPw as an important structural factor that markedly affects the kinetics and mechanism of ternary complex digestion and provide a new theoretical direction for the production of starch-based multicomponent foods.

The Impact of High-Pressure Homogenization and Thermal Processing on the Functional Properties of De-Fatted Chickpea Flour Dispersion

Defatted chickpea flour (DCF), a rich source of protein and starch, is frequently utilized in the food industry. Two crucial methods of modifying food materials are high-pressure homogenization (HPH) and heat treatment (HT). This study investigates the effect of co-treatment (HPH-HT) on the particle size, rheological behavior, and thermal characteristics of DCF suspensions. The results indicate that both HPH and HT can result in a more uniform distribution of particle size in the suspensions. The effect of HPH on G' was observed to be reductionary, whereas HT increased it. Nevertheless, the HPH-HT treatment further amplified G' (notably in high-concentration DCF), which demonstrates that the solid properties of DCF are improved. The apparent viscosity of the suspensions increased with individual and combined treatments, with the HPH-HT treatment of DCF12% exhibiting the most significant increase (from 0.005 to 9.5 Pa·s). The rheological behavior of DCF8% with HPH-HT treatment was found to be comparable to that of DCF12% treated only with HT. In conclusion, HPH-HT treatment shows a synergistic impact of HPH and HT on the rheological properties of DCF suspensions, however, it has limited effect on the particle size distribution and freeze-thaw stability.

Extrusion assisted interaction of rice starch with rice protein and fibre: Effect on physicochemical, thermal and in-vitro digestibility characteristics

Rice starch has high digestibility due to its large carbohydrate content. Macromolecular enrichment of starch has the tendency to retard rate of starch hydrolysis. Hence, the current investigation was aimed to check the combined effect of extrusion assisted addition of rice protein (0, 10, 15 and 20 %) and fibre (0, 4, 8 and 12 %) to rice starch on physico-chemical and in-vitro digestibility characteristics of starch extrudates. It was observed from the study that 'a' and 'b' values, pasting temperature and resistant starch of starch blends and extrudates increased with the addition of protein and fibre. However, lightness value, swelling index, pasting properties and relative crystallinity of blends and extrudates decreased with the addition of protein and fibre. Maximum increase in thermal transition temperatures was observed for ESP₃F₃ extrudates due to absorption capacity of protein molecules which led to late onset of gelatinization. Therefore, enrichment of protein and fibre to rice starch during extrusion can be considered as a novel approach to reduce rate of rice starch digestion for catering nutritional requirements of diabetic population.

Impact of okara on quality and in vitro starch digestibility of noodles: The view based on physicochemical and structural properties

The development of cereal foods with slow starch digestibility is important for the general improvement of human health. In this study, the quality properties of noodles with added okara, in vitro starch digestibility, and the underlying mechanisms of the influence of okara on noodles were studied. Low concentrations (5 and 10 %) of okara improved the texture, cooking, and sensory properties of the noodles. Okara decreased the rapidly digestible starch (RDS) content, increased the resistant starch (RS) content, and reduced the predicted glycaemic index (pGI) of noodles. The pasting viscosity, thermal stability, and dynamic rheological results indicated that okara improved the starch crystallite stability of wheat flour and viscoelasticity of dough. Moreover, Fourier transform infrared (FTIR) spectroscopy showed that okara promoted the formation of starch-lipid complexes and improved the short-range structural order of starch. Additionally, microstructure imaging and protein network analysis (PNA) indicated that low addition of okara promoted the compactness of the okara-gluten-starch matrix, thus reducing the contact between starch and hydrolytic enzymes. These results reveal the effect of okara on the quality properties and starch digestibility in a starch-gluten complex system.

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.

Effects of Far-Infrared Radiation Drying on Starch Digestibility and the Content of Bioactive Compounds in Differently Pigmented Rice Varieties

Far infrared radiation (FIR) was applied to six rice varieties with different coloring of the pericarp (purple, red or non-pigment). Changes were determined in amylose content, in gelatinization parameters, in the content of bioactive compounds, in antioxidant activity and in the in vitro digestibility of pigmented rice as affected by FIR. The highest contents of amylose, total phenolic (TPC), total flavonoid (TFC) and total anthocyanins (TAC) were found in the purple and red varieties. Overall, FIR increased TPC, TFC and TAC, including antioxidant capacity. Quercetin and apigenin contents were increased while rutin and myricetin decreased significantly (p < 0.05) in all FIR-dried samples. Dephinidin, cyanidin-3-glucosides and pelargonidin increased after FIR treatment. Mostly, FIR-treated samples were found to have greater gelatinization enthalpy, compared with unheated rice samples. FIR-dried rice showed lower starch digestibility (25−40%) than unheated rice. This research suggested that the specific genotype of rice had the greatest influence on amylose content in pigmented rice, while FIR drying had no further effect. Our results suggest that FIR could enhance the content of the bioactive compounds capable of inhibiting α-amylase, thereby lowering starch digestibility. Hence, FIR may be considered as an appropriate drying method for pigmented rice regarding health benefits.

Physicochemical, Pasting, and Thermal Properties of Native Corn Starch-Mung Bean Protein Isolate Composites

Starch is widely used in food and non-food industries because of its unique characteristics. However, native starch shows some weaknesses that restrict its applications. Recently, some studies have demonstrated the benefits of using protein to overcome these limitations. Therefore, the aim of the present study was to investigate the effect of mung bean protein isolate (MBPI) (2%, 4%, 6%, and 8%) on the physicochemical, pasting, and thermal properties of native corn starch (NCS), as a novel starch-protein composite. Higher swelling power (SP), water absorbance capacity (WAC), and solubility values of NCS were observed with increasing MBPI concentration. Additionally, by the addition of MBPI, the rapid visco analyzer (RVA) showed a reduction in pasting temperature (77.98 to 76.53 °C), final viscosity (5762 to 4875 cP), and setback (3063 to 2400 cP), while the peak viscosity (4691 to 5648 cP) and breakdown (1992 to 3173 cP) increased. The thermal properties of NCS/MBPI gels investigated by differential scanning calorimetry (DSC) showed higher onset, peak, and conclusion temperatures (69.69 to 72.21 °C, 73.45 to 76.72 °C, and 77.75 to 82.26 °C, respectively), but lower gelatinization enthalpy (10.85 to 8.79 J/g) by increasing MBPI concentration. Fourier transform infrared spectroscopy (FT-IR) indicated that the addition of MBPI decreased the amount of hydrogen bonds within starch. Furthermore, after three cycles of freeze-thaw shocks, the syneresis of NCS-MBPI composites decreased from 38.18 to 22.01%. These results indicated that the MBPI could improve the physicochemical properties of NCS, especially its syneresis and retrogradation characteristics.

Mechanism of peptides from rice hydrolyzed proteins hindering starch digestion subjected to hydrothermal treatment

Clarifying the interactions between food components is critical in designing carbohydrate-based foods with low digestibility. To date, the hindering effect of starch-protein interactions on starch digestion has attracted extensive attention. In this study, rice proteins were further hydrolyzed, and rice peptides (RP) with different molecular weights were obtained by ultrafiltration. The effects and possible mechanisms of RP with different molecular weights on the structure, thermal properties, and in vitro digestibility of cooked rice starch were investigated. All peptides slowed the digestion of rice starch in a concentration-dependent manner. A concentration of 10% RP_>10 decreased the rapidly digestible starch content from 68.02 to 45.90 g/100 g, and increased the resistant starch content from 17.54 to 36.54 g/100 g. The addition of RP improved the thermal stability of the starch and reduced the amount of leached amylose. Infrared analysis shows that strong hydrogen bonds formed between RP (especially RP_>10) and starch during co-gelatinization. In addition, RP improved the compactness of aggregated structure and played an important role in hindering the enzymatic hydrolysis of starch. These results enrich the theory of starch-protein interactions and have important implications for the development of carbohydrate-based foods with low digestibility and protein functional foods.

Effects of Mung Bean (Vigna radiata) Protein Isolate on Rheological, Textural, and Structural Properties of Native Corn Starch

It is critical to understand the starch–protein interactions in food systems to obtain products with desired functional properties. This study aimed to investigate the influence of mung bean protein isolate (MBPI) on the rheological, textural, and structural properties of native corn starch (NCS) and their possible interactions during gelatinization. The dynamic rheological measurements showed a decrease in the storage modulus (G’) and loss modulus (G”) and an increase in the loss factor (tan δ), by adding MBPI to NCS gels. In addition, the textural properties represented a reduction in firmness after the addition of MBPI. The Scanning electron microscope (SEM) images of the freeze-dried NCS/MBPI gels confirmed that the NCS gel became softer by incorporating the MBPI. Moreover, X-ray diffraction (XRD) patterns showed a peak at 17.4°, and the relative crystallinity decreased with increasing MBPI concentrations. The turbidity determination after 120 h refrigerated storage showed that the addition of MBPI could reduce the retrogradation of NCS gels by interacting with leached amylose. Additionally, the syneresis of NCS/MBPI gels decreased at 14 days of refrigerated storage from 60.53 to 47.87%.

Preparation of Slowly Digested Corn Starch Using Branching Enzyme and Immobilized α-Amylase

The aim of this study was to modify the digestibility and structure of corn starch by treatment with compound enzymes. Corn starch was treated with two enzymes (α-amylase, which catalyzes hydrolysis, and branching enzyme, a transglycosidase that catalyzes branch formation), and the reaction was monitored by determining the content of slowly digestible starch in the reaction product. The fine structure and physical and chemical properties of enzyme-modified starch samples were analyzed using scanning electron microscopy, gel chromatography, and X-ray diffraction methods; modified starch has a high degree of branching, a high proportion of short-chain branched structures, and greatly improved solubility. The results show that the slow digestion performance of corn starch was significantly improved after hydrolysis by α-amylase for 4 h and treatment with branching enzyme for 6 h. These results show that enzymatic modification of corn starch can improve its slow digestibility properties.

Study on the Pasting Properties of Indica and Japonica Waxy Rice

In this study, the physicochemical properties of indica (IWR) and japonica (JWR) waxy rice were investigated to find the critical factor that differentiates the pasting behaviors among the two cultivars. The results showed that the peak viscosity of 5 IWR flours was in the range of 1242 to 1371 cP, which was significantly higher than 4 JWR flours (667 to 904 cP). Correlation analysis indicated that all pasting parameters were not correlated (p < 0.05) with physicochemical properties of rice flours and the fine structure of isolated starches. The pasting profiles of IWRs were still significantly higher than those of JWRs after removing lipid, while there were no significant differences between the two cultivars after removing protein sequentially. Meanwhile, the addition of extracted protein from JWR to the isolated starch significantly decreased the viscosity compared to the addition of protein extracted from IWR. The protein composition results found that the IWR protein contained about 18% globulin and 64% glutelin, while the JWR protein contained 11% globulin and 73% glutelin. The addition of glutelin to isolated starch significantly decreased viscosity compared to the addition of globulin. Therefore, the differences in the content of globulin and glutelin might be the main reasons that differentiate the pasting behaviors of the two cultivars.

Preparing potato starch nanocrystals assisted by dielectric barrier discharge plasma and its multiscale structure, physicochemical and rheological properties

Non-thermal plasma has increasingly been used for surface modification of various materials as a novel green technology. In this study, we prepared potato starch nanocrystals (SNCs) assisted by dielectric barrier discharge plasma technology and investigated its multiscale structure, physicochemical properties and rheology. Plasma treatment did not change the morphology and crystalline pattern of SNCs but reduced the crystallinity. The amylose content, swelling power, gelatinization temperature, and apparent viscosity of SNCs decreased after the plasma process by depolymerizing the amylopectin branch chains and degrading SNCs molecules. Besides, plasma increased the rapidly digestible starch and resistant starch content. Changes in rheological properties of plasma treated SNCs suggested that the plasma process increased the flowing capacity. The effective structural and functional changes of plasma treated SNCs confirm that plasma technology has great potential for modification of SNCs.

The impact of gliadin and glutenin on the formation and structure of starch-lipid complexes

This study evaluated the influence of the main gluten fractions (gliadin and glutenin) on the physicochemical properties of binary wheat starch-Lauric acid (WS-LA) complexes during heat processing to explore the complex structure and digestion of WS-LA in the presence of gluten. Ternary WS-LA-glutenin complexes were prepared at different pH (5.2 and 7), whereas WS-LA-gliadin was prepared using ethanol, and their physicochemical properties were analyzed. We found that the addition of glutenin displayed a sharper and higher diffraction peak than samples without protein, which increased short-range order structure (low full width at half-maximum (FWHM) of the band at 480 cm^-1) and good thermal stability (melting peak appeared at a higher temperature); the opposite was shown for gliadin. Even though glutenin increased the resistant starch (RS) content than WS-LA, all samples prepared in 65% ethanol showed higher RS content than WS-LA-glutenin samples. These findings might improve our understanding of the relationship between gliadin/glutenin and binary complexes and provide a theoretical basis for preparing starch-based foods with a low glycemic index.

Modelling multiphasic starch digestograms with multiterm exponential and non-exponential equations

The first-order kinetic and the Peleg models were respectively expanded to yield three-term exponential and non-exponential models for triphasic starch digestograms. Ten typical samples are presented, and the models suitably (r² > 0.95; p < 0.05) described their digestograms. Nonlinear regression constraints or conditions to ensure the stability, convergence, and practicability of the models are discussed. These were extended to existing two-term exponential models and an adapted two-term non-exponential model. The two-term models adequately (r² > 0.88; p < 0.05) described biphasic digestograms with practical digestion parameters, as exemplified by 10 presented digestograms. These multiterm models will add to models for describing multiphasic starch digestograms, ensuring such are properly modelled with objective predictability indices to assist researchers and for inter-laboratory comparisons. The integrals of the multiterm exponential and non-exponential models are presented to estimate or predict in vitro glycaemic indices.