Different Degrees Of Hydrolysis Research Articles

Potential inhibitory effect of highland barley protein hydrolysates on the formation of advanced glycation end-products (AGEs): A mechanism study

Advanced glycation end products (AGEs) can be caused during a glycoxidation reaction. This reaction is associated with complications of diabetes and the consequences of health problems. Therefore, we are exploring the prohibitory effect of highland barley protein hydrolysates (HBPHs) on AGE formation. Herein, first extracted the protein from highland barley with various pH conditions and then hydrolyzed using four different proteolytic enzymes (flavourzyme, trypsin, papain, pepsin) under different degrees of hydrolysis. We assessed three degrees of hydrolysates (lowest, middle, highest) of enzymes used to characterize the antioxidant activity and physicochemical properties. Among all the hydrolysates, flavourzyme-treated hydrolysates F-1, F-2, and F-3 indicated the high ability to scavenge DPPH (IC50 values of 0.97 %, 0.63 %, and 0.90 %), structural and functional properties. Finally, the inhibitory effect of the most active hydrolysates F-1, F-2, and F-3 against the AGEs formation was evaluated in multiple glucose-glycated bovine serum albumin (BSA) systems. Additionally, in a BSA system, F-3 exhibited the strong antiglycation activity, effectively suppressed the non-fluorescent AGE (CML), and the fructosamine level. Moreover, it decreased carbonyl compounds while also preventing the loss of thiol groups. Our results would be beneficial in the application of the food industry as a potential antiglycation agent for several chronic diseases.

Does particle size matter for soy protein nanoparticles in the fabrication and lipolysis of pickering-like emulsions?

Enzyme-mediated nanostructures have gained increasing interests and shown promising applications in functional delivery for food and pharmaceuticals. In our previous study, we fabricated three types of spherical soy protein nanoparticles (SPNP) by flavorzyme to different degree of hydrolysis (DH, 3%, 7% and 11%). These SPNPs exhibited similar subunit composition, secondary structure and surface properties, but differ in size, which is 89 nm, 106 nm and 151 nm, respectively. This study further applied them in emulsion systems for functional delivery. We systematically studied the emulsifying activities, interfacial properties including wettability, interfacial packing pattern, interfacial adsorption and dilatational rheological behavior of SPNPs, and their performance in modulating lipolysis of the emulsions under the influence of lipase, bile salts, pepsin and trypsin. All SPNPs behaved as Pickering-like stabilizers with moderate wettability at oil-water interface with three phase contact angle of 92–101°, and the SPNP with the smallest size has better emulsifying activities (D3,2 = 3.22 ± 0.00 μm in SDS solution) than native soy protein isolate (SPI) (D3,2 = 4.04 ± 0.03 μm in SDS solution). These SPNPs formed similar viscoelastic oil-water interfaces (Ed' = 20.2–21.5 mN/m), which were more glassy-like with weak in-plane interactions compared to SPI (Ed' = 28.6 ± 0.5 mN/m). All SPNPs can delay lipolysis of emulsions by lowering the access/replacement of lipase and bile salts and depressing the proteolysis by trypsin at interface in similar ways. Our work elucidated the role of particle size of enzyme-mediated plant protein-based particle in emulsion stabilization and lipolysis control, and is expected to give the theoretical support for the design of functional food emulsions with controllable energy intake.

Enhancing the functional properties of peanut protein hydrolysates: covalent modification with chlorogenic acid

SummaryThis study aimed to enhance the functional properties of peanut protein hydrolysates (PPHs) by coupling limited enzymatic hydrolysis with chlorogenic acid (CGA) modification, thus offering novel insights into the potential food industry applications of peanut proteins. Initially, peanut protein isolate was hydrolysed using trypsin. Subsequently, covalent conjugation with CGA was achieved via free‐radical grafting. The moderately hydrolysed 4% PPHs had the highest polyphenol‐binding capacity. Measurement of the PPHs‐CGA complex revealed that free amino, thiol, and tryptophan contents were reduced. The amino acid content results also showed that cysteine, lysine, arginine, and methionine (with amino or thiol groups) were the primary binding sites. Spherical or rod‐like structures were observed in the scanning electron microscopy images of PPHs‐CGA, and its particle size was larger than that of the PPHs. After combining PPHs and CGA, the fluorescence intensity decreased, Fourier‐transform infrared spectrum showed a shift in the absorption peak, and electrophoresis band weakened, indicating that covalent binding was successful. PPHs with different degrees of hydrolysis have different levels of exposure to amino acids, and their antioxidant properties differ when combined with CGA. After combining, the surface hydrophobicity was reduced, and the secondary structure was unfolded and extended, thereby improving its emulsifying properties. In summary, PPHs‐CGA may be used in the food industry as a bi‐type food factor and proposes a new application for peanut protein in food.

Construction of hypoallergenic microgel by soy major allergen β-conglycinin through enzymatic hydrolysis and lactic acid bacteria fermentation

Soy allergenicity is a public concern, and the combination of multiple processing methods may be a promising strategy for reducing soy allergenicity. In this study, a novel two-step enzymatic hydrolysis followed by lactic acid bacteria fermentation was proposed for the construction of hypoallergenic soybean protein microgel. β-Conglycinin was used as the main soy allergen. The effects of different enzymatic hydrolysis (Alcalase, Neutrase, and Protamex) and LAB fermentation on β-conglycinin microgel formation and its immunoreactivity were investigated. Results showed that the use of different enzymes and the attainment of different degrees of hydrolysis affected the particle distribution and zeta potential in the microgels and leads to differences in microstructure and immunoreactivity. All hydrolysates compared with intact protein accelerated the formation of gel during LAB fermentation. Among the three assayed enzymes, fermented Protamex hydrolysates at 60 min (PF-60) demonstrated a microgel with an overall reduced average particle size (741.20±7.18 nm), lower absolute values of zeta potential (10.43±0.65 mV), and regular gel network. The antigenicity and IgE-binding capacity decreased to the lowest value of 0.30 % and 6.93 %, respectively. Peptidomics and immunoinformatic analysis suggested that PF-60 disrupted 17/30, 16/44, and 23/75 epitopes in the α, α′, and β subunits, respectively. Unlike the LAB-fermented unhydrolyzed β-conglycinin disrupted epitopes mostly located at the loop domain, PF-60 primarily promoted the exposure and disruption of allergen epitopes with β-sheet structure located at the core barrel domain. These findings can provide new perspectives on the preparation of hypoallergenic soybean-gel products on edible particulate systems.

Extraction, Enzymatic Modification, and Anti-Cancer Potential of an Alternative Plant-Based Protein from Wolffia globosa.

The global plant-based protein demand is rapidly expanding in line with the increase in the world's population. In this study, ultrasonic-assisted extraction (UAE) was applied to extract protein from Wolffia globosa as an alternative source. Enzymatic hydrolysis was used to modify the protein properties for extended use as a functional ingredient. The successful optimal conditions for protein extraction included a liquid to solid ratio of 30 mL/g, 25 min of extraction time, and a 78% sonication amplitude, providing a higher protein extraction yield than alkaline extraction by about 2.17-fold. The derived protein was rich in essential amino acids, including leucine, valine, and phenylalanine. Protamex and Alcalase were used to prepare protein hydrolysates with different degrees of hydrolysis, producing protein fragments with molecular weights ranging between <10 and 61.5 kDa. Enzymatic hydrolysis caused the secondary structural transformations of proteins from β-sheets and random coils to α-helix and β-turn structures. Moreover, it influenced the protein functional properties, particularly enhancing the protein solubility and emulsifying activity. Partial hydrolysis (DH3%) improved the foaming properties of proteins; meanwhile, an excess hydrolysis degree reduced the emulsifying stability and oil-binding capacity. The produced protein hydrolysates showed potential as anti-cancer peptides on human ovarian cancer cell lines.

Enzymatic hydrolysates from camel colostrum and milk proteins display inhibitory activity toward a key enzyme related to obesity

AbstractThis study aimed to investigate the anti-obesity potential of camel colostrum and milk proteins as well as their enzymatic hydrolysates. Camel colostrum and milk proteins were treated using six proteolytic enzymes (pepsin, trypsin, α-chymotrypsin, pancreatin, papain, and pronase). The degree of hydrolysis was measured to verify the degradation of proteins. The in vitro anti-obesity activity was evaluated using the pancreatic lipase inhibitory assay. Camel colostrum and milk protein hydrolysates exhibited different degrees of hydrolysis ranging from 17.69 to 43.97%. The protein content varied between 56.08–61.95% and 37.39–41.72% for camel colostrum and milk protein hydrolysates, respectively. The hydrolysates displayed significantly higher anti-obesity activity than the undigested proteins at all tested concentrations (P &lt; 0.05). Colostrum protein hydrolysate generated with pancreatin had the highest anti-obesity potential (59.92%). These results suggest that colostrum and milk protein hydrolysates could be used to formulate functional foods and nutraceuticals.

Degree of Hydrolysis Regulated by Enzyme Mediation of Wheat Gluten Fibrillation: Structural Characterization and Analysis of the Mechanism of Action.

The impact of different degrees of hydrolysis (DHs) on fibrillation when trypsin mediates wheat gluten (WG) fibrillation has not been thoroughly investigated. This study discussed the differences in amyloid fibrils (AFs) formed from wheat gluten peptides (WGPs) at various DH values. The results from Thioflavin T (ThT) fluorescence analysis indicated that WGPs with DH6 were able to form the most AFs. Changes in Fourier Transform Infrared (FTIR) absorption spectra and secondary structure also suggested a higher degree of fibrillation in DH6 WGPs. Analysis of surface hydrophobicity and ζ-potential showed that DH6 AFs had the highest surface hydrophobicity and the most stable water solutions. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) images revealed the best overall morphology of DH6 AFs. These findings can offer valuable insights into the development of a standardized method for preparing wheat gluten amyloid fibrils.

Insight on the emulsifying mechanisms of low-salt type emulsions stabilized by Maillard conjugates: Myofibrillar protein peptide-dextrin with different degrees of hydrolysis

In this study, we investigated the emulsifying properties and stabilisation mechanisms of low-salt type emulsions stabilised by MP-base conjugates prepared via the Maillard reaction between DX and MP peptides (MPP). Mild hydrolysis by Alcalase promoted a well-controlled Maillard reaction in dry conditions. Combining hydrolysis and Maillard reaction caused the dissociation and unfolding of highly aggregated MP structures; the ordered secondary structure was lost and the hydrophobic residue was exposed. The MPP-DX conjugates greatly improved the emulsifying ability and stability in the low-salt system; the resulting emulsion exhibited a small droplet size and homogeneous microstructure with desirable storage stability. Further, the glycation products were found to effectively suppress gravity-induced creaming. The MPP-DX glycoconjugate developed with 5% DG, exhibiting strongest flocculation and creaming stability, was determined as the optimal emulsifying agent for low-salt type emulsions. These findings provide a theoretical basis for developing low-salt meat products and/or emulsion-based foods.

Predicting fish by-product proteolysis status by RGB laser-scattering imaging combined with machine learning procedures

This work aimed to control the protein hydrolysis process of fish by-products through RGB laser-scattering imaging. By-products from mackerel and sardine waste were hydrolysed with papain, pepsin and Protamex®, and the degree of hydrolysis was measured six times during 6 h. Imaging information was captured at those sampling times to obtain non-destructive data across the process. The used enzymes reached a different degree of hydrolysis depending on the type of fish. After a dimensional reduction of the imaging, data evolved along the process, although the observed kinetics did not fit with those observed in the measurements of the degree of hydrolysis. When imaging data was supervised by a multivariate regression method, a high prediction of the degree of hydrolysis capacity was observed for all cases of enzyme/fish. Moreover, successful prediction models were obtained from all data within each fish. The effect of the type of enzyme was not significant for the prediction capacity. Thus, a common model including data from all cases was developed. In that case, the effect of the fish matrix made intervening data with pre-treatments and variable selection procedures necessary to obtain prediction coefficients up to 0.95. The results evidenced the capacity of this imaging technique to capture the variability generated by the hydrolysis of proteases with the independence of the type of enzyme and fish.

Peptide Mapping with LC-HRMS and In Silico Tools for Evaluation of Potential Allergenicity of Commercially Available Whey Protein Hydrolysates

Hypoallergenic formulas containing hydrolyzed protein are intended for use by infants to prevent cow’s milk protein allergy. The degree of hydrolysis of epitopic areas determines the residual allergenicity of whey protein hydrolysates (WPHs). However, only amino-acid-based infant formulas (IFs) are considered entirely nonallergenic. The aim of this study was to investigate four commercially available WPHs with different degree of hydrolysis (H1–H4) for potential allergenicity, by applying LC-HRMS analysis of peptides, and using in silico tools to search for the immunoglobulin (IgE)-binding allergenic epitopes from the Immune Epitope Database. Additionally, the molecular weight distribution of proteins and peptides in the WPHs was measured by SE-UPLC. Based on the peptide coverage and peptide-length distribution profiles, the WPHs showed different extents of hydrolysis: extensively (H1 and H2), partially (H3), and slightly hydrolyzed (H4). Altogether, numerous peptides related to 46 specific IgE-binding epitopes from β-lactoglobulin and α-lactalbumin were found in all the WPHs, regardless of their extent of hydrolysis. Sequence-based identification of the specific peptide composition, with an application of in silico tools, is a reliable approach for discovering the potential allergenicity of protein hydrolysates for IFs.

Effects of hydrolysis degree on the functional properties of hydrolysates from sour cherry kernel protein concentrate

During the processing of sour cherries into different foodstuffs, a large amount of kernels is produced as waste material, which creates a significant disposal problem for the food industry. Sour cherry kernels containing 25.3–35.5% of protein can be used as a functional protein source in food production. Therefore, we aimed to study the effects of hydrolysis degree on the sour cherry kernel protein hydrolysates.&#x0D; Proteins were extracted from the defatted flour by isoelectric precipitation. The resulting protein concentrate was hydrolyzed (5, 10, and 15% hydrolysis) using Alcalase to yield hydrolysates. We determined their oil and water holding, emulsifying, gelation, and foaming properties, as well as apparent molecular weight distribution and proximate compositions.&#x0D; No protein fractions greater than an apparent molecular weight of about 22 kDa were present in the hydrolysates. The hydrolysis of the protein concentrate mostly led to an increase in protein solubility. As the degree of hydrolysis increased from 5 to 15%, the water holding capacity of the hydrolysates decreased from 2.50 ± 0.03 to 2.03 ± 0.02 g water/g, indicating its deterioration. &#x0D; The hydrolysates obtained at different degrees of hydrolysis had a better solubility than the intact protein concentrate. The oil holding capacity, the foaming stability, and the least gelation concentration of the protein concentrate could not be considerably improved by hydrolysis. In contrast, its emulsifying activity index and foaming capacity could be increased with a limited degree of hydrolysis (up to 10%).

Effects of soy protein and its hydrolysates on the formation of heterocyclic aromatic amines in roasted pork

This study investigated the influence mechanism of soy protein and its hydrolysates (under three different degree of hydrolysis) on formation of heterocyclic aromatic amines (HAAs) formation in roasted pork. The results showed that 7S and its hydrolysates significantly inhibited the formation of quinoxaline HAAs, and the maximum inhibitory rate of MeIQx, 4,8-MeIQx, and IQx was 69%, 79%, and 100%, respectively. However, soy protein and its hydrolysates could promote the formation of pyridine HAAs (PhIP, and DMIP), its content increased significantly with the increase in the degree of hydrolysis of the protein. The content of PhIP increased 41, 54, and 165 times with the addition of SPI, 7S, and 11S at 11% degree of hydrolysis, respectively. In addition, they promoted the formation of β-carboline HAAs (Norharman and Harman), in a manner similar with that of PhIP, especially the 11S group. The inhibitory effect on quinoxaline HAAs was probably correlated with DPPH radical scavenging capacity. Nevertheless, the promotive effect on other HAAs might be related to the high levels of free amino acids and reactive carbonyls. This research may provide recommendation for the application of soy protein in high-temperature meat products.

Ферментативный гидролиз соевого белка

Soy continues to be one of the top sources of vegetable protein. Structurally modified soy proteins and processed products are used as part of functional foods. Enzymatic hydrolysates of food proteins have different degrees of hydrolysis and functional profiles, hence the constant search for the optimal hydrolysis parameters. The present research objective was to design a two-stage enzymatic conversion process of soy protein using mathematical methods, as well as to evaluate the antioxidant properties of the hydrolysate in laboratory conditions.&#x0D; Soy protein isolate was tested to define the maximal value of the hydrolysis degree. It underwent a series of two-factor experiments in the presence of pepsin and trypsin. The study focused on the hydrolysis time and the enzyme-substrate ratio. The results were optimized using the response surface methodology in MathCad 15. The total antioxidant activity of the hydrolysate during hydrolysis was determined on a Tsvet-Yauza-01-AA chromatograph using the amperometric method.&#x0D; For the pepsin test, the processing time was 7 h and the enzyme-to-substrate ratio was 1:22. For the trypsin test, the time was 7 h and the ratio was 1:30. The mathematical modeling revealed the following optimal parameters. The first stage involved hydrolysis with pepsin for 5 h at an enzyme-to-substrate ratio of 1:20; the second stage involved hydrolysis with trypsin for 3 h at an enzyme-to-substrate ratio of 1:19. The resulting hydrolysate demonstrated 88% hydrolysis. The highest summary antioxidant activity was registered after 5 h of hydrolysis and amounted to about 250 mg/100 mL.&#x0D; The resulting enzymatic hydrolysate of soy protein can be used as a food component or an antioxidant feed additive. The obtained peptides can immobilize essential microelements, e.g., Zn, I, and Se, as well as produce polyvalent complexes. Further studies will be aimed at the residual antigenicity of the hydrolysate and other functional indicators.

Structural and antioxidative properties of royal jelly protein by partial enzymatic hydrolysis

The objective of this study was to investigate the structural and antioxidative properties of royal jelly protein (RJP) at different degrees of hydrolysis (DH) by partial enzymatic hydrolysis. RJP was hydrolyzed by alcalase for 0 min, 15 min, 1 h, 5 h and 8 h to obtain hydrolysates at DH of 5.34 %, 11.65 %, 15.19 %, 21.38 % and 23.91 %, respectively. With the increased DH, the RJP hydrolysates showed elevated antioxidative activities. The molecular weight of RJP hydrolysates was significantly decreased but their primary backbone kept unchanged. Analysis of circular dichroism spectra revealed that the enzymolysis reduced the content of α-helix but increased the contents of β-sheet, β-turn and random coil. Meanwhile, the surface hydrophobicity and fluorescence intensity of RJP hydrolysates were decreased and a red shift occurred. As the enzymolysis continued, the surface morphology of RJP was gradually changed from a sheet-like structure into microparticles. Changes in antioxidative activities and structures generally followed a DH-dependent manner, however these changes became insignificant for samples at DH beyond 20 %. Taking into consideration of both effectiveness and productivity, the optimum enzymatic duration was determined at 5 h.

Production and features of antioxidative hydrolysate from wild almond protein isolate using ficin immobilised on the layered double hydroxide

SummaryProtein hydrolysates from wild almond protein isolate (WAPI) with different degrees of hydrolysis (DH) were synthesised using free and immobilised ficin on the magnetic layered double hydroxide and characterised. The highest DH values after 3 h of achieving 11.69 ± 0.15 and 11.37 ± 0.12, respectively, and gained hydrolysate were collected for further analysis. The zeta potential for the hydrolysis of free and immobilised ficin over hydrolysing time due to differences in molecular mass distribution decreased. By increasing the hydrolysing time in the case of free and immobilised ficin, the emulsion activity index gradually decreased, whereas the amount of emulsion stability index did not. The immobilised form of ficin‐treated hydrolysate showed a suitable level of DPPH radical scavenging and appeared to be effective in enhancing the oxidative stability of linoleic acid, sunflower oil and O/W emulsion. Thus WAPI hydrolysates that were treated with immobilised ficin could serve as an alternative antioxidant for food applications.

Evaluation of ATBS Polymers for Mangala Polymer Flood

Summary Mangala field has been under polymer flood since 2015. The polymer flood has been more successful in accelerating recovery compared to waterflood. As the flood matured, field performance indicated that part of the injected polymer was degrading in the reservoir. Laboratory studies and polymer samples collected from the reservoir suggest that the most likely reason for the degradation is increased hydrolysis due to thermal aging. This degradation compels higher dosing of polymer to make up for the lost viscosity and increases operating costs. Polymer precipitation in the reservoir may also lead to loss of reservoir permeability. Literature surveys and preliminary laboratory studies showed that polymers with acrylamide-tertiary-butyl-sulfonic acid monomer units (referred to as ATBS polymers) could be a suitable option for Mangala. To evaluate the hypothesis, the team did a series of laboratory and coreflood studies. The studies include accelerated thermal ageing, rheology, dynamic adsorption, injectivity, waterflood with fresh and degraded samples, and compatibility studies with topside chemicals. Two hydrolyzed polyacrylamide (HPAM) polymers with different degrees of hydrolysis (DOH) and two ATBS polymers were evaluated. The selected ATBS polymer was then tested for compatibility with surface topside chemicals. The studies show that the classic 20 to 25% DOH HPAM suffers viscosity degradation and possible precipitation in Mangala reservoir conditions. ATBS polymers and a lower DOH HPAM provide superior results to the incumbent HPAM with an acrylamide (AM) (86)-ATBS (14) copolymer providing the best results. ATBS polymers were especially resistant to cloudpoint lowering and provide some superiority in shear degradation. The ATBS monomer was resistant to hydrolysis during the period of testing. Contrary to the published literature, ATBS polymers showed higher adsorption and their propagation through cores required a higher pressure drop. ATBS polymer seemed to plug a low-permeability section of the core stack. All polymers reach their peak viscosity at 30 to 40% hydrolysis and decline sharply after 40%, but viscosity and cloudpoints measured during accelerated aging are possibly conservative. A large-scale pilot of ATBS injection in Mangala is under way to validate the laboratory test results. ATBS polymer can be a suitable polymer for some layers of Mangala with a high residence time and permeability. The choice is driven by the economics of the incremental cost of ATBS for the benefits it offers. In some sands with shorter interwell spacing, a lower DOH HPAM may be a more cost-effective solution. The study results in this paper provide insights to operators to understand the reservoir performance of existing polymer floods and plan for future polymer floods.

Effect of Thermal Treatment on the Self-Assembly of Wheat Gluten Polypeptide.

Self-assembled fibrillation of wheat gluten is a common phenomenon in the daily production and processing of wheat flour products. The driving forces for its formation and the factors that influence the morphology of fibrils have not been thoroughly investigated. In this study, the effect of three bonding changes (breaking hydrogen bonds, strengthening hydrophobic interactions, and SH-SS exchange reactions) on gluten polypeptide (GP) fibrillation was simulated by adjusting the heating temperature (room temperature (RT), 45 °C, 65 °C, and 95 °C). The results showed that the breakage of hydrogen bonds could induce conformational transitions in GPs and help to excite fibrillation in GPs. Strengthened hydrophobic interactions significantly contributed to the fibrillation of GPs. Covalent crosslinks generated by SH-SS exchange reactions might also promote the fibrillation of GPs. GPs with different degrees of hydrolysis (4.0%, 6.0%, and 10.0%, represented by DH 4, DH 6, and DH 10, respectively) presented different extents of fibrillation, with DH 10 GPs having a higher propensity to fibrillation than DH 4 and DH 6 GPs. The results of Fourier's transform infrared spectroscopy indicated that hydrophobic interactions drive the transition from a random coil and α-helix to a β-sheet. In addition, hydrophobic interactions also drive the intermolecular polymerization of GPs, resulting in larger molecular weight aggregates. The morphology presented by transmission electron microscopy showed that the greater the DH, the stronger the tendency for the worm-like aggregation of GPs.

Integrated metabolomics analysis of Lactobacillus in fermented milk with fish gelatin hydrolysate in different degrees of hydrolysis

Dual-platform metabolomics combined with multivariate data analysis was used to investigate the effects of adding fish gelatin (FGH) at different degrees of hydrolysis (DH) on the growth and metabolic pathways of different species of Lactobacillus in fermented milk. The results showed that the promotion effect of FGH on Lactobacillus was related to the species of probiotics. The corresponding metabolic pathways also changed, with the promotion of Lactobacillus by FGH mainly regulated through amino acid metabolism, lipid metabolism, and nucleotide metabolism pathways. The excess DH inhibited the growth of L. paracasei by adjusting its metabolic state through reducing nucleotide requirements, allocating protein resources, and adopting a stress response. In conclusion, this study revealed the effectiveness of dual-platform metabolomics in explaining the metabolic mechanisms of probiotics, providing theoretical support and a scientific basis for the development of functional fermented foods.

Starch digestion retarded by wheat protein hydrolysates with different degrees of hydrolysis

Wheat protein hydrolysates (WPH) were prepared by pepsin hydrolysis for 30, 60, and 120 min (WPH30, WPH60, and WPH120). The mixed system of rice starch and WPH was hydrothermally treated to explore the effect of WPH with different degrees of hydrolysis on starch digestion. WPH reduced the first-order rate coefficient (k) of starch digestion. Especially, WPH30 reduced the k value the most and formed the highest slowly digestible starch content due to the entanglement of starch chains and long-chain peptides. WPH60 and WPH120 with more hydrophobic peptides and polar amino acids than WPH30 tended to form hydrogen bonds with starch molecules due to less steric hindrance. Particularly, the complexation of WPH60 promoted the formation of dense aggregate structure and hindered the enzymatic hydrolysis of starch to a certain extent, thereby increasing the resistant starch content. These findings provide significant guidance for the preparation of hypoglycemic reformed food.

The Modification of Polyvinyl Alcohol for Ice Nucleation Based upon the Structures of Antifreeze Glycoproteins Found in Antarctic Fish

Various alternative compounds have been investigated to prevent icing, one of which includes poly(vinyl) alcohol (PVA), which has shown promising anti-freeze effects. However, determining the optimal structures and formulations of PVA for anti-icing applications has remained a challenge. Building upon our previous work, which used molecular dynamics simulations to assess the effects of hydroxyl group separation distance on ice nucleation, in this work, PVA was modified based upon the structures of antifreeze glycoproteins (AFGPs) found in Antarctic fish, and examined as a potential antifreeze compound. Four different PVA samples with different degrees of hydrolysis were fabricated and subsequently examined for their effects on ice crystallization. The results showed that the modified PVA samples with degrees of hydrolysis of 76% and 66% had an effect on ice crystallization, delaying ice crystallization by an average of approximately 20 min, and even preventing ice crystallization altogether in a small portion of the sample. Meanwhile, other samples with degrees of hydrolysis of 100% and 34% either showed no effect on ice crystallization, shortened the ice crystallization time, and appeared to promote ice nucleation.