Extrusion modification of prolamins from distiller's grains to facilitate the construction of biopolymer films.

BACKGROUND: Distiller's grains (DGs), which are rich in natural ingredients such as prolamins, are often used as low-value feed or discarded directly, resulting in great environmental pollution and resource waste. Prolamins from DGs (PDGs) were found to be a potential material for the construction of biopolymer films due to their good film-forming properties. In this study, extrusion processing was conducted to modify the physicochemical and structural properties of PDGs to facilitate the construction of biopolymer films with superior characteristics. RESULTS: Results indicated that extrusion led to improved solubility (17.91% to 39.95%) and increased disulfide bonds (1.46 to 6.13 µmol g-1) in PDGs. The total and sulfur amino acid contents of extruded PDGs were increased by 13.26% and 38.83%, respectively. New aggregation patterns were formed after extrusion according to the results of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Extrusion resulted in reduced surface hydrophobicity of PDGs (10 972 to 3632), sufficient evidence for which could be also found from structure analyses of PDGs. Finally, PDGs extruded at 110 °C were found to facilitate the forming of biopolymer films with superior mechanical properties, water resistance and thermal stability. CONCLUSIONS: Physicochemical and structural properties of PDGs were effectively modified by extrusion processing, and extrusion modification of PDGs could be a great way to facilitate the construction of biopolymer films with superior characteristics. It could provide more possibilities to extend the applications of DGs to alleviate the problems of environmental pollution and resource waste. © 2024 Society of Chemical Industry.

Effects of endosperm type and storage length of whole-plant corn silage on nitrogen fraction, fermentation products, zein profile, and starch digestibility.

Zeins are commercially important proteins found in corn endosperms. The objective of this study was to evaluate the effect of altering zein levels in corn inbred lines carrying endosperm mutations with differential allelic dosage and analyze the effects on the composition, nutritive value, and starch digestibility of whole-plant corn silage (WPCS) at 5 storage lengths. Three inbred lines carrying 3 different endosperm modifiers (opaque-2 [o2], floury-2 [fl2], and soft endosperm-1 [h1]) were pollinated with 2 pollen sources to form pairs of near-isogenic lines with either 2 or 3 doses of the mutant allele for each endosperm modifier. The experiment was designed as a split-plot design with 3 replications. Pollinated genotype was the main plot factor, and storage length was the subplot-level factor. Agronomic precautions were taken to mimic hybrid WPCS to the extent possible. Samples were collected at approximately 30% dry matter (DM) using a forage harvester and ensiled in heat-sealed plastic bags for 0, 30, 60, 120, and 240 d. Thus, the experiment consisted of 30 treatments (6 genotypes × 5 storage lengths) and 90 ensiling units (3 replications per treatment). Measurements included nutrient analysis, including crude protein, soluble crude protein, amylase-treated neutral detergent fiber, acid detergent fiber, lignin, starch, fermentation end products, zein concentration, and in vitro starch digestibility (ivSD). The nutritional profile of the inbred-based silage samples was similar to hybrid values reported in literature. Significant differences were found in fresh (unfermented) sample kernels for endosperm vitreousness and zein profiles between and within isogenic pairs. The o2 homozygous (3 doses of mutant allele) had the highest reduction in vitreousness level (74.5 to 38%) and zein concentration (6.2 to 4.7% of DM) compared with the heterozygous counterpart (2 doses of mutant allele). All genotypes showed significant reduction of total zeins and α-zeins during progressive storage length. In vitro starch digestibility increased with storage length and had significant effects of genotype and storage length but not for genotype by storage length interaction, which suggests that the storage period did not attenuate the difference in ivSD between near-isogenic pairs caused by zeins in WPCS. Both total zeins and α-zeins showed a strong negative correlation with ivSD, which agrees with the general hypothesis that the degradation of zeins increases ruminal starch degradability. Homozygous o2 was the only mutant with significantly higher ivSD compared with the heterozygous version, which suggests that, if all other conditions remain constant in a WPCS systems, substantial reductions in endosperm α-zeins are required to significantly improve ivSD in the silo.

The Composition, Structure, and Functionalities of Prolamins from Highland Barley.

The composition, structure, and functionalities of prolamins from highland barley were investigated. These parameters were compared with those of the commonly applied prolamins (zein). There are more charged and hydrophilic amino acids in highland barely prolamins than zein. The molecular weight of highland barely prolamins was between 30 and 63 kDa, which was larger than that of zein (20 and 24 kDa). The main secondary structure of highland barely prolamins was ß-turn helices, while α-helical structures were the main secondary structure in zein. The water holding capacity, thermal stability, emulsifying capacity, and stability of prolamins from highland barley were significantly higher than in zein, while the opposite results were observed for oil absorption capacity between the two. The diameter of fibers prepared using highland barely prolamins was almost six times that of zein, while highland barely prolamins formed ribbon structures instead of fibers. Therefore, the results provide guidance for applications of prolamins from highland barley.

Applications of Prolamin-Based Edible Coatings in Food Preservation: A Review.

Foods are susceptible to deterioration and sour due to external environmental influences during production and storage. Coating can form a layer of physical barrier on the surface of foods to achieve the purpose of food preservation. Because of its good barrier properties and biocompatibility, prolamin-based film has been valued as a new green and environment-friendly material in the application of food preservation. Single prolamin-based film has weaknesses of poor toughness and stability, and it is necessary to select appropriate modification methods to improve the performance of film according to the application requirements. The practical application effect of film is not only affected by the raw materials and the properties of the film itself, but also affected by the selection of preparation methods and processing techniques of film-forming liquid. In this review, the properties and selection of prolamins, the forming mechanisms and processes of prolamin-based coatings, the coating techniques, and the modifications of prolamin-based coatings were systematically introduced from the perspective of food coating applications. Moreover, the defects and deficiencies in the research and development of prolamin-based coatings were also reviewed in order to provide a reference for the follow-up research on the application of prolamin-based coatings in food preservation.

Recent advances in self-assembly behaviors of prolamins and their applications as functional delivery vehicles.

Prolamins are a group of storage proteins (zeins, kafirins, hordeins, secalins, gliadins, glutenins, and avenins) found in the endosperm of cereal grains and characterized by high glutamine and proline content. With the high proportion of nonpolar amino acids (40-80%) and peculiar solubility (alcohol (60-90%), acetic acid, and alkaline solutions), prolamins exhibit tunable self-assembly behaviors. In recent years, research practices of utilizing prolamins as green building materials of functional delivery vehicles to improve the health benefits of bioactive compounds have surged due to their attractive advantages (e.g. sustainability, biocompatibility, fabrication potential, and cost-competitiveness). This article covers the recent advances in self-assembly behaviors leading to the fabrication of nanoparticles, fibers, and films in the bulk water phase, at the air-liquid interface, and under the electrostatic field. Different fabrication methods, including antisolvent precipitation, evaporation induced self-assembly, thermal treatment, pH-modulation, electrospinning, and solvent casting for assembling nanoarchitectures as functional delivery vehicles are highlighted. Emerging industrial applications by mapping patents, including encapsulation and delivery of bioactive compounds and probiotics, active packaging, Pickering emulsions, and as functional additives to develop safer, healthier, and sustainable food products are discussed. A future perspective concerning the fabrication of prolamins as advanced materials to promote their commercial food applications is proposed.

Specialized endoplasmic reticulum-derived vesicles in plants: Functional diversity, evolution, and biotechnological exploitation.

A central role of the endoplasmic reticulum (ER) is the synthesis, folding and quality control of secretory proteins. Secretory proteins usually exit the ER to enter the Golgi apparatus in coat protein complex II (COPII)-coated vesicles before transport to different subcellular destinations. However, in plants there are specialized ER-derived vesicles (ERDVs) that carry specific proteins but, unlike COPII vesicles, can exist as independent organelles or travel to the vacuole in a Golgi-independent manner. These specialized ERDVs include protein bodies and precursor-accumulating vesicles that accumulate storage proteins in the endosperm during seed development. Specialized ERDVs also include precursor protease vesicles that accumulate amino acid sequence KDEL-tailed cysteine proteases and ER bodies in Brassicales plants that accumulate myrosinases that hydrolyzes glucosinolates. These functionally specialized ERDVs act not only as storage organelles but also as platforms for signal-triggered processing, activation and deployment of specific proteins with important roles in plant growth, development and adaptive responses. Some specialized ERDVs have also been exploited to increase production of recombinant proteins and metabolites. Here we discuss our current understanding of the functional diversity, evolutionary mechanisms and biotechnological application of specialized ERDVs, which are associated with some of the highly remarkable characteristics important to plants.

Genome-wide identification, characteristics and expression of the prolamin genes in Thinopyrum elongatum.

BACKGROUND: Prolamins, unique to Gramineae (grasses), play a key role in the human diet. Thinopyrum elongatum (syn. Agropyron elongatum or Lophopyrum elongatum), a grass of the Triticeae family with a diploid E genome (2n = 2x = 14), is genetically well-characterized, but little is known about its prolamin genes and the relationships with homologous loci in the Triticeae species. RESULTS: In this study, a total of 19 α-gliadin, 9 γ-gliadin, 19 ω-gliadin, 2 high-molecular-weight glutenin subunit (HMW-GS), and 5 low-molecular-weight glutenin subunit (LMW-GS) genes were identified in the Th. elongatum genome. Micro-synteny and phylogenetic analysis revealed dynamic changes of prolamin gene regions and genetic affinities among Th. elongatum, Triticum aestivum, T. urartu and Aegilops tauschii. The Th. elongatum genome, like the B subgenome of T. aestivum, only contained celiac disease epitope DQ8-glia-α1/DQ8.5-glia-α1, which provided a theoretical basis for the low gluten toxicity wheat breeding. The transcriptome data of Th. elongatum exhibited differential expression in quantity and pattern in the same subfamily or different subfamilies. Dough rheological properties of T. aestivum-Th. elongatum disomic substitution (DS) line 1E(1D) showed higher peak height values than that of their parents, and DS6E(6D) exhibited fewer α-gliadins, which indicates the potential usage for wheat quality breeding. CONCLUSIONS: Overall, this study provided a comprehensive overview of the prolamin gene family in Th. elongatum, and suggested a promising use of this species in the generation of improved wheat breeds intended for the human diet.

Progressive Aggregation of 16 kDa Gamma-Zein during Seed Maturation in Transgenic Arabidopsis thaliana.

Prolamins constitute a unique class of seed storage proteins, present only in grasses. In the lumen of the endoplasmic reticulum (ER), prolamins form large, insoluble heteropolymers termed protein bodies (PB). In transgenic Arabidopsis (Arabidopsis thaliana) leaves, the major maize (Zea mays) prolamin, 27 kDa γ-zein (27γz), assembles into insoluble disulfide-linked polymers, as in maize endosperm, forming homotypic PB. The 16 kDa γ-zein (16γz), evolved from 27γz, instead forms disulfide-bonded dispersed electron-dense threads that enlarge the ER lumen without assembling into PB. We have investigated whether the peculiar features of 16γz are also maintained during transgenic seed development. We show that 16γz progressively changes its electron microscopy appearance during transgenic Arabidopsis embryo maturation, from dispersed threads to PB-like, compact structures. In mature seeds, 16γz and 27γz PBs appear very similar. However, when mature embryos are treated with a reducing agent, 27γz is fully solubilized, as expected, whereas 16γz remains largely insoluble also in reducing conditions and drives insolubilization of the ER chaperone BiP. These results indicate that 16γz expressed in the absence of the other zein partners forms aggregates in a storage tissue, strongly supporting the view that 16γz behaves as the unassembled subunit of a large heteropolymer, the PB, and could have evolved successfully only following the emergence of the much more structurally self-sufficient 27γz.

New insights into structural organization and gene duplication in a 1.75-Mb genomic region harboring the α-gliadin gene family in Aegilops tauschii, the source of wheat D genome.

Among the wheat prolamins important for its end-use traits, α-gliadins are the most abundant, and are also a major cause of food-related allergies and intolerances. Previous studies of various wheat species estimated that between 25 and 150 α-gliadin genes reside in the Gli-2 locus regions. To better understand the evolution of this complex gene family, the DNA sequence of a 1.75-Mb genomic region spanning the Gli-2 locus was analyzed in the diploid grass, Aegilops tauschii, the ancestral source of D genome in hexaploid bread wheat. Comparison with orthologous regions from rice, sorghum, and Brachypodium revealed rapid and dynamic changes only occurring to the Ae. tauschii Gli-2 region, including insertions of high numbers of non-syntenic genes and a high rate of tandem gene duplications, the latter of which have given rise to 12 copies of α-gliadin genes clustered within a 550-kb region. Among them, five copies have undergone pseudogenization by various mutation events. Insights into the evolutionary relationship of the duplicated α-gliadin genes were obtained from their genomic organization, transcription patterns, transposable element insertions and phylogenetic analyses. An ancestral glutamate-like receptor (GLR) gene encoding putative amino acid sensor in all four grass species has duplicated only in Ae. tauschii and generated three more copies that are interspersed with the α-gliadin genes. Phylogenetic inference and different gene expression patterns support functional divergence of the Ae. tauschii GLR copies after duplication. Our results suggest that the duplicates of α-gliadin and GLR genes have likely taken different evolutionary paths; conservation for the former and neofunctionalization for the latter.

Rheological characterisation of gluten from triticale (x Triticosecale Wittmack).

BACKGROUND: Triticale gluten still remains very poorly characterised rheologically. In this study the mechanical spectra of gluten isolated from four triticale cultivars were registered and fitted with Cole-Cole functions yielding the visco-elastic plateau parameters. Master spectra were calculated. A retardation test was performed and used to calculate the composite mechanical spectra and the width of visco-elastic plateau l. Protein fractional composition of triticale flour and gluten was studied using capillary zone electrophoresis. RESULTS: Differentiated HMW-GS/SS compositions were identified in the triticale cultivars studied. The rheological parameters reached the following values: JN0 1.05·10-3 to 2.69·10-3 Pa-1 , GN0 372 to 956 Pa, ω0 0.003 to 0.06 rad s-1 , l 169 to 3121, Je0 1.57·10-3 to 5.03·10-3 Pa-1 , Ge0 199 to 637 Pa and η0 1.06·107 to 3.93·107 Pa s. CONCLUSIONS: Visco-elastic properties of triticale gluten correspond to the lower end of medium visco-elasticity shown by common wheat gluten. Master spectra and the composite mechanical spectra prove that four triticale glutens exhibit practically an identical type of visco-elastic behaviour of a biopolymeric visco-elastic liquid similar to wheat gluten. The visco-elastic plateau parameters GN0 , JN0 , ω0 and l appeared significantly correlated with the contents of prolamins and secaloglutenins in triticale flours and glutens. © 2017 Society of Chemical Industry.

OsHrd3 is necessary for maintaining the quality of endoplasmic reticulum-derived protein bodies in rice endosperm.

Large amounts of seed storage proteins (SSPs) are produced in the maturing endosperm of rice seeds. Rice SSPs are synthesized as secretory proteins on the rough endoplasmic reticulum (ER), and are transported and deposited into protein complexes called protein bodies (PB-I and PB-II). Due to the high production of SSPs, unfolded SSPs may be generated during this process. However, it was previously unclear how such unfolded proteins are selected among synthesized products and removed from the ER to maintain protein quality in the endosperm. Since Hrd3/SEL1L recognizes unfolded proteins in yeast and mammalian protein quality control systems, the role of OsHrd3 in protein quality control in rice endosperm was investigated. Co-immunoprecipitation experiments demonstrated that OsHrd3 interacts with components of the Hrd1 ubiquitin ligase complex such as OsOS-9 and OsHrd1 in rice protoplasts. Endosperm-specific suppression of OsHrd3 in transgenic rice reduced the levels of polyubiquitinated proteins and resulted in unfolded protein responses (UPRs) in the endosperm, suggesting that OsHrd3-mediated polyubiquitination plays an important role in ER quality control. It was found that a cysteine-rich 13kDa prolamin, RM1, was polyubiquitinated in wild-type (WT) seeds but not in OsHrd3 knockdown (KD) seeds. RM1 formed aberrant aggregates that were deposited abnormally in OsHrd3 KD seeds, resulting in deformed PB-I. Therefore, the quality of protein bodies is maintained by polyubiquitination of unfolded SSPs through the Hrd1 ubiquitin ligase system in rice endosperm.

Identification of peanut seed prolamins with an antifungal role by 2D-GE and drought treatment.

This work revealed peanut seed prolamins likely displaying a defensive role besides the known nitrogen storage. Drought stress and proteomic approaches were used in varieties of peanuts to explore the prolamin member in association with a test against Aspergillus flavus spore germination. The stress effect was showed by aerial biomass, leaf content of malondialdehyde, and seed contamination by A. flavus. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles were not informative for the antifungal polypeptides. From two-dimensional gel electrophoresis, the suspected polypeptides were those with pI 5.45-5.75 and sizes of 22.0-30.5 kDa specifically in Spanish-type peanuts. Regarding to the drought effect in most of these peanuts, the spot peak volume analysis deduced three novel prolamin-related antifungal polypeptides at pI 5.75-5.8 with 30.5, 27.5-28.5, and 22.0-22.5 kDa, which was confirmed after isoelectric purification at pH 5.60. The data could not yet conclude their correlation with resistance to drought and to seed infection by A. flavus.

Reverse Micelles Extraction of Prolamin from Baijiu Jiuzao: Impact of Isolation Process on Protein Structure and Morphology.

Prolamins, proteins derived from plants, have extensive applications in pharmaceutics and food science. Jiuzao is a byproduct of the Baijiu brewing industry, and is a great source of prolamin. Despite its importance, knowledge regarding the extraction techniques and the properties of prolamin derived from Baijiu Jiuzao (PBJ) remains limited. Reverse micelles (RMs) extraction offers an efficient and cost-effective method for purifying proteins. In the present study, prolamin was extracted from Baijiu Jiuzao using RMs extraction and subsequently characterized in terms of its secondary structure, morphology, and particle size distribution. Our findings indicate that the purified prolamin extracted using further RMs extraction possessed higher α-helix content (+13.25%), forming a large-scale protein network, and narrower particle size distributions compared to the crude prolamin obtained by NaOH-ethanol method. This research suggests that RMs extraction has potential applications in extracting prolamin from brewing industry byproducts, offering an environmentally friendly approach to Baijiu Jiuzao recycling.

Oxidative Stability of Fish Oil-Loaded Nanocapsules Produced by Electrospraying Using Kafirin or Zein Proteins as Wall Materials.

The encapsulation of fish oil by monoaxial electrospraying using kafirin or zein proteins as hydrophobic wall materials was investigated. Kafirin resulted in spherical fish oil-loaded nanocapsules (>50% of capsules below 1 µm), whereas zein led to fish oil-loaded nanocapsules with non-spherical morphology (>80% of capsules below 1 µm). Both hydrophobic encapsulating materials interacted with fish oil, successfully entrapping the oil within the protein matrix as indicated by Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy results. FTIR also suggested hydrogen bonding between fish oil and the proteins. Trapped radicals in the encapsulation matrix that were detected by electron paramagnetic resonance (EPR), indicated oxidation during electrospraying and storage. Results from isothermal (140 °C) differential scanning calorimetry (DSC) denoted that the encapsulation of fish oil by electrospraying using both kafirin or zein as wall materials protected fish oil from oxidation. In particular, the zein-based nanocapsules were 3.3 times more oxidatively stable than the kafirin-based nanocapsules, which correlates with the higher oil encapsulation efficiency found for zein-based capsules. Thus, this study shows that kafirin might be considered a hydrophobic wall material for the encapsulation of fish oil by electrospraying, although it prevented lipid oxidation to a lower extent when compared to zein.

Extraction, Composition, Functionality, and Utilization of Brewer's Spent Grain Protein in Food Formulations.

In recent years, brewer's spent grain (BSG) has gained attention as a plant-based protein source because it occurs in large quantities as a by-product of beer brewing. BSG can contribute to future food requirements and support the development of a circular economy. In light of the dynamic developments in this area, this review aims to understand the proteins present in BSG, and the effect of extraction techniques and conditions on the composition, physicochemical, and techno-functional properties of the obtained protein extracts. The water-insoluble hordeins and glutelins form the major protein fractions in BSG. Depending on the beer brewing process, the extraction technique, and conditions, the BSG protein isolates predominantly contain B, C, and ϒ hordeins, and exhibit a broad molecular weight distribution ranging between <5 kDa and >250 kDa. While the BSG isolates obtained through chemical extraction methods seem promising to obtain gelled food products, physical and enzymatic modifications of BSG proteins through ultrasound and proteolytic hydrolysis offer an effective way to produce soluble and functional protein isolates with good emulsifying and foaming capabilities. Specifically tailored protein extracts to suit different applications can thus be obtained from BSG, highlighting that it is a highly valuable protein source.

3D-Printed Prolamin Scaffolds for Cell-Based Meat Culture.

Cultivating meat from muscle stem cells in vitro requires 3D edible scaffolds as the supporting matrix. Electrohydrodynamic (EHD) printing is an emerging 3D-printing technology for fabricating ultrafine fibrous scaffolds with high precision microstructures for biomedical applications. However, edible EHD-printed scaffolds remain scarce in cultured meat (CM) production partly due to special requirements with regard to the printability of ink. Here, hordein or secalin is mixed, which are cereal prolamins extracted from barley or rye, with zein to produce pure prolamin-based inks, which exhibit favorable printability similar to common polycaprolactone ink. Zein/hordein and zein/secalin scaffolds with highly ordered tessellated structures are successfully fabricated after optimizing printing conditions. The prolamin scaffolds demonstrated good water stability and in vitro degradability due to the porous fiber surface, which is spontaneously generated by culturing muscle cells for 1 week. Moreover, mouse skeletal myoblasts (C2C12) and porcine skeletal muscle satellite cells (PSCs) can adhere and proliferate on the fibrous matrix, and a CM slice is produced by culturing PSCs on prolamin scaffolds with high tissue similarity. The upregulation of myogenic proteins shows that the differentiation process is triggered in the 3D culture, demonstrating the great potential of prolamin scaffolds in CM production.

Difference analysis of the structure and functional properties among coix seed prolamin fractions (α-, ß-, and γ-coixin).

The differences in proteins in structural characteristics are reported to affect their physicochemical and functional properties. In this study, three types of prolamins (γ-, α-, and ß-coixin) derived from coix seed separately distributed among fractions 1-3 extracts. They were studied respecting molecular weight, amino acid composition, secondary structure, microstructure, surface hydrophobicity, solubility, water holding capacity, and oil holding capacity. Results showed that the molecular weights of those three fractions were between 10 and 40 kDa. The secondary structure of those fractions was almost the same, mainly based on ß-sheet and irregular structure. The microstructure of α- and γ-coixin presented an irregular shape, whereas ß-coixin presented a regular spherical shape. Those three fractions exhibited species of abundant essential amino acids with the same amino acid composition but different contents. The ß-coixin fraction had the highest content of hydrophobic amino acids (238.39 mg/g) followed by the α-coixin fraction (235.05 mg/g), whereas the γ-coixin fraction had the lowest content (33.27 mg/g). The γ-coixin fraction has the maximum surface hydrophobicity, whereas the ß-coixin fraction has the highest solubility. In addition, the good amphiphilicity of ß-coixin fraction made it possible to be used as a surfactant. The excellent functional properties of the ß-coixin fraction presented in this research would widen the applications of coix seed prolamins. PRACTICAL APPLICATION: The molecular weights of those three fractions were between 10 and 40 kDa. The secondary structure was almost the same, mainly based on ß-sheet and irregular structure. Those three fractions exhibited species of abundant essential amino acids with the same amino acid composition but different contents. The WHC and OHC of ß-coixin were the best, indicating its potential as a surfactant and forming stable lotion.

Screening and Activity Analysis of α-Glucosidase Inhibitory Peptides Derived from Coix Seed Prolamins Using Bioinformatics and Molecular Docking.

Hydrolysates of coix seed prolamins (CHPs) have an excellent hypoglycemic effect and can effectively inhibit α-glucosidase, which is the therapeutic target enzyme for type 2 diabetes mellitus. However, its hypoglycemic components and molecular mechanisms remain unclear, and its stability in food processing needs to be explored. In this study, four potential α-glucosidase inhibitory peptides (LFPSNPLA, FPCNPLV, HLPFNPQ, LLPFYPN) were identified and screened from CHPs using LC-MS/MS and virtual screening techniques. The results of molecular docking showed that the four peptides mainly inhibited α-glucosidase activity through hydrogen bonding and hydrophobic interactions, with Pro and Leu in the peptides playing important roles. In addition, CHPs can maintain good activity under high temperatures (40~100 °C) and weakly acidic or weakly alkaline conditions (pH 6.0~8.0). The addition of glucose (at 100 °C) and NaCl increased the inhibitory activity of α-glucosidase in CHPs. The addition of metal ions significantly decreased the inhibitory activity of α-glucosidase by CHPs, and their effects varied in magnitude with Cu2+ having the largest effect followed by Zn2+, Fe3+, K+, Mg2+, and Ca2+. These results further highlight the potential of CHPs as a foodborne hypoglycemic ingredient, providing a theoretical basis for the application of CHPs in the healthy food industry.

Processing Enhances Coix Seed Prolamins Structure and Releases Functional Peptides after Digestion: In Silico and In Vitro Studies.

Dipeptidyl peptidase-IV (DPP-IV) is a key target for the treatment of type 2 diabetes mellitus. It is possible that peptides that precisely regulate DPP-IV could be released from coix seed prolamins (CSP), but whether this happens has not yet been investigated. We performed the in silico digestion of CSP and predicted the bioactivity, absorption, transport, toxicity, and allergenicity of the resulting peptides. The simulation predicted that 47 non-toxic bioactive peptides would be released. After screening these, we found that 64.58% of them could possess DPP-IV inhibitory activity. The effect of thermal processing on the amino acid composition and structural properties of CSP was determined, and the DPP-IV inhibitory activity of its digestion-derived peptides was also assessed. The results showed that processing could change the flavour of coix seed and the supply of amino acids. After processing, the spatial conformation of CSP changed from ordered to disordered, and the peptide content and the DPP-IV inhibitory activity of its digestion products significantly increased by 19.89-30.91% and 36.84-42.02%, respectively. These results support the hypothesis that processing can change the protein structure and increase the probability that bioactive peptides will be released. They also have important implications for the development of bioactive peptides and the intensive processing of coix seeds.

Flexible processing technology of coix seed prolamins by combined heat-ultrasound: Effects on their enzymatic hydrolysis characteristics and the hypoglycemic activities of derived peptides.

The self-assembled structures of coix seeds affected the enzymatic efficiency and doesn't facilitate the release of more active peptides. The influence of heating combined with ultrasound pretreatment (HT + US) on the structure, enzymatic properties and hydrolysates (CHPs) of coix seed prolamin was investigated. Results showed that the structural of coix seed prolamins has changed after HT + US, including increased surface hydrophobicity, reduced α-helix and random coil content, and a decrease in particle size. So that, leads to changes in thermodynamic parameters such as an increase in the reaction rate constant and a decrease in activation energy, enthalpy and enthalpy. The fractions of <1000 Da, degree of hydrolysis and α-glucosidase inhibitory were increased in the HT + US group compared to single pretreatment by 0.68%-17.34%, 12.69%-34.43% and 30.00%-53.46%. The peptide content and α-glucosidase inhibitory activity of CHPs could be maintained at 72.21 % and 57.97 % of the initial raw materials after in vitro digestion. Thus, the findings indicate that HT + US provides a feasible and efficient approach to can effectively enhance the enzymatic hydrolysis efficiency and hypoglycaemic efficacy of CHPs.