Action Of Digestive Enzymes Research Articles

How D-amino acids embedded in the protein sequence modify its digestibility: Behaviour of digestive enzymes tested on a model peptide used as target

D-amino acids can affect the action of digestive enzymes, hence the protein digestion. In this work the behaviour of the main stomach and gut digestive enzymes (pepsin, trypsin, and chymotrypsin) in the presence of D-amino acids in the protein chain was monitored over time using a model peptide, Ac-LDAQSAPLRVYVE-NH2 (belonging to β-lactoglobulin, position 48–60), where L-amino acids were systematically substituted by D-amino acids. The results showed several changes in the behaviour of digestive enzymes, not only when the D-amino acids are inserted at the specific cleavage sites (after Val-57), but in some cases also when in distant positions. The effect seemed more pronounced in the case of pepsin rather than the gut enzymes, possibly indicating a better resilience of the upper gut phase of digestion to racemization. These results demonstrated that racemization could impair nutritional value by slowing down digestibility and has different effects according to the enzyme/amino acids involved.

Effect of Medium Chain Triglycerides on the Digestion and Quality Characteristics of Tea Polyphenols-Fortified Cooked Rice.

Nowadays, medium chain triglycerides (MCT) with special health benefits have been increasingly applied for fortifying food products. Therefore, the present work aimed to investigate the effects of MCT on traditional tea polyphenols-fortified cooked rice (TP-FCR). It was visualized by DSC, CLSM, XRD, FT-IR, and Raman spectroscopy. The higher content of starch-MCT complexes with an increase in the relative crystallinity and the generation of short-range ordered structures contributed to a more ordered and compact molecular arrangement, which can hinder the action of digestive enzymes on starch. SEM demonstrated that MCT transformed the microstructure of TP-FCR into a denser and firmer character, making it an essential component hindering the accessibility of digestive enzymes to starch granules and slowing the release of tea polyphenols in TP-FCR to attenuate starch digestion. Consequently, the addition of MCT reduced the polyphenol-regulated starch digestibility from 74.28% in cooked white rice to 64.43% in TP-FCR, and further down to 50.82%. Besides, MCT also reduced the adhesiveness and improved the whiteness of TP-FCR. The findings suggested that MCT incorporation could be a potential strategy in cooked rice production to achieve high sensory quality and low glycemic cooked rice.

Encapsulation and Assessment of Antidiabetic Potential of α-Lactalbumin-Derived Hydrolysates.

Dipeptidyl peptidase-IV (DPP-IV) is an exopeptidase mainly present in epithelial tissues of the liver, kidney, and intestine. It is involved in the cleavage of a variety of substrates including the incretin hormones like glucagon-like peptide-1 (GLP-1). GLP-1 binds to the GLP-1 receptors of pancreatic β-cells and leads to β-cell proliferation and increases insulin secretion through associated gene expression. In diabetes, a constant increase in the glucose level leads to glucotoxicity, which destroys pancreatic β-cells, decreases the insulin level, and further increases the blood glucose level. Inhibition of DPP-IV is one of the strategies for the treatment of type 2 diabetes. In recent years, peptides derived from a variety of dietary proteins have been reported to exhibit inhibitory activity against the DPP-IV enzyme. Such peptides should also be protected from the action of digestive enzymes to keep their bioactivity intact. Therefore, the present investigation was aimed to evaluate the in vitro DPP-IV inhibition potential and in vivo antidiabetic potential of α-lactalbumin in non-encapsulated hydrolysate (NEH), freeze-dried encapsulated hydrolysate (FDEH), and emulsified encapsulated hydrolysate (EEH) forms. Percent DPP-IV inhibition by the NEH, FDEH, and EEH after simulated gastrointestinal digestion was 36 ± 2.28, 54 ± 2.02, and 64 ± 2.02, respectively. The oral administration of the NEH, FDEH, and EEH at a dose of 300 mg/kg body weight was evaluated in nicotinamide-streptozotocin-induced type 2 diabetic experimental rats in a study of 30 days. Rats in the diabetic control group showed an increase in the blood glucose level and liver function enzymes and a decrease in GLP-1, insulin, and antioxidative enzymes. Administration of hydrolysates reversed the parameters by lowering the blood glucose level and increasing GLP-1 and insulin levels in plasma. The blood lipid profile, liver enzyme (ALT, AST, and AP) levels, and catalase and superoxide dismutase activity were also found to be normalized and better managed in experimental diabetic rats.

Parsing structural fragments of thiazolidin-4-one based α-amylase inhibitors: A combined approach employing in vitro colorimetric screening and GA-MLR based QSAR modelling supported by molecular docking, molecular dynamics simulation and ADMET studies

α-Amylase (EC.3.2.1.1) is a ubiquitous digestive endoamylase. The abrupt rise in blood glucose levels due to the hydrolysis of carbohydrates by α-amylase at a faster rate is one of the main reasons for type 2 diabetes. The inhibitors prevent the action of digestive enzymes, slowing the digestion of carbs and eventually assisting in the management of postprandial hyperglycemia. In the course of developing α-amylase inhibitors, we have screened 2-aryliminothiazolidin-4-one based analogs for their in vitro α-amylase inhibitory potential and employed various in silico approaches for the detailed exploration of the bioactivity. The DNSA bioassay revealed that compounds 5c, 5e, 5h, 5j, 5m, 5o and 5t were more potent than the reference drug (IC60 value = 22.94 ± 0.24 μg mL−1). The derivative 5o with –NO2 group at both the rings was the most potent analog with an IC60 value of 19.67 ± 0.20 μg mL−1 whereas derivative 5a with unsubstituted aromatic rings showed poor inhibitory potential with an IC60 value of 33.40 ± 0.15 μg mL−1. The reliable QSAR models were developed using the QSARINS software. The high value of R2ext = 0.9632 for model IM-9 showed that the built model can be applied to predict the α-amylase inhibitory activity of the untested molecules. A consensus modelling approach was also employed to test the reliability and robustness of the developed QSAR models. Molecular docking and molecular dynamics were employed to validate the bioassay results by studying the conformational changes and interaction mechanisms. A step further, these compounds also exhibited good ADMET characteristics and bioavailability when tested for in silico pharmacokinetics prediction parameters.

Evaluation of the Multifunctionality of Soybean Proteins and Peptides in Immune Cell Models.

Inflammatory and oxidative processes are tightly regulated by innate and adaptive immune systems, which are involved in the pathology of a diversity of chronic diseases. Soybean peptides, such as lunasin, have emerged as one of the most hopeful food-derived peptides with a positive impact on health. The aim was to study the potential antioxidant and immunomodulatory activity of a lunasin-enriched soybean extract (LES). The protein profile of LES was characterized, and its behavior under simulated gastrointestinal digestion was evaluated. Besides its in vitro radical scavenging capacity, LES and lunasin's effects on cell viability, phagocytic capacity, oxidative stress, and inflammation-associated biomarkers were investigated in both RAW264.7 macrophages and lymphocytes EL4. Lunasin and other soluble peptides enriched after aqueous solvent extraction partially resisted the action of digestive enzymes, being potentially responsible for the beneficial effects of LES. This extract scavenged radicals, reduced reactive oxygen species (ROS) and exerted immunostimulatory effects, increasing nitric oxide (NO) production, phagocytic activity, and cytokine release in macrophages. Lunasin and LES also exerted dose-dependent immunomodulatory effects on EL4 cell proliferation and cytokine production. The modulatory effects of soybean peptides on both immune cell models suggest their potential protective role against oxidative stress, inflammation, and immune response-associated disorders.

Comparative Evaluation of Heat Treatment of Guinea Fowl Meat

Introduction. The study of quality indicators of guinea fowl meat, depending on the methods of heat treatment, is of particular relevance in the context of increasing interest in ensuring effective health protection of the population and promoting the practices of the best available technologies. Purpose. The purpose of the original study was to conduct a comparative assessment of changes in the quality of guinea fowl meat depending on various methods of heat treatment (baking, sous-vide). Materials and methods. The work was guided by TR CU 021/2011, TR CU 034/2013, MG 4.2.2747-10, and all-Union State Standard. Results. As a result of the research, it was found that guinea fowl meat is a source of complete protein (a lot of tryptophan and isoleucine), a balanced lipid fraction, which allows it to be recommended for therapeutic, functional children's and dietary nutrition. A sous-vide technology has been developed for a product made from guinea fowl meat with high functional and technological properties and organoleptic characteristics. Conclusions. It has been established that the developed product contains 2.96% more moisture, 0.4% protein, has a more delicate texture and accessibility to the action of digestive enzymes (by 1.69%), compared with the product baked in a polyethylene terephthalate bag.

Comparative evaluation of methods for studying the degree of assimilation of feed by animals

Relevance. The activity of the digestive organs is largely determined by the feeding regime, in particular, the frequency, timeliness, and the order of feeding the feed. The digestibility of nutrients is influenced by the preparation of feed for feeding, which facilitates mechanical processing in the digestive tract and the action of digestive enzymes. Against the background of a decrease in the natural resistance of the animal body, an important aspect is the use of mineral supplements and the enrichment of diets with biologically active substances that increase the nutritional value and the degree of assimilation of feed by animals. The aim of the work was a comparative assessment of methods for studying the degree of assimilation of feed by animals.Methods. To determine the degree of food assimilation, 2 drops of isotonic (0.9%) sodium chloride solution and a small amount of intestinal contents were applied to a glass slide, a thin smear was prepared, dried in air for 30 min, and large particles were removed. The preparations were fixed for 15 min with 96% ethyl alcohol, then 3–5 drops of a 1.0% aqueous solution of methylene blue, Lugol, Sudan III were applied. Along with the indicated conventional methods, we tested a method for preparing preparations using fixation in vapors of a 25.0% solution of glutaraldehyde for 30–40 minutes, in vapors of a 1.0% aqueous solution of osmium tetroxide.Results. The kinetics of the formation of intestinal microbiocenoses is characterized by a decrease in the number of lactobacilli and an increase in the number of pathogenic and opportunistic bacteria. In a comparative assessment of the preparation methods, the advantage of microscopic research methods is the possibility of a detailed study of the contents, the degree of assimilation of feed components in the gastrointestinal tract, and a visual assessment of the state of the intestinal microflora. The advantage of the method for preparing preparations with the use of vapor fixation of a 25.0% solution of glutaraldehyde and osmium tetroxide is the possibility of visualizing the formation of monospecific and polyspecies biofilms by optical and scanning electron microscopy. The preparations were sufficiently contrasting, there were no artifacts, bacteria and fungi stained brown, which made it possible to count even pinpoint colonies using a magnifying glass or an optical microscope. The easily digestible feed results in a low fecal yield and a stable consistency. The use of functional food “Pristine Gold Vet” in the nutrition of dogs and fur-bearing animals made it possible to increase the absorption of nutrients by 18,1% and 15,3%.

Effect of low dose γ-irradiation on the structural and functional properties, and in vitro digestibility of ultrasonicated stem starch from Corypha umbraculifera L.

In the present study, non-conventional talipot starch was subjected to single and dual modifications using two non-thermal techniques; ultrasonication and γ-irradiation (1 kGy and 10 kGy). Free radical-mediated low dose γ-irradiation made remarkable changes in the morphological, physicochemical, and functional properties of ultrasonicated talipot starches compared to single modifications. Dual (ultrasonication+γ-irradiation) modification created deep grooves, reduced relative crystallinity and peak intensity of OH and CH2 groups by cavitation and radiolysis. Compared to ultrasonicated and γ-irradiated starches, dual-modified starches showed significantly reduced (p ≤ 0.05) pH, amylose content, and swelling power, and improved storage stability by lowering the retrogradation tendency. The in vitro digestibility of dual-modified talipot starches was increased by the enhanced action of digestive enzymes with starch. The gelatinization, pasting, and rheological properties significantly decreased (p ≤ 0.05) with the increasing dose of γ-irradiation in dual-modified talipot starches and represented soft gel possessing shear-thinning stability.

Feeding Behavior of Collaria scenica (Stål) (Hemiptera: Miridae) on Wheat Plants: an EPG Waveform Characterization.

In this study, we use for the first time the electropenetrography (EPG) technique to characterize and describe the feeding activities of Collaria scenica (Stål) adults and their respective waveforms on wheat, Triticum aestivum L. plants. It comprised of four waveforms, two related to non-feeding (Np and R) and two with feeding activities (CR and I). The Np wave represents the insect resting or walking on the plant surface (75% of the recording time). R wave was associated to sensory evaluation of leaf surface with the tip of the labium (labial dabbing activity-ca. 1% of the recording time). Feeding activities were of relative short duration; cell rupture waveform (CR-ca. 49 min-ca. 15% of the recording time) was highly irregular due to constant movement of the stylets internally in the plant tissue. The waveform I (ca. 28 min-ca. 9% of the recording time) showed stereotypical and repetitive pattern and represents ingestion of the cell contents previously degraded via cell-rupturing activities. The damage caused by C. scenica in wheat leaflets is a result of cell-rupturing activities, generated by action of digestive enzymes plus mechanical action of serrated mandibular stylets. This results in whitish streaks, dots, or spots on the leaflet of wheat plants which cause significant damage and eventually plants' death.

Interpolymer Complexes Based on Carbopol<sup>®</sup> and Poly(2-ethyl-2-oxazoline) as Carriers for Buccal Delivery of Metformin

Introduction. Buccal drug delivery has a number of advantages over oral administration: ease of application, good blood supply to the buccal mucosa, drug can enter the systemic circulation directly, avoiding the "first pass effect through the liver", and are not exposed to the acidic environment of the gastric juice and the destructive action of digestive enzymes. The use of interpolymer complexes (IPCs) makes it possible not only to ensure adhesion to the mucosal membranes of the oral cavity, but also to achieve a prolonged release of drugs.Aim. Development of carriers based on interpolymer complexes using Carbopol® 971 NF (C971) and poly(2-ethyl-2-oxazoline) (POZ) of different molecular weights for buccal delivery of metformin (MF).Materials and methods. The study of IPC adhesion was carried out using a TA.XTplus texture analyzer (Stable Micro Systems, UK); mucin compacts with a diameter of 13 mm were used as a substrate; these were prepared by compressing porcine gastric mucin powder using a manual hydraulic press for IR spectroscopy (PerkinElmer, USA) at a pressure of 2.45 MPa. The study of the swelling capacity was carried out by placing polymer matrices in an artificial saliva medium, with constant thermostating at a temperature of 37.0 ± 0.5 °C for 5 hours. The study of the release of MF from the matrices based on IPC was carried out using a DFZ II apparatus (Erweka, Germany) according to the Flow Through Cell method (USP IV) with cells for tablets (22.6 mm) and adaptors for ointments, creams and gels in a medium simulating saliva. The concentration of MF in the samples from the dissolution tests was determined with UV-spectrophotometry (Lambda, PerkinElmer, USA) at 232.8 nm.Results and discussion. In a comparative study of the mucoadhesive properties of polymer samples, IPC compacts showed a mucoadhesion capacity comparable to that of poly(2-ethyl-2-oxazoline); at the same time, compacts from physical mixtures (PM) and C971 are inferior in terms of the separation force to IPC samples, however, POZes dissolve in an artificial saliva medium, that is, they are not suitable as dosage forms for buccal delivery. For 5 hours of the experiment to assess the swelling capacity, the IPC matrices did not change significantly, which can ensure their comfortable use as carriers for buccal delivery. When evaluating the release of metformin from polymer matrices (with weight ratio MF/IPC 1: 0.5), the most complete release (more than 90 %) is observed from both IPC matrices compared to matrices of PM and individual polymers.Conclusion. Polycomplex matrix systems based on C971-POZ (50 kDa) and C971-POZ (500 kDa) are suitable for buccal delivery of metformin.

Current Evidence on the Bioavailability of Food Bioactive Peptides.

Food protein-derived bioactive peptides are recognized as valuable ingredients of functional foods and/or nutraceuticals to promote health and reduce the risk of chronic diseases. However, although peptides have been demonstrated to exert multiple benefits by biochemical assays, cell culture, and animal models, the ability to translate the new findings into practical or commercial uses remains delayed. This fact is mainly due to the lack of correlation of in vitro findings with in vivo functions of peptides because of their low bioavailability. Once ingested, peptides need to resist the action of digestive enzymes during their transit through the gastrointestinal tract and cross the intestinal epithelial barrier to reach the target organs in an intact and active form to exert their health-promoting properties. Thus, for a better understanding of the in vivo physiological effects of food bioactive peptides, extensive research studies on their gastrointestinal stability and transport are needed. This review summarizes the most current evidence on those factors affecting the digestive and absorptive processes of food bioactive peptides, the recently designed models mimicking the gastrointestinal environment, as well as the novel strategies developed and currently applied to enhance the absorption and bioavailability of peptides.

High-pressure homogenization as compared to pasteurization as a sustainable approach to obtain mandarin juices with improved bioaccessibility of carotenoids and flavonoids

High-pressure technologies are among those with increased interest in the sustainable production of quality-enhanced food products. In this work, Ortanique mandarin juices have been submitted to traditional pasteurization conditions (time/temperature of 65 °C/15 s, 85 °C/15 s and 92 °C/30 s) and energy-saving high-pressure homogenization (HPH, 150 MPa) treatments to compare the effects on the physicochemical composition and in vitro bioaccessibility of carotenoids and flavonoids. In general, physicochemical attributes of the homogenized sample were similar to those found in fresh juice, with similar ascorbic acid content and cloudiness but with significant colour differences in all cases. The bioaccessibility of total carotenoids was similar in fresh and pasteurized juices in contrast to the HPH sample that exhibited a five-fold increase, which suggests a positive effect of particle size reduction to favour the action of digestive enzymes. A clear increase in the levels of epoxycarotenoids was detected in the micellar fractions of digested HPH juices, although such carotenoids are not detected in human fluids or tissues. Regarding the bioaccessibility of flavonoids, no significant differences were found in the samples studied. Results obtained can help the implementation of HPH processing to obtain natural beverages with enhanced nutritional properties.

Emblicanin rich Emblica officinalis extract encapsulated double emulsion: controlled release of bioactive during phagocytosis and in vitro digestion.

Controlled release of Emblicanin rich water soluble extract of Emblica officinalis (EEO) from the inner phase ofwater-in-oil-in-water type double emulsion (DE), during in vitro digestion and phagocytosis was investigated. It was observed that release of EEO (measured as total polyphenols and gallic acid by HPLC) from inner phase of DE was maximum during intestinal digestion followed by gastric and salivary digestion. Main reason was increased particle size of emulsion droplets and change in zeta potential by the action of digestive enzymes. ACE inhibitory activity and antioxidant activity [determined by ABTS (99.58 ± 7.24mM/mL), DPPH (76.93 ± 0.93µM/mL) and FRAP (6.34 ± 0.13mM/mL)] was observed on the higher side in the intestinal digesta of EEO-encapsulated DE (EEODE) as compared to salivary and gastric digesta. However, reverse trend was observed in control sample (unencapsulated-EEO). Phagocytic activity of EEODE increased with increasing its concentration of 2-10µL. These results indicated that the developed DE matrix was effective in protecting active components of EEO during harsh digestive conditions as evident by sustained/target release. This newly developed EEODE formulation can be used as functional ingredient in the preparation of different dairy and food based functional products.

Microalgae of interest as food source: Biochemical composition and digestibility

Microalgae are considered a very interesting source for the development of new food products and can be used to enhance the nutritional value of conventional foods, due to their valuable biochemical composition.The aim of this study was to investigate the biochemical composition, the fatty acid profile and the in vitro digestibility of twelve microalgal biomasses (Arthrospira platensis F&M-C256; a bloom mainly composed of Aphanizomenon flos-aquae from Klamath Lake; Nostoc sphaeroides F&M-C117; Chlorella sorokiniana F&M-M49; Chlorella sorokiniana IAM C-212; Chlorella vulgaris Allma; Tetraselmis suecica F&M-M33, in nutrient replete medium and starved; Porphyridium purpureum F&M-M46; Phaeodactylum tricornutum F&M-M40; Tisochrysis lutea F&M-M36; Nannochloropsis oceanica F&M-M24) of interest as food source.The three cyanobacteria and the Chlorella species presented high protein (50–65%) and low lipid (5–20%) content. A high fiber content (14–17%) was found in T. suecica grown in nutrient replete medium, P. purpureum and P. tricornutum.Biomasses of marine species contained high concentrations of polyunsaturated fatty acids, mainly C20:5ω3 and C22:6ω3, along with substantial amounts of C16:1ω7, C18:1ω9 and C16:0. The freshwater algae contained high amounts of C18:3ω3 and an even higher amount of C16:0.A. platensis, C. sorokiniana IAM-C212 and C. vulgaris showed the highest digestibility, while T. suecica, P. tricornutum, and P. purpureum were the least digestible, likely because of the presence of robust cell walls or of exopolysaccharides that might have limited the action of digestive enzymes.

Bringing together Saccharomyces cerevisiae and bioactive compounds from plants: A new function for a well-known biosorbent

Abstract Use of the Saccharomyces cerevisiae as a biosorbent material has proven versatile in innovative applications like the biosorption of bioactive compounds from plant extracts. The bioactive compounds have different biological activities such antioxidant, antimicrobial and anticancer properties. Thus, the application of S. cerevisiae intends to increase the bioaccessibility of bioactive compounds, increasing absorption by the body compared to direct ingestion. The increase in the bioaccessibility of the bioactive compounds occurs by the protection provided by the yeast cell, reducing the degradation that occurs through the action of digestive enzymes and abrupt changes in pH. This review discusses existing adsorption studies using S. cerevisiae biomass, highlighting its use for the biosorption of bioactive compounds, limitations as well as factors that promote an improvement of the biosorptive capacity and bioaccessibility, the main existing applications and future suggestions.

Multifunctionality of lunasin and peptides released during its simulated gastrointestinal digestion.

Oxidative stress, inflammation, and hypertension are recognized risk factors for non-communicable diseases. Because of the preventable character of these factors, the searching of dietary compounds with counteracting effects against them would provide a new framework for the development of novel multifunctional foods or nutraceuticals. Lunasin is a naturally occurring soybean peptide with chemopreventive and anti-inflammatory properties. Upon oral intake, lunasin is susceptible to the action of digestive enzymes during its transit through gastrointestinal tract. In spite of its cleavage into smaller peptides, these fragments have been suggested to contribute on the health beneficial effects attributed to lunasin. To confirm this hypothesis, the multifunctionality of lunasin derived-fragments was investigated. In vitro, peptides corresponding to the N-terminal and central regions of lunasin were demonstrated to inhibit angiotensin converting enzyme and to scavenge peroxyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radicals. Moreover, lunasin and fragments released during its gastrointestinal digestion exerted potent protective effects on cell viability and oxidative status in macrophages RAW264.7 challenged with chemicals tert-butylhydroperoxide and hydrogen peroxide. These peptides were also able to reduce the nitric oxide production in pro-inflammatory lipopolysaccharide-induced macrophages. These results confirm the promising role of lunasin and its derived-fragments as protective agents against oxidative damage and inflammation-associated diseases.

Marine Mollusks: Food with Benefits.

The extremely vast biodiversity represented by marine mollusks alongside their widespread utility as a source of food and their high nutritional value has aroused great interest from the scientific community. Furthermore, they can be caught with ease, and their commercial breeding and farming is rampant. This article comprehends the global availability of these organisms, their pretreatment and handling procedures, and their health-promoting potential with a focus on their antiviral, anti-inflammatory, and antimicrobial properties. The emphasis herein is on their potential use in the food and nutraceutical industry. In addition, mollusks consumption as part of everyday diet can also be helpful in avoiding many ailments as they are rich in vital nutrients and active secondary metabolites, as well as have the ability to enhance immune response. Moreover, the available literature suggests that normal cooking practices have no notable adverse effects on their nutritional value and they retain certain bioactivities even after the action of digestive enzymes. Though mollusks have been widely studied in relation to the health-promoting effects reviewed here, there is still more scope for further research in this direction in order to fully utilize this enormous source of food and nutraceuticals.

Digestibility of glycated milk proteins and the peptidomics of their in vitro digests.

Milk proteins are widely used in food production and are often glycated by reducing sugar. Although many studies have reported the digestibility of glycated milk protein, most have focused on measuring degree of hydrolysis (DH), showing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) image of digests. Detailed information on the changes in peptide composition of digests has seldom been revealed. Therefore, in addition to measuring the DH and showing the SGS-PAGE images of digests, we also analyzed the peptidomics in digests using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) and Mascot database in this work to further reveal the influence of glycation on protein nutrition. Compared with β-lactoglobulin and bovine serum albumin (BSA), DH of β-casein was suppressed to a lesser extent by glycation in both gastric and intestinal stages. Aggregates of glycated BSA were less sensitive to the action of digestive enzymes throughout gastrointestinal digestion according to SDS-PAGE images. Changes in the peptide composition of digests induced by glycation were distinctly displayed, showing both absence of peptides and occurrence of new peptides, based on the results obtained from LC-ESI-MS/MS. Glycation can greatly change the peptide composition in digests of milk protein. The nutritional impact of the change in the peptide composition requires further investigation, and the impact of MRPs in unabsorbed digests on the gut flora should be an interesting field for further studies. © 2018 Society of Chemical Industry.

Heat and Pressure Treatments on Almond Protein Stability and Change in Immunoreactivity after Simulated Human Digestion.

Almond is consumed worldwide and renowned as a valuable healthy food. Despite this, it is also a potent source of allergenic proteins that can trigger several mild to life-threatening immunoreactions. Food processing proved to alter biochemical characteristics of proteins, thus affecting the respective allergenicity. In this paper, we investigated the effect of autoclaving, preceded or not by a hydration step, on the biochemical and immunological properties of almond proteins. Any variation in the stability and immunoreactivity of almond proteins extracted from the treated materials were evaluated by total protein quantification, Enzyme Linked Immunosorbent Assay (ELISA), and protein profiling by electrophoresis-based separation (SDS-PAGE). The sole autoclaving applied was found to weakly affect almond protein stability, despite what was observed when hydration preceded autoclaving, which resulted in a loss of approximately 70% of total protein content compared to untreated samples, and a remarkable reduction of the final immunoreactivity. The final SDS-PAGE protein pattern recorded for hydrated and autoclaved almonds disclosed significant changes. In addition, the same samples were further submitted to human-simulated gastro-intestinal (GI) digestion to evaluate potential changes induced by these processing methods on allergen digestibility. Digestion products were identified by High Pressure Liquid Chromatography-High Resolution Tandem Mass Spectrometry (HPLC-HRMS/MS) analysis followed by software-based data mining, and complementary information was provided by analyzing the proteolytic fragments lower than 6 kDa in size. The autoclave-based treatment was found not to alter the allergen digestibility, whereas an increased susceptibility to proteolytic action of digestive enzymes was observed in almonds subjected to autoclaving of prehydrated almond kernels. Finally, the residual immunoreactivity of the GI-resistant peptides was in-silico investigated by bioinformatic tools. Results obtained confirm that by adopting both approaches, no epitopes associated with known allergens survived, thus demonstrating the potential effectiveness of these treatments to reduce almond allergenicity.

Inhibition of Lipid Peroxidation of Kiwicha (Amaranthus caudatus) Hydrolyzed Protein Using Zebrafish Larvae and Embryos.

Amaranth protein concentrate (APC) was hydrolyzed under in vitro gastrointestinal conditions. APC proteins were partially degraded by pepsin at pHs 1.2, 2.0, and 3.2. During the intestinal phase (pepsin/pancreatin enzymes at pH 7.0), no polypeptide bands were observed in the gel, suggesting the susceptibility of amaranth proteins to the action of digestive enzymes. The potent in vitro inhibition of lipid peroxidation, shown by the gastric and intestinal digests, was confirmed in the zebrafish larvae, with a 72.86% reduction in oxidation of lipids in the presence of the gastric hydrolysate at pH 2.0, compared to a 95.72% reduction in the presence of the gastrointestinal digest. APC digests were capable of reducing reactive oxygen species (ROS) production in the zebrafish embryo model with a value of fluorescence of 52.5% for the gastric hydrolysate, and 48.4% for the intestinal hydrolysate.