Bioactive peptides in beef: Endogenous generation through postmortem aging

Exploring the effect of part differences on metabolite molecule changes in refrigerated pork: Identifying key metabolite compounds and their conversion pathways

Effect of part differences on metabolite molecule alterations in refrigerated pork was investigated. A metabolomics methodology combined with chemometric analysis was successfully established to identify key compounds and their conversion pathways, including precursors and volatile metabolites, in the Longissimus lumborum as well as the breast and flank stored for 11 days. In total, 12 discriminative precursors were identified using the Short Time-series Expression Miner. In tandem with Random Forest and ANOVA analyses, nine volatile metabolites were identified as key compounds that could be attributed to differences in pork sections. Bidirectional orthogonal partial least squares analysis revealed a potential correlation between these key metabolites and discriminative precursors. Metabolic pathway enrichment analysis demonstrated that the primary metabolic process affected by variations in pork sections is linoleic acid metabolism, which participates in the metabolism of cysteine and glutamic acid to produce methoxy-phenyl-oxime. This study provides valuable insights into the identification of differential metabolites.

Relationship between peptides and the change in quality characteristics of beef strip loin (M. longissimus lumborum) and tenderloin (M. psoas major)

Peptides in fresh and aged beef strip loin (M. longissimus lumborum) and tenderloin (M. psoas major) were quantified to investigate the relationship between proteolysis-induced peptides and beef quality characteristics. A total of 409 and 450 peptides were quantified from strip loin and tenderloin, respectively, and found to be significantly correlated to beef quality characteristics. Changes in redness and yellowness were significantly correlated to the peptides derived from G3P, ENOB, and KCRM in both muscles during 14 days of storage. The peptides produced from MYG, ENOB, HBA, PGK1, and TPIS were strongly associated with improved tenderness, while those derived from major myofibrillar proteins, such as MYH1, MYH2, ACTS, and DESM, were associated with changes in tenderloin color. These results improve our understanding of the association between peptides and changes in meat quality during cold storage, indicating that proteolysis-induced peptides can be indicators of the quality characteristics of fresh and aged meat.

Antioxidant and Renin Inhibitory Activities of Peptides from Food Proteins on Hypertension: A Review

Hypertension is a condition induced by oxidative stress causing an alteration in the endothelium, which increases the risk of suffering from other degenerative diseases. This review compiles the findings on peptides from food proteins with antioxidant and antihypertensive activities. Antihypertensive peptides are mainly focused on renin inhibition. Peptides containing hydrophobic amino acids have antioxidant and renin inhibitory activities, as reported by studies on the biological activity of peptides from various food sources evaluated separately and simultaneously. Peptides from food sources can present multiple biological activities. Moreover, antioxidant peptides have the potential to be evaluated against renin, offering an alternative for hypertension therapy without causing adverse side effects.

Insight from untargeted metabolomics: Revealing the potential marker compounds changes in refrigerated pork based on random forests machine learning algorithm

Data on changes in non-volatile components and metabolic pathways during pork storage were inadequately investigated. Herein, an untargeted metabolomics coupled with random forests machine learning algorithm was proposed to identify the potential marker compounds and their effects on non-volatile production during pork storage by ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS/MS). A total of 873 differential metabolites were identified based on analysis of variance (ANOVA). Bioinformatics analysis shows that the key metabolic pathways for protein degradation and amino acid transport are amino acid metabolism and nucleotide metabolism. Finally, 40 potential marker compounds were screened using the random forest regression model, innovatively proposing the key role of pentose-related metabolism in pork spoilage. Multiple linear regression analysis revealed that d-xylose, xanthine, and pyruvaldehyde could be key marker compounds related to the freshness of refrigerated pork. Therefore, this study could provide new ideas for the identification of marker compounds in refrigerated pork.

Changes in beef protein digestibility in an in vitro infant digestion model with prefreezing temperatures and aging periods

The protein digestibility of beef at three prefreezing temperatures (freezing at -20 °C, F20; freezing at -50 °C, F50; and freezing at -70 °C, F70) and aging periods (4, 14, and 28 days) was investigated using an in vitro infant digestion model. The increased cathepsin B activity in the frozen-then-aged treatments (P < 0.05) resulted in a higher content of 10% trichloroacetic acid-soluble α-amino groups than in the aged-only group on days 14 and 28 (P < 0.05). F50 had the most α-amino groups in the digesta and digested proteins under 3 kDa on day 28 (P < 0.05), with the disappearance of actin band in the digesta electrophoretogram. The secondary and tertiary structures of myofibrillar proteins revealed that F50 underwent irreversible denaturation (P < 0.05), especially in the myosin fraction, while F20 and F70 showed protein renaturation during aging (P < 0.05). In general, prefreezing at -50 °C then aging can improve the in vitro protein digestibility of beef through freezing-induced structural changes.

Stability and bioactivity of peptides in food matrices based on processing conditions

Bioactive peptides (BPs) generated from food proteins can serve therapeutic purposes against degenerative and cardiovascular diseases such as inflammation, diabetes, and cancer. There are numerous reports on the in vitro, animal, and human studies of BPs, but not as much information on the stability and bioactivity of these peptides when incorporated in food matrices. The effects of heat and non-heat processing of the food products, and storage on the bioactivity of the BPs, are also lacking. To this end, we describe the production of BPs in this review, followed by the food processing conditions that affect their storage bioactivity in the food matrices. As this area of research is open for industrial innovation, we conclude that novel analytical methods targeting the interactions of BPs with other components in food matrices would be greatly significant while elucidating their overall bioactivity before, during and after processing.

Novel insights from protein degradation: deciphering the dynamic evolution of biogenic amines as a quality indicator in pork during storage

Biogenic amines (BAs) have drawn great attention as important markers for monitoring food quality. However, the BAs content in protein degradation profiles during pork storage was inadequately investigated. In this work, the Longissimus lumborum and Breast and flank of pork were collected, and their peptides contents, free amino acids (FAAs) contents, BAs contents, and several characteristic physicochemical indexes were monitored during storage at 4 °C. As a result, the differences of nutritional components in the Longissimus lumborum and Breast and flank could not affect the shelf life of refrigerated pork. There are 161 small peptides in the Longissimus lumborum of pork identified by LC-MS. As verified, arginine, glutamic acid, valine, and alanine could serve as four indicative amino acids during protein degradation in pork, and the arginine degradation pathway is more complex. Redundancy analysis confirmed that putrescine and cadaverine were significantly related to the precursor FAAs content, and their sum value could be used as a novel quality indicator instead of the biogenic amine index (BAI). Finally, the above prediction was also verified by the other species (beef, mutton and chicken) to improve the index system of meat quality evaluation in cold chain logistics.

Bioactive peptides from meat: Current status on production, biological activity, safety, and regulatory framework

By-products of the meat processing industry which are often discarded as waste are excellent protein substrates for producing bioactive peptides through enzymatic hydrolysis. These peptides have tremendous potential for the development of functional food products but there is scanty information about the regulations on bioactive peptides or products in various parts of the world. This review focuses on the diverse bioactive peptides identified from different meat and meat by-products, their bioactivity and challenges associated in their production as well as factors limiting their effective commercialization. Furthermore, this report provides additional information on the possible toxic peptides formed during production of the bioactive peptides, which enables delineation of associated safety and risk. The regulatory framework in place for bioactive peptide-based foods in different jurisdictions and the future research directions are also discussed. Uniform quality, high cost, poor sensory acceptance, lack of toxicological studies and clinical evidence, paltry stability, and lack of bioavailability data are some of the key challenges hindering commercial advancement of bioactive peptide-based functional foods. Absorption, distribution, metabolism and excretion (ADME) studies in rodents, in vitro genotoxicity, and immunogenicity data could be considered as absolute pre-requisites to ensure safety of bioactive peptides. In the absence of ADME and genotoxicity data, long term usage to evaluate safety is highly warranted. Differences in legislations among countries pose challenge in the international trade of bioactive peptides-based functional foods. Harmonization of regulations could be a way out and hence further research in this area is encouraged.

Plant- and Animal-Based Antioxidants' Structure, Efficacy, Mechanisms, and Applications: A Review

Antioxidants are compounds that normally prevent lipid and protein oxidation. They play a major role in preventing many adverse conditions in the human body, including inflammation and cancer. Synthetic antioxidants are widely used in the food industry to prevent the production of adverse compounds that harm humans. However, plant- and animal-based antioxidants are more appealing to consumers than synthetic antioxidants. Plant-based antioxidants are mainly phenolic compounds, carotenoids, and vitamins, while animal-based antioxidants are mainly whole protein or the peptides of meat, fish, egg, milk, and plant proteins. Plant-based antioxidants mainly consist of aromatic rings, while animal-based antioxidants mainly consist of amino acids. The phenolic compounds and peptides act differently in preventing oxidation and can be used in the food and pharmaceutical industries. Therefore, compared with animal-based antioxidants, plant-based compounds are more practical in the food industry. Even though plant-based antioxidant compounds are good sources of antioxidants, animal-based peptides (individual peptides) cannot be considered antioxidant compounds to add to food. However, they can be considered an ingredient that will enhance the antioxidant capacity. This review mainly compares plant- and animal-based antioxidants’ structure, efficacy, mechanisms, and applications.

Trends in In Silico Approaches to the Prediction of Biologically Active Peptides in Meat and Meat Products as an Important Factor for Preventing Food-Related Chronic Diseases

The increasing awareness of modern consumers regarding the nutritional and health value of food has changed their preferences, as well their requirements, for food products, including meat and meat products. Expanding the knowledge on the impact of food on human health is currently one of the most important research areas for scientists worldwide, and it is also of interest to consumers who want to consciously compose their daily diets. New research methods, such as in silico techniques, offer solutions to these new challenges. These research methods are preferred over food evaluation, e.g., from meat, because of their advantages, such as low costs, shorter analysis times, and general availability (e.g., online databases), and are often used to design in vitro and, subsequently, in vivo tests. This review focuses on the possible use of in silico computerized methods to assess the potential of food as a source of these health-relevant biomolecules by using examples from the literature on meat and meat products. This review also provides information and important suggestions for analyzing peptides in terms of assessing their best sources, and screening those resistant to digestive factors and that show biological activity. The information provided in this review could contribute to the development of new sources of foods as biomolecules important for preventing or treating food-related chronic diseases, such as obesity, hypertension, and diabetes.

Meat and Human Health-Current Knowledge and Research Gaps

Meat is highly nutritious and contributes with several essential nutrients which are difficult to obtain in the right amounts from other food sources. Industrially processed meat contains preservatives including salts, possibly exerting negative effects on health. During maturation, some processed meat products develop a specific microbiota, forming probiotic metabolites with physiological and biological effects yet unidentified, while the concentration of nutrients also increases. Meat is a source of saturated fatty acids, and current WHO nutrition recommendations advise limiting saturated fat to less than ten percent of total energy consumption. Recent meta-analyses of both observational and randomized controlled trials do not support any effect of saturated fat on cardiovascular disease or diabetes. The current evidence regarding the effect of meat consumption on health is potentially confounded, and there is a need for sufficiently powered high-quality trials assessing the health effects of meat consumption. Future studies should include biomarkers of meat intake, identify metabolic pathways and include detailed study of fermented and other processed meats and their potential of increasing nutrient availability and metabolic effects of compounds.

Bioactivities generated from meat proteins by enzymatic hydrolysis and the Maillard reaction

Bioactive peptides are released from meat proteins by enzymatic hydrolysis (i.e., gastrointestinal digestion, aging/storage, fermentation, and protease treatment). Such peptides attribute physiological functions to meat and meat products and are promising food ingredients for developing functional foods. Meat by-products (e.g., blood and collagen) are also good sources for generating bioactive peptides, since they are produced in large quantities and are rich in proteins. Although protein-derived bioactive peptides are attractive ingredients, their changes by the Maillard reaction during processing, cooking, and storage should be investigated. This article briefly reviews the production of bioactive peptides from meat and meat by-products. Such diverse peptides affects circulatory, nervous, alimentary, and immune systems. Then, the bioactivities of Maillard reaction products (MRPs) generated from protein hydrolysates are discussed. Special attention is paid to bioactivities of 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) inhalation. As such activities, we have evaluated the impact of DMHF on blood pressure, moods, brainwaves, and dietary intake. Our efforts for understanding various aspects and implication of peptides and MRPs from meat proteins would open new avenues in the meat and food industry.

Utilizing Pork Exudate Metabolomics to Reveal the Impact of Aging on Meat Quality

This study was performed to assess the changes in meat quality and metabolome profiles of meat exudate during postmortem aging. At 24 h postmortem, longissimus lumborum muscles were collected from 10 pork carcasses, cut into three sections, and randomly assigned to three aging period groups (2, 9, and 16 d). Meat quality and chemical analyses, along with the metabolomics of meat exudates using ultra-high-performance liquid chromatography coupled with a quadrupole time-of-flight mass spectrometer (UHPLC-QTOF-MS) platform, were conducted. Results indicated a declined (p < 0.05) display color stability, and increased (p < 0.05) purge loss, meat tenderness, and lipid oxidation as aging extended. The principal component analysis and hierarchical clustering analysis exhibited distinct clusters of the exudate metabolome of each aging treatment. A total of 39 significantly changed features were tentatively identified via matching them to METLIN database according to their MS/MS information. Some of those features are associated with adenosine triphosphate metabolism (creatine and hypoxanthine), antioxidation (oxidized glutathione and carnosine), and proteolysis (dipeptides and tripeptides). The findings provide valuable information that reflects the meat quality’s attributes and could be used as a source of potential biomarkers for predicting aging times and meat quality changes.

Use of Rapid Evaporative Ionisation Mass Spectrometry fingerprinting to determine the metabolic changes to dry-aged lean beef due to different ageing regimes

Rapid Evaporative Ionisation Mass Spectrometry (REIMS) was used to determine the impact of in-bag ageing regimes (stepwise-ageing at different air velocities and straight-dry-ageing) and trimming on the metabolic profile of dry-aged lean beef. Orthogonal projection to latent structures-discriminant analysis (OPLS-DA) models based on 1705 tentatively identified m/z features were found for ageing methods (Q² = 0.85), ageing time (0 vs. 21 days, Q² = 0.95) and sampling locations (surface meat vs. trimmings, Q² = 0.94). No significant (P > 0.05) difference in metabolites due to air velocities. Small metabolites such as dipeptides and amino acids were more abundant, especially on the surface of untrimmed lean beef, following 21 days of straight-dry-ageing. Stepwise-ageing produced different metabolic profiles from straight-dry-ageing, suggesting that the two methods may differ in dry-aged meat quality and flavour. This work demonstrates REIMS's potential for real time differentiation of meat on processing parameters.

The identification and characterisation of novel bioactive peptides derived from porcine liver

Bioactive peptides (BAPs) can be derived from a variety of sources; these could be from dietary proteins which are then broken down in the gastrointestinal tract to release BAPs, or they can be isolated from various sources ex vivo. Sources include plant-based proteins such as soy, and chickpeas, and animal proteins from waste from the meat industry and from fish skin. Bioinformatics is also a useful approach to assess the peptides released from digests due to the great number of possible sequences that can be isolated from proteins. Therefore, an in silico analysis of peptides could potentially lead to a more rapid discovery of BAPs. This article investigates a "crude" liver peptide mixture derived from papain hydrolysis of porcine liver and purified peptides derived from the hydrolysates following HPLC fractionation and in silico digestion of the host proteins identified using LC-MS/MS. This allowed the identification of two proteins (cytosol aminopeptidase and haemoglobin subunit alpha) present in the "crude" mixture after LC-MS/MS. In silico hydrolysis of these proteins identified that several peptides were predicted to be both present in the crude mixture using the BIOPEP database and to have potential bioactivity using the Peptide Ranker tool. Peptides (FWG, MFLG and SDPPLVFVG) with the greatest potential bioactivity and which had not previously been reported in the literature were then synthesised. The results indicated that the predicted bioactivity of the synthetic peptides would likely include antioxidant activity. FWG and MFLG derived from the in silico papain hydrolysis of cytosol aminopeptidase showed activity better or comparable to Trolox in the Oxygen Radical Absorbance Capacity (ORAC) assay. The use of these in silico tools, alongside a robust range of biochemical assays which cover a wider range of bioactivities would be a way of improving the discovery of novel bioactive peptides.

Structural Changes and Evolution of Peptides During Chill Storage of Pork

In this work, we investigated changes in protein structures in vacuum-packed pork during chill storage and its impact on the in vitro protein digestion. Longissimus dorsi muscles were vacuum packed and stored at 4°C for 3 days. Samples were subjected to Raman spectroscopy, in vitro digestion and nano LC-MS/MS. The 3 d samples had lower α-helix content, but higher β-sheet, β-turn, and random coil contents than the 0 d samples (P < 0.05). SDS-PAGE revealed significant protein degradation in the 3 d samples and the differences in digested products across the storage time. Proteome analysis indicated that the 3 d samples had the higher susceptibility to digestion. Increasing protein digestibility was mainly attributed to the degradation of myofibrillar proteins. Thus, exposure of more enzymatic sites in loose protein structure during chill storage could increase protein degradation in meat.

Characteristic Metabolic Changes of the Crust from Dry-Aged Beef Using 2D NMR Spectroscopy

Two-dimensional quantitative nuclear magnetic resonance (2D qNMR)-based metabolomics was performed to understand characteristic metabolic profiles in different aging regimes (crust from dry-aged beef, inner edible flesh of dry-aged beef, and wet-aged beef striploin) over 4 weeks. Samples were extracted using 0.6 M perchlorate to acquire polar metabolites. Partial least squares-discriminant analysis showed a good cumulative explained variation (R² = 0.967) and predictive ability (Q² = 0.935). Metabolites of crust and aged beef (dry- and wet-aged beef) were separated in the first week and showed a completely different aspect in the second week via NMR-based multivariable analyses. Moreover, NMR-based multivariable analyses could be used to distinguish the method, degree, and doneness of beef aging. Among them, the crust showed more unique metabolic changes that accelerated proteolysis (total free amino acids and biogenic amines) and inosine 5′-monophosphate depletion than dry-aged beef and generated specific microbial catabolites (3-indoxyl sulfate) and γ-aminobutyric acid (GABA), while asparagine, glutamine, tryptophan, and glucose in the crust were maintained or decreased. Compared to the crust, dry-aged beef showed similar patterns of biogenic amines, as well as bioactive compounds and GABA, without a decrease in free amino acids and glucose. Based on these results, the crust allows the inner dry-aged beef to be aged similarly to wet-aged beef without microbial effects. Thus, 2D qNMR-based metabolomic techniques could provide complementary information about biochemical factors for beef aging.

Comparative peptidomic profile and bioactivities of cooked beef, pork, chicken and turkey meat after in vitro gastro-intestinal digestion

This study was designed to investigate the potential contribution of bioactive peptides to the biological activities related to the consumption of pork, beef, chicken and turkey meat following in vitro gastro-intestinal digestion. After extraction of the peptidic fractions from digested samples, the bioactivities were evaluated by in vitro antioxidant activity as well as angiotensin-converting enzyme (ACE) and dipeptidyl peptidase-IV (DPP-IV) inhibition assays. Pork and turkey meat appeared to be the best sources of antioxidant peptides. Pork was found to be the best source of DPP-IV-inhibitory peptides whereas chicken meat supplied peptides with the highest ACE-inhibitory activity. The comprehensive analysis of the peptidomic profile of digested samples was performed by nano-LC-ESI-QTOF MS/MS analysis. A total of 217, 214, 257 and 248 peptides were identified in digested pork, beef, chicken and turkey meat, respectively. Chicken and turkey meat showed the highest similarity in peptide sequences with 202 common peptides. Sixty-two peptides matched with sequences with previously demonstrated biological activity. In particular, 35 peptides showed ACE-inhibitory activity and 23 DPP-IV inhibitory activity. Twenty-two bioactive peptides were commonly released from the different types of meat. The relative amount of identified bioactive peptides were positively correlated to the biological activities of the different digested meats. BIOLOGICAL SIGNIFICANCE: The present study describes for the first time a comprehensive peptide profile of four types of meat after in vitro gastro-intestinal digestion. The peptide inventory was used to identify 62 bioactive peptides with ACE- and DPPIV-inhibitory and antioxidant activities. The bioactivity analysis revealed interesting and significant differences between the studied meats. The originality of this work lay in the description of intrinsic differences in physiological functions after the ingestion of meat proteins from different species. In a context in which the current research scene relates meat consumption to the onset of chronic pathologies, this peptide profiling and bioactivity analysis shed light on the possible health benefits of peptides released from meat proteins. In fact, this paper represents a sort of detailed peptide list that may help to predict which peptides could be generated after meat intake and detectable at gastro-intestinal level. It also provides a thorough investigation of novel biological activities associated to meat protein hydrolysates, giving a new positive aspect to meat consumption.

Amount of Collagen in the Meat Contained in Japanese Daily Dishes and the Collagen Peptide Content in Human Blood after Ingestion of Cooked Fish Meat

Objectives of the present study were to evaluate amounts of collagen in Japanese daily dishes and contents of food-derived collagen peptides in human blood. The meat in one serving of most Japanese daily dishes contains 0.2-2.5 g of collagen, except for beef tendon, eel with skin, and skinned shark tail (7.6-13.3 g). After ingestion of cooked shark meat, nine collagen di- and tripeptides were detected in plasma and the area under the curve of most peptides, except for Hyp-Gly and Pro-Hyp-Gly, was ∼30% of that after ingestion of collagen hydrolysate containing an equivalent amount of collagen. Likewise, only ∼30% of the total collagen in the meat was liberated into solution by pepsin and pancreatin digestion. Thus, ingestion of collagen-rich meat increases the collagen peptides in blood, which depends on not only the collagen content in the meat but also the susceptibility of the collagen/gelatin to digestive endoproteinases.

Food protein-derived renin-inhibitory peptides: in vitro and in vivo properties

Renin catalyzes the rate-determining step in the renin-angiotensin-aldosterone system that regulates mammalian blood pressure by converting angiotensinogen to angiotensin I (Ang I). Excessive plasma levels of Ang I is a causative factor in hypertension development. Therefore, inhibition of renin activity can lower blood pressure and provide relief from clinical symptoms associated with hypertension. Synthetic compounds are currently the most used group of renin inhibitors; however, only aliskiren is approved as a drug for hypertension treatment. But some negative side effects are associated with aliskiren therapy, which have necessitated the search for alternative natural compounds such as food protein-derived renin-inhibitory peptides with blood pressure-reducing effects. This paper is a concise review of the currently known sources and methods of production of renin-inhibitory peptides including their potential in vitro and in vivo extent of renin inhibition. PRACTICAL APPLICATIONS: Hypertension is a major human chronic disease that leads to severe cardiovascular impairment and ultimately death if not managed properly. Current therapeutic approach to hypertension management involves the use of drugs that inhibit excessive activities of renin and angiotensin converting enzyme (ACE), the two main enzymes that control mammalian blood pressure. Since renin catalyzes a single reaction that is the rate-determining step in the renin-angiotensin system, inhibition of this enzyme activity could be a highly effective strategy for controlling blood pressure without severe negative side effects. However, therapeutic control of renin activity remains difficult with only one approved drug. Some food protein-derived peptides have been found to inhibit renin activity inhibition, which could offer a drug-free treatment for hypertension. Therefore, this review provides a summary of recent developments in the advances and efficacy testing of renin-inhibitory peptides.

Isolation and identification of angiotensin I-converting enzyme inhibitory peptides derived from thermolysin-injected beef M. longissimus

Objective

This study identified angiotensin I-converting enzyme (ACE) inhibitory peptides in beef M. longissimus injected with thermolysin (80 ppm) and stored for 3 days at 5°C.

Methods

Crude peptides (molecular weight <3 kDa) were obtained from the thermolysin hydrolysate and separated into seven fractions. Fraction V showing the highest ACE inhibitory activity was further fractionated, yielding subfractions V-15, V-m1, and V-m2, and selected for superior ACE inhibitory activity. Finally, twelve peptides were identified from the three peak fractions and the ACE inhibitory activity (IC₅₀) of each peptide was evaluated.

Results

The Leu-Ser-Trp, Phe-Gly-Tyr, and Tyr-Arg-Gln peptides exhibited the strongest ACE inhibitory activity (IC₅₀ values of 0.89, 2.69, and 3.09 mM, respectively) and had higher concentrations (6.63, 10.60, and 29.91 pg/g; p<0.05) relative to the other peptides tested.

Conclusion

These results suggest that the thermolysin injection process is beneficial to the generation of bioactive peptides with strong ACE inhibitory activity.

Combined in vivo and in silico approaches for predicting the release of bioactive peptides from meat digestion

We studied the kinetics of peptide release during the gastric digestion of meat proteins in vivo, in view to predicting the release of bioactive peptides further on in the digestive tract. Six mini pigs fitted with gastric cannulas received a meal with cooked beef as protein source. Digesta was collected at regular time intervals up to 5½ h. The peptides generated by the gastric digestion of meat were identified and quantified using label-free LC MS, thereafter subjected to in silico digestion mimicking the action of intestinal enzymes. Three clusters of proteins presenting similar evolutions according to their dynamic hydrolysis were obtained. This study clearly improves the in silico prediction of the intestinal release of bioactive peptides by mapping meat protein degradation in the stomach in an in vivo model. Knowledge of the conformation of the peptides released in the stomach further improves this prediction.

Antioxidant and Anti-Inflammatory Activities of Hydrolysates and Peptide Fractions Obtained by Enzymatic Hydrolysis of Selected Heat-Treated Edible Insects

This study investigated the effect of heat treatment of edible insects on antioxidant and anti-inflammatory activities of peptides obtained by in vitro gastrointestinal digestion and absorption process thereof. The antioxidant potential of edible insect hydrolysates was determined as free radical-scavenging activity, ion chelating activity, and reducing power, whereas the anti-inflammatory activity was expressed as lipoxygenase and cyclooxygenase-2 inhibitory activity. The highest antiradical activity against DPPH• (2,2-diphenyl-1-picrylhydrazyl radical) was noted for a peptide fraction from baked cricket Gryllodes sigillatus hydrolysate (IC50 value 10.9 µg/mL) and that against ABTS•+ (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical) was the highest for raw mealworm Tenebrio molitor hydrolysate (inhibitory concentration (IC50 value) 5.3 µg/mL). The peptides obtained from boiled locust Schistocerca gregaria hydrolysate showed the highest Fe2+ chelation ability (IC50 value 2.57 µg/mL); furthermore, the highest reducing power was observed for raw G. sigillatus hydrolysate (0.771). The peptide fraction from a protein preparation from the locust S. gregaria exhibited the most significant lipoxygenase and cyclooxygenase-2 inhibitory activity (IC50 value 3.13 µg/mL and 5.05 µg/mL, respectively).

Generation of bioactive peptides from duck meat during post-mortem aging

The objective of this study was to investigate the endogenous release of bioactive peptides in duck meat during 7days of post-mortem aging. The degradation of muscle proteins led to release of small peptides (<5kDa). The peptides formed in the samples after 3days post-mortem exhibited highest DPPH radical scavenging, oxygen radical scavenging (ORAC) and ferric reducing antioxidant power (FRAP). By using size-exclusion chromatography, the initial extract was purified into three fractions (A-C) in which fraction C exhibited the highest antioxidant activity. In total 18 peptides were sequenced and identified in the fractions by nano LC-MS/MS. Among these peptides, the peptides of fraction C possessed the lowest molecular weight and consisted of the highest amount of hydrophobic amino acid, which might be responsible for the antioxidant property of aged duck meat. The present findings provide an insight into the release of bioactive peptides in duck meat during post-mortem aging.

Bioactive Peptides in Animal Food Products

Proteins of animal origin represent physiologically active components in the human diet; they exert a direct action or constitute a substrate for enzymatic hydrolysis upon food processing and consumption. Bioactive peptides may descend from the hydrolysis by digestive enzymes, enzymes endogenous to raw food materials, and enzymes from microorganisms added during food processing. Milk proteins have different polymorphisms for each dairy species that influence the amount and the biochemical characteristics (e.g., amino acid chain, phosphorylation, and glycosylation) of the protein. Milk from other species alternative to cow has been exploited for their role in children with cow milk allergy and in some infant pathologies, such as epilepsy, by monitoring the immune status. Different mechanisms concur for bioactive peptides generation from meat and meat products, and their functionality and application as functional ingredients have proven effects on consumer health. Animal food proteins are currently the main source of a range of biologically-active peptides which have gained special interest because they may also influence numerous physiological responses in the organism. The addition of probiotics to animal food products represent a strategy for the increase of molecules with health and functional properties.

Effect of cooking and simulated gastrointestinal digestion on the activity of generated bioactive peptides in aged beef meat

Ageing is widely used in the meat industry to improve tenderness mainly as a result of the breakdown of muscular proteins through the action of endopeptidases during storage time.