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The utilization of animal bones as a protein source could be used as a sustainable pathway for the production of bioactive compounds. In this study, bones were pretreated with pepsin enzyme (PEP) and then sequentially hydrolyzed with Alcalase (PA) and Alcalase, as well as Protana prime (PAPP). The degree of hydrolysis, antioxidant activity, and DPP-IV inhibitory activity were measured. All three hydrolysates showed antioxidant and DPP-IV inhibitory activity; however, the highest result in both bioactivities was obtained with the PAPP hydrolysate. The obtained free amino acid content was 54.62, 88.12, and 668.46 mg/100 mL of hydrolyzed in PEP, PA, and PAPP, respectively. Pepsin pretreatment did not significantly affect the degree of hydrolysis; however, it is suggested that it promoted the cleavage of certain bonds for subsequent protease action. Accordingly, a total of 550 peptides were identified in PEP hydrolysate, 1087 in PA hydrolysate, and 1124 in PAPP hydrolysate using an LC-MS/MS approach. Pepsin pretreatment could be an effective method in the utilization of bone sources for the production of antioxidant and hypoglycemic peptides.

This Special Issue of the International Journal of Molecular Sciences is focused on bioactive peptides in foods or hydrolyzates of food by-products, the methods for the extraction and purification of bioactive peptides, their structural and functional characterization, and the mechanisms of action that regulate their activity and support the reported health benefits [...]

The ultrasound-induced impacts on the peptide characteristics and taste of unsmoked bacon have been evaluated through the use of peptidomics and bioinformatics approaches. Furthermore, the effect of such ultrasound-induced changes on the main endogenous proteases responsible for peptide generation was also investigated. In fact, the activity of main endogenous proteases was significantly increased after ultrasonic treatment during the processing of unsmoked bacon, and contributed to an increased number and an enhanced LFQ intensity of peptides. Besides, such increased amount of peptides and LFQ intensity with up to 500 W ultrasonic treatment were beneficial for the taste improvement of the final products as shown by taste prediction analysis. Nevertheless, an excessive ultrasonic power like 750 W hindered protein hydrolysis and further exerted a negative effect on peptide generation. Therefore, ultrasound under controlled conditions could be considered as a promising way to improve the taste of unsmoked bacon., This work was financially supported by the earmarked fund for China Agriculture Research System (CARS-35) and the Kekedala City of the 4th Division Science and Technology Plan (2022GY03).

The aim of this study was to investigate the modifications of the proteome and flavor-related proteins in unsmoked bacon resulting from ultrasound treatment with the application of label-free quantitation technology together with bioinformatics analysis. Results showed that the expression levels of 137 proteins were markedly affected by ultrasound with most of them being significantly upregulated. The proteins distributed in the cytoplasm and the cytosol, the mitochondrion, and the nucleus were more susceptible to ultrasound treatment. Meanwhile, 20 flavor-related proteins, mostly myofibrillar proteins and metabolic enzymes mainly involved in the metabolic pathways of signaling and cellular processes and environmental information processing, were screened out. In addition, the differential expressions of flavor-related proteins induced by ultrasound were verified by western blotting. This study displayed insightful information from the proteomics perspective for a better understanding of the influential effect of ultrasound treatment on meat flavor., This work was financially supported by the China Agriculture Research System of MOF and MARA (CARS-35), the earmarked fund for the Jiangsu Agricultural Industry Technology System (JATS(2021)476), and the Kekedala City of the 4th Division Science and Technology Plan (2022GY03).

We thank Dr. López-Moreno for the comment [...].

There is an intense research activity on bioactive peptides derived from food proteins in view of their health benefits for consumers. However, their identification is quite challenging as a consequence of their small size and low abundance in complex matrices such as foods or hydrolyzates. Recent advances in peptidomics and bioinformatics are getting improved sensitivity and accuracy and therefore such tools are contributing to the development of sophisticated methodologies for the identification and quantification of peptides. These developments are very useful for the follow-up of peptides released through proteolysis either in the food itself through the action of endogenous peptidases during processing stages like fermentation, drying or ripening, or from food proteins hydrolyzed by commercial peptidases or microorganisms with proteolytic activity. This chapter is presenting the latest advances in peptidomics and its use for the identification and quantification of peptides, and as a useful tool for controlling the proteolysis phenomena in foods and protein hydrolyzates.

Fat, composed mainly of triacylglycerols and phospholipids, and protein, composed of amino acids, constitute major components of meat. Carbohydrate, in the form of glycogen, is present in very low amounts. This article describes the main methodologies available for the analysis of these substances, discusses their advantages and disadvantages, and gives recommendations for the choice of methods.

Alcohol hydydrogenase (ADH) is a key enzyme that influences alcohol metabolism in vivo. Our previous study showed that chicken-derived tripeptide KPC could stabilize ADH in a dose-dependant manner. In this study, possible mechanism underlying how KPC could stabilize ADH was further investigated. Fluorescence quenching data showed that KPC induced a dynamic fluorescence quenching with a quenching rate constant value of 1.074 × 1010 M−1s−1, indicating a conformational change. Circular dichroism further suggested a possible transformation from α-helix (14.03%–13.90%) to random coil (31.98–33.04%) in ADH structure as affected by KPC (5 mmol/L). Molecular docking analysis predicted that KPC may bind to ADH through hydrophobic interaction and hydrogen bonds. Validation of ADH stabilizing activity of fragment peptides and amino acids from KPC implied the vital role of Cys residue to the bio-activity of KPC. These results indicated that KPC may stabilize ADH through peptide-enzyme interactions, and protect ADH against oxidative modification. Besides, a favorable absorption, distribution, metabolism, excretion, and toxicity (ADMET) profile of KPC was obtained using in silico assays. Overall, this study provided a comprehensive understanding on the interaction mechanism between KPC and ADH, and illustrated the potential applicability of KPC as drug or functional food ingredient., This work was supported by the National Natural Science Foundation of China (No. 32101896 and No. 31871746), Key-Area Research and Development Program of Guangdong Province (2021B0707060001), the Self-innovation Research Funding Project of Hanjiang Laboratory (HJL202010B002, HJL202101B001, HJL202101B004,and HJL202101B005), and the Chaozhou Science and Technology Project (2020PT01).

The reduction of salt in meat products influences the natural mechanisms of proteolysis occurring in their processing, and could affect the final characteristics of the product in terms of texture and flavor due to its effect on the activity of enzymes. In the present study, the quantitation of dipeptides PA, GA, VG, EE, ES, DA, and DG in low-salt Spanish dry-cured ham was carried out using a triple quadrupole mass spectrometry instrument. The developed methodology demonstrated the advantages of hydrophilic interaction liquid chromatography in the removal of salt as a clean-up/separation step before ionization. This resulted in a value of 44.88 μg/g dry-cured ham for GA dipeptide, and values ranging from 2 to 8 μg/g dry-cured ham for VG, EE, ES, DA, and DG dipeptides. PA showed the lowest concentration with a value of 0.18 μg/g dry-cured ham. These outcomes prove the remarkable activity of muscular dipeptidyl peptidases during dry-curing as well as confirming the presence of these dipeptides which are related to certain taste attributes (e.g., 'bitter' or 'umami'). Such dipeptides have also been confirmed as anti-inflammatory and potential cardiovascular protectors using in vitro assays, with the advantage of dipeptides small size increases their chance to resist both gastrointestinal digestion and intestinal/bloodstream transport without being degraded or modified., Grant AGL2017-89381-R funded by MCIN/AEI/10.13039/501100011033 by “ERDF A way of making Europe” is acknowledged. Grant PRE2018-083367 (A.H.) funded by MCIN/AEI /10.13039/501100011033 and “ESF Investing in your future” and grant RYC-2016-19635 (L.M.) funded by MCIN/AEI/10.13039/501100011033 and “ESF Investing in your future” are also acknowledged.

Chicken hydrolysates (CHs) have been reported to protect mice against alcoholic liver injury possibly through oxidative stress reduction. In this study, the antioxidant activity of CHs was studied. Results showed that CHs exhibited significant antioxidant activity (around 600 and 400 μM TEAC/g in ORAC and ABTS assay, respectively) and could resist simulated gastrointestinal digestion. A total of 22 peptides were identified after antioxidant activity-oriented isolation using size-exclusion chromatography and high-performance liquid chromatography. Further in silico analysis and the validation of antioxidant activity revealed that novel peptides (RWGG and YYCQ) exhibited strong antioxidant activity. The most active peptide YYCQ displayed a TEAC value of 3.54 and 4.28 μM TEAC/μM in ORAC and ABTS assay, respectively. These peptides could contribute to reduce oxidative stress and protect against alcohol-induced liver injury. However, further studies understanding the bioactivity of such peptides in vivo are necessary before further applying them as functional food ingredient., This work was supported by the National Natural Science Foundation of China (No. 32101896 and No. 31871746), Key-Area Research and Development Program of Guangdong Province (2021B0707060001), and Self-innovation Research Funding Project of Hanjiang Laboratory (HJL202010B002). Grant AGL2017-89381-R funded by MCIN/ AEI /10.13039/501100011033 by “ERDF A way of making Europe” is acknowledged and grant RYC-2016-19635 (L.M.) funded by MCIN/AEI /10.13039/501100011033 and “ESF Investing in your future” is also acknowledged.

Blood is a meat by-product rich in proteins with properties that can be improved after hydrolysis, making it a sustainable alternative for use in the generation of bioactive peptides. The objective of this study was to identify dipeptidyl peptidase IV (DPP-IV) inhibitory peptides obtained from different chicken blood hydrolysates prepared using combinations of four different enzymes. Best results were observed for AP (2% Alcalase + 5% Protana Prime) and APP (2% Alcalase + 5% Protana Prime + 3% Protana UBoost) hydrolysates obtaining inhibition values of 60.55 and 53.61%, respectively, assayed at a concentration of 10 mg/mL. Free amino acids were determined to establish the impact of exopeptidase activity in the samples. A total of 79 and 12 sequences of peptides were identified by liquid chromatography and mass spectrometry in tandem (LC-MS/MS) in AP and APP samples, respectively. Nine of the identified peptides were established as potential DPP-IV inhibitory using in silico approaches and later synthesized for confirmation. Thus, peptides GPF, IGL, and GGGW showed good DPP-IV inhibitory activity with IC50 values of 0.94, 2.22, and 2.73 mM, respectively. This study confirmed the potential of peptides obtained from chicken blood hydrolysates to be used as DPP-IV inhibitors and, therefore, in the control or modulation of type 2 diabetes., This research was funded by Grant PID2020-119684RB-I00 funded by MCIN/AEI/10.13039/501100011033. Grant GRISOLIAP/2020/021 de la Consellería de Innovació, Universitats, Ciència i Societat Digital de la Generalitat Valenciana (GCA) is also acknowledged. The proteomic analysis was performed in the proteomics facility of SCSIE University of Valencia that belongs to Proteored.

We thank Dr. López-Moreno for the comment [...]

Small peptides such as dipeptides contribute to a great extent to the characteristic taste of dry-cured hams. In this study, hydrophilic interaction liquid chromatography (HILIC) combined to tandem mass spectrometry was used to separate, identify, and quantify seven dipeptides in dry-cured hams sampled at different processing times (6, 12, 18, and 24 months). Results showed an increased concentration of dipeptides DA, DG, EE, ES, and EV with the length of processing, obtaining values up to 23 μg/g of dry-cured ham, which suggests an intense action of muscle enzymes dipeptidyl peptidases during the process. The dipeptide VG significantly decreased from 7 to 4 μg/g of dry-cured ham as the processing increased from 6 to 24 months, whereas the dipeptide PA showed low values between 380 and 550 ng/g of dry-cured ham at all the sampling times. Additionally, in silico analyses reported the sensory characteristics of the studied dipeptides, mostly giving bitter and umami taste, and predicted their allergenicity, toxicity, and physicochemical properties. These results could be useful for further studies related to the pleasant taste of dry-cured hams., Grant AGL2017-89381-R and FEDER funds from the Spanish Ministry of Economy, Industry and Competitiveness are acknowledged.