Caseins as source of bioactive peptides

Effect of In Vitro Digestion on Bioactive Peptides Related to Immune and Gut Health in Intact Cow's Milk and Hydrolyzed Protein-Based Infant Formulas

Background/Objectives: Human milk is the optimal source of nutrition and protection against infection for infants. If breastfeeding is not possible, standard and hydrolyzed infant formulas (IF) are an alternative. Extensively hydrolyzed IFs (eHFs) contain bioactive peptides, but their activities have rarely been evaluated. The aim of this study was to characterize and compare the bioactive peptide profiles of different eHFs and standard IFs before and after in vitro digestion. Methods: Two forms, liquid and powder, of intact protein formula (iPF) and eHF were subjected to in vitro gastrointestinal digestion, mimicking a young infant's gut (age 0-4 months) and an older infant's gut (>6 months). Bioactive peptides of in vitro digested and undigested formulas were analysed with Liquid Chromatography-Mass Spectrometry (LC-MS). Results: In all samples, a variety of peptides with potential bioactive properties were found. Immuno-regulatory peptides, followed by antimicrobial and antioxidative peptides were most frequent, as were peptides promoting wound healing, increasing mucin secretion, regulating cholesterol metabolism, and preventing bacterial infection. Peptides typically found in yoghurt and colostrum were identified in some formula samples. Conclusions: The high amounts of bioactive peptides with various properties in eHFs and iPFs indicate a possible contribution to infection protection, healthy gut microbiomes, and immunological development of infants. eHFs showed similar compositions of bioactive peptides to iPFs, with intermittently increased peptide variety and quantity.

Effect of supercritical carbon dioxide on protein structure modification and antimicrobial peptides production of Mongolian cheese and its in vitro digestion

The aim of this research was to investigate the effects of supercritical carbon dioxide (SC-CO2) treatment on protein structure in Mongolian cheese. The peptides during the digestive process of the SC-CO2 treated cheese were also studied. SC-CO2 technology was utilized to treat Mongolian cheese at three temperatures (45, 55 and 65 °C) and three pressures (7.5, 12.5 and 17.5 MPa). The results of fluorescence, ultraviolet-visible, Fourier transform infrared spectroscopy and free sulfhydryl groups showed that SC-CO2, particularly at 65 °C and 17.5 MPa, modified the protein structure in Mongolian cheese effectively. The data of LC-MS/MS-based peptidomics showed that the content of antimicrobial peptides found in the SC-CO2 treated Mongolian cheese was 1.55 times that of the untreated Mongolian cheese; the content of unique antimicrobial peptides in the digested SC-CO2 treated Mongolian cheese was 1.46 times that of the digested untreated Mongolian cheese, which proved that SC-CO2 could help produce antimicrobial peptides in cheese not only during the process of SC-CO2 treatment but during subsequent simulated gastrointestinal digestion as well. In conclusion, SC-CO2 could be considered a promising method to develop cheese products with potential health benefits.

Human colostrum in vitro protein digestion: peptidomics by liquid chromatography-Orbitrap-high-resolution MS and prospection for bioactive peptides via bioinformatics

Breast milk is known to contain bioactive peptides that are released during digestion, being a major source of bioactive peptides to the new-born, some of which act against invading pathogens. However, the formation of bioactive peptides during digestion of human colostrum remains largely uninvestigated. This study aimed to investigate the formation of peptides during simulated digestion of human colostrum from adult women and to prospect antimicrobial peptides. For this purpose, we used high-resolution MS to monitor the release of peptides during in vitro digestion. Bioinformatics was used for the prospection of antimicrobial activity of peptides. During simulated digestion (oral, gastric and duodenal phases), 2318 peptide sequences derived from 112 precursor proteins were identified. At the end of simulated digestion, casein-derived peptide sequences were the most frequently observed. Among precursors, some proteins were seen for the first time in this study. The resulting peptides were rich in proline, glutamine, valine and leucine residues, providing characteristic traits of antimicrobial peptides. From bioinformatics analysis, seven peptides showed potentially high antimicrobial activity towards bacteria, viruses and fungi, from which the latter was the most prominent predicted activity. Antimicrobial peptides released during digestion may provide a defence platform with controlled release for the new-born.

Comprehensive review of clean-label antimicrobials used in dairy products

Consumers expect safe, healthy, natural, and sustainable food. Within the food industry, ingredient use is changing due to these consumer demands. While no single agreed-upon definition of clean label exists, a "clean label" in the context of food refers to a product that has a simplified and transparent ingredient list, with easily recognizable and commonly understood components to the general public. Clean-label products necessitate and foster a heightened level of transparency between companies and consumers. Dairy products are vulnerable to being contaminated by both pathogens and spoilage microorganisms. These microorganisms can be effectively controlled by replacing conventional antimicrobials with clean-label ingredients such as protective cultures or bacterial/fungal fermentates. This review summarizes the perspectives of consumers and the food industry regarding the definition of "clean label," and the current and potential future use of clean-label antimicrobials in dairy products. A key goal of this review is to make the concept of clean-label antimicrobial agents better understood by both manufacturers and researchers.

Predicting milk protein fractions using infrared spectroscopy and a gradient boosting machine for breeding purposes in Holstein cattle

In recent years, increasing attention has been focused on the genetic evaluation of protein fractions in cow milk with the aim of improving milk quality and technological characteristics. In this context, advances in high-throughput phenotyping by Fourier transform infrared (FTIR) spectroscopy offer the opportunity for large-scale, efficient measurement of novel traits that can be exploited in breeding programs as indicator traits. We took milk samples from 2,558 Holstein cows belonging to 38 herds in northern Italy, operating under different production systems. Fourier transform infrared spectra were collected on the same day as milk sampling and stored for subsequent analysis. Two sets of data (i.e., phenotypes and FTIR spectra) collected in 2 different years (2013 and 2019-2020) were compiled. The following traits were assessed using HPLC: true protein, major casein fractions [α_S1-casein (CN), α_S2-CN, β-CN, κ-CN, and glycosylated-κ-CN], and major whey proteins (β-lactoglobulin and α-lactalbumin), all of which were measured both in grams per liter (g/L) and proportion of total nitrogen (% N). The FTIR predictions were calculated using the gradient boosting machine technique and tested by 3 different cross-validation (CRV) methods. We used the following CRV scenarios: (1) random 10-fold, which randomly split the whole into 10-folds of equal size (9-folds for training and 1-fold for validation); (2) herd/date-out CRV, which assigned 80% of herd/date as the training set with independence of 20% of herd/date assigned as the validation set; (3) forward/backward CRV, which split the data set in training and validation set according with the year of milk sampling (FTIR and gold standard data assessed in 2013 or 2019-2020) using the "old" and "new" databases for training and validation, and vice-versa with independence among them; (4) the CRV for genetic parameters (CRV-gen), where animals without pedigree as assigned as a fixed training population and animals with pedigree information was split in 5-folds, in which 1-fold was assigned to the fixed training population, and 4-folds were assigned to the validation set (independent from the training set). The results (i.e., measures and predictions) of CRV-gen were used to infer the genetic parameters for gold standard laboratory measurements (i.e., proteins assessed with HPLC) and FTIR-based predictions considering the CRV-gen scenario from a bi-trait animal model using single-step genomic BLUP. We found that the prediction accuracies of the gradient boosting machine equations differed according to the way in which the proteins were expressed, achieving higher accuracy when expressed in g/L than when expressed as % N in all CRV scenarios. Concerning the reproducibility of the equations over the different years, the results showed no relevant differences in predictive ability between using "old" data as the training set and "new" data as the validation set and vice-versa. Comparing the additive genetic variance estimates for milk protein fractions between the FTIR predicted and HPLC measures, we found reductions of -19.7% for milk protein fractions expressed in g/L, and -21.19% expressed as % N. Although we found reductions in the heritability estimates, they were small, with values ranging from -1.9 to -7.25% for g/L, and -1.6 to -7.9% for % N. The posterior distributions of the additive genetic correlations (r_a) between the FTIR predictions and the laboratory measurements were generally high (>0.8), even when the milk protein fractions were expressed as % N. Our results show the potential of using FTIR predictions in breeding programs as indicator traits for the selection of animals to enhance milk protein fraction contents. We expect acceptable responses to selection due to the high genetic correlations between HPLC measurements and FTIR predictions.

Influence of storage time on protein composition and simulated digestion of UHT milk and centrifugation presterilized UHT milk in vitro

The centrifugation presterilizing UHT (C-UHT) sterilization method removes 90% of the microorganism and somatic cells from raw milk using high-speed centrifugation following UHT treatment. This study aimed to study the changes in protein composition and plasmin in the UHT and C-UHT milk. The digestive characteristics, composition, and peptide spectrum of milk protein sterilized with the 2 technologies were studied using a dynamic digestive system of a simulated human stomach. The Pierce bicinchoninic acid assay, laser scanning confocal microscope, liquid chromatography-tandem mass spectrometry, and AA analysis were used to study the digestive fluid at different time points of gastric digestion in vitro. The results demonstrated that C-UHT milk had considerably higher protein degradation than UHT milk. Different processes resulted during the cleavage of milk proteins at different sites during digestion, resulting in different derived peptides. The results showed there was no significant effect of UHT and C-UHT on the peptide spectrum of milk proteins, but C-UHT could release relatively more bioactive peptides and free AA.

Caseins: Versatility of Their Micellar Organization in Relation to the Functional and Nutritional Properties of Milk

The milk of mammals is a complex fluid mixture of various proteins, minerals, lipids, and other micronutrients that play a critical role in providing nutrition and immunity to newborns. Casein proteins together with calcium phosphate form large colloidal particles, called casein micelles. Caseins and their micelles have received great scientific interest, but their versatility and role in the functional and nutritional properties of milk from different animal species are not fully understood. Caseins belong to a class of proteins that exhibit open and flexible conformations. Here, we discuss the key features that maintain the structures of the protein sequences in four selected animal species: cow, camel, human, and African elephant. The primary sequences of these proteins and their posttranslational modifications (phosphorylation and glycosylation) that determine their secondary structures have distinctively evolved in these different animal species, leading to differences in their structural, functional, and nutritional properties. The variability in the structures of milk caseins influence the properties of their dairy products, such as cheese and yogurt, as well as their digestibility and allergic properties. Such differences are beneficial to the development of different functionally improved casein molecules with variable biological and industrial utilities.

Peptidomics-based identification of an antimicrobial peptide derived from goat milk fermented by Lactobacillus rhamnosus (C25)

Antimicrobial peptides (AMPs) are emerging as promising novel drug applicants. In the present study, goat milk was fermented using Lactobacillus rhamnosus C25 to generate bioactive peptides (BAPs). The peptide fractions generated were separated using ultrafiltration membranes with molecular weight cut-offs of 3, 5, and 10 kDa, and their antimicrobial activity toward Gram-positive and Gram-negative bacteria was investigated. Isolated AMPs were characterized using RP-HPLC and identified by LC-MS/MS. A total of 569 sequences of peptides were identified by mass spectrometry. Out of the 569, 36 were predicted as AMPs, 21 were predicted as cationic, and out of 21, 6 AMPs were helical peptides. In silico analysis indicated that the majority of peptides were antimicrobial and cationic in nature, an important factor for peptide interaction with the negative charge membrane of bacteria. The results showed that the peptides of <5 kDa exhibited maximum antibacterial activity against E. faecalis, E. coli, and S. typhi. Further, molecular docking was used to evaluate the potent MurD ligase inhibitors. On the basis of ligand binding energy, six predicted AMPs were selected and then analyzed by AutoDock tools. Among the six AMPs, peptides IGHFKLIFSLLRV (-7.5 kcal/mol) and KSFCPAPVAPPPPT (-7.6 kcal/mol), were predicted as a high-potent antimicrobial. Based on these findings, in silico investigations reveal that proteins of goat milk are a potential source of AMPs. This is for the first time that the antimicrobial peptides produced by Lactobacillus rhamnosus (C25) fermentation of goat milk have been identified via LC-MS/MS and predicted as AMPs, cationic charges, helical structure in nature, and potent MurD ligase inhibitors. These peptides can be synthesized and improved for use as antimicrobial agents. PRACTICAL APPLICATIONS: Goat milk is considered a high-quality source of milk protein. According to this study, goat milk protein is a potential source of AMPs, Fermentation can yield goat milk-derived peptides with a broad antibacterial activity spectrum at a low cost. The approach described here could be beneficial in that the significant AMPs can be synthesized and used in the pharmaceutical and food industries.

Demographic pattern of A1/A2 beta casein variants indicates conservation of A2 type haplotype across native cattle breeds (Bos indicus) of India

Genetic variations of the beta casein gene hold importance because of their probable association with human health. Comparative sequence analysis of β-casein gene across Indian native, crossbred and exotic breeds in India revealed 15 SNPs and 4 INDELs corresponding to 14 haplotypes. The frequency of A2 type haplotype was maximum (0.941) across all Indian native breeds. Among the 15 variants reported for taurine breeds, only three (A1, A2 and B) were observed in analysed populations. Allelic profiling of A1/A2 β-casein variants in ~ 4000 animals belonging to three cattle types and breeding bulls also revealed the predominance of A2 allele (0.95) in Indian cattle. The high proportion of A2 allele/haplotype indicates that Indian native cattle are the best suited to meet the demands for A2 milk globally. However, a higher percentage of heterozygous genotype (A1A2) in breeding bulls warrants the need to screen sire lines so as to drift the herd towards A2.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03232-0.

Enhancing Intestinal Permeability of Theaflavin-3,3'-digallate by Chitosan-Caseinophosphopeptides Nanocomplexes

Low intestinal permeability is an unfavorable feature that limits the bioavailability of many hydrophilic polyphenols. In this study, chitosan (CS) was used to complex with caseinophosphopeptides (CPPs), aiming to improve the intestinal permeability of theaflavin-3,3'-digallate (TF-3), a characteristic polyphenol in black tea with poor intestinal permeability. Complexation between CS and CPPs was systemically investigated by turbidimetric titration under various conditions, revealing that electrostatic interaction was the dominant force. The sizes, PDIs, and ζ potentials of CS-CPP nanocomplexes varied with their compositions. The optimized CS-CPP nanocomplex was subsequently used to encapsulate TF-3, which showed high encapsulation efficiency and low cytotoxicity. Microstructural studies showed strong intermolecular associations between CS, CPPs, and TF-3. Encapsulation of TF-3 maintained the globular unit structure of CS-CPP nanocomplexes, but high concentrations of TF-3 resulted in aggregation. Importantly, as proved using the Caco-2 monolayer model, the intestinal permeability of TF-3 was significantly enhanced by the CS-CPP nanocomplexes.

Bioactivities, Applications, Safety, and Health Benefits of Bioactive Peptides From Food and By-Products: A Review

Bioactive peptides generated from food proteins have great potential as functional foods and nutraceuticals. Bioactive peptides possess several significant functions, such as antioxidative, anti-inflammatory, anticancer, antimicrobial, immunomodulatory, and antihypertensive effects in the living body. In recent years, numerous reports have been published describing bioactive peptides/hydrolysates produced from various food sources. Herein, we reviewed the bioactive peptides or protein hydrolysates found in the plant, animal, marine, and dairy products, as well as their by-products. This review also emphasizes the health benefits, bioactivities, and utilization of active peptides obtained from the mentioned sources. Their possible application in functional product development, feed, wound healing, pharmaceutical and cosmetic industries, and their use as food additives have all been investigated alongside considerations on their safety.

Plant-Based Proteins: The Good, Bad, and Ugly

Our global population is growing at a pace to exceed 10 billion people by the year 2050. This growth will place pressure on the agricultural production of food to feed the hungry masses. One category that will be strained is protein. Per capita protein consumption is rising in virtually every country for both nutritional reasons and consumption enjoyment. The United Nations estimates protein demand will double by 2050, and this will result in a critical overall protein shortage if drastic changes are not made in the years preceding these changes. Therefore, the world is in the midst of identifying technological breakthroughs to make protein more readily available and sustainable for future generations. One protein sourcing category that has grown in the past decade is plant-based proteins, which seem to fit criteria established by discerning consumers, including healthy, sustainable, ethical, and relatively inexpensive. Although demand for plant-based protein continues to increase, these proteins are challenging to utilize in novel food formulations.

Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Exploring the DPP-IV Inhibitory, Antioxidant and Antibacterial Potential of Ovine "Scotta" Hydrolysates

The aim of this work was to valorize the by-product derived from the ricotta cheese process (scotta). In this study, ovine scotta was concentrated by ultrafiltration and then subjected to enzymatic hydrolyses using proteases of both vegetable (4% E:S, 4 h, 50 °C) and animal origin (4% E:S, 4 h, 40 °C). The DPP-IV inhibitory, antioxidant, and antibacterial activities of hydrolysates from bromelain (BSPH) and pancreatin (PSPH) were measured in vitro. Both the obtained hydrolysates showed a significantly higher DPP-IV inhibitory activity compared to the control. In particular, BSPH proved to be more effective than PSPH (IC₅₀ 8.5 ± 0.2 vs. 13 ± 1 mg mL⁻¹). Moreover, BSPH showed the best antioxidant power, while PSPH was more able to produce low-MW peptides. BSPH and PSPH hydrolysates showed a variable but slightly inhibitory effect depending on the species or strain of bacteria tested. BSPH and PSPH samples were separated by gel permeation chromatography (GPC). LC-MS/MS analysis of selected GPC fractions allowed identification of differential peptides. Among the peptides 388 were more abundant in BSPH than in the CTRL groups, 667 were more abundant in the PSPH group compared to CTRL, and 97 and 75 of them contained sequences with a reported biological activity, respectively.

Antioxidant Activity of Novel Casein-Derived Peptides with Microbial Proteases as Characterized via Keap1-Nrf2 Pathway in HepG2 Cells

Casein-derived antioxidant peptides by using microbial proteases have gained increasing attention. Combination of two microbial proteases, Protin SD-NY10 and Protease A "Amano" 2SD, was employed to hydrolyze casein to obtain potential antioxidant peptides that were identified by LCMS/ MS, chemically synthesized and characterized in a oxidatively damaged HepG2 cell model. Four peptides, YQLD, FSDIPNPIGSEN, FSDIPNPIGSE, YFYP were found to possess high 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging ability. Evaluation with HepG2 cells showed that the 4 peptides at low concentrations (< 1.0 mg/ml) protected the cells against oxidative damage. The 4 peptides exhibited different levels of antioxidant activity by stimulating mRNA and protein expression of the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), as well as nuclear factor erythroid-2-related factor 2 (Nrf2), but decreasing the mRNA expression of Kelch-like ECH-associated protein 1 (Keap1). Furthermore, these peptides decreased production of reactive oxygen species (ROS) and malondialdehyde (MDA), but increased glutathione (GSH) production in HepG2 cells. Therefore, the 4 casein-derived peptides obtained by using microbial proteases exhibited different antioxidant activity by activating the Keap1-Nrf2 signaling pathway, and they could serve as potential antioxidant agents in functional foods or pharmaceutic preparation.

Donkey Milk Fermentation by Lactococcus lactis subsp. cremoris and Lactobacillus rhamnosus Affects the Antiviral and Antibacterial Milk Properties

BACKGROUND

Milk is considered an important source of bioactive peptides, which can be produced by endogenous or starter bacteria, such as lactic acid bacteria, that are considered effective and safe producers of food-grade bioactive peptides. Among the various types of milk, donkey milk has been gaining more and more attention for its nutraceutical properties.

METHODS

Lactobacillus rhamnosus 17D10 and Lactococcus lactis subsp. cremoris 40FEL3 were selected for their ability to produce peptides from donkey milk. The endogenous peptides and those obtained after bacterial fermentation were assayed for their antioxidant, antibacterial, and antiviral activities. The peptide mixtures were characterized by means of LC-MS/MS and then analyzed in silico using the Milk Bioactive Peptide DataBase.

RESULTS

The peptides produced by the two selected bacteria enhanced the antioxidant activity and reduced E. coli growth. Only the peptides produced by L. rhamnosus 17D10 were able to reduce S. aureus growth. All the peptide mixtures were able to inhibit the replication of HSV-1 by more than 50%. Seventeen peptides were found to have 60% sequence similarity with already known bioactive peptides.

CONCLUSIONS

A lactic acid bacterium fermentation process is able to enhance the value of donkey milk through bioactivities that are important for human health.

Formation of Free Amino Acids and Bioactive Peptides During the Ripening of Bulgarian White Brined Cheeses

Bioactive peptides and free amino acids obtained from Bulgarian goat, sheep and cow white brined cheeses, produced with same starter culture, during ripening were evaluated. The concentration of total free amino acids was increasing in all tested cheeses in the first 30 days of ripening. In the next 30 days in sheep cheeses, the concentration increased as recorded for most of the amino acids. Amino acids with highest levels detected throughout the whole ripening period in goat, sheep and cow cheese types were leucine, phenylalanine, arginine, valine and lysine. MALDI-TOF analysis of evaluated cheeses resulted in detection of production of bioactive peptide derivates from milk proteins: 51 peptides in cow, 31 peptides in sheep and 22 peptides in goat cheeses. Peptide αs1-CN (f35-40) was found only in cow cheese. In cow cheese, higher intensity was detected for αs1-CN (f1-9) and β-CN (f194-203 and f203-219) peptides. In goat cheese was recorded αs1-CN peptides, and there was a tendency to increase the peptides released from β-CN, with the highest intensity of fragments αs1-CN (f1-9 and f24-30) and β-CN (f194-209 and f203-219). In sheep cheese, the recorded primarily peptides were αs1-CN and peptides released from β-CN. Different bioactive peptides, derivate from casein, were detected as follows: 6 peptides were ACE inhibitory peptides, 3 peptides were αS1-casokinins, 1 peptide was caseinophopeptide, 1 peptide was immunopeptide. Twelve bioactive peptides were recorded to be derivates from β-casein: 1 peptide was ACE peptide, 4 peptides were caseino-phosphopeptides, 1 peptide was immunopeptide, 1 peptide β-casokinin, 1 antibacterial peptide and 4 multifunctional peptides. Of peptides released by proteolysis of αS2-CN was found 1 bioactive peptide with antimicrobial activity. On our best knowledge, this paper contributes new data about free amino acids and bioactive peptides in the connection between type of milk and period for cheese ripening in the Bulgarian goat, sheep and cow white brined cheeses.

Nutritional, antimicrobial and medicinal properties of Camel's milk: A review

Camel's milk is an important part of staple diet in several parts of the world, particularly in the arid and semi-arid zones. Camel's milk is rich in health-beneficial substances, such as bioactive peptides, lactoferrin, zinc, and mono and polyunsaturated fatty acids. These substances could help in the treatment of some important human diseases like tuberculosis, asthma, gastrointestinal diseases, and jaundice. Camel's milk composition is more variable compared to cow's milk. The effects of feed, breed, age, and lactation stage on milk composition are more significant in camel. Region and season significantly change the ratio of compounds in camel's milk. Camel's whey protein is not only composed of numerous soluble proteins, but also has indigenous proteases such as chymotrypsin A and cathepsin D. In addition to their high nutritional value, these whey proteins have unique characteristics, including physical, chemical, physiological, functional, and technological features that are useful in the food application. The hydrolysis of camel's milk proteins leads to the formation of bioactive peptides, which affect major organ systems of the body and impart physiological functions to these systems. The camel's milk has antioxidant, antimicrobial, angiotensin-I-converting enzyme (ACE)-inhibitory peptides, antidiabetic as well as anticholesterol activities.

A quantitative calcium phosphate nanocluster model of the casein micelle: the average size, size distribution and surface properties

Caseins (α_S1, α_S2, β and κ) are the main protein fraction of bovine milk. Together with nanoclusters of amorphous calcium phosphate (CaP) and divalent cations, they combine to form a polydisperse distribution of particles called casein micelles. A casein micelle model is proposed which is consistent with the way in which intrinsically disordered proteins interact through predominantly polar, short, linear, motifs. Using the model, an expression is derived for the size distribution of casein micelles formed when caseins bind to the CaP nanoclusters and the complexes further associate with each other and the remaining mixture of free caseins. The result is a refined coat-core model in which the core is formed mainly by the nanocluster complexes and the coat is formed exclusively by the free caseins. Example calculations of the size distribution and surface composition of an average bovine milk are compared with experiment. The average size, size distribution and surface composition of the micelles is shown to depend on the affinity of the nanocluster complexes for each other in competition with their affinity for free caseins, and on the concentrations of free caseins, calcium ions and other salts in the continuous phase.

Use of α-Lactalbumin and Caseinoglycomacropeptide as Biopeptide Precursors and as Functional Additives in Milk Beverages Fermented by L. helveticus

The objective of this investigation was to verify whether biologically active peptides (BAPs) could be obtained from water solutions of α-lactalbumin (α-la) and caseinoglycomacropeptide (CGMP) through an application of the new Lactobacillus helveticus strains. Also, the aim of this research was to determine the influence of addition of the analyzed protein preparations to milk subjected to fermentation by tested bacterial strains on the physicochemical properties of obtained milk beverages. The results indicate that CGMP is a more preferable source for the production of BAPs by the test bacteria than α-la. The antihypertensive and ACE inhibitory effects were the most widespread bioactivities among the detected BAPs. α-la containing fermented milk beverages had higher values of springiness, gumminess, chewiness, and resilience than analogous products containing CGMP, while CGMP-supplemented fermented products exhibited higher values of the hardness parameter. The highest values of hardness (0.416 ± 0.05 N) were recorded for beverages fermented by DSMZ containing the addition of CGMP, while the lowest value of this parameter (0.186 ± 0.06 N) was noted for products containing α-la and fermented by B734. Moreover, CGMP-containing fermented products were characterized by a generally higher value of the proteolysis index (PI) than analogous variants containing α-la. The use of analyzed strains and the selected protein preparations has a positive effect on the texture of fermented milk beverages and might contribute to an increase in the health-promoting potential of such products.

Structural equation modeling for unraveling the multivariate genomic architecture of milk proteins in dairy cattle

The aims of this study were to investigate potential functional relationships among milk protein fractions in dairy cattle and to carry out a structural equation model (SEM) GWAS to provide a decomposition of total SNP effects into direct effects and effects mediated by traits that are upstream in a phenotypic network. To achieve these aims, we first fitted a mixed Bayesian multitrait genomic model to infer the genomic correlations among 6 milk nitrogen fractions [4 caseins (CN), namely κ-, β-, α_S1-, and α_S2-CN, and 2 whey proteins, namely β-lactoglobulin (β-LG) and α-lactalbumin (α-LA)], in a population of 989 Italian Brown Swiss cows. Animals were genotyped with the Illumina BovineSNP50 Bead Chip v.2 (Illumina Inc.). A Bayesian network approach using the max-min hill-climbing (MMHC) algorithm was implemented to model the dependencies or independence among traits. Strong and negative genomic correlations were found between β-CN and α_S1-CN (-0.706) and between β-CN and κ-CN (-0.735). The application of the MMHC algorithm revealed that κ-CN and β-CN seemed to directly or indirectly influence all other milk protein fractions. By integrating multitrait model GWAS and SEM-GWAS, we identified a total of 127 significant SNP for κ-CN, 89 SNP for β-CN, 30 SNP for α_S1-CN, and 14 SNP for α_S2-CN (mostly shared among CN and located on Bos taurus autosome 6) and 15 SNP for β-LG (mostly located on Bos taurus autosome 11), whereas no SNP passed the significance threshold for α-LA. For the significant SNP, we assessed and quantified the contribution of direct and indirect paths to total marker effect. Pathway analyses confirmed that common regulatory mechanisms (e.g., energy metabolism and hormonal and neural signals) are involved in the control of milk protein synthesis and metabolism. The information acquired might be leveraged for setting up optimal management and selection strategies aimed at improving milk quality and technological characteristics in dairy cattle.

Allergenicity of Fermented Foods: Emphasis on Seeds Protein-Based Products

Food allergy is an IgE-mediated abnormal response to otherwise harmless food proteins, affecting between 5% and 10% of the world preschool children population and 1% to 5% adults. Several physical, chemical, and biotechnological approaches have been used to reduce the allergenicity of food allergens. Fermentation processes that contribute to technological and desirable changes in taste, flavor, digestibility, and texture of food products constitute one of these approaches. Lactic acid bacteria (LAB), used as starter cultures in dairy products, are a subject of increasing interest in fermentation of plant proteins. However, the studies designed to assess the impact of LAB on reduction of allergenicity of seed proteins are at an early stage. This review presents the current knowledge on food fermentation, with a focus on seed proteins that are increasingly used as ingredients, and its impacts on food potential allergenicity.

Effect of multi-frequency power ultrasound (MFPU) treatment on enzyme hydrolysis of casein

Effect of multi-frequency power ultrasound (MFPU) pretreatments on the degree of hydrolysis (DH) and mechanism of casein during alcalase enzymolysis was investigated. Results showed that MFPU pretreatment in tri-frequency 20/40/60 kHz mode significantly (p < 0.05) improved the DH value of casein. Variation of intrinsic fluorescence spectrum indicated the unfolding and degradation of casein occurred after MFPU pretreatment. Fourier transform infrared spectra showed that α-helix and β-sheet content of MFPU pretreated casein decreased, while β-turn and random coil content increased. Surface topography and nanostructures of caseins were found modified after MFPU pretreatments by the analysis of scanning electron microscopy (SEM) and atomic force microscopy (AFM). The SEM analysis also indicated that the enzymolysis residues of casein pretreated by MFPU were smaller than untreated samples. In conclusion, the MFPU can be used as an efficient pretreatment method to promote the enzymolysis of casein.

Emerging Roles of Heat-Induced circRNAs Related to Lactogenesis in Lactating Sows

Heat stress negatively influences milk production and disrupts normal physiological activity of lactating sows, but the precious mechanisms by which hyperthermia adversely affects milk synthesis in sows still remain for further study. Circular RNAs are a novel class of non-coding RNAs with regulatory functions in various physiological and pathological processes. The expression profiles and functions of circRNAs of sows in lactogenesis remain largely unknown. In the present study, long-term heat stress (HS) resulted in a greater concentration of serum HSP70, LDH, and IgG, as well as decreased levels of COR, SOD, and PRL. HS reduced the total solids, fat, and lactose of sow milk, and HS significantly depressed CSNαs1, CSNαs2, and CSNκ biosynthesis. Transcriptome sequencing of lactating porcine mammary glands identified 42 upregulated and 25 downregulated transcripts in HS vs. control. Functional annotation of these differentially-expressed transcripts revealed four heat-induced genes involved in lactation. Moreover, 29 upregulated and 21 downregulated circRNA candidates were found in response to HS. Forty-two positively correlated circRNA-mRNA expression patterns were constructed between the four lactogenic genes and differentially expressed circRNAs. Five circRNA-miRNA-mRNA post-transcriptional networks were identified involving genes in the HS response of lactating sows. In this study we establish a valuable resource for circRNA biology in sow lactation. Analysis of a circRNA-miRNA-mRNA network further uncovered a novel layer of post-transcriptional regulation that could be used to improve sow milk production.

Impact of Type and Enzymatic/High Pressure Treatment of Milk on the Quality and Bio-Functional Profile of Yoghurt

The objective of the present study was to investigate the effect of the high pressure (HP) processing and transglutaminase (TGase) treatment of bovine (cow) or ovine (sheep) milk, when applied individually or sequentially, on the quality parameters and anti-hypertensive and immunomodulatory properties of yoghurt. Low-fat (2% w/w) bovine or ovine milk samples were used. Results showed that HP treatment of milk led to acid gels with equivalent quality attributes to thermal treatment, with the more representative attributes being whey separation and firmness, which ranged from 47.5% to 49.8% and 23.8% to 32.2% for bovine and ovine yoghurt, respectively, and 74.3–89.0 g and 219–220 g for bovine and ovine yoghurt, respectively. On the other hand, TGase treatment of milk, solely or more effectively following HP processing, resulted in the improvement of the textural attributes of yoghurt and reduced whey separation, regardless of milk type, exhibiting values of 32.9% and 8.7% for the whey separation of bovine and ovine yoghurt, respectively, and 333 g and 548 g for the firmness of bovine and ovine yoghurt, respectively. The HP processing and TGase treatment of milk led to the preservation or improvement of the anti-hypertensive activity of the samples, especially in the case in which ovine milk was used, with Inhibitory activity of Angiotensin Converting Enzyme (IACE) values of 76.9% and 88.5% for bovine and ovine yoghurt, respectively. The expression of pro-inflammatory genes decreased and that of anti-inflammatory genes increased in the case of samples from HP-processed and/or TGase-treated milk as compared to the corresponding expressions for samples from thermally treated milk. Thus, it can be stated that, apart from the quality improvement, HP processing and TGase treatment of milk may lead to the enhancement of the bio-functional properties of low-fat yoghurt made from either bovine or ovine milk.

Cardoon as a Sustainable Crop for Biomass and Bioactive Compounds Production

Cardoon is a multi-purpose and versatile Mediterranean crop, adapted to climate change, with a wide spectrum of potential applications due its added value as a rich source of fibers, oils and bioactive compounds. The Cynara species are a component of the Mediterranean diet and have been used as food and medicine since ancient times. The important role of cardoon in human nutrition, as a functional food, is due to its high content of nutraceutical and bioactive compounds such as oligofructose inulin, caffeoylquinic acids, flavonoids, anthocyanins, sesquiterpenes lactones, triterpenes, fatty acids and aspartic proteases. The present review highlights the characteristics and functions of cardoon biomass which permits the development of innovative products in food and nutrition, pharmaceutics and cosmetics, plant protection and biocides, oils and energy, lignocellulose materials, and healthcare industries following the actual trends of a circular economy.

Use of Mass Spectrometry to Profile Peptides in Whey Protein Isolate Medium Fermented by Lactobacillus helveticus LH-2 and Lactobacillus acidophilus La-5

Peptides in the 3-kDa ultrafiltrate of fermented whey protein isolate (WPI) medium could be responsible for the antivirulence activity of Lactobacillus helveticus LH-2 and Lactobacillus acidophilus La-5 against Salmonella Typhimurium. Non-fermented and fermented media containing 5.6% WPI were fractionated at a 3 kDa cut-off and the filtrate was analyzed by mass spectrometry. The non-fermented WPI medium contained 109 milk derived peptides, which originated from β-casein (52), αs1-casein (22), αs2-casein (10), κ-casein (8), and β-lactoglobulin (17). Most of these peptides were not found in the fermented media, except for 14 peptides from β-casein and one peptide from αs2-casein. Database searches confirmed that 39 out of the 109 peptides had established physiological functions, including angiotensin-converting-enzyme (ACE) inhibitory, antioxidant, antimicrobial, or immunomodulating activity. A total of 75 peptides were found in the LH-2 cell free spent medium (CFSM): 54 from β-casein, 14 from k-casein, 4 from β-lactoglobulin and 3 from αs2-casein. From these peptides, 19 have previously been associated with several categories of bioactivity. For La-5 CFSM, a total of 15 peptides were sequenced: 8 from β-casein, 5 from αs1-casein, 2 from β-lactoglobulin. Only 5 of these have previously been reported as having bioactivity. Many of the peptides remaining in the fermented medium would contain low-affinity residues for oligopeptide binding proteins and higher resistance to peptidase hydrolysis. These properties of the sequenced peptides could explain their accumulation after fermentation despite the active proteolytic enzymes of LH-2 and La-5 strains. Down-regulated expression of hilA and ssrB genes in S. Typhimurium was observed in the presence of La-5 and LH-2 CFSM. Downregulation was not observed for the Salmonella oppA mutant strain exposed to the same CFSM used to treat the S. Typhimurium DT104 wild-type strain. This result suggests the importance of peptide transport by S. Typhimurium for down regulation of virulence genes in Salmonella.

α-Glucosidase and ACE dual inhibitory protein hydrolysates and peptide fractions of sprouted quinoa yoghurt beverages inoculated with Lactobacillus casei

Dietary protein peptides from quinoa yoghurt beverage (QYB) fermented with probiotic lactic acid bacteria strains play a protective role against diabetes and hypertension. In this study, the α-glucosidase and ACE inhibitory activities of germination-based protein hydrolysates of QYB were investigated. All protein hydrolysates exhibited a dose and strain-dependent inhibition on the enzymes. The inhibition of α-glucosidase was the highest in QLCSY13 (IC₅₀ = 8.86 mg/mL), while ACE inhibition was the highest in QLCZ (IC₅₀ = 0.03 mg/mL). Overall, QLCSY13 had the highest inhibitory activities, which was ascribed to its relatively higher amino acid contents and hydrophobicity. In addition, the ACE and α-glucosidase inhibitory activities of peptide fractions identified by RP-HPLC were 127 ± 4.29 mg/mL and 10.39 ± 4.73 mg/mL respectively. Among the potent inhibitory peptide sequences identified, both LAHMIVAGA and VAHPVF significantly had α-glucosidase and ACE inhibitory activities. Consequently, dietary protein peptides present in QYB had anti-hypertensive and anti-diabetic potentials.

The Effect of In Vitro Digestion on Antioxidant, ACE-Inhibitory and Antimicrobial Potentials of Traditional Serbian White-Brined Cheeses

This study deals with the effect of in vitro digestion on the functional potential of traditional Serbian white-brined cheeses. The total antioxidant capacity, reducing power and iron (II) chelating properties as well as angiotensin-converting enyzme-inhibitory (ACE-inhibitory) and antimicrobial activities of traditional Serbian white-brined cheeses before and after in vitro digestion were assayed. The traditional cheeses had different antioxidant properties as well as different ACE-inhibitory activities. In vitro digestion improved the total antioxidant capacity (8.42⁻58.56 times) and the reducing power (by 17.90⁻99.30%) of investigated cheeses, whereas their chelating ability was slightly improved or unaffected after digestion. In vitro digestion reduced the ACE-inhibitory potential of water-soluble protein fractions, and digested water-insoluble fractions were the major source of ACE-inhibitory peptides. The digestates did not exhibit any antibacterial potential, whereas they showed moderate antifungal potential toward selected micromycetes. The best antifungal potential had Svrljig ovine cheese and Homolje cow cheese. The results of this study clearly point to a significant functionality of traditional white-brined cheeses.

Effect of Casein Hydrolysates on Intestinal Cell Migration and Their Peptide Profiles by LC-ESI/MS/MS

Potential beneficial effects of bioactive peptides derived from casein on epithelial cellular wound healing in the gastrointestinal tract were studied. Bovine casein was digested by a combination of pepsin and pancreatic proteases at different time intervals to represent ranges of duration of gastrointestinal digestion. Intestinal epithelial cells were used as an in vitro model of the small intestine. The effect of casein hydrolysates on cell migration was studied by scratch assay as a model of wound healing. Casein digested by pepsin and pancreatin for 10 to 30 min were found to have a significant stimulatory effect of >40% on cell migration relative to the control. A potential effect of casein gastrointestinal digests on gastro-intestinal wound healing has not previously been reported. The peptide profiles of active as well as inactive casein hydrolysates were characterised by liquid chromatography coupled to ion trap tandem mass spectrometry. By comparison of identified peptides in active and inactive casein hydrolysates, a pool of 11 peptides derived from casein were identified as potential candidates for effects on cell migration. Searching the milk bioactive peptide database (MBPDB) showed that 15 of the identified peptides had known biological functions such as antimicrobial, antioxidant, and immunomodulatory activity.

Milk-derived mammary epithelial cells as non-invasive source to define stage-specific abundance of milk protein and fat synthesis transcripts in native Sahiwal cows and Murrah buffaloes

The molecular physiology of milk production of two important dairy species; Sahiwal cows (Bos indicus) and Murrah buffaloes (Bubalus bubalis) are not fully understood due to constraints in obtaining mammary tissue samples because of sacred and ethical reasons. The present study suggests the use of milk-derived mammary epithelial cells (MECs) as a non-invasive method to understand molecular aspects of lactation biology in dairy animals. A total of 76 MECs were collected from five different lactation periods viz. colostrum (0-2), early (5-20), peak (30-50), mid (90-140) and late lactation (> 215 days) stages from Sahiwal cows and Murrah buffaloes to study the transcription kinetics of milk protein, fat synthesis, and their regulatory genes. Significant changes were observed in milk composition of both dairy species with lactation stages. High mRNA abundance of all milk protein and fat synthesis genes was observed in MECs of Murrah buffaloes as compared to Sahiwal cows. The mRNA abundance of caseins (CSN1S1, CSN1S2, CSN2, and CSN3) and whey protein (LALBA, LF) were higher in early lactation stage. Similarly, the expression of milk fat synthesis genes (SCD, BTN1A1, ACACA, GPAM, FAPB3, FASN) was also high in early lactation stage. The relative abundance of 4 regulatory genes (JAK2, STAT5, SREBF1 and EIF4BP41) remained high during early lactation indicating their regulatory roles in lactogenesis process. Overall, results suggested a significant effect of lactation stages on milk composition and transcription abundance of milk protein and fat synthesis genes. The present study establishes the fact that milk-derived MECs could be utilized as a valuable source to understand mammary gland functioning of native cows and buffaloes.

Health Implications of Bioactive Peptides: A Review

Abstract. Today, due to immobility, improper food habits, and changes in lifestyle, communities are faced with an increase in health problems such as blood pressure, cholesterol, diabetes, and thrombosis. Bioactive peptides are considered as being the main products of protein hydrolysis which exert high effects on the nervous, immune, and gastrointestinal systems. Unlike synthetic drugs, bioactive peptides have no side effects and this advantage has qualified them as an alternative to such drugs. Due to the above-mentioned properties, this paper focuses on the study of health-improving attributes of bioactive peptides such as anti-oxidative, anti-hypertensive, immunomodulatory, anti-microbial, anti-allergenic, opioid, anti-thrombotic, mineral-binding, anti-inflammatory, hypocholesterolemic, and anti-cancer effects. We also discuss the formation of bioactive peptides during fermentation, the main restrictions on the use of bioactive peptides and their applications in the field of functional foods. In general, food-derived biologically active peptides play an important role in human health and may be used in the development of novel foods with certain health claims.

Meta-Analysis for Correlating Structure of Bioactive Peptides in Foods of Animal Origin with Regard to Effect and Stability

Amino acid (AA) sequences of 807 bioactive peptides from foods of animal origin were examined in order to correlate peptide structure with activity (antihypertensive, antioxidative, immunomodulatory, antimicrobial, hypolipidemic, antithrombotic, and opioid) and stability in vivo. Food sources, such as milk, meat, eggs, and marine products, show different frequencies of bioactive peptides exhibiting specific effects. There is a correlation of peptide structure and effect, depending on type and position of AA. Opioid peptides contain a high percentage of aromatic AA residues, while antimicrobial peptides show an excess of positively charged AAs. AA residue position is significant, with those in the first and penultimate positions having the biggest effects on peptide activity. Peptides that have activity in vivo contain a high percentage (67%) of proline residues, but the positions of proline in the sequence depend on the length of the peptide. We also discuss the influence of processing on activity of these peptides, as well as methods for predicting release from the source protein and activity of peptides.

Sensoproteomics: A New Approach for the Identification of Taste-Active Peptides in Fermented Foods

Aiming at the identification of the key bitter peptides in fermented foods, a new approach, coined "sensoproteomics", was developed and applied to fresh cheese samples differing in bitter taste intensity. By means of MPLC fractionation of the water-soluble cheese extracts in combination with taste dilution analysis, complex fractions with intense bitter taste were located and then screened by UPLC-MS/MS for the entire repertoire of ∼1600 candidate peptides, extracted from a literature meta-analysis on dairy products, by using a total of 120 selected reaction monitoring methods computed in silico. A total of 340 out of the 1600 peptides were found in the cheese samples, among which 17 peptides were identified as candidate bitter peptides by considering only peptides that were located in the bitter-tasting MPLC fractions (signal-to-noise ratio: ≥10) with a fold-change of ≥3 when comparing the less bitter to the more bitter cheese sample and that were validated by comparison with the synthetic reference peptides. While EIVPNS[phos]VEQK (α_s1-CN_70-78) and INTIASGEPT (κ-CN_122-131) did not exhibit any bitter taste up to 2000 μmol/L, 15 of the 17 target peptides showed bitter taste thresholds ranging from 30 (ARHPHPHLSFM, κ-CN_96-106) to 690 μmol/L (IQKEDVPS, α_s1-CN_81-88). Finally, quantitative peptide analysis followed by calculation of dose-overthreshold factors revealed a primary contribution of MAPKHKEMPFPKYPVEPF (β-CN_102-119) and ARHPHPHLSFM (κ-CN_96-106) to the perceived bitter taste of the fresh cheese samples. Finally, the evolution of the bitter peptides throughout two different fresh cheese manufacturing processes was quantitatively recorded.