Identification of bioactive peptides in hypoallergenic infant milk formulas by CE-TOF-MS assisted by semiempirical model of electromigration behavior

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.

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.

Peptidomics and Capillary Electrophoresis

Peptides play a crucial role in many vitally important functions of living organisms. The goal of peptidomics is the identification of the "peptidome," the whole peptide content of a cell, organ, tissue, body fluid, or organism. In peptidomic or proteomic studies, capillary electrophoresis (CE) is an alternative technique for liquid chromatography. It is a highly efficient and fast separation method requiring extremely low amounts of sample. In peptidomic approaches, CE is commonly combined with mass spectrometric (MS) detection. Most often, CE is coupled with electrospray ionization MS and less frequently with matrix-assisted laser desorption/ionization MS. CE-MS has been employed in numerous studies dealing with determination of peptide biomarkers in different body fluids for various diseases, or in food peptidomic research for the analysis and identification of peptides with special biological activities. In addition to the above topics, sample preparation techniques commonly applied in peptidomics before CE separation and possibilities for peptide identification and quantification by CE-MS or CE-MS/MS methods are discussed in this chapter.

Investigating the position of the separation capillary and emitter tube tips in a nanoflow sheath-liquid CE-ESI-MS interface to decouple the ESI potential

Robust decoupling of the ESI potential from the separation potential in CE-ESI-MS interfaces is very important for the high performance of the CE-ESI-MS devices and their applications for highly sensitive analyses of ionogenic compounds. In this study, we utilize a nanoflow sheath-liquid CE-ESI-MS interface composed of a quartz emitter and a separation fused silica capillary treated by etching, which are threaded to cross coupling for sheath liquid and electrode connection. Specifically, we have tested the ability of the interface to decouple the ESI potential from the separation potential at different positions of the separation capillary and ESI emitter tube tips. The interface with the separation capillary tip protruding the emitter tip by 20 μm did not provide sufficient robustness. The real ESI potential (delivered as 2.0 kV from the independent high voltage power supply HV2) ranged from 2.1 kV to 4.5 kV depending on the applied separation voltage (12.0-20.0 kV, provided by the power supply HV1) and electric conductivity of the background electrolyte (BGE) used. The interface robustness was partially improved when the capillary tip was aligned with the emitter tip. However, the complete decoupling of the spray and separation potentials was achieved only when the capillary tip was retracted 20 μm inside the emitter. In this arrangement, the ESI potential was stable and independent of both the separation potential (voltage) and the BGE conductivity. Moreover, this setting provided better sensitivity for the CE-ESI-MS analysis of selected drugs and benzylpyridinium cations than the setup with the capillary tip aligned with or protruding the emitter tip.

Food-derived antithrombotic peptides: Preparation, identification, and interactions with thrombin

Thromboembolism and its sequelae have been the leading causes of morbidity and mortality throughout the world. Food-derived antithrombotic peptides, as potential ingredients in health-promoting functional foods targeting thrombus, have attracted increasing attention because of their high biological activities, low toxicity, and ease of metabolism in the human body. This review presents the conventional workflow of preparation, isolation and identification of antithrombotic peptides from various kinds of food materials. More importantly, to analyze the antithrombotic effects and mechanism of antithrombotic peptides, methods for interaction of anticoagulant peptides and thrombin, the main participant in thrombosis, were analyzed from biochemistry, solution chemistry and crystal chemistry. The present study is intended to highlight the recent advances in research of food-derived antithrombotic peptide as a novel vehicle in the field of food science and nutrition. Future outlooks are highlighted with the aim to suggest a research line to be followed in further studies with the introduced research approach.

Identification of peptides with tolerogenic potential in a hydrolysed whey-based infant formula

BACKGROUND

Failure to induce oral tolerance may result in food allergy. Hydrolysed cow's milk-based infant formulas are recommended in subjects with a high risk of developing allergic disease. Presentation of T cell epitopes is a prerequisite to generate regulatory T cells that could contribute to oral tolerance.

OBJECTIVE

To investigate whether a specific hydrolysed whey-based infant formula contains peptides that function as T cell epitopes to support the development of oral tolerance to whey.

METHODS

First, a novel liquid chromatography-mass spectrometry (LC-MS) method was developed to characterize β-lactoglobulin-derived peptides present in a specific infant formula with a focus on region AA#13-48 of β-lactoglobulin, which has previously been described to contain T cell epitopes with tolerogenic potential. Second, the formula was subjected to the ProImmune ProPresent^® antigen presentation assay and MHC class II binding algorithm to identify relevant HLA-DRB1-restricted peptides. Third, identified peptides were tested on human cow's milk protein-specific T cell lines to determine T cell recognition.

RESULTS

Thirteen peptides of minimal 9AAs long that overlap with AA#13-48 of β-lactoglobulin were identified. Six of them were found across all batches analysed. It was further confirmed that these peptides were processed and presented by human dendritic cells. The identified HLA-DRB1-restricted peptides were correlated to AA#11-30 and AA#23-39 of β-lactoglobulin. Importantly, the proliferation assay showed that the synthetic peptides were recognized by cow's milk protein-specific T cell lines and induced T cell proliferation.

CONCLUSION AND CLINICAL RELEVANCE

This study demonstrates that the tested hydrolysed infant formula contains functional HLA-DRB1-restricted T cell epitopes, which can potentially support the development of oral tolerance to whey.

Optimization of a capillary zone electrophoresis-contactless conductivity detection method for the determination of nisin

Determination of natural preservatives using electrophoretic or chromatographic techniques in fermented milk products is a complex task due to the following reasons: (i) the concentrations of the analytes can be below the detection limits, (ii) complex matrix and comigrating/coeluting compounds in the sample can interfere with the analytes of the interest, (iii) low recovery of the analytes, and (iv) the necessity of complex sample preparation. The aim of this study was to apply capillary zone electrophoresis coupled with contactless conductivity detection for the separation and determination of nisin in fermented milk products. In this work, separation and determination of natural preservative-nisin in fermented milk products is described. Optimized conditions using capillary zone electrophoresis coupled with capacitance-to-digital technology based contactless conductivity detector and data conditioning, which filter the noise of the electropherogram adaptively to the peak migration time, allowed precise, accurate, sensitive (limit of quantification: 0.02 μg/mL), and most importantly requiring very minute sample preparation, determination of nisin. Sample preparation includes following steps: (i) extraction/dilution and (ii) centrifugation. This method was applied for the determination of nisin in real samples, i.e. fermented milk products. The values of different nisin forms were ranging from 0.056 ± 0.003 μg/mL to 9.307 ± 0.437 μg/g.

CE-ESI-MS for bottom-up proteomics: Advances in separation, interfacing and applications

With the development of more sensitive hyphenation strategies for capillary electrophoresis-electrospray-mass spectrometry the technique has reemerged as technique with high separation power combined with high sensitivity in the analysis of peptides and protein digests. This review will discuss the newly developed hyphenation strategies for CE-ESI-MS and their application in bottom-up proteomics as well as the applications in the same time span, 2009 to present, using co-axial sheathliquid. Subsequently all separate aspects in the development of a CE-ESI-MS method for bottom-up proteomics shall be discussed, highlighting certain applications and discussing pros and cons of the various choices. The separation of peptides in a capillary electrophoresis system is discussed including the great potential for modeling of this migration of peptides due to the simple electrophoretic separation process. Furthermore, the technical aspects of method development are discussed, namely; background electrolyte choice, coating of the separation capillary and chosen loading method. Finally, conclusions and an outlook on future developments in the field of bottom-up proteomics by CE-ESI-MS will be provided.

Capillary Electrophoresis in Food and Foodomics

Quality and safety assessment as well as the evaluation of other nutritional and functional properties of foods imply the use of robust, efficient, sensitive, and cost-effective analytical methodologies. Among analytical technologies used in the fields of food analysis and foodomics, capillary electrophoresis (CE) has generated great interest for the analyses of a large number of compounds due to its high separation efficiency, extremely small sample and reagent requirements, and rapid analysis. The introductory section of this chapter provides an overview of the recent applications of capillary electrophoresis (CE) in food analysis and foodomics. Relevant reviews and research articles on these topics are tabulated including papers published in the period 2011-2014. In addition, to illustrate the great capabilities of CE in foodomics the chapter describes the main experimental points to be taken into consideration for a metabolomic study of the antiproliferative effect of carnosic acid (a natural diterpene found in rosemary) against HT-29 human colon cancer cells.

Novel approaches to improve the intrinsic microbiological safety of powdered infant milk formula

Human milk is recognised as the best form of nutrition for infants. However; in instances where breast-feeding is not possible, unsuitable or inadequate, infant milk formulae are used as breast milk substitutes. These formulae are designed to provide infants with optimum nutrition for normal growth and development and are available in either powdered or liquid forms. Powdered infant formula is widely used for convenience and economic reasons. However; current manufacturing processes are not capable of producing a sterile powdered infant formula. Due to their immature immune systems and permeable gastro-intestinal tracts, infants can be more susceptible to infection via foodborne pathogenic bacteria than other age-groups. Consumption of powdered infant formula contaminated by pathogenic microbes can be a cause of serious illness. In this review paper, we discuss the current manufacturing practices present in the infant formula industry, the pathogens of greatest concern, Cronobacter and Salmonella and methods of improving the intrinsic safety of powdered infant formula via the addition of antimicrobials such as: bioactive peptides; organic acids; probiotics and prebiotics.

Modelling the electrophoretic migration behaviour of peptides and glycopeptides from glycoprotein digests in capillary electrophoresis-mass spectrometry

In this study, the classical semiempirical relationships between the electrophoretic mobility and the charge-to-mass ratio (me vs. q/M(α)) were used to model the migration behaviour of peptides and glycopeptides originated from the digestion of recombinant human erythropoietin (rhEPO), a biologically and therapeutically relevant glycoprotein. The Stoke's law (α=1/3), the classical polymer model (α=1/2) and the Offord's surface law (α=2/3) were evaluated to predict migration of peptides and glycopeptides, with and without sialic acids (SiA), in rhEPO digested with trypsin and trypsin-neuraminidase. The Stoke's law resulted in better correlations for the set of peptides used to evaluate the models, while glycopeptides fitted better with the classical polymer model. Once predicted migration times with both models, it was easy to simulate their separation electropherogram. Results were later validated predicting migration and simulating separation of a different set of rhEPO glycopeptides and also human transferrin (Tf) peptides and glycopeptides. The excellent agreement between the experimental and the simulated electropherograms with rhEPO and Tf digests confirmed the potential applicability of this simple strategy to predict, in general, the peptide-glycopeptide electrophoretic map of any digested glycoprotein.

Health-promoting properties of bioactive peptides derived from milk proteins in infant food: a review

Milk proteins have attracted extensive interest in terms of their bioavailability following ingestion. Enzymatic digestion of dairy products generates numerous peptides with various biological activities. Both human milk and infant formulas based on cow's milk are potential sources of bioactive peptides. This review aims to present current knowledge on the formation and fate of bioactive peptides from milk feeds intended for infants. Emphasis is placed on the source of the bioactive peptides with the nutritional impact of human milk and cow milk-based formulas on infant health being critically discussed from that perspective. Furthermore, the effect of processing and in vitro or in vivo digestion on the release and availability of peptides with bioactive sequences is evaluated. Considerable differences with respect to bioavailability and metabolic effects between the biologically active fragments generated following ingestion of human milk and infant formulas are documented. Peptides from milk protein of bovine origin could be a valuable supplement to human milk as multiple health-promoting properties are attributed to peptide fractions identified in standard cow milk-based infant formulas.