High Hydrostatic Pressure Pretreatment of Whey Protein Isolates Improves Their Digestibility and Antioxidant Capacity

Plant resources for immunonutrients and immunomodulators to combat infectious respiratory viral diseases: a review

Boosting the immune system has become a crucial aspect in the global battle against the COVID-19 pandemic and other similar infections to protect oneself against symptoms, especially in the prevention of viral infections of the lower respiratory tract. The importance of conducting more studies to create successful herbal formulations as infection prevention measures is emphasized in this review, which looks at the function of immune-boosting nutrients, medicinal plants, and herbal treatments. We reviewed and analyzed 207 studies published from 1946 to the present using reputable databases like Google Scholar, PubMed, and NCBI. The review examined 115 plant species in total and identified 12 key nutrients, including vitamins A, D, C, omega-3 fatty acids, iron, and zinc, while noting that four plant families, Rosaceae, Asteraceae, Amaryllidaceae, and Acanthaceae, show potential against respiratory infections like influenza, RSV, and SARS-CoV. To lower the risk of infection, it is recommended to consume nutritious meals that have immune-modulating qualities. Information on the bioactive components of medicinal herbs, spices, and plants that have been effective in treating respiratory viral infections and related conditions is compiled in this review, which highlights phytoactive substances with antibacterial and antiviral activity as effective modulators to lower the risk of infections. Furthermore, it is highlighted that ancient knowledge systems, like Ayurveda and Naturopathy, should be integrated to help develop new herbal formulations. To improve immunity and lessen vulnerability to serious respiratory infections, the results highlight the need for including immune-modulating foods and plant-based medicines into everyday routines.

Deciphering the impact of stickwater hydrolysate on growth performance, immune response, and IGF-1/PI3K/AKT/mTOR signaling pathway in Siberian sturgeon (Acipenser baerii) fingerlings

A feeding trial lasting 56 days was carried out to assess how the inclusion of stickwater hydrolysate (SWH) in the diet of Siberian sturgeon (Acipenser baerii) fingerlings affected their growth performance, immunity, digestive enzyme activity, and gene expression linked to the IGF-1/PI3K/AKT/mTOR signaling pathway. Siberian sturgeon fingerlings were acclimatized and fed isonitrogenous, isoenergetic diets with varying SWH concentrations (0%, 0.5%, 1.5%, and 2.5%). Growth parameters, serum proteins, immunological and digestive enzyme activities, and gene expression levels were assessed post-trial. Results demonstrated that 0.5%, and 1.5% SWH treatments significantly improved weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio. Notably, these diets also elevated serum protein and plasma globulin levels, reduced albumin-to-globulin ratios, and enhanced lysozyme, myeloperoxidase (MPO) activities, and immunoglobulin (Ig) M levels, indicating an immunostimulatory effect. Digestive enzyme activities were markedly increased in the SWH groups, particularly at 1.5%. Gene expression analyses revealed upregulation of mtorc1, s6K, akt, pi3k, and igf1, with concurrent downregulation of 4e-bp1 in the muscle of fish, signifying activation of the IGF-1/PI3K/AKT/mTOR pathway, which is central to protein synthesis and muscle growth. In conclusion, SWH at appropriate levels significantly enhances growth, digestive efficiency, and immune function in Siberian sturgeon fingerlings, while also activating key metabolic pathways.

Effect of whey protein isolate addition on set-type camel milk yogurt: Rheological properties and biological activities of the bioaccessible fraction

The manufacture of camel milk (CM) yogurt has been associated with several challenges, such as the weak structure and watery texture, thereby decreasing its acceptability. Therefore, this study aimed to investigate the effect of whey protein isolate (WPI) addition on the health-promoting benefits, texture profile, and rheological properties of CM yogurt after 1 and 15 d of storage. Yogurt was prepared from CM supplemented with 0, 3, and 5% of WPI and compared with bovine milk yogurt. The results show that the water holding capacity was affected by WPI addition representing 31.3%, 56.8%, 64.7%, and 45.1% for yogurt from CM containing 0, 3 or 5% WPI, and bovine milk yogurt, respectively, after 15 d. The addition of WPI increased yogurt hardness, adhesiveness, and decreased the resilience. CM yogurt without WPI showed lower apparent viscosity, storage modulus, and loss modulus values compared with other samples. The supplementation of CM with WPI improved the rheological properties of the obtained yogurt. Furthermore, the antioxidant activities of yogurt before and after in vitro digestion varied among yogurt treatments, which significantly increased after digestion except the superoxide anion scavenging and lipid oxidation inhibition. After in vitro digestion at d 1, the superoxide anion scavenging of the 4 yogurt treatments respectively decreased from 83.7%, 83.0%, 79.1%, and 87.4% to 36.7%, 38.3%, 44.6%, and 41.3%. The inhibition of α-amylase and α-glucosidase, angiotensin-converting enzyme inhibition, cholesterol removal, and degree of hydrolysis exhibited different values before and after in vitro digestion.

The use of 15N-labelled protein to account for the endogenous nitrogen contribution to in vitro protein digestibility measurement

Protein digestibility, a key indicator of dietary protein quality for human nutrition, can be estimated using an in vitro digestion model, however its definition and determination remain variable across studies. The present study aimed to determine the contribution of the endogenous nitrogen (N) to the plant and animal protein digestibility values obtained in vitro. 15N-labelled gluten and caseins (4, 8 and 16 % of the model meal) were used to differentiate dietary and endogenous N and were digested using the INFOGEST in vitro digestion model with no oral phase. The dietary and endogenous N were measured before and during digestion after centrifugation and 10 kDa ultrafiltration. The proteolysis degree was measured by the OPA method. The endogenous and dietary N were determined by elemental analyser coupled with isotopic ratio mass spectrometry. Apparent and true digestibility were determined and values of 135, 92 and 71 % for apparent vs. 78, 69, 60 % for true digestibility were obtained for 4, 8 and 16 % dietary protein level, respectively, with a significant effect of protein level. Differences between apparent and true digestibility pointed out the important contribution of the endogenous nitrogen. Our results showed that 40 % of the N below 10 kDa, i.e., the digestible fraction, were from endogenous origin (i.e. from the pancreatin) and was even present before digestion. An average value of 27 % for pancreatin N autolysis was estimated independently of the protein levels or sources. The use of 15N-labelled protein to evaluate in vitro protein digestibility highlighted the important contribution of the endogenous N, in particular when low dietary protein solution (4 %) are digested. This gives new keys to overcome drawbacks of in vitro models for determining protein digestibility.

Digestion-resistant whey peptides promote antioxidant effect on Caco-2 cells

Enteric endothelial cells are the first structure to come in contact with digested food and may suffer oxidative damage by innumerous exogenous factors. Although peptides derived from whey digestion have presented antioxidant potential, little is known regarding antioxidant pathways activation in Caco-2 cell line model. Hence, we evaluated the ability to form whey peptides resistant to simulated gastrointestinal digestive processes, with potential antioxidant activity on gastrointestinal cells and associated with sequence structure and activity. Using the INFOGEST method of simulated static digestion, we achieved 35.2% proteolysis, with formation of peptides of low molecular mass (<600 Da) evaluated by FPLC. The digestion-resistant peptides showed a high proportion of hydrophobic and acidic amino acids, but with average surface hydrophobicity. We identified 24 peptide sequences, mainly originated from β-lactoglobulin, that exhibit various bioactivities. Structurally, the sequenced peptides predominantly contained the amino acids lysine and valine in the N-terminal region, and tyrosine in the C-terminal region, which are known to exhibit antioxidant properties. The antioxidant activity of the peptide digests was on average twice as potent as that of the protein isolates for the same concentration, as evaluated by ABTS, DPPH and ORAC. Evaluation of biological activity in Caco-2 intestinal cells, stimulated with hydrogen peroxide, showed that they attenuated the production of reactive oxygen species and prevented GSH reduction and SOD activity increase. Caco-2 cells were not responsive to nitric oxide secretion. This study suggests that whey peptides formed during gastric digestion exhibit biological antioxidant activity, without the need for previously hydrolysis with exogenous enzymes for supplement application. The study's primary contribution was demonstrating the antioxidant activity of whey peptides in maintaining the gastrointestinal epithelial cells, potentially preventing oxidative stress that affects the digestive system.

Potential Application of High Hydrostatic Pressure on the Production of Hydrolyzed Proteins with Antioxidant and Antihypertensive Properties and Low Allergenicity: A Review

The high hydrostatic pressure (HHP) process has been studied for several applications in food technology and has been commercially implemented in several countries, mainly for non-thermal pasteurization and shelf-life extension of food products. HHP processing has been demonstrated to accelerate proteolytic hydrolysis at a specific combination of pressure and pressure-holding time for a given protein source and enzyme. The enzymatic hydrolysis of proteins is a well-known alternative to producing biologically active peptides, with antioxidant and antihypertensive capacity, from different food protein sources. However, some of these protein sources contain allergenic epitopes which are often not degraded by traditional hydrolysis. Moreover, the peptide profile and related biological activity of a hydrolysate depend on the protein source, the enzymes used, the parameters of the proteolysis process (pH, temperature, time of hydrolysis), and the use of other technologies such as HHP. The present review aims to provide an update on the use of HHP for improving enzymatic hydrolysis, with a particular focus on studies which evaluated hydrolysate antihypertensive and antioxidant capacity, as well as residual allergenicity. Overall, HHP has been shown to improve the biological properties of hydrolysates. While protein allergenicity can be reduced with traditional hydrolysis, HHP can further reduce the allergenicity. Compared with traditional hydrolysis methods, HHP-assisted protein hydrolysis offers a greater opportunity to add value to protein-rich products through conversion into high-end hydrolysate products with enhanced nutritional and functional properties.

Hypoxia-Driven Changes in a Human Intestinal Organoid Model and the Protective Effects of Hydrolyzed Whey

Many whey proteins, peptides and protein-derived amino acids have been suggested to improve gut health through their anti-oxidant, anti-microbial, barrier-protective and immune-modulating effects. Interestingly, although the degree of hydrolysis influences peptide composition and, thereby, biological function, this important aspect is often overlooked. In the current study, we aimed to investigate the effects of whey protein fractions with different degrees of enzymatic hydrolysis on the intestinal epithelium in health and disease with a novel 2D human intestinal organoid (HIO) monolayer model. In addition, we aimed to assess the anti-microbial activity and immune effects of the whey protein fractions. Human intestinal organoids were cultured from adult small intestines, and a model enabling apical administration of nutritional components during hypoxia-induced intestinal inflammation and normoxia (control) in crypt-like and villus-like HIO was established. Subsequently, the potential beneficial effects of whey protein isolate (WPI) and two whey protein hydrolysates with a 27.7% degree of hydrolysis (DH28) and a 50.9% degree of hydrolysis (DH51) were assessed. In addition, possible immune modulatory effects on human peripheral immune cells and anti-microbial activity on four microbial strains of the whey protein fractions were investigated. Exposure to DH28 prevented paracellular barrier loss of crypt-like HIO following hypoxia-induced intestinal inflammation with a concomitant decrease in hypoxia inducible factor 1 alpha (HIF1α) mRNA expression. WPI increased Treg numbers and Treg expression of cluster of differentiation 25 (CD25) and CD69 and reduced CD4+ T cell proliferation, whereas no anti-microbial effects were observed. The observed biological effects were differentially mediated by diverse whey protein fractions, indicating that (degree of) hydrolysis influences their biological effects. Moreover, these new insights may provide opportunities to improve immune tolerance and promote intestinal health.

Effect of high hydrostatic pressure processing on the structure, functionality, and nutritional properties of food proteins: A review

Proteins are important food ingredients that possess both functional and nutritional properties. High hydrostatic pressure (HHP) is an emerging nonthermal food processing technology that has been subject to great advancements in the last two decades. It is well established that pressure can induce changes in protein folding and oligomerization, and consequently, HHP has the potential to modify the desired protein properties. In this review article, the research progress over the last 15 years regarding the effect of HHP on protein structures, as well as the applications of HHP in modifying protein functionalities (i.e., solubility, water/oil holding capacity, emulsification, foaming and gelation) and nutritional properties (i.e., digestibility and bioactivity) are systematically discussed. Protein unfolding generally occurs during HHP treatment, which can result in increased conformational flexibility and the exposure of interior residues. Through the optimization of HHP and environmental conditions, a balance in protein hydrophobicity and hydrophilicity may be obtained, and therefore, the desired protein functionality can be improved. Moreover, after HHP treatment, there might be greater accessibility of the interior residues to digestive enzymes or the altered conformation of specific active sites, which may lead to modified nutritional properties. However, the practical applications of HHP in developing functional protein ingredients are underutilized and require more research concerning the impact of other food components or additives during HHP treatment. Furthermore, possible negative impacts on nutritional properties of proteins and other compounds must be also considered.

Factors affecting the modification of bovine milk proteins in high hydrostatic pressure processing: An updated review

High hydrostatic pressure (HHP) treatment induces structural changes in bovine milk proteins depending on factors such as the temperature, pH, concentration, decompression rate, cycling, composition of the medium and pressure level and duration. An in-depth understanding of the impact of these factors is important for controlling HHP-induced modification of milk proteins and the interactions within or between them, which can be applied to prevent undesired aggregation, gelation, and precipitation during HHP processing or to obtain specific milk protein modifications to attain specific protein properties. In this regard, understanding the influences of these factors can provide insight into the modulation and optimization of HHP conditions to attain specific milk protein structures. In recent years, there has been a great research attention on HHP-induced changes in milk proteins influenced by factors such as pH, temperature, concentration, cycling, decompression condition, and medium composition. Hence, to provide insight into how these factors control milk protein structures under HHP treatment and to understand if their effects depend on HHP parameters and environmental conditions, this review discusses recent findings on how various factors (pH, temperature, cycling, decompression rate, medium composition, and concentration) affect HHP-induced bovine milk protein modification. Practical Application: The information provided in this review will be very useful to anticipate the challenges related to the formulation and development of pressure-treated milk and dairy products.

Structural changes and exposed amino acids of ethanol-modified whey proteins isolates promote its antioxidant potential

Whey protein isolates (WPI) were treated with different ethanol level (20, 40, 60, and 80%, v/v) to promote structural unfolding and subsequent aggregation. In general, protein aggregation gradually increased with increasing ethanol level in a dose-dependent manner, which was implied by notably increased turbidity and gradually decreased solubility. The formation of aggregates, which were confirmed by the results of circular dichroism spectrum and total sulfhydryl content, were promoted mainly through disulfide bonds and intra-molecular hydrogen bonds. Moreover, ethanol treated WPI (E-WPI) had significantly enhanced antioxidant activities over native WPI, which was mainly attribute to the higher contents of specific amino acids (such as hydrophobic amino acids, aromatic amino acids, and sulfur-containing amino acids), and E-WPI prepared with moderate ethanol concentration (40% in our present study) exhibited the highest antioxidant activities. These results reveal that antioxidant activities of WPI can be increased by ethanol treatment and are possibly achieved through molecular unfolding of native WPI.

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Ethanol treatment caused unfolding and aggregation of whey protein isolate (WPI).

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Aggregation enhanced with increasing ethanol concentration (EC).

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Medium EC (40%, v/v) rendered the highest antioxidant activities of WPI.

Assessment of Bioavailability after In Vitro Digestion and First Pass Metabolism of Bioactive Peptides from Collagen Hydrolysates

Collagen hydrolysates (CHs) are composed of bioactive peptides (BAPs), which possess health enhancing properties. There is a knowledge gap regarding the bioavailability of these BAPs that involves intestinal transport and hepatic first pass effects. A simulated gastrointestinal model was used to generate digesta from two CHs (CH-GL and CH-OPT), which were applied to a novel transwell co-culture of human intestinal epithelium cell line-6 (HIEC-6) and hepatic (HepG2) cells to simulate in vivo conditions of absorption and first pass metabolism. Peptide transport, hepatic first pass effects, and bioavailability were determined by measuring BAPs (Gly-Pro, Hyp-Gly, Ala-Hyp, Pro-Hyp, Gly-Pro-Hyp) using an innovative capillary electrophoresis method. All peptides were transported across the intestinal cell layer to varying degrees with both CHs; however, Gly-Pro-Hyp was transported only with CH-GL, but not CH-OPT. Notable hepatic production was observed for Ala-Hyp with both CH treatments, and for Pro-Hyp and Gly-Pro with CH-GL only. All peptides were bioavailable (>10%), except for Gly-Pro-Hyp after CH-OPT. Overall, a high degree of transport and hepatic first pass effects on CH-derived BAPs were observed. Further research is needed to explore the hepatic mechanisms related to the production of BAPs and the bifunctional effects of the bioavailable BAPs noted in this study.

Physicochemical properties and antioxidant activity of gluten-free riceberry-cheese cracker under simulated gastrointestinal transit

This study aimed to develop a gluten-free cracker by substituting wheat flour (WF) with riceberry flour (RB) combined with cheese's milk proteins to replace gluten. The effect of substitution of WF with RB at 50 and 100% (RB50 and RB100, respectively) on cracker properties were evaluated. The results showed that water activity, hunter colour value (L*), hardness, and thickness decreased with an increase in the RB content. This related to a compact structure and a weaker crystallinity of RB cracker when compared with WF-based cracker. The substitution of WF with RB50 and RB100 in cracker significantly (P < 0.05)increased the phytochemical content resulting in increased antioxidant properties.The synergistic effect of the bioactive compound of RB and the bioactive peptides originating from cheese's milk proteins on antioxidant capacity was observed under simulated GI digestion. The greatest increase in the ABTS•+ radical scavenging activity and reducing power was observed in the RB100 cracker at the intestinal digestive phase with the values of 15.74 ± 0.27 and 3.70 ± 0.06 mg Trolox eq./g sample, respectively. The results suggest that the substituted 100% RB combined with cheese's milk proteins have a potentiality to be developed into a novel gluten-free product with enhanced antioxidant properties.

Influence of high-intensity ultrasound on the IgE binding capacity of Act d 2 allergen, secondary structure, and In-vitro digestibility of kiwifruit proteins

Kiwifruit can trigger allergic reactions that can lead to death, causing public health concerns worldwide. In the present study, we treated kiwifruit samples with high-intensity ultrasound (20 kHz, 400 W, 50% duty cycle) for 0 to 16 min to evaluate its effect on the IgE binding capacity of kiwifruit allergen Act d 2, secondary structure and in-vitro digestibility of kiwifruit proteins. The changes in the protein solubility and microstructures of kiwifruit were also analyzed. The results showed that treatment with powerful ultrasound caused a significant disruption in the microstructure of kiwifruit tissues, leading to the changes in the secondary structures of proteins, including a loss of alpha-helixes and an increase in beta-sheet structures. These structural changes were due to the ultrasound treatment, especially 16 min of treatment, resulted in a 50% reduction in Act d 2 allergen content and significantly improved in-vitro digestibility up to 62% from the initial level of 35%. Furthermore, the solubility of the total proteins present in kiwifruit samples was significantly decreased by 20% after 16-min ultrasound processing. The results of this work showed that high-intensity ultrasound treatment has a potential application in reducing the allergenicity of kiwifruit or related products.

Production of biologically active peptides by hydrolysis of whey protein isolates using hydrodynamic cavitation

Whey protein isolate (WPI) hydrolysates have higher solubility in aqueous phase and enhanced biological properties. Hydrolysis of WPI was optimized using operating pressure (ΔP, bar), number of passes (N), and WPI concentration (C, %) as deciding parameters in hydrodynamic cavitation treatment. The optimum conditions for generation of WPI hydrolysate with full factorial design were 8 bar, 28 passes, and 4.5% WPI concentration yielding 32.69 ± 1.22 mg/mL soluble proteins. WPI hydrolysate showed alterations in binding capacity over WPI. SDS-PAGE and particle size analysis confirmed the hydrolysis of WPI. Spectroscopic, thermal and crystallinity analyses showed typical properties of proteins with slight variations after hydrodynamic cavitation treatment. ABTS, DPPH and FRAP assays of WPI hydrolysate showed 7-66, 9-149, and 0.038-0.272 µmol/mL GAE at 1-10, 0.25-4, and 3-30 mg/mL concentration, respectively. Further, a considerable enhancement in fresh weight, chlorophyll, carotenoids, reducing sugars, total soluble sugars, soluble proteins content and total phenolics content was noticed during in vitro growth of sugarcane in WPI hydrolysate supplemented medium at 50-200 mg/L concentration over the control. The process cost (INR/kg) to hydrolyze WPI was also calculated.

Production and processing of antioxidant bioactive peptides: A driving force for the functional food market

Recently, the demand for functional foods in the global market has increased rapidly due to the increasing occurrences of non-communicable diseases and technological advancement. Antioxidant peptides have been suggested as ingredients used to produce health-promoting foods. These peptides are encrypted from various food derived protein sources by chemical and enzymatic hydrolysis, and microbial fermentation. However, the industrial-scale production of antioxidant peptides is hampered by different problems such as high production cost, and low yield and bioactivity. Accordingly, novel processing technologies, such as high pressure, microwave and pulsed electric field, have been recently emerged to overcome the problems associated with the conventional hydrolysis methods. This particular review, therefore, discussed the current processing technologies used to produce antioxidant peptides. The review also suggested further perspectives that should be addressed in the future.

Egg-Derived Tripeptide IRW Attenuates LPS-Induced Osteoclastogenesis in RAW 264.7 Macrophages via Inhibition of Inflammatory Responses and NF-κB/MAPK Activation

Excessive bone resorption, because of increased osteoclastic activity, is a key underlying cause of osteolytic disorders. Lipopolysaccharide (LPS) is a potent factor to stimulate osteoclastic activity by inducing inflammatory stress. An egg-derived tripeptide IRW (Ile-Arg-Trp) was previously shown to exert anti-inflammatory activity. The overall objective of this study was to investigate the effect of IRW on inhibiting LPS-induced osteoclastogenesis and inflammatory bone resorption in the mouse macrophage RAW 264.7 cells. IRW (25 and 50 μM) significantly inhibited the LPS-induced osteoclast formation and resorptive activity. Meanwhile, IRW significantly suppressed the LPS-induced expression of TNF-α, IL-6, iNOS, COXII, NO, and PGE2. Furthermore, IRW regulated a group of osteoclastogenesis-associated factors (TRAF6, c-Fos, NFATc1, and cathepsin K) because of the inhibition of LPS-activated NF-κB and MAPK pathways. In conclusion, our study suggested the ability of IRW to prevent LPS-induced inflammatory bone resorption activity via the inhibition of inflammatory responses and the activation of osteoclastogenesis-associated signaling pathways.

In Vitro Characterisation of the Antioxidative Properties of Whey Protein Hydrolysates Generated under pH- and Non pH-Controlled Conditions

Bovine whey protein concentrate (WPC) was hydrolysed under pH-stat (ST) and non pH-controlled (free-fall, FF) conditions using Debitrase (DBT) and FlavorPro Whey (FPW). The resultant whey protein hydrolysates (WPHs) were assessed for the impact of hydrolysis conditions on the physicochemical and the in vitro antioxidant and intracellular reactive oxygen species (ROS) generation in oxidatively stressed HepG2 cells. Enzyme and hydrolysis condition dependent differences in the physicochemical properties of the hydrolysates were observed, however, the extent of hydrolysis was similar under ST and FF conditions. Significantly higher (p < 0.05) in vitro and cellular antioxidant activities were observed for the DBT compared to the FPW-WPHs. The WPHs generated under ST conditions displayed significantly higher (p < 0.05) oxygen radical absorbance capacity (ORAC) and Trolox equivalent antioxidant capacity (TEAC) values compared to the FF-WPHs. The impact of hydrolysis conditions was more pronounced in the in vitro compared to the cellular antioxidant assay. WPH peptide profiles (LC-MS/MS) were also enzyme and hydrolysis conditions dependent as illustrated in the case of β-lactoglobulin. Therefore, variation in the profiles of the peptides released may explain the observed differences in the antioxidant activity. Targeted generation of antioxidant hydrolysates needs to consider the hydrolysis conditions and the antioxidant assessment method employed.

Effect of Soluble Solids and High Pressure Treatment on Rheological Properties of Protein Enriched Mango Puree

The effects of high pressure treatment on the rheological properties of protein enriched mango puree were evaluated. In the first part, the original soluble solids in mango puree (28° Brix) was lowered to 26, 23 and 20° Brix, and each was supplemented with 2, 5 and 8% of whey protein to assess the influence of added protein. The samples were then evaluated by dynamic rheology. Pressure treatment resulted in a progressive increase in elastic (G') and viscous modulii (G″) as well as complex viscosity (η*). Values of G' were higher than G″ demonstrating that the product behaved more like a gel. Additional tests were carried out by simultaneously varying protein and soluble solids contents, and keeping the total solids at 28%. In this case, the effects of pressure levels and holding times were similar to previous results. However, the positive effects of higher protein were negated by the negative effects of lower soluble solids, resulting in an overall decreasing effect on rheology. The developed models effectively predicted the combined influence of protein and soluble solid concentrations on rheological parameters (R2 > 0.85). Sensory evaluation of 2% and 5% protein supplemented and pressure treated (500 MPa/3 min) mango puree yielded acceptable sensory qualities, resulting in a product with enriched protein content.

Immunomodulatory Protein Hydrolysates and Their Application

Immunomodulatory protein hydrolysate consumption may delay or prevent western immune-related diseases. In order to purposively develop protein hydrolysates with an optimal and reproducible immunomodulatory effect, knowledge is needed on which components in protein hydrolysates are responsible for the immune effects. Important advances have been made on this aspect. Also, knowledge on mechanisms underlying the immune modulating effects is indispensable. In this review, we discuss the most promising application possibilities for immunomodulatory protein hydrolysates. In order to do so, an overview is provided on reported in vivo immune effects of protein hydrolysates in both local intestinal and systemic organs, and the current insights in the underlying mechanisms of these effects. Furthermore, we discuss current knowledge and physicochemical approaches to identify the immune active protein sequence(s). We conclude that multiple hydrolysate compositions show specific immune effects. This knowledge can improve the efficacy of existing hydrolysate-containing products such as sports nutrition, clinical nutrition, and infant formula. We also provide arguments for why immunomodulatory protein hydrolysates could be applied to manage the immune response in the increasing number of individuals with a higher risk of immune dysfunction due to, for example, increasing age or stress.

Invited review: Whey proteins as antioxidants and promoters of cellular antioxidant pathways

Oxidative stress contributes to cell injury and aggravates several chronic diseases. Dietary antioxidants help the body to fight against free radicals and, therefore, avoid or reduce oxidative stress. Recently, proteins from milk whey liquid have been described as antioxidants. This review summarizes the evidence that whey products exhibit radical scavenging activity and reducing power. It examines the processing and treatment attempts to increase the antioxidant bioactivity and identifies 1 enzyme, subtilisin, which consistently produces the most potent whey fractions. The review compares whey from different milk sources and puts whey proteins in the context of other known food antioxidants. However, for efficacy, the antioxidant activity of whey proteins must not only survive processing, but also upper gut transit and arrival in the bloodstream, if whey products are to promote antioxidant levels in target organs. Studies reveal that direct cell exposure to whey samples increases intracellular antioxidants such as glutathione. However, the physiological relevance of these in vitro assays is questionable, and evidence is conflicting from dietary intervention trials, with both rats and humans, that whey products can boost cellular antioxidant biomarkers.

Bioactive properties of milk proteins in humans: A review

Many studies have demonstrated that milk protein consumption has benefits in terms of promoting human health. This review assesses the intervention studies which have evaluated potential health enhancing effects in humans following the ingestion of milk proteins. The impact of milk protein ingestion has been studied to asses their satiating, hypotensive, antimicrobial, anti-inflammatory, anticancer, antioxidant and insulinotropic properties as well as their impact on morphological modifications (e.g., muscle and fat mass) in humans. Consistent health promoting effects appear to have been observed in certain instances (i.e., muscle protein synthesis, insulinotropic and hypotensive activity). However, controversial outcomes have also been reported (i.e., antimicrobial, anti-inflammatory, anticancer and antioxidant properties). Several factors including interindividual differences, the timing of protein ingestion as well as the potency of the active components may explain these differences. In addition, processing conditions have been reported, in certain instances, to affect milk protein structure and therefore modify their bioactive potential. It is thought that the health promoting properties of milk proteins are linked to the release of bioactive peptides (BAPs) during gastrointestinal digestion. There is a need for further research to develop a more in-depth understanding on the possible mechanisms involved in the observed physiological effects. In addition, more carefully controlled and appropriately powered human intervention studies are required to demonstrate the health enhancing properties of milk proteins in humans.