Advances in modifying and understanding whey protein functionality

Exploring the role of γ-Oryzanol on stabilization mechanism of Pickering emulsion gels loaded by α-Lactalbumin or β-Lactoglobulin via multiscale approaches

The research explored the role of γ-oryzanol (γs) on stabilization behavior of Pickering emulsion gels (PEGs) loaded by α-lactalbumin (α-LA) or β-lactoglobulin (β-LG), being analyzed by experimental and computer methods (molecular dynamic simulation, MD). Primarily, the average particle size of β-LG-γS was expressed 100.07% decrease over that of α-LA-γS. In addition, γs decreased the dynamic interfacial tension of two proteins with the order of β-LG < α-LA. Meanwhile, quartz crystal microbalance with dissipation proved that β-LG-γS exhibited higher adsorption mass and denser rigid interface layer than α-LA-γS. Moreover, the hydrophobic group of γS had electrostatic repulsion with polar water molecules in the aqueous phase, which spread to the oil phase. β-LG-γS had lower RMSD/Rg value and narrower fluctuation compared with α-LA-γS. This work strength the exploration of interfacial stabilization mechanism of whey protein-based PEGs, which enriched its theoretical research for industrial-scale production as the replacement of trans fat and cholesterol.

Novel high-protein dairy product based on fresh white cheese and whey protein isolate

The aim of the study was to obtain hard cheese similar to the rennet hard cheese starting from the fresh white cheese (low and full-fat). This was accomplished with adding a powdered whey protein isolate to the fresh white cheese and heating. Fresh white cheese was produced from full or skim milk and ground with the whey protein isolate powder. The obtained mixture was heated at different temperatures. The increased heating temperature resulted in a more compact product characterized by higher hardness and elasticity compared with the full-fat product. The product approved by the organoleptic analysis panel was obtained by heating the mixed fat white cheese and the powdered whey protein isolate at 80°C for 30 min. The most significant achievement was to obtain in ca. one hour a product similar to that produced in ca. one year that is the hard rennet cheese. It contained ca. 39% wt/wt of protein and can be an interesting offer for dairy industry.

Characterization of Peptide Profiles and the Hypoallergenic and High Antioxidant Activity of Whey Protein Hydrolysate Prepared Using Different Hydrolysis Modes

Food proteins and peptides are generally considered a source of dietary antioxidants. The aim of this study was to investigate the antioxidant activity, allergenicity, and peptide profiles of whey protein hydrolysates (WPHs) using different hydrolysis methods. The results demonstrated that the degrees of hydrolysis of the hydrolysates with one-step (O-AD) and two-step (T-AD) methods reached 16.25% and 17.64%, respectively. The size exclusion chromatography results showed that the O-AD had a higher content of >5 and <0.3 kDa, and the distribution of peptide profiles for the two hydrolysates was significantly different. Furthermore, 5 bioactive peptides and 15 allergenic peptides were identified using peptidomics. The peptide profiles and the composition of the master proteins of the O-AD and T-AD were different. The DPPH and ABTS radical scavenging abilities of WPHs were measured, and hydrolysates were found to exhibit a strong radical scavenging ability after being treated using different hydrolysis methods. An enzyme-linked immunosorbent assay showed that the sensitization of WPHs was significantly reduced. This study may provide useful information regarding the antioxidant properties and allergenicity of WPHs.

Impact of quercetin conjugation using alkaline and free radical methods with tandem ultrasonication on the functional properties of camel whey and its hydrolysates

The structural and functional properties of whey-quercetin and whey hydrolysate-quercetin conjugates synthesized using alkaline and free radical-mediated methods (AM and FRM) coupled with sonication were studied. FTIR showed new peaks at 3000-3500 cm-1 (N-H stretching regions) and the 1000-1100 cm-1 region with the conjugates. Conjugation increased the random coils and α-helix content while decreasing the β-sheets and turns. It also increased the particle size and surface hydrophobicity which was significantly (p < 0.05) higher in AM than FRM conjugates. AM conjugates had higher radical scavenging activity but lower quercetin content than FRM conjugates. Overall, the functional properties of whey-quercetin conjugates were better than whey hydrolysate-quercetin conjugates. However, hydrolysate conjugates had significantly higher denaturation temperatures irrespective of the method of production. Sonication improved the radical scavenging activity and quercetin content of FRM conjugates while it decreased both for AM conjugates. This study suggested that whey-quercetin conjugates generally had better quality than whey hydrolysate conjugates and sonication tended to further improve these properties. This study highlights the potential for using camel whey or whey hydrolysate-quercetin conjugates to enhance the functional properties of food products in the food industry.

The Influence of pH on the Emulsification Properties of Heated Whey Protein-Pectin Complexes

Interactions between proteins and polysaccharides could improve protein functional properties. Most studies focus on the formation of complex coacervates at pHs < pI. Much less attention has been given to the interactions at pHs > pI, especially when the mixtures are heated. The objective of this study was to investigate the emulsification properties of heated whey protein isolate (WPI) and pectin complexes formed at near neutral pHs. Heated soluble complexes (Cpxs) were formed by heating mixed WPI (3 wt% protein) and pectin (0 to 0.60 wt%) at pH 6.0, 6.5, or 7.0 at 85 °C for 30 min. Emulsions (5 wt% oil, 0.5 wt% protein, and pH 5.5) were characterized by measuring droplet size, zeta potential, rheological properties, and creaming stability. The results showed that, regardless of heating pH, Cpxs formed more stable emulsions with significantly smaller droplet sizes, higher negative charges, and less shear-thinning behavior in comparison to emulsions stabilized by heated WPI (p < 0.05). At fixed pectin concentrations, the emulsions stabilized by Cpx formed at pH 7.0 were the most stable. Increasing pectin concentrations led to a decrease in mean droplet sizes and an increase in negative charge. Maximum stability was achieved with the emulsion stabilized by Cpx formed with 0.60 wt% pectin at pH 7.0. The formation of Cpxs under proper conditions will allow for the utilization of WPI in a wider range of applications and fulfill the consumer need for clean label food products.

Reducing Effects of Whey Protein Hydrolysate on Coloration of Cured Sausages

Curing produces a characteristic pink color during meat processing through the production of nitrosyl myoglobin (NOMb), which requires nitric oxide (NO). Nitrites and nitrates in coloring agents are crucial NO sources; however, a reducing agent is necessary to facilitate their chemical conversion to NO. This study aimed to investigate the effect of the reducing properties of whey protein hydrolysate (WPH) on the reddening of cured meat products. Cured and cooked sausage models were treated with WPH, which enhanced the reddening of the meat color and increased the a* value in the models compared with that of the controls. Additionally, ethanol-extracted WPH induced Fe3⁺ reduction, lowered oxidation-reduction potential, and decreased nitrite (NO2-) levels. Moreover, ethanol-extracted WPH promoted the formation of NOMb in myoglobin solution. This effect was also observed when ethanol-extracted WPH treated with maleimide was used, implying that certain peptides rather than the thiol group of WPH are involved in promoting NOMb formation. Furthermore, the peptides that decreased NO2- levels were isolated from ethanol-extracted WPH, identified, and synthesized. These synthesized peptides, particularly the FFVAPFPEVFGK peptide, showed NO2--reducing activity. Hence, WPH may promote the coloration of cured meat products through the reducing potential of the peptides contained within.

Temperature dependent molecular dynamics simulation study to understand the stabilizing effect of NADES on the protein β-Lactoglobulin

The thermal stability of a protein is an important concern for its practical application in food processing industries. In this study, we have carried out classical molecular dynamics simulations to systematically investigate the effect of NADES (natural deep eutectic solvent) on the stabilization of the protein β-Lactoglobulin (BLG) at different temperatures. This study sheds light on the very aspects of NADES composed of betaine and sorbitol on the stability of the protein. NADES provides better stability to the protein up to a temperature of 400 K than in water. It is observed that the protein starts to unfold above temperature 400 K in spite of the presence of NADES which is quiet evident from the root mean square deviation (RMSD) and radius of gyration (Rg) plots. The decreasing average solvent accessible surface area (SASA) values and increasing intra-protein hydrogen bonds indicate better stability of the protein in NADES medium than in water at temperatures 300 K and 400 K. At high temperatures viz. 450 K and 500 K the number and distribution of solvent species (betaine and sorbitol) around the protein surface show an increment that are evident from the calculations of solvation shell, radial and spatial distribution functions. Increased number of betaine molecules that interact with the protein through electrostatic interaction may lead to destabilization of the protein at these temperatures. This study suggests that NADES could be used as an ideal medium for thermal stability of the protein BLG up to a temperature of 400 K. Beyond this temperature, NADES used for this study fails to exert stabilization effect on the protein.

Milk Protein Hydrolysis by Actinidin-Kinetic and Thermodynamic Characterisation and Comparison to Bromelain and Papain

Plant proteases, including actinidin, papain and bromelain, have been widely used in the food industry but with limited application in dairy systems. This research aimed to establish and compare operational parameters (kinetics, temperature, enzyme type, time and thermodynamics) relevant to the applications of these enzymes in the hydrolysis of whey protein isolates (WPI), whey protein concentrates (WPC) or milk protein concentrates (MPC). The degree of hydrolysis (DH) increased with the rise in temperature, and the maximum DH was achieved at 60 °C for all three dairy systems. The addition of papain resulted in a greater %DH of whey proteins in comparison to bromelain. The cleavage of proteins was clearly time-dependent (p < 0.05), while the pH did not change significantly (p > 0.05) during this time. PAGE analysis revealed that all three enzymes mainly acted on α-lactalbumin and αs-casein in WPI and MPC, respectively. Kinetic parameters from the Lineweaver-Burk plot at 60 °C using WPC and MPC as a substrate varied widely, establishing that WPC hydrolysis was characterised by a lower KM, higher kcat, kcat/KM and Vmax compared to MPC in the case of all three enzymes. The difference in kcat/KM values amongst all enzymes (actinidin > papain > bromelain) indicated the difference in the strength of substrate binding sites. The thermodynamic parameters of these enzymes with MPC and WPC were also determined at a temperature range of 15-60 °C, and the results indicate the potential application of papain and actinidin in the dairy industry.

Tiger Nut Oil-Based Oil Gel: Preparation, Characterization, and Storage Stability

In this study, Tiger nut (Cyperus esculentus L.) oil-based oleogels were prepared using the emulsion template method with whey protein (WPI; 0.5-2.5% (w/v) and Xanthan gum (XG; 0.1-0.5% (w/v). The microstructure of the oleogels obtained from the high internal phase emulsion (HIPE) and an emulsion after further shearing were observed using an optical microscope and laser confocal microscopy. A series of rheological tests were conducted to evaluate the effect of WPI and XG concentrations on the strength of the emulsion and oleogel. The texture, oil holding capacity, and oxidative stability of oleogels were characterized. The results showed that XG alone could not form oleogel, while the concentration of WPI had more effect than XG. When WPI was at a fixed concentration, the viscoelasticity of HIPE increased with the addition of XG. This was due to the complexation of WPI and XG, forming a stable gel network between the tight emulsion droplets and thus giving it a higher viscoelasticity. With an increase in WPI concentration, the stability and viscoelasticity of the emulsion were increased, and the oil-holding capacity and gel strength of the oleogels were enhanced. Moreover, the addition of XG could significantly enhance the stability and viscoelasticity of the emulsion (p < 0.05), and an increase in the concentration had a positive effect on it. The oleogels showed high gel strength (G' > 15,000 Pa) and good thixotropic recovery when the XG concentration was higher than 0.3% (w/v). WPI (2.0%) and XG (>0.3%) could be used to obtain HIPE with good physicochemical and viscoelastic properties, which in turn lead to oleogels with minimal oil loss, viscoelastic and thixotropic recovery, and temperature stability. Compared with tiger nut oil-based oleogel, tiger nut oil contained more polyunsaturated fatty acids, which were more easily decomposed through oxidation during storage and had lower oxidation stability. This study provides a reference for the preparation of oleogels from food-approved polymers and provides additional theoretical support for their potential application as solid fat substitutes.

Calcium bioaccessibility increased during gastrointestinal digestion of α-lactalbumin and β-lactoglobulin

Calcium bioaccessibility depends on the amount of soluble calcium under intestinal digestion. The changes in calcium during in vitro static digestion of α-lactalbumin and β-lactoglobulin in presence of calcium chloride (0 mM, 20 mM and 50 mM) were followed by combining electrochemical determination of free calcium with the determination of soluble calcium by inductively coupled plasma optical emission spectroscopy. α-Lactalbumin and, more evident, β-lactoglobulin were found to increase calcium bioaccessibility with increasing intestinal digestion time by around 5% and 10%, respectively, due to the complex binding of calcium to peptides formed from protein hydrolysis by gastrointestinal enzymes. In vitro digested samples of β-lactoglobulin in presence of CaCl₂ had nearly twice as much complex bound calcium as α-lactalbumin samples. The calcium bioaccessibility decreased significantly with the increasing concentration of added calcium chloride, although the amount of calcium chloride had little effect on the extension of digestion of α-lactalbumin and β-lactoglobulin. Simulated digestion fluids were found to have a negative effect on calcium bioaccessibility, especially the presence of hydrogen phosphate, and the amount of precipitated calcium increased significantly with increasing amount of added calcium chloride. Based on analysis and visualization by sequences of the peptides formed during digestion of α-lactalbumin and β-lactoglobulin, it was observed that peptides containing aspartic acid and glutamic acid acting as calcium chelators, may prevent precipitation of calcium in the intestines and increase calcium bioaccessibility. These results provide knowledge for the design of new dairy based functional foods to prevent calcium deficiency.

Impacts of the Dynamic High-Pressure Pre-Treatment and Post-Treatment of Whey Protein Aggregates on Their Physicochemical Properties and Emulsifying Activities

The impacts of dynamic high-pressure (DHP) pretreatment and post-treatment (100 MPa) on the physicochemical and functional properties of whey protein isolate (WPI) aggregates formed by thermal treatment were investigated in this study. When WPI aggregates were formed by thermal treatment, the size of the aggregates formed with the DHP pretreated WPI was smaller than that of the aggregates formed with the original WPI. The size of the WPI aggregates formed by thermal treatment decreased with DHP post-treatment. The conformational parameters (ζ-potential, surface hydrophobicity, and intrinsic fluorescence intensity) of the WPI subjected to DHP pretreatment were not significantly influenced by thermal treatment. However, DHP post-treatment affected these parameters for the WPI aggregates formed during thermal treatment because of dissociation caused by intense shear and cavitation forces during DHP treatment. The emulsifying activity index (EAI) of the WPI aggregates slightly improved with DHP treatment, but its order had little effect on the magnitude of the EAI increase. DHP pretreatment or post-treatment can modulate the conformational structures and the physicochemical properties of protein aggregates.

Formulation and characterization of plant-based egg white analogs using RuBisCO protein

RuBisCO protein, which can be isolated from abundant and sustainable plant sources, can mimic some of the desirable functional attributes of egg white proteins. In this study, plant-based egg white analogs were successfully produced using 10 w% RuBisCO solutions (pH 8). These protein solutions had similar apparent viscosity-shear rate profiles, shear modulus-temperature profiles, gelling temperatures, and final gel strengths as egg white. However, there were some differences. RuBisCO protein gels were slightly darker than egg white, which was attributed to the presence of phenolic impurities. Moreover, RuBisCo proteins exhibited a single thermal transition temperature (∼66 °C) whereas egg white proteins exhibited two (∼66 and ∼81 °C). RuBisCO gels were more brittle but less chewy and resilient than egg white gels. This study provides valuable insights into the potential of RuBisCO protein for formulating plant-based egg white analogs.

Whey Protein Hydrolysates of Sheep/Goat Origin Produced by the Action of Trypsin without pH Control: Degree of Hydrolysis, Antihypertensive Potential and Antioxidant Activities

Tryptic WPHs with considerable residual whey protein content intact were developed from two sheep/goat WPCs (65% and 80% protein) without pH control. Pasteurization was used to avoid denaturation. Changes in non-protein nitrogen (DH_TCASN), free amino groups (DH_TNBS), and major whey proteins were used to investigate the degree and extent of hydrolysis. Antihypertensive potential (ACE-IA), radical scavenging (DPPH-RSA), and iron chelation (Fe-CA) were assessed. No statistically significant changes in pH (5.84−6.29) were observed during hydrolysis and storage. At the start of hydrolysis, DH_TCASN was ≅11% for both substrates whereas DH_TNBS was >10% and >5% for WP65 and WP80, respectively. After one-hour hydrolysis, DH_TCASN was ≅17% for both substrates and DH_TNBS was ≅15% and ≅11% for WP65 and WP80, respectively. The β-lactoglobulin, α-lactalbumin, and caseinomacropeptide of WP65 were hydrolyzed by 14 ± 1.3%, 73.9 ± 2.6% and 37 ± 2.6%. The respective values for WP80 were 14.9 ± 1.7%, 79.9 ± 1%, and 32.7 ± 4.8%. ACE-IA of the hydrolysates of both substrates was much higher (>80%) than that of controls (<10%). Hydrolysis, substrate type, and storage did not affect the DPPH-RSA (45−54%). Fe-CA of the WP65 and WP80 hydrolysates were ≅40% and ≅20%, respectively; a similar outcome was found in the respective controls. Refrigerated storage for 17 h did not affect the degree of hydrolysis and biofunctional activities.

Characterization of a Commercial Whey Protein Hydrolysate and Its Use as a Binding Agent in the Whey Protein Isolate Agglomeration Process

The first objective of this study was to characterize the chemical properties of three lots of whey protein hydrolysate (WPH) obtained from a commercial manufacturer. The degree of hydrolysis (DH) of WPH was between 13.82 and 15.35%, and was not significantly (p > 0.05) different between the batches. From MALDI-TOF, 10 to 13 different peptides were observed in the range of 2.5−5 kDa and 5−8 kDa, respectively. The second objective of the study was to evaluate the effectiveness of WPH as a binder in whey protein isolate (WPI) wet agglomeration. For this purpose, a 3 × 3 × 2 factorial design was conducted with pre-wet mass (60, 100, and 140 g), WPH concentration (15, 20, and 25%), and flow rate (4.0 and 5.6 mL·min−1) as independent variables. WPI agglomeration was carried out in a top-spray fluid bed granulator (Midi-Glatt, Binzen, Germany). Agglomerated WPI samples were stored at 25 °C and analyzed for moisture content (MC), water activity, relative dissolution index (RDI), and emulsifying capacity. Pre-wet mass, flow rate, and the WPH concentration had a significant (p < 0.05) effect on the MC. Moreover, all interactions among the main effects had also a significant (p < 0.05) effect on MC. High MC and water activity were observed for the treatments with a higher pre-wet volume and higher flow rate, which also resulted in clumping of the powders. The treatment with the 60 g pre-wet mass, 20% WPH concentration, and 5.6 mL·min−1 flow rate combination had the highest RDI among all the samples. In conclusion, WPH can be used as a potential alternative to soy lecithin in WPI wet agglomeration.

The effects of different protease treatments on the techno-functional, structural, and bioactive properties of bovine casein

In this study, bovine sodium caseinate (NaCas) was hydrolyzed with four proteases, alcalase, savinase, subtilisin A, and flavourzyme. In addition to the structural changes occurred through the enzymatic hydrolysis, the solubility, oil binding capacity, zeta potential, emulsification properties, and in vitro antioxidant capacity, anti-carcinogenic and antidiabetic properties of hydrolysates were determined. FTIR combined with hierarchical cluster analysis (HCA) made in Amide I region enable to classification of the samples based on the changes of the secondary structure depending on the enzyme type and degree of fragmentation. Technological properties of NaCas were enhanced through the enzymatic hydrolysis, and those were more prominent in serine-type enzymes, regardless of the enzyme type, all hydrolysates showed high antioxidant capacities. All hydrolysates, specifically those produced by savinase and alcalase, reduced the viability of the carcinogenic Caco-2 cells in a dose-dependent manner and showed a very low level of cytotoxicity against healthy HEK-293 cells. The hydrolysis treatment made a significant contribution to the antidiabetic activity of NaCas. Particularly alcalase and savinase hydrolysates suppressed the activity of α- amylase and α- glucosidase. Therefore, the generated milk protein hydrolysates could be used in functional food developments for specific dietary purposes.

Advanced nanocellulose-based gas barrier materials: Present status and prospects

Nanocellulose based gas barrier materials have become an increasingly important subject, since it is a widespread environmentally friendly natural polymer. Previous studies have shown that super-high gas barrier can be achieved with pure and hierarchical nanocellulose films fabricated through simple suspension or layer-by-layer technique either by itself or incorporating with other polymers or nanoparticles. Improved gas barrier properties were observed for nanocellulose-reinforced composites, where nanocellulose partially impermeable nanoparticles decreased gas permeability effectively. However, for nanocellulose-based materials, the higher gas barrier performance is jeopardized by water absorption and shape deformation under high humidity conditions which is a challenge for maintaining properties in material applications. Thus, numerous investigations have been done to solve the problem of water absorption in nanocellulose-based materials. In this literature review, gas barrier properties of pure, layer-by-layer and composite nanocellulose films are investigated. The possible theoretical gas barrier mechanisms are described, and the prospects for nanocellulose-based materials are discussed.

Structure and in vitro bioactive properties of O/W emulsions generated with fava bean protein hydrolysates

The use of plant-derived proteins in the generation of food products is gaining popularity as an alternative to proteins of animal origin. This study described the emulsifying and bioactive properties of fava bean protein hydrolysates (FBH) generated at low and high degree of hydrolysis (DH), i.e., FBH₈ (low DH: 8.4 ± 0.3) and FBH₂₁₀ (high DH: 15.6 ± 0.7) when adjusted to three different pHs (3.0, 5.0 and 8.0). Overall, FBH₈, had more favourable emulsifying properties compared to the FBH_210. The emulsion generated with FBH₈ at pH 8.0 also had the highest antioxidant activity when measured by the oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays with values of 1108.6 ± 3.8 and 1159.9 ± 20.5 μmol Trolox Eq·g^-1 emulsion, respectively. The antioxidant activity of the emulsions, in most cases, remained unchanged following in vitro simulated gastrointestinal digestion. Both the FBH₈ and FBH₂₁₀ emulsions following in vitro simulated gastrointestinal digestion were able to inhibit the activities of dipeptidyl peptidase-IV (DPP-IV) and angiotensin converting enzyme (ACE) with ∼45% and 65% inhibition, respectively. These results indicated that hydrolysates from fava bean may find use for the generation of bioactive emulsions.

Influence of whey protein isolate on pasting, thermal, and structural characteristics of oat starch

We investigated the effects of different concentrations of whey protein isolate (WPI) on oat starch characteristics in terms of pasting, thermal, and structural properties. The pasting properties of the starch showed that hot paste viscosity increased with the addition of WPI in the system, and relative breakdown decreased. Thermal analysis showed a significant effect of WPI on oat starch by increasing the peak temperature of differential scanning calorimeter endotherms. The X-ray diffraction and Fourier transform infrared spectroscopy studies revealed that WPI increased the ordered structuration of starch paste, as evident by an increase in relative crystallinity; in addition, a decrease in infrared bands at 1,024 cm^-1 and 1,080 cm^-1 suggested decreased gelatinization of oat starch granules. Overall, WPI at different concentrations affected the oat starch gelatinization properties.

Calcium: A comprehensive review on quantification, interaction with milk proteins and implications for processing of dairy products

Calcium (Ca) is a key micronutrient of high relevance for human nutrition that also influences the texture and taste of dairy products and their processability. In bovine milk, Ca is presented in several speciation forms, such as complexed with other milk components or free as ionic calcium while being distributed between colloidal and serum phases of milk. Partitioning of Ca between these phases is highly dynamic and influenced by factors, such as temperature, ionic strength, pH, and milk composition. Processing steps used during the manufacture of dairy products, such as preconditioning, concentration, acidification, salting, cooling, and heating, all contribute to modify Ca speciation and partition, thereby influencing product functionality, product yield, and fouling of equipment. This review aims to provide a comprehensive understanding of the influence of Ca partition on dairy products properties to support the development of kinetics models to reduce product losses and develop added-value products with improved functionality. To achieve this objective, approaches to separate milk phases, analytical approaches to determine Ca partition and speciation, the role of Ca on protein-protein interactions, and their influence on processing of dairy products are discussed.

Stability and bioaccessibility of curcumin emulsions stabilized by casein hydrolysates after maleic anhydride acylation and pullulan glycation

The effects of maleic anhydride (MA) acylation and pullulan glycation on casein hydrolysates (CH) and the physicochemical stability of modified or unmodified CH-stabilized emulsions were explored. Compared with casein, the solubility of CH was improved, and CH₁ (hydrolysis degree 4%) exhibited the optimal emulsifying properties. After the acylation of MA, degrees of acylation (DA) increased with increasing addition of MA. Fourier-transform infrared spectroscopy revealed that a covalent bond was formed between MA and CH₁. The results of pullulan glycation indicated that the degree of glycation decreased with increasing DA. Acylation combined with glycation effectively reduced the surface hydrophobicity of CH. Results of analysis of physicochemical stability and gastrointestinal fate of curcumin in emulsions revealed that CH modified by MA acylation and pullulan glycation played a positive role in enhancing the stability and bioaccessibility of curcumin loaded in emulsions.

Dairy By-Products: A Review on the Valorization of Whey and Second Cheese Whey

The search for new food products that promote consumers health has always been of great interest. The dairy industry is perhaps the best example regarding the emergence of new products with claimed health benefits. Cheese whey (CW), the by-product resulting from cheese production, and second cheese whey (SCW), which is the by-product of whey cheese manufacture, have proven to contain potential ingredients for the development of food products with improved nutritional characteristics and other functionalities. Nowadays, due to their nutritional quality, whey products have gained a prominent position among healthy food products. However, for a long time, CW and SCW were usually treated as waste or as animal feed. Due to their high organic content, these by-products can cause serious environmental problems if discarded without appropriate treatment. Small and medium size dairy companies do not have the equipment and structure to process whey and second cheese whey. In these cases, generally, they are used for animal feed or discarded without an appropriate treatment, being the cause of several constraints. There are several studies regarding CW valorization and there is a wide range of whey products in the market. However, in the case of SCW, there remains a lack of studies regarding its nutritional and functional properties, as well as ways to reuse this by-product in order to create economic value and reduce environmental impacts associated to its disposal.

Production of whey protein hydrolyzates and its incorporation into milk

Abstract

Whey proteins provide an excellent source of low-molecular-weight bioactive peptides with important functional properties and bioactivities like antihypertensive, opioid, and antimicrobial effects. Presence of peptide molecules with lower molecular weight has a great role in food for health promotion. In this investigation, the release of low-molecular-weight peptides from whey protein concentrate was attempted by using enzymatic digestion. The hydrolyzate was then incorporated into milk to obtain enriched milk (EM) with low-molecular-weight peptides. Based on sensory analysis of EM, electrophoretic and RP-HPLC studies, hydrolyzates of 10% protein (degree of hydrolysis 5%; enzyme/ substrate E/S, 1:50) were finally incorporated into milk at 20% (v/v) to develop an acceptable product enriched with low-molecular-weight peptides. EM had higher protein content, viscosity and emulsifying properties than control milk with 3% fat. It is recommended that EM should not be sterilized as it results in coagulation, but can be safely pasteurized and spray dried without any undesirable effects. Maximum ACE-inhibition activity was obtained in hydrolyzate, followed by EM. This study is expected to boost the opportunity for the dairy industry to venture further into the nutraceutical dairy market.

Graphical abstract

Effect of methylglyoxal on the alteration in structure and digestibility of α-lactalbumin, and the formation of advanced glycation end products under simulated thermal processing

α-Dicarbonyl compounds (α-DCs) are a class of compounds generated during the thermal processing of food. Due to the high reactivity, α-DCs were endowed with the ability to react with food components thus lowering nutrition value and even leading to a potential risk for food safety. In this study, methylglyoxal (MG), the most abundant α-DCs, was selected to investigate the alteration effects on the structure and digestibility of α-lactalbumin (αLA) under thermal processing (60-100°C). The results showed that the modification degree of αLA by MG increased with the rise of processing temperature, accompanied by the significant changes in molecular weight, intrinsic fluorescence, and secondary structures of αLA. High-resolution mass spectrometry analysis identified that lysine (Lys) and arginine (Arg) are the modification sites, and Nε-(carboxyethyl)-L-lysine is the main modification type. Since the Lys and Arg are also the cleavage sites of trypsin, the digestibility of MG modified αLA (MG-αLA) by trypsin correspondingly decreased with an increase of processing temperature. The reacted Lys and Arg residues, and the protein-bound AGEs were quantified, and the contents were found to be highly dependent on the temperature.

Hypotensive and Hepatoprotective Properties of the Polysaccharide-Stabilized Foaming Composition Containing Hydrolysate of Whey Proteins

Whey protein hydrolysates (WPHs) are one of the most promising sources of biofunctional peptides with such beneficial properties as antioxidant, antihypertensive, anti-inflammatory and others. WPHs also could be used as foaming agents for aerated products (e.g., milk shake type drinks). However, WPH alone has a bitter taste and foamed WPH should be stabilized by additional ingredients. Here, we present a composition including WPH and three polysaccharides-pumpkin pectin, sodium alginate and ι-carrageenan-used as foam stabilizers. Polysaccharide content was selected according to foaming, organoleptic antioxidant and angiotensin-I-converting enzyme inhibitory characteristics of the resulted composition. Further, the hypotensive, antioxidant and hepatoprotective properties of the composition were proved by in vivo tests performed in spontaneously hypertensive rats and Wistar rats with CCl₄-induced hepatic injury.

Differences in Regulatory Mechanisms Induced by β-Lactoglobulin and κ-Casein in Cow's Milk Allergy Mouse Model-In Vivo and Ex Vivo Studies

The presence of various proteins, including modified ones, in food which exhibit diverse immunogenic and sensitizing properties increases the difficulty of predicting host immune responses. Still, there is a lack of sufficiently reliable and comparable data and research models describing allergens in dietary matrices. The aim of the study was to estimate the immunomodulatory effects of β-lactoglobulin (β-lg) in comparison to those elicited by κ-casein (κ-CN), in vivo and ex vivo, using naïve splenocytes and a mouse sensitization model. Our results revealed that the humoral and cellular responses triggered by β-lg and κ-CN were of diverse magnitudes and showed different dynamics in the induction of control mechanisms. β-Lg turned out to be more immunogenic and induced a more dominant Th1 response than κ-CN, which triggered a significantly higher IgE response. For both proteins, CD4⁺ lymphocyte profiles correlated with CD4⁺CD25⁺ and CD4⁺CD25⁺Foxp3⁺ T cells induction and interleukin 10 secretion, but β-lg induced more CD4⁺CD25⁺Foxp3^- Tregs. Moreover, ex vivo studies showed the risk of interaction of immune responses to different milk proteins, which may exacerbate allergy, especially the one caused by β-lg. In conclusion, the applied model of in vivo and ex vivo exposure to β-lg and κ-CN showed significant differences in immunoreactivity of the tested proteins (κ-CN demonstrated stronger allergenic potential than β-lg), and may be useful for the estimation of allergenic potential of various food proteins, including those modified in technological processes.

Limited hydrolysis and conjugation of zein with chitosan oligosaccharide by enzymatic reaction to improve functional properties

In order to improve its aqueous solubility and emulsifying function, zein was partially hydrolyzed by trypsin and conjugated to chitosan oligosaccharide lactate by transglutaminase. Hydrolysis and covalent linkage to chitosan oligosaccharide was confirmed by free amine content, gel electrophoresis, and infrared spectroscopy. Enzymatic glycosylation was optimized at pH 6, 44 °C, and 4 h to bind approximately 95% of the free amines in the hydrolysates to chitosan oligosaccharide. Hydrolysis and conjugation increased solubility of zein by 47.60% and 72.93%. Hydrolysis and conjugation also decreased surface hydrophobicity by more than 20% and more than doubled emulsifying activity index, emulsion stability index, and foaming capacity. This enzymatic modification has potential to be applied to improve functional properties of other prolamins.

Nanoemulsions for health, food, and cosmetics: a review

Nanoemulsions are gaining importance in healthcare and cosmetics sectors as a result of the unique properties of nanosized droplets, such as high surface area. Here we review nanotechnology and nanoemulsions with focus on emulsifiers and nanoemulsifiers, and applications for drugs and vaccines delivery, cancer therapy, inflammation treatment, cosmetics, perfumes, polymers, and food. We discuss nanoemulsion safety and properties, e.g., stability, emulsification, solubility, molecular number and arrangements, ionic strength, pH and temperature.

Effect of cold and hot enzyme deactivation on the structural and functional properties of rice dreg protein hydrolysates

This study explored the effect of three different enzyme deactivation treatments: 4 °C slow cold deactivation (RDPH-(4 °C)), -18 °C rapid cold deactivation (RDPH-(-18 °C)) and 100 °C water bath (RDPH-(100 °C)), compared to that without enzyme deactivation (RDPH-(control)) on the structural and functional properties of rice dreg protein hydrolysates (RDPHs). The RDPHs from the different enzyme deactivation methods led to significant differences in the degree of hydrolysis, surface hydrophobicity, average particle size, intrinsic fluorescence and emulsion stability. FTIR analysis revealed that the strength of RDPH-(100 °C) spectrum peaks decreased significantly. All samples showed high solubility (>85%) and potent antioxidant capacity: DPPH (~90%), ABTS (~99%), and reducing power (0.86-1.03). Among the hydrolysates evaluated, the RDPH-(100 °C) led to the lowest reducing power and hydroxyl radical scavenging activity. Results reported here will be instrumental for the development of rice protein-based products and in the optimization and scale up of manufacturing process.

Methods of Incorporating Plant-Derived Bioactive Compounds into Films Made with Agro-Based Polymers for Application as Food Packaging: A Brief Review

Plastic, usually derived from non-renewable sources, is among the most used materials in food packaging. Despite its barrier properties, plastic packaging has a recycling rate below the ideal and its accumulation in the environment leads to environmental issues. One of the solutions approached to minimize this impact is the development of food packaging materials made from polymers from renewable sources that, in addition to being biodegradable, can also be edible. Different biopolymers from agricultural renewable sources such as gelatin, whey protein, starch, chitosan, alginate and pectin, among other, have been analyzed for the development of biodegradable films. Moreover, these films can serve as vehicles for transporting bioactive compounds, extending their applicability as bioactive, edible, compostable and biodegradable films. Biopolymer films incorporated with plant-derived bioactive compounds have become an interesting area of research. The interaction between environment-friendly biopolymers and bioactive compounds improves functionality. In addition to interfering with thermal, mechanical and barrier properties of films, depending on the properties of the bioactive compounds, new characteristics are attributed to films, such as antimicrobial and antioxidant properties, color and innovative flavors. This review compiles information on agro-based biopolymers and plant-derived bioactive compounds used in the production of bioactive films. Particular emphasis has been given to the methods used for incorporating bioactive compounds from plant-derived into films and their influence on the functional properties of biopolymer films. Some limitations to be overcome for future advances are also briefly summarized. This review will benefit future prospects for exploring innovative methods of incorporating plant-derived bioactive compounds into films made from agricultural polymers.