Acute effects of a ketone monoester, whey protein, or their coingestion on mTOR trafficking and protein-protein colocalization in human skeletal muscle.

We recently demonstrated that acute oral ketone monoester intake induces a stimulation of postprandial myofibrillar protein synthesis rates comparable to that elicited following the ingestion of 10 g whey protein or their coingestion. The present investigation aimed to determine the acute effects of ingesting a ketone monoester, whey protein, or their coingestion on mechanistic target of rapamycin (mTOR)-related protein-protein colocalization and intracellular trafficking in human skeletal muscle. In a randomized, double-blind, parallel group design, 36 healthy recreationally active young males (age: 24.2 ± 4.1 yr) ingested either: 1) 0.36 g·kg-1 bodyweight of the ketone monoester (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (KET), 2) 10 g whey protein (PRO), or 3) the combination of both (KET + PRO). Muscle biopsies were obtained in the overnight postabsorptive state (basal conditions), and at 120 and 300 min in the postprandial period for immunofluorescence assessment of protein translocation and colocalization of mTOR-related signaling molecules. All treatments resulted in a significant (Interaction: P < 0.0001) decrease in tuberous sclerosis complex 2 (TSC2)-Ras homolog enriched in brain (Rheb) colocalization at 120 min versus basal; however, the decrease was sustained at 300 min versus basal (P < 0.0001) only in KET + PRO. PRO and KET + PRO increased (Interaction: P < 0.0001) mTOR-Rheb colocalization at 120 min versus basal; however, KET + PRO resulted in a sustained increase in mTOR-Rheb colocalization at 300 min that was greater than KET and PRO. Treatment intake increased mTOR-wheat germ agglutinin (WGA) colocalization at 120 and 300 min (Time: P = 0.0031), suggesting translocation toward the fiber periphery. These findings demonstrate that ketone monoester intake can influence the spatial mechanisms involved in the regulation of mTORC1 in human skeletal muscle.NEW & NOTEWORTHY We explored the effects of a ketone monoester (KET), whey protein (PRO), or their coingestion (KET + PRO) on mTOR-related protein-protein colocalization and intracellular trafficking in human muscle. All treatments decreased TSC2-Rheb colocalization at 120 minutes; however, KET + PRO sustained the decrease at 300 min. Only PRO and KET + PRO increased mTOR-Rheb colocalization; however, the increase at 300 min was greater in KET + PRO. Treatment intake increased mTOR-WGA colocalization, suggesting translocation to the fiber periphery. Ketone bodies influence the spatial regulation of mTOR.

Neonatal Gut and Immune Responses to ß-Casein Enriched Formula in Piglets.

BACKGROUND: ß-casein is the main casein constituent in human milk (HM) and a source of bioactive peptides for the developing gastrointestinal tract and immune system. Infant formulas contain less ß-casein than HM, but whether different concentrations of ß-casein affect tolerability and gut and immune maturation in newborns is unknown. OBJECTIVES: Using near-term piglets as a model for newborn infants, we investigated whether increasing the ß-casein fraction in bovine-based formula is clinically safe and may improve gut and immune maturation. METHODS: Three groups of near-term pigs (96% gestation) were fed formula with bovine casein and whey protein (ratio 40:60): 1) standard skim milk casein (BCN-standard, 35% ß-casein of total casein, n = 18); 2) ß-casein enrichment to HM concentrations (BCN-medium, 65%, n = 19); and 3) high ß-casein enrichment (BCN-high, 91%, n = 19). A reference group was fed 100% whey protein concentrate (WPC) as protein (WPC, n = 18). Intestinal and immune parameters were assessed before and after euthanasia on day 5. RESULTS: Clinical variables (mortality, activity, body growth, and diarrhea) were similar among the groups, and no differences in intestinal or biochemical parameters were observed between BCN-standard and BCN-medium pigs. However, pigs receiving high amounts of ß-casein (BCN-high) had lower small intestine weight and tended to have more intestinal complications (highest gut pathology score, permeability, and interleukin-8) than the other groups, particularly those receiving no casein (WPC pigs). Blood lymphocyte, thrombocyte, and reticulocyte counts were increased with higher ß-casein, whereas eosinophil counts were reduced. In vitro blood immune cell responses were similar among groups. CONCLUSIONS: ß-casein enrichment of bovine-based formula to HM concentrations is clinically safe, as judged from newborn, near-term pigs, whereas no additional benefits to gut maturation were observed. However, excessive ß-casein supplementation, beyond concentrations in HM, may potentially induce gut inflammation together with increased blood cell populations relative to natural ß-casein concentrations or pure whey-based formula.

Protein Ingredient Quality within Infant Formulas Impacts Plasma Amino Acid Concentrations in Neonatal Minipiglets.

BACKGROUND: Infant formulas (IFs), the only adequate substitute to human milk, are complex matrices that require numerous ingredients and processing steps that may impact protein digestion and subsequent amino acid (AA) absorption. OBJECTIVES: The objective was to understand the impact of the protein ingredient quality within IFs on postprandial plasma AA profiles. METHODS: Four isonitrogenous and isocaloric IFs were produced at a semi-industrial scale using whey proteins from different origins (cheese compared with ideal whey) and denaturation levels (IF-A, -B, -C), and caseins with different supramolecular organizations (IF-C, -D). Ten Yucatan minipiglets (12- to 27-d-old) were used as a human infant model and received each IF for 3 d according to a Williams Latin square followed by a 2-d wash-out period. Jugular plasma was regularly sampled from 10 min preprandial to 4 h postprandial on the third day to measure free AAs, urea, insulin, and glucose concentrations. Data were statistically analyzed using a mixed linear model with diet (IFs), time, and sex as fixed factors and piglet as random factor. RESULTS: IFs made with cheese whey (IF-A and -B) elicited significantly higher plasma total and essential AA concentrations than IFs made with ideal whey (IF-C and -D), regardless of the pre- and postprandial times. Most of the differences observed postprandially were explained by AA homeostasis modifications. IFs based on cheese whey induced an increased plasma concentration of Thr due to both a higher Thr content in these IFs and a Thr-limiting degrading capability in piglets. The use of a nonmicellar casein ingredient led to reduced plasma content of AA catabolism markers (IF-D compared with IF-C). CONCLUSIONS: Overall, our results highlight the importance of the protein ingredient quality (composition and structure) within IFs on neonatal plasma AA profiles, which may further impact infant protein metabolism.

Mice Regulate Dietary Amino Acid Balance and Energy Intake by Selecting between Complementary Protein Sources.

BACKGROUND: A balanced intake of protein and constituent amino acids (AAs) requires adjustments to total food intake (protein leverage [PL]) and food selection to balance deficits and excesses (complementary feeding). We provided mice with choices of casein and whey, 2 protein sources that are complementary in AA balance, across a range of protein concentrations (P%) of digestible energy (DE). OBJECTIVES: We aimed to determine if: 1) PL operates similarly for casein and whey; 2) one protein source is preferred at control P%; 3) the preference changes as P% falls; and 4) AA intakes under control and low P% levels identify AAs that drive changes in protein selection. METHODS: Food intake and plasma fibroblast growth factor-21 (FGF21) concentrations were measured in mice at various P% (P7.5%-P33%). For direct comparisons, defined diets were used in which the protein source was either casein or whey. In food choice studies, mice had access to foods in which both casein and whey were provided at the same P% level at the same time. RESULTS: PL operated at different P% thresholds in casein (13%)- and whey (10%)-based diets, and the magnitude of PL was greater for casein. Although mice preferred casein under control conditions (P23%), a pronounced preference shift to whey occurred as P% fell to P13% and P10%. At low P%, increases in food intake were accompanied by increases in plasma FGF21, a protein hunger signal. Among AAs deficient in casein and enriched in whey, the intake of Cys was the most invariant as P% changed between P23% and P10%, appearing to drive the switch in protein preference. CONCLUSIONS: Mice selected between complementary protein sources, casein and whey, achieving stable total energy intake and regulated intake of AAs as P% varied. Supplementation of low P% casein diets with one whey-enriched AA, Cys, suppressed plasma FGF21 and total food intake.

Structure Response of Preadsorbed Saliva Pellicle to the Interaction between Dairy and Saliva Protein.

Using the surface characterization techniques of quartz crystal microbalance with dissipation, atomic force microscopy, and scanning electron microscopy, the structure of the salivary pellicle was investigated before and after it was exposed to dairy proteins, including micellar casein, skim milk, whey protein isolate (WPI), and a mixture of skim milk and WPI. We have shown that the hydration, viscoelasticity, and adsorbed proteinaceous mass of a preadsorbed salivary pellicle on a PDMS surface are greatly affected by the type of dairy protein. After interaction with whey protein, the preadsorbed saliva pellicle becomes softer. However, exposure of the saliva pellicle to micellar casein causes the pellicle to partially collapse, which results in a thinner and more rigid surface layer. This structure change correlates with the measured lubrication behavior when the saliva pellicle is exposed to dairy proteins. While previous studies suggest that whey protein is the main component in milk to interact with salivary proteins, our study indicates interactions with casein are more important. The knowledge gained here provides insights into the mechanisms by which different components of dairy foods and beverages contribute to mouthfeel and texture perception, as well as influence oral hygiene.

Purification of α-lactalbumin and ß-lactoglobulin from cow milk.

Whey, a valuable byproduct of dairy processing, contains essential proteins like ß-lactoglobulin (ßLG) and α-lactalbumin (αLA), making it a focus of research for its nutritional benefits. Various techniques, including chromatography and membrane filtration, are employed for protein extraction, often requiring multiple purification steps. One approach that has gained prominence for the purification and concentration of proteins, including those present in whey, is the use of polyethylene glycol (PEG) in aqueous two-phase systems. Our study simplifies this process by using PEG alone for whey protein purification. This approach yielded impressive results, achieving 92 % purity for ßLG and 90 % for αLA. These findings underscore the effectiveness of PEG-based purification in isolating whey proteins with high purity.

Combining pretreatments and co-fermentation as successful approach to improve biohydrogen production from dairy cow manure.

The present paper is focused on enhancing the production of biohydrogen (bioH2) from dairy cow manure (DCM) through dark fermentation (DF). Two enhancement production strategies have been tested: i) the combination of H2O2 with sonification as pretreatment and ii) the co-fermentation with cheese whey as co-substrate. Concerning the pretreatment, the best combination was investigated according to the response surface methodology (RSM) by varying H2O2 dosage between 0.0015 and 0.06 g/gTS and ultrasonic specific energy input (USEI) between 35.48 and 1419.36 J/gTS. The increase of carbohydrates concentration was used as target parameter. Results showed that the combination of 0.06 g/gTS of H2O2 with 1419.36 J/gTS of USEI maximized the concentration of carbohydrates. The optimized conditions were used to pretreat the substrate prior conducting DF tests. The use of pretreatment resulted in obtaining a cumulative bioH2 volume of 51.25 mL/L and enhanced the bioH2 production by 125% compared to the control test conducted using raw DCM. Moreover, the second strategy, i.e. co-fermentation with cheese whey (20% v/v) as co-substrate ended up to enhancing the DF performance as the bioH2 production reached a value of 334.90 mL/L with an increase of 1372% compared to the control DF test. To further improve the process, dark fermentation effluents (DFEs) were valorized via photo fermentation (PF), obtaining an additional hydrogen production aliquot.

Enzymes for production of whey protein hydrolysates and other value-added products.

Whey is a byproduct of dairy industries, the aqueous portion which separates from cheese during the coagulation of milk. It represents approximately 85-95% of milk's volume and retains much of its nutrients, including functional proteins and peptides, lipids, lactose, minerals, and vitamins. Due to its composition, mainly proteins and lactose, it can be considered a raw material for value-added products. Whey-derived products are often used to supplement food, as they have shown several physiological effects on the body. Whey protein hydrolysates are reported to have different activities, including antihypertensive, antioxidant, antithrombotic, opioid, antimicrobial, cytomodulatory, and immuno-modulatory. On the other hand, galactooligosaccharides obtained from lactose can be used as prebiotic for beneficial microorganisms for the human gastrointestinal tract. All these compounds can be obtained through physicochemical, microbial, or enzymatic treatments. Particularly, enzymatic processes have the advantage of being highly selective, more stable than chemical transformations, and less polluting, making that the global enzyme market grow at accelerated rates. The sources and different products associated with the most used enzymes are particularly highlighted in this review. Moreover, we discuss metagenomics as a tool to identify novel proteolytic enzymes, from both cultivable and uncultivable microorganisms, which are expected to have new interesting activities. Finally enzymes for the transformation of whey sugar are reviewed. In this sense, carbozymes with ß-galactosidase activity are capable of lactose hydrolysis, to obtain free monomers, and transgalactosylation for prebiotics production. KEY POINTS: • Whey can be used to obtain value-added products efficiently through enzymatic treatments • Proteases transform whey proteins into biopeptides with physiological activities • Lactose can be transformed into prebiotic compounds using ß-galactosidases.

Effects of bovine whey protein on exercise-induced gut permeability in healthy adults: a randomised controlled trial.

PURPOSE: Intestinal permeability is a critical component of gut barrier function. Barrier dysfunction can be triggered by certain stressors such as exercise, and if left unmanaged can lead to local and systemic disorders. The aim of this study was to investigate the effects of a specific whey protein fraction in alleviating exercise-induced gut permeability as assessed by recovery of lactulose/rhamnose (L/R) and lactulose/mannitol (L/M) urinary probes. METHODS: Eight males and eight females (aged 18-50) completed two arms of a double-blind, placebo-controlled, crossover study. For each arm participants performed two baseline intestinal permeability assessments, following which they consumed the treatment (2 g/day of milk powder containing 200 mg of whey protein) or placebo (2 g/day of milk powder) for 14 days, before performing a post-exercise permeability assessment. The exercise protocol involved a 20-min run at 80% of maximal oxygen uptake on a 1% incline. RESULTS: Mixed model analysis revealed an increase in L/R (23%; P < 0.001) and L/M (20%; P < 0.01) recovery following exercise. However, there was no treatment or treatment × exercise effect. CONCLUSION: The exercise protocol utilised in our study induces gut permeability. However, consuming whey protein, at the dose and timing prescribed, is not able to mitigate this effect.

Appetite, food intake, and gut hormone responses to glycomacropeptide protein ingestion in older adults: A feasibility, acceptability, and pilot study.

Glycomacropeptide (GMP) has a unique amino acid profile which may make less satiating than other dietary proteins. This study assessed the feasibility and likely acceptability of a leucine-enriched GMP drink and determined appetite response in older adults (OA). Thirteen OA (11f; 70 ± 4 years) were recruited for sensory assessments of a leucine-enriched GMP drink when mixed with water and with fruit smoothie, compared with whey protein isolate (WHEY). Participants also partook in a single focus group exploring acceptability to protein and supplementation. Separately, a counterbalanced, double-blind study with twelve OA (8f; 69 ± 3 years) was conducted to determine appetite and gut hormone responses. Fasting subjective appetite was recorded using visual analogue scales and a fasted venous blood sample was collected (to measures acyl-ghrelin, PYY, GLP-1, and CCK) before participants consumed either: GMP protein (27g + 3g leucine, 350 mL water), WHEY (30g, 350 mL water), or water. Participants rested for 240 min, with appetite measures and blood sampling throughout. An ad libitum pasta-based meal was then consumed. Sensory testing revealed low pleasantness rating for GMP in water vs. WHEY (16 ± 14 vs 31 ± 24, p = 0.016). GMP addition to smoothie reduced pleasantness (26 ± 21 vs. 61 ± 29, p = 0.009) and worsened the aroma (46 ± 15 vs. 69 ± 28, p = 0.014). The focus group revealed uncertainty of protein needs and a scepticism of supplements, with preference for food. Gut hormone response did not differ between GMP and WHEY (nAUC for all gut hormones p > 0.05). There was no difference between conditions for lunch ad libitum intake (549 ± 171 kcal, 512 ± 238 kcal, 460 ± 199 kcal for GMP, WHEY, and water, p = 0.175), or for subjective appetite response. Leucine-enriched GMP was not less satiating than WHEY, and low palatability and scepticism of supplements question the likely acceptability of GMP supplementation. Providing trusted nutritional advice and food enrichment/fortification may be preferred strategies for increasing protein intake in OA.

Microbial composition and viability of natural whey starters used in PDO Comté cheese-making.

Natural whey starters (NWS) are cultures with undefined multiple-strains species commonly used to speed up the fermentation process of cheeses. The aim of this study was to explore the diversity and the viability of Comté cheese NWS microbiota. Culture-dependent methods, i.e. plate counting and genotypic characterization, and culture-independent methods, i.e. qPCR, viability-qPCR, fluorescence microscopy and DNA metabarcoding, were combined to analyze thirty-six NWS collected in six Comté cheese factories at two seasons. Our results highlighted that NWS were dominated by Streptococcus thermophilus (ST) and thermophilic lactobacilli. These species showed a diversity of strains based on Rep-PCR. The dominance of Lactobacillus helveticus (LH) over Lactobacillus delbrueckii (LD) varied depending on the factory and the season. This highlighted two types of NWS: the type-ST/LD (LD > LH) and the type-ST/LH (LD < LH). The microbial composition varied depending on cheese factory. One factory was distinguished by its level of culturable microbial groups (ST, enterococci and yeast) and its fungi diversity. The approaches used to estimate the viability showed that most NWS cells were viable. Further investigations are needed to understand the microbial diversity of these NWS.

Co-culturing Propionibacterium freudenreichii and Bifidobacterium animalis subsp. lactis improves short-chain fatty acids and vitamin B12 contents in soy whey.

The lack of vitamin B12 in unprocessed plant-based foods can lead to health problems in strict vegetarians and vegans. The main aim of this study was to investigate the potential synergy of co-culturing Bifidobacterium animalis subsp. lactis and Propionibacterium freudenreichii in improving production of vitamin B12 and short-chain fatty acids in soy whey. Different strategies including mono-, sequential and simultaneous cultures were adopted. Growth, short-chain fatty acids and vitamin B12 were assessed throughout the fermentation while free amino acids, volatiles, and isoflavones were determined on the final day. P. freudenreichii monoculture grew well in soy whey, whereas B. lactis monoculture entered the death phase by day 4. Principal component analysis demonstrates that metabolic changes in both sequential cultures did not show drastic differences to those of P. freudenreichii monoculture. However, simultaneous culturing significantly improved vitamin B12, acetic acid and propionic acid contents (1.3 times, 5 times, 2.5 times, compared to the next highest treatment [sequential cultures]) in fermented soy whey relative to other culturing modes. Hence, co-culturing of P. freudenreichii and B. lactis would provide an alternative method to improve vitamin B12, acetic acid and propionic acid contents in fermented foods.

Whey Protein, Vitamins C and E Decrease Interleukin-10 in Chronic Hemodialysis Patients: A Pioneer, Randomized, Double-Blind Pilot Trial.

OBJECTIVE: To evaluate the effects of supplementation with whey protein combined with vitamins C and E on inflammatory markers in hemodialysis (HD) patients. DESIGN AND METHODS: This was a pioneer, randomized and double-blinded study. Patients were randomized into two groups and stratified by HD frequency. The supplementation group received 20 g of whey protein, 250 mg of vitamin C, and 600 IU of vitamin E; the placebo group, 20 g of rice flour, and microcrystalline cellulose capsules. The interventions were given after HD, 3 times a week, for 8 weeks. The inflammatory markers were assessed: interleukin (IL) IL-12p70, IL-10, IL-6, IL-8, and tumor necrosis factor alpha. For statistical analysis, the χ2 test, Student's t-test, Mann-Whitney test, analysis of variance for repeated two-way measurements, paired t test, and Wilcoxon test were performed. P < .05 was considered statistically significant. RESULTS: Twenty-three patients completed the study. No significant differences were found in inflammatory markers when comparing the groups postintervention. In the intragroup was a decrease in IL-10 in the supplementation group after 8 weeks (P = .0382). IL-6 tended to decrease by 810.95% in the supplementation group and increased by 732.8% (nonsignificant) in the placebo group. CONCLUSION: Whey protein combined with vitamins C and E significantly reduced IL-10 in the supplementation group and could be beneficial to reduce IL-6 in HD patients. Future studies are suggested with a larger sample size, different supplementation doses, and longer interventions.

Heat-stable whey protein isolate made using isoelectric precipitation and clarification.

Residual lipids (RL) in whey protein isolate (WPI) are detrimental to optimal functional applications (e.g., foaming and low turbidity) and contribute to off-flavor development during powder storage. The objective of this research was to prepare an experimental WPI by removing RL without using the traditional microfiltration process and compare its properties with commercially available WPI made using microfiltration and some other whey powders. We hypothesize that by adjusting the pH of whey to <5.0, we would be close to the isoelectric point of any remaining denatured proteins (DP) and phospholipoproteins (PLP), and therefore reduce electrostatic repulsion between these molecules. Furthermore, demineralization of the acidified whey protein solution by UF combined with diafiltration (DF) should reduce ionic hindrance to aggregation and thereby help with the aggregation of these DP as well as most RL; centrifugation or clarification could be used to remove these materials. Calcium should also be more extensively removed by this approach, which should improve the heat stability of the experimental WPI. Demineralization was achieved on a pilot scale by acidifying liquid (cheese) whey protein concentrate containing 34% protein (WPC-34) to pH 4.5 using HCl, and UF of the whey protein solution along with extensive DF using acidified (pH ∼3.5) reverse osmosis filtered water. Demineralized whey protein solution was adjusted to various combinations of pH (4.1-4.9), conductivities (500-2,000 µS/cm), and protein concentrations (1%-7%) and then centrifuged at 10,000 × g for 10 min. The effective sedimentation (precipitation) of RL in these treatments was estimated by measuring the turbidity of the supernatants. Maximum precipitation was observed at pH 4.5 to 4.7. Reducing conductivity via UF/DF increased the precipitation of RL due to reduced ionic hindrance to aggregation. Maximum sedimentation of RL was observed at protein concentrations ≤3% because of a higher density difference between the precipitate and serum phase. Analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis confirmed the sedimentation of phospholipoproteins, caseins, and DP upon isoelectric precipitation at pH ∼4.5, while native whey proteins or undenatured whey proteins remained soluble in the supernatant, unaffected by the pretreatment. To scale up the process, 750 L of fluid WPC-34 was acidified and demineralized by UF (volume concentration factor = 1.35) and DF until the permeate solids reached 0.1% (when desired demineralization was achieved), clarified using a pilot-scale desludging clarifier to remove RL, neutralized, ultrafiltered to concentrate the protein, and then spray-dried to produce an experimental WPI (91% protein and 1.8% fat on a dry basis [db]). In another trial, demineralized UF concentrate was clarified by gravity sedimentation and the supernatant was neutralized, ultrafiltered, and spray-dried to produce a second experimental WPI (91% protein and <1% fat db). These experimental WPI powders were compared with several commercially available WPI powders to assess functional properties such as solubility, heat stability, foamability and foam strength, gelation, and sensory attributes over accelerated storage. Experimental WPI had excellent functional properties, had low turbidity, were highly heat stable, and only developed very slight-to-slight off-flavors upon accelerated storage, and their properties were comparable to the WPI manufactured commercially using microfiltration even after accelerated storage.

Optimization of lactic acid bacterial starter culture to improve the quality and flavor characteristics of traditional Hurood.

Hurood is a traditional fermented milk product prepared by traditional Mongolian techniques of fermenting raw milk, partial degreasing, heating, whey drainage, emulsification of curd, and molding. Currently, Hurood available in the market is generally prepared by small-scale enterprises at home or in open air. Therefore, lack of standardization of bacterial starter culture leads to variation in the flavor and sensory properties of Hurood from batch to batch. In this study, we aimed to assess the best starter culture combination obtained from 37 lactic acid bacterial strains isolated from traditional Hurood. The solidification state and sensory quality were used as indexes for determining the fermentation efficiency of the bacterial starter culture combinations. The yield and texture characteristics were used to determine the optimal ratio of bacterial strains in a combination and the processing conditions for traditional Hurood production. The most optimal bacterial culture combination was observed to be NF 9-3:NF 10-4:CH 3-1 in 5:4:1 ratio and in 3% amount. The most optimal whey temperature and heating-stirring temperature were observed to be 55°C to 60°C and 85°C to 90°C, respectively. Hurood prepared with the optimal combination of bacterial strains exhibited significantly enhanced sensory quality, flavor, and contents of AA and fatty acids. Therefore, the use of optimal starter culture of lactic acid bacteria could produce Hurood with significantly superior sensory qualities, making the product more acceptable to consumers.

Structure and functionality of whey protein, pea protein, and mixed whey and pea proteins treated by pH shift or high-intensity ultrasound.

Three modifications (pH shift, ultrasound, combined pH shift and ultrasound) induced alterations in pure whey protein isolate (WPI), pea protein isolate (PPI), and mixed whey and pea protein (WPI-PPI) were investigated. The processing effect was related to the protein type and technique used. Solubility of WPI remained unchanged by various treatments. Particle size was enlarged by pH shift while reduced by ultrasound and combined approach. All methods exposed more surface hydrophobic groups on WPI, while pH shift and joint processing was detrimental to its emulsifying activity. The PPI and mixture exhibited similar responses toward the modifications. Solubility of PPI and the blend enhanced in the sequence of pH shift and ultrasound > ultrasound > pH shift. Individual approach expanded while co-handling diminished the particle diameter. Treatments also caused more disclosure of hydrophobic regions in PPI and WPI-PPI and emulsifying activity was ameliorated in the order of pH shift and ultrasound > ultrasound > pH shift.

Water thermodynamics and lipid oxidation in stored whey butter.

Whey butter is the result of the rational use of the whey component, which is cream whey. It is an alternative to milk cream butter. The aim of the presented study was to analyze the effect of storage conditions on water thermodynamics and cholesterol oxidation products as reliable markers of quality and safety. After 4 mo of storage, the water loss (at 3°C and 13°C) and water activity in whey butter (only at 13°C) were reduced. Three-factorial ANOVA showed that the value of water activity was independent of the type of butter in interaction with the storage temperature. The duration of the translational movement of water molecules from the inside of whey butter was definitely longer than in butter and shortened with storage time. This was in contrast to butter. For whey butter stored at 13°C, the kinetics of the movement of water molecules was at the highest speed. In the case of whey butter and butter, the higher storage temperature almost doubled the gloss. Increasing the temperature to 13°C resulted in different yellowness index, chroma, and browning index between whey butter and butter. There were no statistically significant differences in the percentage of fatty acids and triacylglycerols in whey butter and milk cream butter during storage. In whey butter, compared with butter, the cholesterol content was higher, but the amount of cholesterol oxidation products was smaller. However, in whey butter, these amounts increased significantly. The presence of epoxides and their transformation products (i.e., triol cholesterol) was found in storage whey butter.

Destabilization of ultra-instantaneous ultra-high-temperature sterilized milk stored at different temperatures.

Ultra-instantaneous UHT (UI-UHT, >155°C, <0.1 s) treated milk exhibits higher retention of active protein than regular UHT milk. However, UI-UHT products demonstrate increased susceptibility to destabilization during storage. This study aimed at monitoring the destabilizing process of UI-UHT milk across different storage temperatures and uncovering its potential mechanisms. Compared with regular UHT treatment, ultra-instantaneous treatment markedly accelerated the milk's destabilization process. Aged gel formation occurred after 45 d of storage at 25°C, whereas creaming and sedimentation were observed after 15 d at 37°C. To elucidate the instability mechanism, measurements of plasmin activity, protein hydrolysis levels, and proteomics of the aged gel were conducted. In UI-UHT milk, plasmin activity, and protein hydrolysis levels significantly increased during storage. Excessive protein hydrolysis at 37°C resulted in sedimentation, whereas moderate hydrolysis and an increase in protein particle size at 25°C resulted in aged gel formation. Proteomics analysis results indicated that the aged gel from UI-UHT milk contained intact caseins, major whey proteins, and their derived peptides. Furthermore, specific whey proteins including albumin, lactotransferrin, enterotoxin-binding glycoprotein PP20K, and MFGM proteins were identified in the gel. Additionally, MFGM proteins in UI-UHT milk experienced considerable hydrolysis during storage, contributing to fat instability. This study lays a theoretical foundation for optimizing UI-UHT milk storage conditions to enhance the quality of liquid milk products.

Docosahexaenoic acid-mediated milk protein treated by ultrasound-assisted pH shifting for enhanced astaxanthin delivery and processed cheese application.

Whey protein isolate (WPI)-based nanodelivery systems have recently attracted an increasing amount of attention. Despite this, research focusing on milk protein concentrate (MPC) and micellar casein (MCC) as carriers loaded in hydrophobic compounds is lacking. This study investigated the mediated effect of docosahexaenoic acid (DHA) in 3 different milk proteins for the embedding of astaxanthin (ASTA) after ultrasound-assisted pH-shifting treatment. We then evaluated the application of milk protein carriers in cheese processing by comparing MPC, MCC, and WPI. The particle size, polydispersity index, and zeta potential results of the milk protein-DHA complex suggested that the addition of 0.36 µmol/mL DHA optimized the delivery of milk protein to ASTA. All 3 DHA-mediated milk proteins induced an improvement in encapsulation efficiency and antioxidant properties of ASTA. Furthermore, the DHA-mediated MPC and MCC played a stronger role in improving the bioaccessibility and thermal and storage stability of ASTA than those without DHA. Tests conducted to examine the application in cheese production indicated that MCC carrier had a positive effect on the texture of cheeses. However, the delivery effect was dependent on the milk protein variety, and MCC exhibited the best protection ability of ASTA, followed by MPC and WPI. The simulated digestion and storage stability results of cheese further confirmed that the protein encapsulation mediated by DHA was more conducive to ASTA absorption. These findings suggested that the DHA-mediated milk protein complexes studied here may be suitable hydrophilic delivery carriers for the hydrophobic nutrient ASTA, potentially playing different roles in improving its storage stability and bioaccessibility.

Effect of processing methods on the distribution of mineral elements in goat milk fractions.

Milk and dairy products are excellent sources of mineral elements, including Ca, P, Mg, Na, K, and Zn. The purpose of this study was to determine the effect of nonthermal (homogenization) and thermal (heat treatment) treatments on the distribution of mineral elements in 4 milk fractions: fat, casein, whey protein, and aqueous phase. The study results revealed that the distribution of mineral elements (such as Mg and Fe) in fat fractions is extremely low, whereas significant mineral elements such as Ca, Zn, Fe, and Cu are mostly dispersed in casein fractions. For nontreated goat milk, Mo is the only element identified in the whey protein fraction, whereas K and Na are mostly found in the aqueous phase. Mineral element concentrations in fat (K, Zn, and so on) and casein fractions (Fe, Mo, and so on) increased dramatically after homogenization. Homogenization greatly decreased the concentration of mineral elements in the whey protein fraction (Ca, Na, and so on) and aqueous phase (Fe, Cu, and so on). After heat treatment, the element content in the fat fraction and casein fraction increased greatly when compared with raw milk, such as Cu and Mg in the fat fraction, Na and Cu in the whey protein fraction, the concentration of components such as Mg and Na in casein fraction increased considerably. In contrast, after homogenization, Zn in the aqueous phase decreased substantially, whereas Fe increased significantly. Therefore, both homogenization and heat treatment have an effect on the mineral element distribution in goat milk fractions.