• Dietary alpha-lactalbumin alters energy balance, gut microbiota composition and intestinal nutrient transporter expression in high-fat diet fed mice

      Boscaini, Serena; Cabrera-Rubio, Raul; Speakman, John R.; Cotter, Paul D.; Cryan, John F.; Nilaweera, Kanishka; Teagasc Walsh Fellowship Programme; Science Foundation Ireland; BBSRC; Teagasc; et al. (Cambridge University Press, 2019-03-05)
      Recently there has been a considerable rise in the frequency of metabolic diseases, such as obesity, due to changes in lifestyle and resultant imbalances between energy intake and expenditure. Whey proteins are considered as potentially important components of a dietary solution to the obesity problem. However, the roles of individual whey proteins in energy balance remain poorly understood. This study investigated the effects of a high fat diet (HFD) containing alphalactalbumin (LAB), a specific whey protein, or the non-whey protein casein (CAS), on energy balance, nutrient transporters expression, and enteric microbial populations. C57BL/6J mice (n = 8) were given a HFD containing either 20% CAS or LAB as protein sources or a low-fat diet (LFD) containing CAS for 10 weeks. HFD-LAB fed mice showed a significant increase in cumulative energy intake (P=0.043), without differences in body weight, energy expenditure, locomotor activity, respiratory exchange ratio or subcutaneous and epididymal adipose tissue weight. HFD-LAB intake led to a decrease in the expression of glucose transporter glut2 in the ileum (P=0.05)and in the fatty acid transporter cd36 (P<0.001) in both ileum and jejunum. This suggests a reduction of absorption efficiency within the small intestine in the HFD-LAB group. DNA from faecal samples was used for 16S rRNA-based assessment of intestinal microbiota populations; the genera Lactobacillus, Parabacteroides and Bifidobacterium were present in significantly higher proportions in the HFD-LAB group. These data indicate a possible functional relationship between gut microbiota, intestinal nutrient transporters and energy balance, with no impact on weight gain.
    • Influence of calcium-binding salts on heat stability and fouling of whey protein isolate dispersions

      Hebishy, Essam; Joubran, Yousef; Murphy, Eoin; O'Mahony, James A.; Enterprise Ireland; Technology Centres programme; TC/2014/0016 (Elsevier, 2018-12-31)
      The effect of the calcium-binding salts (CBS), trisodium citrate (TSC), tripotassium citrate (TPC) and disodium hydrogen phosphate (DSHP) at concentrations of 1–45 mm on the heat stability and fouling of whey protein isolate (WPI) dispersions (3%, w/v, protein) was investigated. The WPI dispersions were assessed for heat stability in an oil bath at 95 °C for 30 min, viscosity changes during simulated high-temperature short-time (HTST) and fouling behaviour using a lab-scale fouling rig. Adding CBS at levels of 5–30 mm for TSC and TPC and 25–35 mm for DSHP improved thermal stability of WPI dispersions by decreasing the ionic calcium (Ca2+) concentration; however, lower or higher concentrations destabilised the systems on heating. Adding CBS improved heat transfer during thermal processing, and resulted in lower viscosity and fouling. This study demonstrates that adding CBS is an effective means of increasing WPI protein stability during HTST thermal processing.
    • Influence of desialylation of caseinomacropeptide on the denaturation and aggregation of whey proteins

      Sunds, Anne V.; Larsen, Lotte B.; Poulsen, Nina A.; O'Mahony, James A.; Kelly, Alan L.; Brodkorb, Andre; Dairy Levy Research Trust; Teagasc Walsh Fellowship PRogramme; Aarhus University Research Foundation (AUFF); Graduate School of Science and Technology (GSST) at Aarhus University; et al. (Elsevier for American Dairy Science Association, 2020-06-30)
      ABSTRACT The effect of the addition of caseinomacropeptide (CMP) or desialylated CMP on the heat-induced denaturation and aggregation of whey proteins was investigated in the pH range 3 to 7 after heating at 80°C for 30 min. The rate and temperature of denaturation, the extent of aggregation, and the changes in secondary structure of the whey proteins heated in presence of CMP or desialylated CMP were measured. The sialic acid bound to CMP favored the denaturation and aggregation of whey proteins when the whey proteins were oppositely charged to CMP at pH 4. A transition occurred at pH 6, below which the removal of sialic acid enhanced the stabilizing properties of CMP against the denaturation and aggregation of the whey proteins. At pH >6, the interactions between desialylated CMP and the whey proteins led to more extensive denaturation and aggregation. Sialic acid bound to CMP influenced the denaturation and aggregation behavior of whey proteins in a pH-dependent manner, and this should be considered in future studies on the heat stability of such systems containing CMP.
    • Isolation and characterisation of κ-casein/whey protein particles from heated milk protein concentrate and role of κ-casein in whey protein aggregation

      Gaspard, Sophie J.; Auty, Mark; Kelly, Alan L.; O'Mahony, James A.; Brodkorb, Andre; Teagasc Walsh Fellowship Programme; Dairy Levy Research Trust; 2012211 (Elsevier, 12/06/2017)
      Milk protein concentrate (79% protein) reconstituted at 13.5% (w/v) protein was heated (90 °C, 25 min, pH 7.2) with or without added calcium chloride. After fractionation of the casein and whey protein aggregates by fast protein liquid chromatography, the heat stability (90 °C, up to 1 h) of the fractions (0.25%, w/v, protein) was assessed. The heat-induced aggregates were composed of whey protein and casein, in whey protein:casein ratios ranging from 1:0.5 to 1:9. The heat stability was positively correlated with the casein concentration in the samples. The samples containing the highest proportion of caseins were the most heat-stable, and close to 100% (w/w) of the aggregates were recovered post-heat treatment in the supernatant of such samples (centrifugation for 30 min at 10,000 × g). κ-Casein appeared to act as a chaperone controlling the aggregation of whey proteins, and this effect was stronger in the presence of αS- and β-casein.
    • Pilot-scale formation of whey protein aggregates determine the stability of heat-treated whey protein solutions—Effect of pH and protein concentration

      Buggy, Aoife K.; McManus, Jennifer J.; Brodkorb, Andre; Hogan, Sean; Fenelon, Mark; Teagasc Walsh Fellowship Programme; Department of Agriculture, Food and the Marine; 11/F/037 (American Dairy Science Association, 2018-09-20)
      Denaturation and consequent aggregation in whey protein solutions is critical to product functionality during processing. Solutions of whey protein isolate (WPI) prepared at 1, 4, 8, and 12% (wt/wt) and pH 6.2, 6.7, or 7.2 were subjected to heat treatment (85°C × 30 s) using a pilot-scale heat exchanger. The effects of heat treatment on whey protein denaturation and aggregation were determined by chromatography, particle size, turbidity, and rheological analyses. The influence of pH and WPI concentration during heat treatment on the thermal stability of the resulting dispersions was also investigated. Whey protein isolate solutions heated at pH 6.2 were more extensively denatured, had a greater proportion of insoluble aggregates, higher particle size and turbidity, and were significantly less heat-stable than equivalent samples prepared at pH 6.7 and 7.2. The effects of WPI concentration on denaturation/aggregation behavior were more apparent at higher pH where the stabilizing effects of charge repulsion became increasingly influential. Solutions containing 12% (wt/wt) WPI had significantly higher apparent viscosities, at each pH, compared with lower protein concentrations, with solutions prepared at pH 6.2 forming a gel. Smaller average particle size and a higher proportion of soluble aggregates in WPI solutions, pre-heated at pH 6.7 and 7.2, resulted in improved thermal stability on subsequent heating. Higher pH during secondary heating also increased thermal stability. This study offers insight into the interactive effects of pH and whey protein concentration during pilot-scale processing and demonstrates how protein functionality can be controlled through manipulation of these factors.
    • Protein quality and quantity influence the effect of dietary fat on weight gain and tissue partitioning via host-microbiota changes

      Nychyk, Oleksandr; Barton, Wiley; Rudolf, Agata M.; Boscaini, Serena; Walsh, Aaron; Bastiaanssen, Thomaz F.S.; Giblin, Linda; Cormican, Paul; Chen, Liang; Piotrowicz, Yolanda; et al. (Elsevier BV, 2021-05-11)
      We investigated how protein quantity (10%–30%) and quality (casein and whey) interact with dietary fat (20%–55%) to affect metabolic health in adult mice. Although dietary fat was the main driver of body weight gain and individual tissue weight, high (30%) casein intake accentuated and high whey intake reduced the negative metabolic aspects of high fat. Jejunum and liver transcriptomics revealed increased intestinal permeability, low-grade inflammation, altered lipid metabolism, and liver dysfunction in casein-fed but not whey-fed animals. These differential effects were accompanied by altered gut size and microbial functions related to amino acid degradation and lipid metabolism. Fecal microbiota transfer confirmed that the casein microbiota increases and the whey microbiota impedes weight gain. These data show that the effects of dietary fat on weight gain and tissue partitioning are further influenced by the quantity and quality of the associated protein, primarily via effects on the microbiota.
    • Whey for Sarcopenia; Can Whey Peptides, Hydrolysates or Proteins Play a Beneficial Role?

      Gilmartin, Sarah; O’Brien, Nora; Giblin, Linda; Department of Agriculture, Food and the Marine; Science Foundation Ireland; Teagasc Walsh Fellowship Programme; FIRM 15F604-TOMI; 16/RC/3835-VistaMilk (MDPI AG, 2020-06-05)
      As the human body ages, skeletal muscle loses its mass and strength. It is estimated that in 10% of individuals over the age of 60, this muscle frailty has progressed to sarcopenia. Biomarkers of sarcopenia include increases in inflammatory markers and oxidative stress markers and decreases in muscle anabolic markers. Whey is a high-quality, easily digested dairy protein which is widely used in the sports industry. This review explores the evidence that whey protein, hydrolysates or peptides may have beneficial effects on sarcopenic biomarkers in myoblast cell lines, in aged rodents and in human dietary intervention trials with the older consumer. A daily dietary supplementation of 35 g of whey is likely to improve sarcopenic biomarkers in frail or sarcopenia individuals. Whey supplementation, consumed by an older, healthy adult certainly improves muscle mTOR signaling, but exercise appears to have the greatest benefit to older muscle. In vitro cellular assays are central for bioactive and bioavailable peptide identification and to determine their mechanism of action on ageing muscle.