Browsing by Author "Hefer C"

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    Effect of Heat Treatment on Protein Self-Digestion in Ruminants' Milk
    (MDPI (Basel, Switzerland), 2023-09-21) Leite JAS; Montoya CA; Maes E; Hefer C; Cruz RAPA; Roy NC; McNabb WC; Liu Q; Liu H; Zhang J
    This study investigated whether heat treatments (raw, 63 °C for 30 min, and 85 °C for 5 min) affect protein hydrolysis by endogenous enzymes in the milk of ruminants (bovine, ovine, and caprine) using a self-digestion model. Self-digestion consisted of the incubation for six hours at 37 °C of the ruminants' milk. Free amino group concentration was measured by the o-phthaldialdehyde method, and peptide sequences were identified by chromatography-mass spectrometry. Results showed that heat treatments prior to self-digestion decreased the free NH2 by 59% in bovine milk heated at 85 °C/5 min, and by 44 and 53% in caprine milk heated at 63 °C/30 min and 85 °C/5 min, respectively. However, after self-digestion, only new free amino groups were observed for the raw and heated at 63 °C/30 min milk. β-Casein was the most cleaved protein in the raw and heated at 63 °C/30 min bovine milk. A similar trend was observed in raw ovine and caprine milk. Self-digestion increased 6.8-fold the potential antithrombin peptides in the bovine milk heated at 63 °C/30 min. Enhancing bioactive peptide abundance through self-digestion has potential applications in the industry for functional products. Overall, heat treatments affected the free amino groups according to the species and heat treatment applied, which was reflected in the varying degrees of cleaved peptide bonds and peptides released during self-digestion.
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    Effects of whey protein treatment in an in vitro intestinal cell model following oxidative stress or inflammatory challenge
    (Elsevier Ltd, 2025-01-28) Willems E; Purba A; Savoian MS; Hefer C; Maes E; Ulluwishewa D
    Bovine milk whey proteins with an isoelectric point >6.8 (‘whey’) have demonstrated anti-inflammatory and antioxidant properties. In the present study, pre-treatment of human intestinal cells (Caco-2) with whey mitigated intracellular reactive oxygen species produced in response to the pro-oxidant 2,2′-azobis (2-methylpropionamide)-dihydrochloride (AAPH). The mitigating effect was dose-dependent, and persisted when whey was removed prior to the addition of AAPH. Whey treatment also improved transepithelial electrical resistance (TEER), but returned to untreated-control levels upon removal of whey. Hence, whey can lead to cellular adaptations that aid intestinal function, but can exert additional properties while in contact with cells. Confocal imaging indicated that the previously observed TEER improvements in inflammatory-challenged Caco-2 monolayers were not due to the localisation of occludin or zonula occludens-1 tight junction proteins. However, proteomics analysis indicated a role for other tight junction proteins and provided insights into cellular adaptations that occur in response to whey pre-treatment.