Mildly Pasteurized Whey Protein Promotes Gut Tolerance in Immature Piglets Compared with Extensively Heated Whey Protein.

Human milk is the optimal diet for infant development, but infant milk formula (IMF) must be available as an alternative. To develop high-quality IMF, bovine milk processing is required to ensure microbial safety and to obtain a protein composition that mimics human milk. However, processing can impact the quality of milk proteins, which can influence gastro-intestinal (GI) tolerance by changing digestion, transit time and/or absorption. The aim of this study was to evaluate the impact of structural changes of proteins due to thermal processing on gastro-intestinal tolerance in the immature GI tract. Preterm and near-term piglets received enteral nutrition based on whey protein concentrate (WPC) either mildly pasteurized (MP-WPC) or extensively heated (EH-WPC). Clinical symptoms, transit time and gastric residuals were evaluated. In addition, protein coagulation and protein composition of coagulates formed during in vitro digestion were analyzed in more detail. Characterization of MP-WPC and EH-WPC revealed that mild pasteurization maintained protein nativity and reduced aggregation of ß-lactoglobulin and α-lactalbumin, relative to EH-WPC. Mild pasteurization reduced the formation of coagulates during digestion, resulting in reduced gastric residual volume and increased intestinal tract content. In addition, preterm piglets receiving MP-WPC showed reduced mucosal bacterial adherence in the proximal small intestine. Finally, in vitro digestion studies revealed less protein coagulation and lower levels of ß-lactoglobulin and α-lactalbumin in the coagulates of MP-WPC compared with EH-WPC. In conclusion, minimal heat treatment of WPC compared with extensive heating promoted GI tolerance in immature piglets, implying that minimal heated WPC could improve the GI tolerance of milk formulas in infants.

Effects of thermized donkey milk with lysozyme activity on altered gut barrier in mice exposed to water-avoidance stress.

Nutrition plays a crucial role in human gut health through the improvement of gut barrier functionality. Donkey milk represents an interesting source of natural antimicrobial factors such as lysozyme. Recently, anti-inflammatory properties of donkey milk lysozyme activity were described in a mouse model of ileitis. The current increase of donkey milk consumption highlights the necessity to propose a healthy milk compliant with microbiological standards. This study aims to define a heat treatment of donkey milk, retaining its high lysozyme activity, and to evaluate its beneficial effects on a gut barrier impairment model due to chronic stress in mice. To perform this experiment, samples of raw donkey milk were collected in 15 distinct French farms. Microbiological analysis and lysozyme content and activity were evaluated for each sample. Then, several heat treatments were carried out to define a time and temperature combination that allowed for both a reduction in the number of total micro-organisms, increasing the shelf-life of the product, and preservation of lysozyme activity. The beneficial effect of heated donkey milk on the gut barrier of mice was evaluated and compared with raw donkey milk. We found that samples of raw donkey milk showed low total mesophilic microbial counts, and no pathogens were detected. Among the different heat-treatment procedures tested, a 2-min, 72°C combination was determined to be the most optimal time and temperature combination to preserve lysozyme activity and increase the shelf-life of donkey milk. Oral administration of this heat-treated donkey milk in mice counteracted chronic stress-induced intestinal damage, illustrated by gut hyper-permeability and low-grade inflammation, similar to raw donkey milk. We have demonstrated for the first time that oral intervention with donkey milk, optimally heat-treated to retain enzymatic lysozyme activity, improves intestinal barrier damage linked to psychological stress in mice.