Development of a human milk protein concentrate from donor milk: Impact of the pasteurization method on static in vitro digestion in a preterm newborn model

The impact of high temperature short time (HTST, 72 degrees C, 15 s), Holder pasteurization-(63 degrees C, 30 min) and high hydrostatic pressure (HHP, 600 MPa-10 min) was evaluated on the digestibility of human milk protein concentrate (HMPC) by using a static in vitro gastrointestinal digestion system. The results showed that the processing steps used to produce the HMPC induced a decrease in readily available nitrogen (non-protein ni-trogen and peptides). Overall, digestibility was similar between pasteurized and raw HMPC (degree of hydrolysis ranged from 26 to 34 %). Lactoferrin was more susceptible to gastric and intestinal digestion after thermal pasteurization. Additionally, the resistance of beta-casein to digestion increased after HHP and Holder pasteuriza-tion due to aggregation and changes in protein structure. During intestinal digestion, Holder pasteurization induced a higher release of arginine, phenylalanine and tyrosine from HMPC compared to raw and HHP-treated HMPC. Overall, protein structural changes induced by human milk (HM) processing (freeze-thawing and filtration) and pasteurization treatments affected HMPC proteolysis during in vitro digestion. However, protein digestion behaviors were quite similar for raw and HHP-treated HMPC compared to the thermal-treated HMPC, with no effect on lactoferrin digestion. Consequently, pasteurization of HMPC by HHP represents an interesting non-thermal process that preserves the HM bioactive proteins during digestion.

Automated summary

The impact of different processing methods on the digestibility of human milk protein concentrate (HMPC) was evaluated. Results showed that heat treatments and high hydrostatic pressure (HHP) affected the release of certain amino acids during digestion. However, overall digestibility was similar between pasteurized and raw HMPC. The non-thermal HHP process was found to preserve the bioactive proteins in HMPC during digestion.