In vitro digestion of heat-treated milk using the dynamic human stomach-intestine Ⅳ+

Abstract

ObjectiveTo study the effects of different heat treatments on milk digestion in vitro.MethodsThe dynamic human stomach-intestine Ⅳ+ was used to analyze the pH change， protein digestibility， gastric emptying and peptide distribution of four different heat-treated milk products： raw milk， pasteurized milk， ultra-high-temperature sterilized （UHT） milk and direct steam infusion （INF） milk.ResultsThe pH change trends of raw milk and pasteurized milk in the stomach were very similar. Pasteurized milk took the shortest time to digest into a near-fasting state in the stomach. The protein digestibility of pasteurized milk was also the highest， whereas that of UHT milk was significantly lower than the other three samples. The molecular weight of peptides generated by the four kinds of milk after in vitro gastric digestion was below 5 000 u. After in vitro gastrointestinal digestion， the molecular weight of the peptides reached below 1 000 u， which is easy for digestion and absorption by the human body. Pasteurized milk and INF milk have advantages in protein digestibility and the molecular weight analysis of peptides of their digestion products. However， the general trend was the same without significant differences： they were both superior to UHT milk.ConclusionThe in vitro digestion profiles of INF milk and pasteurized milk were the same， which were better than those of UHT milk， providing consumers with a new choice for dairy products.

Keywords

• heat treatment
• milk
• protein
• in vitro dynamic digestion