In vivo digestion of bovine milk fat globules: Effect of processing and interfacial structural changes. II. Upper digestive tract digestion

The aim of this research was to study the effect of milk processing on the in vivo upper digestive tract digestion of milk fat globules. Fasted rats were serially gavaged over a 5 h period with cream from raw, pasteurised, or pasteurised and homogenised milk. Only a few intact dietary proteins and peptides were present in the small intestinal digesta. Significantly (P < 0.05) more longer chain (C ⩾ 10) fatty acids were present in the digesta of rats gavaged with raw (448 mg g−1 digesta dry matter (DDM)) and homogenised creams (528 mg g−1 DDM), as compared to pasteurised and homogenised cream (249 mg g−1 DDM). Microscopy techniques were used to investigate the structural changes during digestion. Liquid–crystalline lamellar phases surrounding the fat globules, fatty acid soap crystals and lipid–mucin interactions were evident in all small intestinal digesta. Overall, the pasteurised and homogenised cream appeared to be digested to a greater extent.