Dynamic In Vitro Gastric Digestion of Sheep Milk: Influence of Homogenization and Heat Treatment.

Zheng Pan,Harjinder Singh,Karl Fraser,Anant Dave,Siqi Li,Aiqian Ye

doi:10.3390/foods10081938

Zheng Pan, Harjinder Singh + Show 4 more

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https://doi.org/10.3390/foods10081938

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Abstract

Milk is commonly exposed to processing including homogenization and thermal treatment before consumption, and this processing could have an impact on its digestion behavior in the stomach. In this study, we investigated the in vitro gastric digestion behavior of differently processed sheep milks. The samples were raw, pasteurized (75 °C/15 s), homogenized (200/20 bar at 65 °C)–pasteurized, and homogenized–heated (95 °C/5 min) milks. The digestion was performed using a dynamic in vitro gastric digestion system, the human gastric simulator with simulated gastric fluid without gastric lipase. The pH, structure, and composition of the milks in the stomach and the emptied digesta, and the rate of protein hydrolysis were examined. Curds formed from homogenized and heated milk had much looser and more fragmented structures than those formed from unhomogenized milk; this accelerated the curd breakdown, protein digestion and promoted the release of protein, fat, and calcium from the curds into the digesta. Coalescence and flocculation of fat globules were observed during gastric digestion, and most of the fat globules were incorporated into the emptied protein/peptide particles in the homogenized milks. The study provides a better understanding of the gastric emptying and digestion of processed sheep milk under in vitro gastric conditions.

Highlights

Homo-heat a a aa ac a a ab Weight of total solid of curd (g/200 g milk) pasteurization alone of that sheep milk did notalone haveof much on not the have breakdown of the. These results suggested pasteurization sheepimpact milk did much impact curd with milk; pasteurization combined homogenization on thecompared breakdown of the theraw curdsheep compared with the raw sheep milk;with pasteurization comsignificantly accelerated thesignificantly disintegration of the sheep milk curds; more heat bined with homogenization accelerated the disintegration of theintense sheep milk treatment of the homogenized sheep milk did not further impact the breakdown of the curds; more intense heat treatment of the homogenized sheep milk did not further impact curds compared with the homo–past sheep milk but resulted in a significantly higher the breakdown of the curds compared with the homo–past sheep milk but resulted in a weight of thehigher curds weight at 20 min
This study demonstrated the effect of heat treatment and homogenization on the dynamic in vitro gastric digestion of sheep milk
The curds formed from the homogenized milks had a much looser and fractured structure than those formed from the unhomogenized milks because of the inclusion of smaller fat globules into the curd; the homogenization of sheep milk followed by heating at 90 ◦ C for 5 min resulted in crumblier curds compared with homogenization coupled with pasteurization because of the incorporation of more whey proteins into the curd

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Sheep milk is of high nutritional value and has potential for the development of nutritional and functional milk products, attracting a growing number of consumers worldwide [1]. As an important source of protein for humans, has been widely examined for its digestion behavior in both in vivo and in vitro studies [2,3,4]. The digestion of cow milk has been investigated extensively, whereas the digestion of noncow milk (i.e., sheep milk) is less studied

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