Dairy Processing Affects the Gut Digestion and Microecology by Changing the Structure and Composition of Milk Fat Globules

Abstract

Milk fat globules (MFGs) are the major source of energy for infants' dietary intake. In this study, the effects of changes in the structure and composition of MFG after dairy processing on lipolysis and immune regulation were investigated. Pasteurized MFG tends to form protein aggregates to prevent lipolysis. However, the aggregate is rich in neutrophil degranulation products, which are effective in killing pathogens. Homogenized MFG has the lowest hydrolysis rate due to the reconstituted antilipase barrier and exposed apolipoprotein. Simultaneously, the reconstituted barrier can compensate for the lack of the complement cascade. Spray-dried MFG had the highest hydrolysis rate attributable to the disrupted MFG barrier and the release of lipoprotein lipase and endothelial lipase. The immunomodulatory properties of spray-dried MFG proteins are mainly mediated by the toll-like receptor (TLR) signaling pathway. This research provides the improvement basis of dairy processing and functional infant formulas.

Influence of pasteurization and spray drying on the fat digestion behavior of human milk fat analog emulsion: a simulated in vitro infant digestion study

“…The decrease in the lipolysis degree of P‐HMFAE is mainly related to protein denaturation caused by heat treatment. Studies have shown that denatured milk proteins can form protein aggregates, hinder the interaction between lipase and internal triglycerides core, and limit the fat hydrolysis of lipid droplets 17 …”

“…Studies have shown that denatured milk proteins can form protein aggregates, hinder the interaction between lipase and internal triglycerides core, and limit the fat hydrolysis of lipid droplets. 17 After pre-digestion in the gastric phase, fat of HMFAEs hydrolyzed rapidly in the intestinal phase. After 30 min of intestinal digestion, the lipolysis degree of HM, HMFAE, P-HMFAE, and S-HMFAE reached 45.89%, 46.32%, 44.55%, and 42.89%, respectively.…”

“…This phenomenon is specifically manifested by the reduction of phospholipid unsaturated fatty acid and cholesterol content, which maintain the skeleton of MFGM. 17 In turn, the changes in the interfacial properties of fat globules determine their fat digestion behavior. Our previous research has also shown that regulating the interfacial properties of fat globules can improve the fat digestion characteristics of infant formula.…”

Evaluating the total antioxidant capacity of processed milk: utilising applicable antioxidant assays and key antioxidant components

“…The separation of phospholipid antioxidant components is likely due to changes in milk fat structure caused by dairy processing (Yao et al ., 2015). PE is located within milk fat globules, and heat treatment promotes the formation of milk fat aggregates and causes PE to become embedded (Zhou et al ., 2021). In contrast, PC and SM are mainly located in the outer barrier of milk fat globules.…”

“…Fat‐soluble antioxidants in skimmed milk will be greatly lost, especially α‐tocopherol and vitamin A, which are concentrated in low melting point milk fat (Khan et al ., 2019). In addition, heating and homogenisation treatment have a remarkable effect on the loss of natural antioxidants, protein degradation, unfolding and formation of heat‐induced antioxidants or pro‐oxidants (Dias et al ., 2020; Zhou et al ., 2021). Thus, milk processing can affect TAC levels in various ways.…”