Structural characteristics of triacylglycerols contributes to the distinct in vitro gastric digestibility of sheep and cow milk fat

The fatty acid (FA) regiodistribution in triacylglycerols (TAGs) is highly correlated to the digestion and absorption of dietary fats. During the in vitro gastric digestion, medium-long-medium (or short) chain triacylglycerols (MLM) showed the best digestibility among 105 TAG species, resulting from the regiospecificity of gastric lipase towards medium chain fatty acids (MCFAs). After 60 min, the percentage of digestion of each MLM was 16.6 to 31.2 % and 12.3 to 18.6 % respectively in the raw sheep and cow milk, and it reached to 32.1 to 45.5 % and 23.0 to 46.1 % respectively, after milk homogenisation. Sheep milk TAGs were digested to a higher percentage than cow milk TAGs prior (16.1 % and 12.4 %, respectively) and after homogenisation (24.1 % and 20.3 %, respectively) due to the higher proportions of MCFAs esterified on the sn-1/3 positions of sheep milk TAGs (48.3-67.3 % and 12.8-47.1 %, respectively for raw sheep and cow milk; 48.6-64.8 % and 11.9-51.5 %, respectively for homogenised sheep and cow milk). FAs regiodistribution was highly correlated to the gastric digestibility of TAGs in vitro. Homogenisation favoured the TAG lipolysis; however, it did not affect the lipase regiospecificity towards individual TAG species.