Hydrolysed and non-hydrolysed dairy and soy proteins with vegetable oils are commonly used in infant formulations. Lipid digestion of these infant formula emulsions was studied under an in vitro gastrointestinal condition for 60 min in the stomach and 120 min in the small intestine (with and without the presence of enzyme proteases). The distribution of oil droplets, the released free fatty acids, and micro-structure changes of the digesta were monitored over the digestion period. Oil droplet coalescence was observed during gastric phase but not in the intestinal phase for most of formulations. The emulsion structure and the oil-water interface of the oil droplets play an important part in lipolysis kinetics. Higher rate of lipolysis in infant formula emulsion stabilized by hydrolysed proteins was noted. The obtained results suggest that digestive proteases had a limited impact on lipolysis of infant formulations.
Keywords: Digestibility; Gastric lipase; Infant formulation; Micro-structure; Non-hydrolysed proteins; Pancreatic triglyceride lipase.
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