Mimicking Lipid Self-assembly in Digesting Milk-like Emulsions

Malinda Salim, Anna C Pham, Syaza Binte Abu Bakar, Adrian Hawley, Ben J Boyd

Monash Institute of Pharmaceutical Sciences; Monash Institute of Pharmaceutical Sciences; Monash Institute of Pharmaceutical Sciences; Australian Synchrotron, ANSTO; Monash Institute of Pharmaceutical Sciences

Hypothesis &

Objective: Milk is nature’s emulsion for delivering fats and fat-soluble nutrients to infants. Intestinal lipolysis of milk triglycerides yields fatty acids and monoglycerides that spontaneously assemble into different liquid crystalline phases depending on species. It was hypothesized that specific liquid crystalline phases are advantageous for nutrient absorption by different species and that controlling liquid crystalline structure formation is key to nutrient delivery. A key issue in testing this hypothesis is the chemical complexity of milk fats, making the analysis of the individual lipid components challenging. The objective of this work was therefore to design simplified triglyceride mixtures that mimic the liquid crystalline phase progressions occurring during milk lipid digestion for use in representative intestinal colloid mimics.

Methods: Simulated intestinal digestions were performed in vitro using the pH-stat technique. Synchrotron small angle X-ray scattering with in situ lipolysis was used to reveal the self-assembly of amphiphilic digestion products generated during digestion of triglyceride emulsions.

Results: The progression of liquid crystalline phases formed during the digestion of bovine and human milk were compared with commercial infant formulas. The liquid crystalline phases formed by digesting human milk were dependent on processing but those of bovine milk were not. In most cases infant formula did not mimic human milk. Triglyceride emulsions comprising homotriglycerides were prepared and the simplest emulsions required to mimic milk digestion behaviour were identified.

Conclusion: The progression of liquid crystalline phases observed in digesting bovine and human milk can be mimicked using simplified homotriglyceride mixtures.