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Mechanisms by which interfacial layers control lipolysis on digestion

Final Report Summary - LIPOGEST (Mechanisms by which interfacial layers control lipolysis on digestion)

LIPOGEST aimed to determine, at a fundamental level, how changes in the interfacial composition and structure of processed food emulsions during digestion influence lipolysis. This project focused on answering generic questions to shed light on the process of food digestion. Introducing these nanoscience and colloidal science concepts will enable rational development of healthier foods with improved functionality, designed to combat the deleterious health effects resulting from the current obesity crisis in the EU.

To develop realistic scenarios of the physicochemical processes occurring during digestion of processed food emulsions the research fellow, Dr Julia Maldonado-Valderrama, has developed novel methodology (atomic force microscopy and interfacial science methods) to define the effects of digestion (acid pH, body temperature, enzymes, phospholipids and bile salts) on the structure of representative interfacial protein networks. Initial model studies at air-water interfaces were extended to more realistic oil-water interfaces and oil in water emulsions with direct practical relevance to the future design of novel functional foods. The results demonstrate feasible approaches for modifying interfacial structures to control (reduce) the rate of lipolysis and hence potentially induce physiological responses that could moderate fat consumption.

Approach

The project initially looked at the mechanism of displacement of interfacial proteins by bile salts in the duodenum and identified the approaches needed to moderate lipolysis. These studies were then extended to investigate effects of gastric conditions on interfacial structures in order to identify how to implement these approaches in real systems.

Conclusions

LIPOGEST has shown the value of a fundamental physical approach to understanding this type of complex biological problem: improved understanding will enable rational design of food emulsions, an acceptable form of nanotechnology. Lipase-colipase complexes adsorb to lipid droplet surfaces to enable fat hydrolyis (lipolysis). LIPOGEST pioneered use of AFM and surface science tools to probe effects of digestion on interfacial structures. Use of nanoscience methods to visualise bile salt adsorption under in vitro duodenum conditions suggest that interfacial structures of protein-stabilised emulsions could be designed rationally (strengthened) to control bile salt adsorption, reducing lipase-colipase adsorption and rates of lipolysis, inducing satiety, and thus lowering fat intake in the diet.

The important finding of novel synergisms between surfactants and proteolytic enzymes suggest that similar approaches would also offset surfactant-induced proteolysis in the stomach enabling such strategies to work for processed food emulsions. The studies showed the importance of the nature of the oil phase used in designing such foods. The challenge is to manipulate natural nanostructures in foods to rationally design healthier foods. This is generating renewed scientific interest due to the growing social and economic consequences of the obesity crisis in the developed world.

Design of healthier foods to control fat uptake is a top priority in the EU: it is estimated that treating obesity and related conditions uses ~ 7 % of the total healthcare budget. Improved understanding of the digestion and metabolism of lipids, and possible ways that this can be modified is of paramount importance in order to address this problem effectively, and LIPOGEST has helped pioneer such studies.