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Research Project: Adding Value to Plant-Based Waste Materials through Development of Novel, Healthy Ingredients and Functional Foods

Location: Healthy Processed Foods Research

Title: Enzymatic degradation and bioaccessibility of protein encapsulated ß-carotene nano-emulsions during in vitro gastro-intestinal digestion

item CHEN, LING - Jiangnan University
item Yokoyama, Wallace - Wally
item LIANG, RONG - Jiangnan University
item ZHONG, FANG - Jiangnan University

Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/2019
Publication Date: 7/9/2019
Citation: Chen, L., Yokoyama, W.H., Liang, R., Zhong, F. 2019. Enzymatic degradation and bioaccessibility of protein encapsulated ß-carotene nano-emulsions during in vitro gastro-intestinal digestion. Food Hydrocolloids. 100. Article 105177.

Interpretive Summary: Many bioactive compounds have limited bioavailability because they do not dissolve in water or aqueous systems. Bioavailability increases when compounds are dispersed at the molecular level. Oil in water emulsions are often used to deliver lipid soluble bioactive compounds. Synthetic emulsifiers are very efficient but there are concerns about their safety. Proteins are natural products and their emulsification properties and release properties in a simulated digestion process were studied. During the breakdown of the emulsifier and lipid carrier small molecules that adsorbed to the surface of the carrier lipids were found to impede release of the bioactive materials.

Technical Abstract: The aim of this research was to investigate the impact of proteolysis, lipolysis and bile salts on the stability of oil in water emulsions stabilized by proteins and their effect on bioaccessibility of ß-carotene in an O/W emulsion system. Nano-emulsions were prepared with whey protein isolate (WPI), soy protein isolate (SPI) and sodium casein (SC) with a microfluidizer under the same operating conditions. The emulsions were characterized by particle size, confocal microscopy, interfacial composition, zeta-potential and digestive properties as a function of time during simulated gastro-intestinal incubation. The WPI-based emulsion was relatively stable in simulated gastric fluid due to the emulsifying activity of ß-lactoglobulin, a major component of WPI, while SPI and SC was inclined to aggregate in the presence of pepsin. However, rapid adsorption of lipolysis products and bile salts at the oil-water interfaces for WPI and SC samples sterically hindered the approach of lipase to the lipid core, leading to decreased lipolysis and micellization rates. In the case of SPI-based emulsions, bile salts adsorption and displacement occurred at a lower rate but a higher extent, which provided more surface binding sites for enzymes and accelerated lipolysis. These studies provide information about the relationship between the effects of digestion of the interfacial proteins and the bioaccessibility of lipophilic emulsion contents that could guide the design of safe protein based emulsified bioactive molecular delivery systems.