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Microencapsulation of fish oil to improve delivery of omega-3 fatty acids for food applications


NSF-MILES IGERT co-director Susan Duncan, and MILES IGERT trainee and recent graduate (December 2009) Sabrina Hannah have developed and characterized spray-dried fish oil microcapsules for use in foods. Fish oil is a good source of omega-3 fatty acids and therefore has value as a food ingredient. However, is technically challenging to incorporate fish oil into foods due to the high susceptibility to oxidative deterioration, off flavors and odors associated with the source, and food matrix compatibility issues. Capturing fish oils into a very small capsule of a food-compatible material, called microencapsulation, offers advantages for solubility and protection of sensitive ingredients. Microencapsulation can improve the stability of fish oil and facilitate its use of as a food ingredient.

Chitosan, a carbohydrate molecule, can be used as an encapsulating material and offers low ingredient costs, high availability, and potential health benefits. This molecule is nontoxic, biocompatible, and biodegradable. It offers unique and beneficial properties for food and pharmaceutical applications, including antimicrobial activity, emulsion stabilization, metal chelation, bioadhesion, immunostimulatory activity and the potential for controlled release. Researchers at Virginia Tech studied two types of chitosan differing in molecular weight and variation in glucosamine units as encapsulating material for fish oil.

Microcapsules of fish oil in chitosan were formed by spray drying at two different oil load levels. Oxidative stability of the fish oil and interaction of fish oil and chitosan were studied. The type of chitosan and the oil load both affected the oil droplet size and encapsulating efficiency during the process and the final microcapsule properties. Lower levels of glucosamine units and lower molecular weight of the microcapsules structures provided better incorporation of lipid into the microcapsule structure and higher encapsulation efficiency. However, microcapsules with more glucosamine units were better able to withstand oxidation. The researchers also evaluated unique encapsulation materials (chitosan, high-amylose starch, and pullulan). Higher encapsulation efficiencies were observed for chitosan with a greater amount of amino groups (95% deacetylated) and low molecular weight than for chitosan with fewer amino groups (78% deacetylated) and medium molecular weight, however; microcapsules prepared from the latter chitosan may afford better protection against oxidation as evidenced by accelerated oxidative stability tests. Microcapsules prepared from blends of chitosan, starch and pullulan appeared to exhibit even greater oxidative stability than those prepared from chitosan alone. All microcapsules prepared had suitable properties for use in a variety of food matrices. This work also showed that chitosan is a promising material for improving emulsion stability.

Address Goals

The food and pharmaceutical industries can use this information in the development of new technologies and applications for including fish oils into foods, supplements, cosmetics, and pharmaceutical products. Using chitosan as an encapsulating ingredient offers protection for the fish oil and provides a low cost source of another ingredient with potential health benefit.