Using freezing and drying techniques of emulsions for the microencapsulation of fish oil to improve oxidation stability

Epidemiological investigations show that n-3-polyunsaturated fatty acids (PUFA) have a protective effect with respect to coronary heart disease. For a long time fish oil has been known as a source of PUFA. The successful incorporation of fish oil into the normal food components offers an opportunity to increase the intake of PUFA, but fish oil has to be protected against oxidation preferably by microencapsulation. The high temperatures during the traditional spray-drying microencapsulation process lead to an increased oxidation of the PUFA. The authors demonstrate the application of a freeze-drying technique with respect to the production of dried microencapsulated fish oil with high quality and oxidation stability. The influence of emulsion parameters, freezing parameters and formulation on the stability of a dried fish oil emulsion is presented and illustrated. The used procedure gave a product with a good oxidation stability which is available as pellets or powder. It was found that the stability was mainly influenced by the freezing process and the used encapsulation carbohydrate, whereby the powder showed a better shelf life than the pellets. Concluding, it can be summarized that the production of dried microencapsulated fish oil by freezing and subsequent freeze-drying offers an opportunity to achieve a product with a good oxidation stability. (C) 1999 Elsevier Science B.V. All rights reserved.