Microencapsulation of fish oil with n-octenylsuccinate-derivatised starch:: Flow properties and oxidative stability

Fish oil with 33% long-chain polyunsaturated fatty acids was microencapsulated in a matrix of n-octenylsuccinate-derivatised starch and glucose syrup and stored at varying temperatures (5, 20 and 40 degrees C) and relative humidities (11, 33, 48-59 and 75%). Development of lipid oxidation parameters upon storage depended to a certain extent on temperature, but to a much greater extent on relative humidity. Temperature had no significant effect on the development of lipid oxidation parameters when samples were stored at 11 or 33% relative humidity. Hydroperoxide concentration doubled over the storage period and reached from 88 to 146 mmol/kg oil in the samples stored at 11 and 33% relative humidity, respectively. An increase in hydroperoxide concentration with increasing storage temperature was observed at 48-59% relative humidity. In all samples, the increase in the lipid oxidation parameters was not linear or exponential and significantly differed from the course as it is described in the literature for bulk oils and emulsions. Based on data for colour measurement, moisture sorption and extractable fat, the course of lipid oxidation is discussed. Finally, the use of silica derivatives and tricalciumphosphate efficiently improved the flowing properties of microencapsulated fish oil without affecting the oxidative stability of the products.