The aim of the present research was to identify principal parameters determining the oxidative stability of microencapsulated fish oil. Microcapsules were prepared by spray-drying using different types of n-octenylsuccinate-derivatized starch, gum Arabic, sugar beet pectin, sodium caseinate, and/or glucose syrup. Two principal components to classify the different microcapsules accounting for up to 79% of the variance were identified. The principal components were determined by physicochemical parameters reflecting the emulsifying ability of the encapsulant and the drying behavior of the parent emulsion. Microcapsules, which were identified by principal component analysis to be significantly different, exhibited a low stability upon storage, showing that the principal components and, thus, the underlying physicochemical parameters analyzed in the present study are correlated with core material stability.

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a b s t r a c tThere is a growing interest in using fibrils from food grade protein, e.g. b-lactoglobulin, as functional ingredients. In the present study, the functionality of fibrillar b-lactoglobulin from whey protein isolate (WPI) was compared to native WPI in terms of interfacial dilatational rheology and emulsifying activity at acidic conditions (pH 2.0 and 3.0). We report here for the first time data on microencapsulation of fish oil by spray-drying as well as oxidative stability of the oil in emulsions and microcapsules in dependence of WPI conformation. WPI fibrils exerted a significantly higher elasticity at the oil-water (o/w) interface and a better emulsifying activity at a fixed oil content compared to native WPI. Microencapsulation efficiency was also higher with fibrillar WPI (>95%) compared to native WPI ($90%) at pH 2.0 and a total oil and protein content of 40% and 2.2%, respectively, in the final powder. The oxidative deterioration was lower in emulsions and microcapsules prepared with fibrillar than with native WPI. This was attributed to improved interfacial barrier properties provided by fibrils and antioxidative effects of coexisting unconverted monomers, particularly hydrophilic peptides.

Microencapsulation of fish oil with n-octenylsuccinate-derivatised starch: Flow properties and oxidative stabilityFish 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 7C) 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.