Preparation And Release Behavior Of Flaxseed Oil Microencapsulation

Flaxseed oil belongs to the vegetable origin which contains a variety of unsaturated fatty aids including α-linolenic acid, linoleic acid, oleic acid etc. Especially the content up to 53% of α-linolenic acid inside is more than any other vegetable oils. The application of flaxseed oil in food has been largely restricted, because the unsaturated fatty acids exsited are easily oxidized and also provide a specific kind of smell. In order to slow down the oxidation of unsaturated fatty acids in liquid oil, flaxseed oil microcapsules were prepared by spray drying, with the mixture of SPI and MD, as wall materials and flaxseed gum as the emulsifier.In the preparation of microcapsules, firstly the O/W type emulsion was formed during shearing emulsification, followed by high pressure homogenization, and then the microcapsules were produced by spray drying. Four factors and three levels orthogonal experiments were designed by four single factor experiments, and the optimized experimental conditions were: solid content 15%, core-to-wall material ratio 1:1.5, emulsifier content 1.6g/500 mL, inlet temperature 180℃. The encapsulation rate reached 86% in further validation experiments.The physicochemical properties and stabilities of the microcapsules were studied, the result showed that the flaxseed oil microcapsules had total oil content of 38.03%, surface oil content of 4.99%, encapsulation efficiency of 86.87%, water content of 1.30%, the bulk density was 0.24g/cm3; the angle of repose was 33.82° and presented good flowing characteristics; particle analysis found that the sizes of microcapsules were equally distributed, focused on 7.5μm-31.62μm; roundness is 0.84 and closed to sphere; the solubility of the product is good at room temperature; the result of TG and DSC analysis indicated that the microcapsules started thermal decomposition when the temperature reach 190℃; acceleration storage test showed that POV of microencapsulation flaxseed oil was changed slowly and had better stability. According to the microcapsule figure by SEM and LCSM, it was showed that the embedding structure had been formed.In this research the releasing behavior of flaxseed oil microcapsules in different conditions was studied: Avrami’s equation was used to fit the releasing progress underdifferent tempertures and RH, R2 > 0.97. When it comed to 5℃, RH=34%, the releasing speed arrived at the bottom which is an appropriate condition for storing. The releasing rate constants under SGF and SIF conditions were compared base on first-order kinetic model. It was obviously that BSGF=2.485×10-2 was far lower than BSIF=4.592×10-2 which meant microcapsules had sustained-release behavior in SGF solvent. The observation to microcapsules by LCSM after fluorescence staining supports the result that only a small amount oil was released in SGF solvent while nearly 60% releasing was found in pancreatic juice which comply with the human intestinal digestion and absorption.The sensory evaluation, heat composition detection, fatty acid composition, size distribution, instant solubility etc. were compared among three types of powdered lipid products( self-made products and two commercial ones). On the whole, these production showed some differences on size distribution and instant solubility, but self-made product contained more unsaturated fatty acids which were beneficial to human health.