大豆蛋白/壳聚糖凝聚法制备微藻油乳液及其稳定性研究

微藻油富含ω-3多不饱和脂肪酸二十二碳六烯酸(DHA)与二十碳五烯酸(EPA),在液体食品中的应用日趋广泛。但是微藻油极易在食品加工、保藏和消化过程中发生氧化劣变;同时脂溶性的微藻油难以添加至液体食品中。因此,改善和提高微藻油的稳定性是其应用到食品中的关键问题。本文利用大豆分离蛋白(SPI)/壳聚糖(CS)复合凝聚物(Coacervate)制备了微藻油乳液。由于乳液的氧化稳定性很大程度上依赖于其物理稳定性,本文系统研究了微生物谷氨酰胺转氨酶(m TGase)交联对微藻油乳液物理稳定性及氧化稳定性的影响。实验结果表明,在p H为6.0,CS/SPI比例为0.1 g/g,m TGase浓度为25 U/g SPI的条件下,m TGase对SPI/CS凝聚物的交联效果最好。m TGase交联明显改善了微藻油乳液的物理稳定性及氧化稳定性,并显著提高了微藻油的乳化效率。通过此方法制备的微藻油乳液产品可应用于豆奶等液体蛋白饮料从而达到强化DHA的目的。

Preparation and Evaluation of the Stability of a Microalgae Oil-water Emulsion by Using Soybean Protein-chitosan Coacervate as an Emulsifier

Microalgae oil is rich in polyunsaturated fatty acids, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), commonly added to liquid foods. However, microalgae oil is prone to oxidative deterioration during food processing, preservation, and digestion. In addition, it is difficult to add liposoluble microalgae oil to liquid foods. Therefore, improving the stability of microalgae oil is critical for its application in the food industry. Here, a microalgae oil-water emulsion was prepared using soybean protein isolate (SPI) and chitosan (CS) coacervate. Because the oxidative stability of emulsions depends greatly on their physical stability, the effects of cross-linking with microbial transglutaminase (mTGase) on the physical and oxidative stabilities of the microalgae oil-water emulsion were investigated. The results indicated that the optimum cross-linking effect of mTGase on SPI/CS coacervate was achieved under the following conditions: pH: 6.0; Cs to SPI ratio: 0.1 g/g; mTGase concentration: 25 U/g SPI. Cross-linking with mTGase significantly improved the physical and oxidative stabilities of the microalgae oil-water emulsion, as well as the emulsifying efficiency of microalgae oil. The microalgae oil emulsion product prepared using this method can be added to soy milk and other liquid protein drinks, thus enhancing the health benefits from DHA.