Preparation Of Flaxseed Oil Microcapsule And Its Application In Soybean Milk

Alpha-linolenic acid is a kind of?-3 fatty acid,which is essential for human body.It has a variety of health care functions and has a positive effect on human health.Nowadays,the average intake of?-3 fatty acid in China is far less than the recommended amount by the National Health Organization,which do great harm to people's health.Therefore,it is necessary to enhance the intake of?-3 fatty acid.Soybean milk is a kind of plant protein beverage which is very popular in China.In this study,linseed oil microcapsules with high quality were prepared by vacuum freeze-drying technology with linseed oil as raw material(more than 50%of the fatty acids in linseed oil are?-linolenic acid),and then applied to soybean milk to develop a kind of nutritional soybean milk rich in?-linolenic acid,so that people can obtain?-linolenic acid(?-3 fatty acid)in daily diet.The main test contents and results are as follows:(1)The linseed oil was embedded with starch sodium octenyl succinate(SSOS),whey protein concentrate(WPC)and trehalose as compound wall materials and sodium caseinate as emulsifier.Taking the stability of emulsion as the index,using single factor and orthogonal experiment,the optimum conditions for preparing the emulsion are as follows:the ratio of wall material(SSOS:WPC:trehalose)is 3:1:2,sodium caseinate additive amount is 1%,the stirring temperature is 50?,and the shearing time is 3 minutes.Under these conditions,the stability of emulsion is 98.3%.(2)Taking the embedding rate of microcapsules as an index,single factor test was carried out to determine that the solid content is 17.5%and the wall-core ratio was 2:1.Next,through response surface test,the influencing order of embedding rate of flax oil microcapsules is as following:loading quantity>freezing temperature>drying time.The optimal vacuum freeze-drying parameters of linseed oil microcapsules were as follows:loading capacity was 68 g,drying time was 19 h,and freezing temperature was-30?.Under these conditions,the embedding rate of linseed oil microcapsules was 60.92%.(3)According to the quality analysis,it is concluded that the powder of linseed oil microcapsule is opalescent with fine granules and no bad smell.The water content is less than 5%,the density is 0.217 g/cm~3,the angle of repose is 33.82°,good dispersion;the solubility is 91.83%,higher solubility.It can be seen by SEM that the flax oil microcapsule particles are full and round without obvious depression,and the embedding effect is good.Through the analysis of color difference and peroxide value,it is found that microencapsulation can effectively embed linseed oil,and reduce its color change and oxidation rate.(4)Taking the stability coefficient and sensory score as the evaluation index,single factor and orthogonal test were carried out to determine the best technological parameters of a nutritious soybean milk rich in alpha-linolenic acid:the flax oil microcapsules addition amount is 2%,the addition temperature is 40?,the total amount of trehalose and white granulated sugar is 3%and the ratio of trehalose to white granulated sugar is 4:6.The results showed that the physical and chemical indexes of soybean milk rich in alpha-linolenic acid met the national requirements.Besides,based on the gas chromatography analysis,the content of alpha-linolenic acid in soybean milk added with linseed oil microcapsules is much higher than that in pure soybean milk,which shows the remarkable strengthening effect.