Studies On The Preparation Of Fruit Juice Soymilk And Its Stability

A suitable method for soy milk extraction was developed by testing the influences of processing parameters on yield of soy protein. Whole bean was soaked in 0.5% NaHCO3 at bean / water ratio 1:3, solution at 20℃for about 10 hours followed. After that, bean was grond with hot water for two times at bean / water ratio 1:6.The percentage addition of soymilk,fruit juice,sugar and acid were decided upon, by organoleptic evauation, at 2 times,10%,12% and 0.4%,relatively.The stability actions of hydrocolloids on soymilk system were studied. The result showed that PGA,CMC and pectin could stabilize fruit juice soymilk effectively. Their optimum added quantity were found as 0.2%, 0.5%, 0.8% respectively. Propylene glycol alginate(PGA) was selected the best stabilizer of the product, and the proper amount of PGA was 0.3%. And CMC, pectin , guar gum could not decrease the addition amount of PGA.The effects of single phosphate,citrate and complex phosphate on the stability of fruit juice soymilk were studied by single factor and orthogonal tests .The results indicated that the viscosity,particle size and stability of the fruit juice soymilk were improved and different by adding different amounts and different kinds of salts. The optimum amount of citrate ,SHMP,STP,SPP and complex phosphate is 0.07%,0.07%,0.07%,0.05%,0.073%.,relatively.The effect of stability of added citrate is better than that of added single phosphate, but inferior to complex phosphates. The effect of emulsifier on the stability of fruit juice milk is researched. The best suitable HLB and the best combination of emulsifers are made up. The results showed that the suitable HLB was 9.1 and the best combination of emulsifiers were 30%DMG + 34% tri-polyglyceryl fatty acid ester + 36% Tween40.The optimal usage level of combination of emulsifiers was determined as 1/15. The suitable combination of emulsifiers were 0.1%～0.15% in fruit juice milk.Finally, from the rheological test , The result showed that PGA was not change the rheologic character of soymilk , but improved the viscosity of Fruit Juice soymilk. Complex phosphate was not change the rheologic character of soymilk too ,but increased the viscosity that made by PGA and improved the stability of this system. In addition, the mechanism of stabilization for fruit juice milk emulsion was also investiged.The result showed pH and content of protein are the main factors effecting the stability.The stability of the system mainly depends on the concrete interaction between the additives and the protein, the oil,while increasing the viscosity to decrease the sediment velocity is less important.