The Study Of The All-soymilk On The Preparation Process And Stability

A suitable preparation process and the basic formula of the all-soymilk was developed based on the precipitation rate, protein content and sensory evaluation index. The bean was soaked in 0.5%NaHCO3 in the bean/solution with ratio 1:3 for 12 hours. Afterwards, the bean was ground four times in 80℃hot water. The soya bean milk was heated at 90℃for 8 minutes. After cooling down to 70℃, the soya bean milk was homogenized respectively twice at homogeneous pressure 40MPa and 50Mpa. And then we can carry out filling and sterilizing. Finally, the procedure about the sterilizing temperature and time was determined to be 121℃and 15 minutes, respectively, with a nine-month guarantee of the product based on the microbiology experiments. The concentration of the all-soymilk is 6.25% and the protein concentration of the all-soymilk is larger than 2.0%.The stability of hydrocolloids on all-soymilk system was studied. The results showed that 0.12% carrageenan can best stabilize the all-soymilk, followed by pectin, PGA and agar, and then the gum arabic, gelatin and gellan gum. These hydrocolloids were mutually regrouped with the total amount of 0.12%, and the eventual optimum compound formulation of hydrocolloids was determined to be that carrageenan: pectin: Arabic gum ratio is 1:5:12. The best suitable dosage range of the compound hydrocolloids was between 0.18% and 0.24%.The effects of single phosphate, citrate and complex phosphate on the stability of all-soymilk were studied by single factor and orthogonal tests. The results indicated adding salts into all-soymilk can improve the viscosity and stability of the all-soymilk. However, adding amounts and kinds of salts have optimal value, and stabilizing effect is also different with different kinds of salts. Compound salt is better than the single salt in the stabilizing effect. The best compound salt formula, which is 0.013% sodium hexametaphosphate, 0.033% sodium tripolyphosphate and 0.027% sodium pyrophosphate, was obtained by orthogonal tests and sedimentation rate index.The effect of emulsifier on the stability of all-soymilk was studied. The best suitable HLB is between 8.3 and 9.3 with the optimal value of 8.8. The results showed that compound emulsifier is better than single emulsifier for the stability of all-soymilk. The best suitable compound emulsifier formula of all-soymilk is 30%DMG, 34% tripolyglyceryl fatty acid ester and 36% soy lecithin. The total amount of compound emulsifier is between 0.1% and 0.15%. In order to further improve the stability of all-soymilk system, the compound hydrocolloids were composited with compound emulsifier and complex salts. The best stabilizer formula of the all-soymilk is 0.24% complex hydrocolloids (carrageenan: pectin: Arabic gum ratio is 1:5:12), 0.063% compound salts (sodium hexametaphosphate: STPP: sodium pyrophosphate ratio is 0.013:0.033:0.027) and 0.15% complex emulsifier (distilled monoglycerides molecules: tripolyglyceryl fatty acid ester: soy lecithin ratio is 30:34:36).Finally, the stability mechanism of the stabilizer and homogeneous process on all-soymilk was studied preliminarily by the microscope observation with camera, laser particle size analysis and rheological method. The results indicated that, homogeneous processes can greatly reduce the size of the material, different homogenization pressure can affect the interaction between colloidal particles and system particles to some extent and the complex stabilizer have kept the dispersion state of system in the way of packaging particles. Complex hydrocolloids and compound salts have not changed pseudoplastic rheological characteristics of the all-soymilk, however, they increased the apparent viscosity of the system, which decreased with the increasing shear rate.