The Preparation Of Soy Protein For Drinks By Diafiltration-ultrafiltration Technology

Soy protein has a high nutritional value and excellent functional properties, been widely used in baked foods, meat products, fortified foods, and other fields. Although the range of applications and demand of soy protein continued to expand, but the applications of soy protein in the beverage industry is not affirmative, due to the impact of its own nature. In this paper dedicated to acidic drinks and high solubility and high transparency soy protein products was prepared, lead to the value of soybean resources was increased. This paper studies process conditions of preparation of soy protein by the enzyme assisted processing combined with ultrafiltration- filtration technology integration, the functional properties of soy protein prepared by this method and application characteristics in sports drinks and juice drinks were studied. The main conclusions are as follows:(1) A optimization technology to prepare soy protein were established with salt mention,enzyme assisted processing combined with ultrafiltration-percolation process. Defatted soybean meal and defatted soybean meal enriched with 7S were used as two kinds of raw materials, 0.4~0.5M Ca Cl2 solution selected as as an extract, acidic soluble fraction were extracted from different raw materials, respectively, and the phytic acid content was reduced by phytase. The pigment, phytic acid, trypsin inhibitors and other undesirable impurities were effectively removed by ultrafiltration-diafiltration technology three treatments for three times,after the hydrolysis completed, while sufficiently concentrated protein solution, and then a soy protein products were obtained after Pasteurization and spray-drying.(2) The functional properties of soy protein prepared by ultrafiltration-preparation percolation was studied. The results showed: the phytic acid content of SPI and 7S prepared by ultrafiltration-preparation percolation were only 0.694% and 0.665%, respectively; has high solubility in the acidic range, particularly in the vicinity of p H 4.0, nitrogen solubility index of7 S was up to 90 % or more; the thermal stability and oil retention of SPI, 7S were reduced;enzymatic liquid of SPI exhibited better foaming, foam stability was excellent, foam was fine and milky white; enzymatic liquid of 7S exhibited poor foaming, foam was very unstable,foam almost completely disappeared after 2h. 7S prepared by ultrafiltration-preparation percolation show better tolerance to Ca2+, conversely, poor tolerance to K+; in the acidic range,the turbidity SPI prepared by ultrafiltration-preparation percolation was reduced after the addition of a calcium solution, the potential of 30 m V could reach the stable value, the particle size wass concentrated in the range of 10~50μm.(3) The complex applications of soy protein prepared by ultrafiltration-preparationpercolation in sports drinks and juice drinks. 1% concentration of the protein complex solution were obtained by SPI, 7S dissolved in Gatorade, Sprite, respectively, this complex liquid been provided many advantages,such as low sour taste, good taste, high clarity, etc.Electronic tongue bionic test results speculated the add of this soy protein has little effect on the original flavor of the beverage; the interaction of protein fluid and saliva were studied by simulation experiment outside the body, microscopy results also proved the degree of aggregation of soy protein was very lower after mixed.