Study on Soy Protein-Starch Conjugate
The conjugation of soy protein and starch at 60℃ and relative humidity 75% completed in 192 hours. The conjugates showed better solubility in all pHs, and better thermal stability, emulsion, foaming, and water holding capacity over the untreated soy protein at pH6. The molecular weight of starch hydrolysates had some impact on the properties and the reaction of the conjugates. Glucose, which reacted with soy protein swiftly and thoroughly, did not result in conjugate with good physicochemical properties. On the contrary, the lower residue of lysine amino acid in the conjugate would impair the nutrition quality of the modified protein products. On the other hand, high molecular weight reactants like native starch, with lower concentration of reducing carbonyl groups than other glycosyl reactants, resulted in reaction with lower reaction rate and lower reaction extend, and hence made it commercially unfavorable. As a whole, conjugates from starch hydrolysate with DE 5～10 showed better functional properties.