Preparation and characterization of rice protein isolates

Various enzymes were used to treat a protein-enriched rice flour for the pr oduction of rice protein isolates. The rice flour containing 49% protein wa s a by-product from the processing of brown rice for syrup production. The treatment sequence of alpha-amylase followed by glucoamylase was most effec tive, resulting in a product with 85% protein content. The product was then treated with a mixture of cellulase and xylanase, which raised the protein content in the insoluble fraction to 91%. Inorganic impurities, such as th e metal manganese in the starting rice flour, were effectively removed. The recovered rice proteins, practically intact according to electrophoretic a nalysis, had relatively poor solubility and emulsification properties; howe ver, these functional properties were improved substantially by adding xant han gum as a functionality-enhancing agent.