Enzymatical Hydrolysis of Soy Sauce Lees Proteins to Improve Their Bioactivity

Soy sauce is a traditional condiment in China and many other Asian countries. The main byproduct of soy sauce processing is soy sauce lees, which accounts for 10% of the fermentation material, soybean. Soy sauce lees is mainly used as ingredient of animal feeds. To our knowledge, soy sauce lees is a good source of plant proteins. The protein content reaches 20% of total weight. Due to the poor solubility in water and low extraction efficiency, it is difficult to utilize these proteins in food.

With the financial support of Guangdong Province/Chinese Academy of Science Full Strategic Collaboration Foundation, Prof. JIANG Yueming and Dr. YANG Bao, from Postharvest Biology Group of South China Botanical Garden, Chinese Academy of Sciences, have tried to hydrolyse soy sauce lees proteins enzymatically in combination with ultrasound treatment. The protein recovery can be significantly improved after this treatment. The peptide fraction with molecular weight 3-5 kDa was increased by the hydrolysis. Tyrosine was determined to be the leading free amino acid. Moreover, all the hydrolysates showed good radical scavenging activity. The results will be helpful for extensive utilization of soy sauce lees.

The results have been published on Food Chemsitry. Please see website
http://www.sciencedirect.com/science/article/pii/S0308814610007806.

The radical scavenging activities of six hydrolysates of soy sauce lees proteins.