Influence of partial hydrolysis on the protein extraction from sunflower meal

Abstract

We investigated the influence of protein hydrolysis degree in the presence of neutral protease from Bacillus subtilis on the process of protein extraction from sunflower meal. Correlation between protein hydrolysis degree and affectivity of protein extraction was analyzed. Materials and methods. The degree of protein hydrolysis was determined as increase of TCA-soluble proteins concentration compared to control samples. Protein concentration in extracts was determined photometrically. Result and discussion. Determination of protein concentration in obtained extracts have shown that main part of soluble proteins was extracted during first 20 min. The protein concentration in extracts obtained in the presence of protease was approximately twice higher than in control samples. The protein hydrolysis degree was sufficiently low and varied from 3,5 % to 5,2 % at moderate enzyme/substrate ratio. When enzyme/substrate ratio increased the degree of hydrolysis was also rising and it reached 9,0-9,5 % during 40- 60 min. Such level of hydrolysis is desirable for improvement of protein functional properties and higher hydrolysis level results in loss of protein functionality. The protein hydrolysis degree was dependent from the enzyme/substrate ratio and the duration of reaction. Nonlinear model was obtained for estimation of the affectivity of protein extraction as function of enzyme/substrate ratio and extraction time. Obtained model explains 92.81% of data variation and approximates well the available data. It was shown also that high correlation (r=0,69) exists between concentration of proteins in extracts and degree of protein hydrolysis. Conclusion. The partial hydrolysis of sunflower meal proteins by neutral protease resulted in increase of protein concentration in extracts. Obtained model could be used in prediction of protein hydrolysis level during protein extraction from sunflower meal in the presence of proteolitic enzymes and their functional properties.