On Method Improvement For Oil Extraction And Comprehensive Utilization Of Protein In Sliybum Maruianum Seed Kernel

The shell and kernel of Sliybum maruianum seed was separated first, and then the oil and protein in the kernel were studied. For oil utilization: a) Effects of oil extraction methods on the properties of the oil and proteins were compared, and the best oil extraction method was obtained; b) For the chosen method, factors of influence on oil extraction rate were studied, the major factors were identified, and the oil extraction process was optimized; c) Effects of treatments on the cell structure were observed by scanning electronic microscopy, and mechanism of oil extraction affected by the treatments was explored. For protein utilization, proteins left after oil extraction were hydrolyzed with enzymes, and process of enzymatic hydrolysis was optimized with aim of high antioxidant activities. The results were as follows.1. Among the four methods of oil extraction (the aqueous extraction, oppression extraction, SFE-CO₂ extraction, and solvent extraction), the aqueous extraction had least effect on the physical-chemical properties of extracted oil, with low acid value, high conservation of vitamin E, low color, and no unpleasant flavor. The Differential Scanning Calorimetry plot of proteins showed that the aqueous extraction had little effect on protein structures, which is good for valuable utilization of the Sliybum maruianum proteins.2. Different treatments had different effects on the cell structure of Sliybum maruianum kernel, observed by scanning electronic microscopy. Mechanical oppression alone can break the cell wall but was hard to break the membrane of lipoprotein bodies; and excessive mechanical treatment might result in additional emulsification, causing lower rate of oil extraction. Preceded by proper mechanical treatment, suitable ultrasonic treatment improved oil extraction rate about 20%.3. In terms of antioxidant activities of their enzymatic hydrolysates, the enzymes had the following order: papain >natural protease>flavormase>trysin; Enzymatic hydrolysate of papain had the best sensory quality. By central composition design and response surface method, the parameters affecting antioxidant activity were optimized as: when concentration of the substrate is 2.73%, the enzymatic hydrolysis time, temperature, pH, and ratio of enzyme to substrate were 280.8min, 54.3℃, 6.2, and 0.01, respectively. Under these conditions, the enzymatic hydrolysate had antioxidant activity of 18.84 U/mg proteins and nitrogen recovery of over 80%, with light yellow in color and no bitter in taste. The equation relating antioxidant activity with pH, time and temperature was obtained with statistic analysis software, and the predicted values were verified well by the experimental data (R²=0.934), indicating that this model could be used for predicting and controlling the related enzymatic hydrolysis processes.