Extraction Of Ginger Protease

Ginger protease was extracted by solvent precipitation from different raw materials. The influences of operation conditions on extraction rates were studied by single factor experiment. Ginger proteases extracted from differennt raw materials were studied. The method used to mensurate the content of ginger protease was studied. The method of mensurating the activity of ginger protease was estabilished. Uniform Design experimental method was used to study the activity mensuration condition. Ginger oleoresin was extracted by SC-CO₂ from the remainder of ginger protease extracting, and the extraction rates, chemical compositions and physical properties were compared with ginger oleoresins extracted from sundried ginger by SC-CO₂ and solvent.The analysis and test methods were confirmed by experiments firstly. The experiments and conclusions are described below.The content of ginger protease was measured by the method of Coomassie Brillrant Blue G-250. It was testified that this method could measure the content of protease in the raw extract accurately, and the linear scope was 10～50μg/ml.The activity of ginger protease was measured by casein assimilation method. In the Uniform design experiment, five facters in the reaction were considered that influenced the activity of ginger protease, which were temperature, pH, the concentration of casein, protease and activation. The concentration of L-Tyrosine as the resultant in reaction was tested. By uniform design and data analysis, the relational expression was acquired to explain the relationships of ginger protease activity and mensuration condition, and the best condition was gotten and validated. Under optimal conditions, the equation had a 0.586(Abs) report for protease activity. In fact, the activity was 0.565(Abs), so the deviation could be accepted.Gas Chromatography/Mass Spectrometry was used to quantify and qualify the chemical compositions of the oleoresins. The testing condition was ascertained by experiment, and the fragrant and pungent compounds were main compositions examined.The physical properties of the oleoresins were mensurated according to standards.Secondly, the best condition in the extraction of ginger protease by solvent precipitation was studied. The best condition and the analysis methods described above were used to determine the influences of material preprocessing on the extraction rates and activities of ginger proteases.The possibility of extracting oleoresin from the remainder of ginger protease extracting was confirmed by studing the extraction rate and chemical compositions analysed by GC/MS of the oleoresin. And it was compared with the oleoresins extracted from sundried ginger by SC-CO2 and solvent. The physical properties of the oleoresins, such as optical rotation, refractive index and relative density of ginger oleoresins were also tested.Conclusions obtained from the extraction experiments described below.It was proved that ethanol is suitable solvent in solvent precipitation.The analysis results of solvent precipitation indicated that the extraction rates of raw extracts and ginger proteases rose with the increase of ethanol quantities, but the activities of ginger proiease fell. The quantities of soiveni shougd be considered in the aspects of extraction rates and actixities of ginger protease.Compared the extraction rates and activities of ginger proteases extracted from different materials, it showed that the activities and rates from the remainders of SCFE were all declined compared to fresh ginger. The rates and activities of the two remainders were of no obvious differences. And the process of freeze-dry had some negative influences on ginger protease.By comparing the extraction rates, chemical compositions and physical properties of ginger oleoresins, which were extracted from sundried ginger, the remainder of ginger protease extracting by SC-CO₂ and solvent, it showed that the extraction rate of ginger oleoresin eatracted from the remainder was the same as from sundried ginger by SCFE. The extraction rate of solvent was higher than SCFE. The main compositions of the oleoresins were all sesquiterpene and pungent compounds. The pungent compound in solvent extract was highest, higher than the extracts by SCFE, and the extract from sundried ginger by SCFE was poorest. The optical rotations and refractive indexes of the oleoresins were of no obvious differences, and the relative density of solvent extract was heavier than the other. It implied that the oleoresin extracted from the remainder of ginger protease extracting was comparative in extraction rate, chemical compositions and physical properties with oleoresins extracted from sundried ginger.