Study on the Extraction Process of Tea Leaves with Compound Enzymes Including Cellulase and Pectinase
|School||Zhejiang University of Technology|
|Keywords||cellulase pectinase tea leaves extraction purification compound enzymes|
The application of enzymes in the extraction of function components is a hot area of tea deep-processing. Tea extracts with enzyme extraction is widely used as a mainly raw material in tea beverage manufacture and also used as an additive in food and pharmaceutical industries. In this article cellulases and pectinases were selected for the tea leaves enzyme extration with a goal to improve extraction yield and tea quality.The results showed that single enzyme treatment with homemade or commercially available cellulase and pectinase didn’t break down tea cell wall well. However, the imported viscozyme was a complex enzyme which had relatively high activity against cellulose and pectin. Compare with single enzyme treatment, viscozyme can completely hydrosis the tea cell wall polysaccharides with the extraction yield and tea infusion quality improved.By single factor and orthogonal test draw the optimal condition of viscozyme treatment in tea leaves extraction were:enzyme dosage2.4 U/g, substrate concentration6.5%, hydrolysis temperature50℃hydrolysis time8h and pH value5.0. Under this condition the content of reducing sugar reached287.8mg/g and water extracts content reached56.5%, which were96.9%and38.5%higher than that of tea leaves extraction without enzyme treatment. The viscozyme was recovered for second batch enzyme extraction. When tea leaves dosage was400mg and cellulase dosage was0.3IU/g, the content of reducing sugar reached241.8mg/g and water extracts content reached61.5%after6h hydrolyzation, equal to the level of the first batch enzyme extraction.The compositions of viscozyme were purified and analyzed for further study. Through two steps of purification, ploygalacturonase, pectin lyase and cellulase were isolated from viscozyme. One kind of ploygalacturonase was purified with the specific activity of51.8U/mg, the yield of5.2%and the purification fold of4.1; One kind of pectin lyase was purified with the specific activity of15.5U/mg, the yield of47.6%and the purification fold of13.1; One kind of cellulase was purified with the specific activity of4.5IU/mg, the yield of13.0%and the purification fold of12.5.According to the compositions of viscozyme, the homemade or commercially available cellulase and pectinase were properly compounded for combination treatment in tea leaves extraction. The optimal condition was carried out with the dosage of cellulase and pectinase at1.2IU/g and0.4U/g, respectively. And the content of reducing sugar reached284.1mg/g, water extracts content reached57.5%. In addition, comparing with the tea extracts without enzyme treatment, the tea infusion qualities with compound enzymes treatment including liquor color, odour and flavor improved a lot. In general, the efficiency of compound enzyme treatment reached the level of viscozyme treatment. Through analysis of costs, compound enzymes including homemade cellulase and pectinase can take place of viscozyme in tea leaves extraction. The costs of former to manufacture one ton tea concentrate (solid content45%) were2086yuan less than that of viscozyme.