4. Conclusions
Enzyme pre-treatment of ginger had a significant influence on the yield of oleoresin, 6-gingerol and the total polyphenols. Highest yield of 6-gingerol was obtained in the case of treatment of ginger with viscozyme or amylase followed by acetone extraction. The gingerol yield was also high in acetone extracts obtained from ginger pre-treated with pectinase and cellulase. Highest yield of oleoresin and polyphenols was obtained with cellulase treatment of ginger followed by extraction with ethanol. In addition to higher yield of resin, ethanol as extracting solvent has other advantages like environment-friendliness, obviation of solvent-residues and improved oleoresin solubility in water and oil. Ethanol-extracted ginger oleoresin obtained from cellulase treatment exhibited good antioxidant activity which could be due to the presence of the bioactive compounds viz., 6-gingerol, shogaols, paradol and zingerone. Ginger oleoresin, with its nutraceutical constituents and a characteristic flavour profile, can be a potent ingredient in functional food formulations. The study indicates that the enzymatic approach would be beneficial to spice industries when the enzymes are used at optimal concentrations as oleoresins are value-added products of commercial importance.
Acknowledgements
The authors are grateful to Dr. G. Venkateswara Rao, Director, CFTRI, for his support and constant encouragement for the work. The help of Mrs. G. Sulochanamma in HPLC analysis and Mr. Padmere Mukund Lakshman in the MS studies of the compounds is gratefully acknowledged.