3. Results and discussion
3.1. Effect of enzyme pre-treatment on yield of oleoresin and gingerol
The enzyme concentration of 0.5% was found to afford optimal results both in terms of oleoresin and gingerol yields. The oleoresin yield was higher (20–21%) on pre-treatment of ginger with cellulase, amylase, pectinase and viscozyme enzymes at 0.5% concentration followed by extraction with acetone (Table 1). The gingerol content in these resins obtained from enzyme treatment was in the range of 10.1–12.2%. The comparative yield of resin and gingerol content obtained from ginger without enzyme pre-treatment were 15% and 6.4% respectively. These results demonstrated that the gingerol content yield could be improved up to 90% on treatment with amylase and viscozyme enzymes and resin to 40% on treating with cellulase enzyme respectively. The yield of oleoresin was found to be optimal in case of extraction of ginger with ethanol (31%), but the gingerol content in the resin was only 5.5%. Although, the yields of resin from ethanol extraction of ginger treated with enzymes showed little or only slight change up to 32%, the gingerol content in resins from ethanol extraction of enzyme-treated ginger samples was higher (6.1–6.3%). These results clearly demonstrated that efficient extraction of the bioactive compound 6-gingerol along with improved yield of the resin could be achieved on pre-treatment of ginger with various enzymes at 0.5% concentration.