Optimization of processing parameters on the yield of oleoresin from zingiber zerumbet and its antibacterial activity

Abstract

The effect of processing parameters on the yield of oleoresin from Zingiber zerumbet and its antibacterial activity was investigated. The preliminary experiments were carried out to determine the main parameters that affect the yield of oleoresin, zerumbone content and antibacterial activity on the Escherichia coli and Staphylococcus aureus of Z. zerumbet oleoresin. The main parameters were found to be extraction time, type of solvent used and blanching treatment. The range of those parameters that was investigated to get the highest of all yield were blanching treatments (untreated, boiled, steamed), solvent (acetone, ethanol and methanol) and extraction time (6 hours to 18 hours). A D-optimal design was employed to study the effect of different range parameter of Z. zerumbet oleoresin on four response variables; the yield of oleoresin, the zerumbone content, the antibacterial activity on the E. coli and S. aureus. Analysis of variance and response surface methodology were applied to identify the optimal processing parameter. The optimal processing parameters that fulfilled the requirement for yield of oleoresin, zerumbone content, antibacterial activity on the E. coli and S. aureus with high desirability were found to be 18 hours of extraction time, methanol as the solvent used and steaming as the blanching treatment. The desirability value was 84 %. Meanwhile, the optimal yield of Z. zerumbet oleoresin was 31.50 % (w/w), the zerumbone content was 0.56 % (w/w) and the antibacterial activities (inhibition zone) on the E. coli and S. aureus were 14.58 mm and 13.51 mm respectively. Processing optimization has resulted in an increase of overall antibacterial activity on the E. coli and S. aureus of Z. zerumbet oleoresin as well as the increment yield of oleoresin and zerumbone content