柚苷酶對柑桔Flavanone-Glycoside水解之研究 (2)柚苷酶對柚類脫苦味之效果

Abstract

Owing to the bitterness of naringin is frequently cited as the principal deterrent to the profitable marketing of pummelo or grapefruit products, an investigation on the enzymatic hydrolysis of citrus flavanone-glycoside by naringinase was made. By using that crude enzyme solution which induced from Aspergillus niger or Asp. oryzae consisted of β-D-glucosidase and α-L-rhamnosidase, favanone-glycoside could be partially hydrolyzed. The β-D-glucosidase was inactivated by heating the crude enzyme solution at 63℃ with pH 6.5 for one hour whereas the α-L-rhamnosidase was very stable under such treatment. Prunin from naringin and persicin from hesperidin were obtained by α-L-rhamnosicase simultaneously, naringenin from prunin and hesperetin from persicin were obtained by the β-D-gIucosidase. It indicated that naringinase S1 was the strongest one of three enzymatic activity as measured by this experiment, Sclase was unsuitably for the cloudy juice making doe to the fact that pectin-hydrolyzed enzyme has contained in it. The lower concentration of naringinase S1 (below 0.5) was used, the better quality would be obtained. The technical method for applying the naringinase to debitter the pummelo or pomelo juice in practice may be introduced by author as follows: Coot the blanched fruit juice or segments to 60℃, and an adequate syrup and naringinase in it, then set it for one day under vacuum in order to decompose the bitter-taste naringin into bitterless, put the debittering juice or segments for canning or bottling. Though hesperidin in tonkan juice or segment could be decomposed by the naringinase too, however, the yield of its decomposed matter was very poor. The mudiness in syrup of the canned tonkan segments can be efficiently prevented by the methyl cellulose method.