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

Studies on the Enzymatic Hydrolysis of Citus Flavanone-Glycoside by Naringinase (2) Debittering of Pummelo and Pomelo Fruits by Naringinase

因柚苷之苦味使柚類或葡萄柚類之果實不能達到加工製造之目的，本研究即應分解柚苷酶素（Naringinase）對柑橘黃齫酮糖苷（Citrus flavanone-glycoside）之水解活性加以採究。發現若所應用之酵素液加熱至63℃及pH 6.5經一小時，其中所含之B-D-glucosidase則失去活性，而所含另一酵素α-L-Rhamnosiease則仍可保持相當之活性，該酵素能將柚苷分解出Prunin，柑果苷分解出Persicin，若同時存在有β-D-glucosidase，則可將Prunin分解柚苷素（naringenin）或將Persicin分解出柑苷素（Hesperetin）。柚苷酶所用之濃度經在0.5%左右，則可獲得較佳之柚果果汁或瓤片罐頭之品質，實際若應用此柚苷酶於柚果之脫苦味，本文介紹其方法如下：冷卻經殺菁之果汁或瓤片至63℃以下，加入適量之柚苷酶及糖液，在真空處理下讓酵素水解柚苷為無苦味質，經一天後，再將脫苦味後之果汁或瓤片製罐或瓶裝則可。雖然桶柑之果汁或瓤片中之柑果苷亦可由柚苷酶予以分解，但其分解率操作尚不及早基變維素法來得簡單而有效。

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.