原料「幾丁聚醣」中去乙醯化程度之檢驗研究   全文下載

chitosan, degree of deacetylation, double indicators of titration

幾丁聚醣（chitosan），又稱為甲殼素，經幾丁質部分去乙醯化作用形成D-葡萄糖胺（D-glucosamine）及N-乙醯葡萄糖胺（N-acetyl-D-glucosamine）之直鏈共聚物。本研究配合行政管理之施行，以雙指示劑滴定法建立原料「幾丁聚醣」中去乙醯化程度（degree of deacetylation, DDA）之檢驗方法。檢體於105℃乾燥24小時後以0.1M鹽酸溶解，於60℃水浴振盪約2小時，藉由酚肽與甲基橙－苯胺藍作為指示劑，以0.1M鹽酸將檢液由藍綠色滴定至紫紅色達滴定終點。確效結果顯示，同日間5種不同DDA之標準品及1種食品級原料的檢測值與標示值之百分比及變異係數分別介於96.0－105.0％及0.3－0.9％；異日間的檢測值與標示值之百分比及變異係數分別介於97.－105.0％及0.4－0.9％。另取標示DDA分別為76及94％之兩種幾丁聚醣標準品以1:1等重量比例混合做為回收率試驗基質，其同日間及異日間回收率分別為100.2及100.1％，變異係數為0.3及0.2％，顯示具有良好之回收率、精密度與準確度。另檢驗1件已知配方且有幾丁聚醣去乙醯化程度標示之膠囊食品，其DDA之平均檢測值與原料COA標示值之百分比為108.1％，變異係數為1.6％，顯示本方法對此膠囊食品亦具有良好之準確度與精密度。

Chitosan is a straight-chain copolymer composed of D-glucosamine and N-acetyl-D-glucosamine, and is obtained by the partial deacetylation of chitin. In this study, a titration method utilized double indicators was established to test the degree of deacetylation (DDA) in raw material. Sample each was dried in oven at 105℃ for about 24 hours, and then dissolved in 0.1 M hydrochloric acid. The solution was incubated in 60℃ water bath with reciprocal shaking for about 2 hours. Two indicators, phenolphthalein and methyl orange-aniline blue, were added into the solution, and the blue-green chitosan solution was titrated with 0.1 M hydrochloric acid until it turned purple-red. A method validation contained five chitosan standards with different DDAs and one raw-food material was conducted. The results showed that the detected values and the labeled values in intra-day study were between 96.7 and 105.0%, and the coefficients of variation were between 0.3 and 0.9%, respectively. For the inter-day study, the detected values to the labeled values were between 97.0 and 105.0%, and the coefficients of variation were between 0.4 and 0.9%, respectively. Two chitosan standards with DDAs 76% and 94% were blended at the ratio of 1:1 in weight for recovery study. The results showed, the recoveries in intra-day and interday were 100.2 and 100.1%, and the coefficients of variation were 0.3 and 0.2%, respectively. This method offered high recovery, precision and accuracy. One capsule sample with known ingredients and DDA was analyzed. The detected value to the labeled value was 108.1%, and the coefficient of variation was 1.6%. This results showed that this method was accurate and precise for capsule sample as well.