Dtermination of Carbohydrates and Free Amino Acids in Tea Plants with Immobilized Enzymes and H2O2 Electrode

[摘要] To measure the content of glucose, sucrose, starch and free amino acids, the method using immobilized enzyme membranes and H2O2 electrode was investigated. From tea powder, each substrate was extracted with distilled water at 60°C for 1-2 hr. Sucrose and starch were converted to β-D-glucose by invertase, mutarotase and amyloglucosidase, respectively. By immobilized glucose oxidase and amino acid oxidase, glucose and free amino acids reacted with O2 and formed H2O2 of which content was measured with H2O2 electrode. When values of carbohydrates content obtained from immobilized enzyme method were compared with those obtained from the modified method of MURAYAMA et al, correlation coefficients of glucose, sucrose and starch were 0.962 (n=9), 0.991 (n=13) and 0.971 (n=10), respectively. Correlation coefficients of free amino acids contents between immobilized enzyme method and ninhydrin method were 0.999 (n=4) in different organs and 0.725 (n=20) in different varieties. The immobilized enzyme method showed some characteristics as follows; 1)Compared to HANES method that is based on chemical reactions, this method is highly specific to substrates and shows linearity in relative wide range. 2)Owing to the specificity to substrates, samples can be extracted with hot water, resulting in a simple mamuplation. 3)By using enzymes immobilized to membrane, the amount of H2O2 formed from each substrate is easily measured. 4)Fructose cannot be, however, measured by this method. These results show that the immobilized enzyme method is useful to study physiological changes in these metabolites.

[学科分类] 农业科学（综合）