후지 사과 Polyphenol Oxidase 의 특성 및 활성억제 = Characteristics and Inhibition of Polyphenol Oxidase from Fuji Apples

다국어 초록 (Multilingual Abstract)

As a basic research for inhibition of enzymatic browning of apples during dehydration or processing, polyphenol oxidase was extracted from Fuji apples to investigate heat inactivation, chemical inhibition and other properties. Polyphenol oxidase showed the highest activity at 20℃ and pH 5.5 with catechol as substrate, and the Michaelis constant of 0.14 M under the same condition of substrate and pH. The thermal inactivation followed pseudo first-order kinetics to have activation energy of 23.0 k㎈/㏖ and z value of 19.7℃. As for substrate specificity the polyphenol oxidase showed high affinity toward the o-diphenolic compounds, particularly chlorogenic acid. Neither the m- and p-dihydroxy phenols nor monophenols were attacked. Browning by polyphenol oxidase was completely inhibited at the concentrations of l0mM for potassiummetasulfite and thiourea and 1mM for L-cysteine, ascorbic acid and sodium diethyldithiocarbarnate.