Abstract
Into the browning system of apple·enzyme·catechol, each one of the following amino acids was added and the activity of polyphenol oxidase and the absorption spectra were estimated in order to investigate the effect of amino acid on the enzymatic browning; lysine, methionine, cystine, cysteine, phenylalanine, tyrosine, threonine, arginine, histidine, aspartic acid, glutamic acid and serine.
The activity of polyphenol oxidase was more or less repressed by some amino acids. The mode of the repression was roughly divided into 2 groups.
The maximum of the visible spectrum at 400 nm was moved to 470-480 nm when amino acid was added to the browning system except cysteine and serine. The absorbancy was increased at around 500-520 nm and decreased at around 400 nm. However, by comparing the rate of the increase with that of the decrease, 3 groups of the variation of the absorbancy were observed.
On the other hand, shift of the maximum of the UV spectrum was not observed by the addition of amino acid, although the variation of the absorbancy was brought about. The variation of the absorbancy was grouped into 2 and the effect of amino acid on the variation was divided into 3 groups.
