PT  - JOURNAL ARTICLE
AU  - S. H. Kelly
AU  - B. J. Finkle
TI  - Action of a Ring-Cleaving Enzyme in Preventing Oxidative Darkening of Juices
AID  - 10.5344/ajev.1969.20.4.221
DP  - 1969 Jan 01
TA  - American Journal of Enology and Viticulture
PG  - 221--226
VI  - 20
IP  - 4
4099  - http://www.ajevonline.org/content/20/4/221.short
4100  - http://www.ajevonline.org/content/20/4/221.full
SO  - Am J Enol Vitic.1969 Jan 01; 20
AB  - Catechol type compounds such as chlorogenic acid are the natural substrates for polyphenol oxidase in fruit juices, and these compounds are converted by the enzyme to polymers that result in a dark juice. When apple juice, in the presence of ascorbate, was treated with the enzyme protocatechuate 3,4-dioxygenas, darkening was permanently prevented since the enzyme oxidatively cleaves the benzene ring of the substrates to yield branched chain derivatives of muconic acid. The muconic acid derivatives cannot participate in the polyphenol oxidase browning reaction.