Federico Zocca

Antibrowning potential of Brassicacaea processing water

The effects of Brassicacaea processing water on polyphenol oxidases from different plant sources were investigated. Results showed that processing water (PW) prepared by cooking young Brassicacaea leaves with water has the capacity to inhibit both commercial tyrosinase and plant polyphenol oxidases. PW was freeze-dried (LPW) in an attempt to increase its utility and improve its efficiency at inhibition of polyphenol oxidases, however this resulted in a loss of activity, probably due to the stresses of the freezing and/or drying processes. The addition of PW to ascorbic acid resulted in complete inhibition of grape polyphenol oxidase, suggesting that the combination of the two antibrowning agents may be a promising tool to control this enzymatic activity.

3,4-Dihydroxyphenylalanine gel diffusion assay for polyphenol oxidase quantification

We have developed a simple, inexpensive plate assay to detect and quantify polyphenol oxidase (PPO) activity from different origins. The logarithm of enzyme activity is linearly correlated with the diameter of the dark, l-3,4-dihydroxyphenylalanine (l-DOPA) oxidized circles produced in the gel, thereby allowing quantification of PPO. Moreover, precision and high reproducibility of the assay were confirmed by statistical analysis.