Endogenous Polyphenoloxidase Activity Associated with the “Black Ring” Defect in Canned Beet (Beta vulgaris L.) Root Slices

Abstract

ABSTRACT Discoloration of canned beet root slices resulted after 5–10 min exposure of beet roots to live steam, and subsequent incubation of slices in air at least 20 min. The “black ring” of discoloration moved radially toward the center of the slice as time of steam‐peeling was increased. Dipping slices (prepared after steam‐peeling) in solutions of inhibitors of PPO before incubation in air inhibited or prevented discoloration. Based on these data, thermal stability of PPO and POX, heat penetration profiles, and location of the discoloration zone, a model to explain discoloration was developed.