Studies on phenolase and internal discoloration (blackspot) in Russet Burbank potatoes

Abstract

In an investigation of phenolase-blackspot relationships, experiments were conducted to study sources of variability in phenolase determinations that could account for the inability to get consistent and reproducible data between trials. There was no reproducibility between trials in the pattern of apparent relationships between phenolase and blackspot when phenolase in bruised and unbruised tissue from blackspot-susceptible and-resistant tubers was calculated on a fresh-weight basis. Also, apparent blackspot-phenolase relationships differed with the type of substrate used. However, when phenolase activity was determined from freeze-dried tissue taken from some of the same tubers, the pattern of an apparent relationship between phenolase and blackspot became more clearly defined and was quite consistent when activity was calculated on either a dry-weight or protein basis, regardless of the substrate used.