Changes in several enzyme activities accompanying the pulp browning of bamboo shoots during storage

The changes in glucose-6-phosphate dehydrogenase (G6PDH), shikimic acid dehydrogenase (SADH), phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL) and polyphenol oxidase (PPO) activities of bamboo shoots during storage at 20 degrees C were examined in relation to their browning. 1. Determination of G6PDH, SADH and PPO activities in the three sections of bamboo shoots revealed that G6PDH and SADH were the highest in the apical section and the least in the basal section, and also that G6PDH activity was the highest among the three enzymes, while PPO maintained nearly the same activity in the three sections. 2. After 2 days in storage, G6PDH and SADH activities of bamboo shoots increased to about 1.3 and 1.7 times those of the initial day, respectively, then decreased over 9 days as browning increased. Meanwhile PPO activity increased slightly after 2 days, then decreased. 3. PAL activity of bamboo shoots was the highest in the basal and the least in the apical sections. TAL activity in all sections was quite low, compared to PAL activity but they exhibited the same trends. 4. Both PAL and TAL activities in the basal section of bamboo shoots decreased after 2 days, then stayed at the same level; after 9 days they increased rapidly.