ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Biochemical changes in iceberg lettuce (Lactuca sativa) during postharvest storage at 4 deg C.

Zhang DongLin; Quantick, P. C.; Grigor, J. M.; Wiktorowicz, R.; Irven, J.;

Food Science and Technology Today Year: 2000 Vol: 14 Issue: 4 Pages: 209-212 Ref: 18 ref.

2000

บทคัดย่อ

Fresh iceberg lettuces, wrapped in 30 micro m- thick polypropylene bags, were stored at 4 deg C for 16 days. The outer, middle part and core of lettuce leaves were sampled separately for analysis of phenolics, polyphenol oxidase (PPO) [catechol oxidase], peroxidase (POD) and phenylalanine ammonia-lyase (PAL) activity over the storage period. The leaves contained mainly chlorogenic acid analogues. At day 0, phenolic content in the core leaves was 4.96 times higher than in the outer leaves and 4.43 times higher than in the middle leaves. Phenolic content in the core increased and reached the highest level at day 9 and then declined. Phenolic content in the middle leaves increased continuously during storage. At day 0, POD activities in the core and middle leaves were 34.0% and 14.1% lower than in the outer leaves, respectively. POD activities in all leaves increased continuously during storage. At day 0, PPO activities in the core and middle leaves were 11.9% and 7.7% lower than in the outer leave

s, respectively. PPO activities in all leaves also increased continuously during storage. At day 0, PAL activity in the core leaves was 5.69 times and 4.60 times higher than in the outer and the middle leaves, respectively. PAL activity in the core declined continuously during storage. However, PAL activities in the outer and middle leaves increased slowly during storage.