Changes in Enzyme Activities During Postharvest Deterioration of Green Asparagus Spears

Fresh asparagus (Asparagus officinalis L.) deteriorates rapidly after harvest. Early enzymatic changes that follow harvesting of asparagus are important factors contributing to postharvest deterioration. We held asparagus spears at 25°C for up to 5 days after harvest and examined changes in the activities of Acid invertase (AI), Sucrose Synthase (SS), Glutamine Synthetase (GS) and Phenylalanine ammonia Lyase (PAL) in both top and bottom portions of the spears. Soluble AI activity increased during the first day of storage and after that it decreased gradually up to five days in both top and bottom portions. Sucrose synthase activity was higher in the bottom portion than in the top; its activity declined daily for five days. Sucrose content was negatively correlated with invertase and sucrose synthase in both portions.GS enzyme activity in both top and bottom portion declined throughout the experimental period which may be related to increased ammonia accumulation. The increase in PAL activity continued until day 3 and declined thereafter.