Effects of post-harvest stigmasterol treatment on quality-related parameters and antioxidant enzymes of green asparagus (Asparagus officinalis L.)

The effects of immersion of green asparagus spears in stigmasterol solution (0, 0.5 and 1.0gl(-1), 15min, 25 degrees C) on weight loss, surface colour, enzyme activities and content of malondialdehyde, total phenol, lignin and chlorophyll were investigated during 40days of storage at 4 +/- 0.5 degrees C. Of the concentrations tested, 0.5gl(-1) treatment was most effective. Stigmasterol (0.5gl(-1)) treatment significantly reduced colour changes and losses of fresh weight and chlorophyll content. Superoxide dismutase (SOD) and catalase (CAT) activities were maintained higher in stigmasterol-treated (0.5gl(-1)) asparagus, whereas the activity of peroxidase (POD) was significantly reduced. Stigmasterol treatment (0.5gl(-1)) also significantly decreased the content of malondialdehyde (MDA) and increased total phenol content. Accumulation of lignin was positively correlated to activity of guaiacol-POD (r=0.960, p<0.01) in stigmasterol-treated (0.5gl(-1)) asparagus. The polyphenol oxidase (PPO) activity decreased and showed a significant negative correlation with the chroma L* value (r= -0.899, p<0.01) in stigmasterol-treated (0.5gl(-1)) asparagus. It was concluded that stigmasterol treatment (0.5gl(-1)) could inhibit the senescence of green asparagus, and therefore prolong its shelf-life, maintaining the quality of post-harvest green asparagus.