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

Abstract

The effects of immersion of green asparagus spears in stigmasterol solution (0, 0.5 and 1.0 g l^-1, 15 min, 25°C) on weight loss, surface colour, enzyme activities and content of malondialdehyde, total phenol, lignin and chlorophyll were investigated during 40 days of storage at 4 ± 0.5°C. Of the concentrations tested, 0.5 g l^-1 treatment was most effective. Stigmasterol (0.5 g l^-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 (0.5 g l^-1) asparagus, whereas the activity of peroxidase (POD) was significantly reduced. Stigmasterol treatment (0.5 g l^-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 (0.5 g l^-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 (0.5 g l^-1) asparagus. It was concluded that stigmasterol treatment (0.5 g l^-1) could inhibit the senescence of green asparagus, and therefore prolong its shelf-life, maintaining the quality of post-harvest green asparagus.