Effect of exogenous spermine on quality and sucrose metabolism of vegetable soya bean (Glycine max L.) during cold storage

Vegetable soya bean deteriorates quickly after harvest at ambient temperature due to loss of green colour and consequent yellowing of grains. To seek an effective method to control the postharvest quality, the effect of exogenous spermine on visual quality, sugar loss and sucrose‐metabolising enzyme activities of vegetable soya bean (Glycine max L.) during cold storage was investigated. The results showed that exogenous spermine (1.0 mmol L^?1) noticeably prolonged shelf life, inhibited the increase of weight loss and decay index and retained the colour. It also significantly minimised sucrose loss by regulating the activities of sucrose‐metabolising enzymes. Sucrose content negatively correlated with acid invertase (AI) activity at P < 0.05, while positively with sucrose phosphate synthase (SPS) activity at P < 0.01. There was no significant correlation with the activities of neutral invertase and sucrose synthase. These results indicated that the AI and SPS activities might play an important role in the control of sucrose metabolism resulting in reduction of sucrose loss.