Abstract: In order to improve the storage quality of highland-grown spinach harvested in summer in Lanzhou, Gansu, we investigated the effects of different preservative treatments, water at ambient temperature (control), 1 g/L lysozyme, 2.3 mg/L ozone water and ice water combined with lysozyme, on spinach quality and nitrate content during storage at 4 ℃. Results indicated that combined treatment with ice water and lysozyme maintained higher levels of VC, chlorophyll, soluble sugar, soluble protein, folic acid, nitrate reductase (NR) and peroxidase (POD) activity in spinach during stroage, thus delaying the formation of oxalic acid, nitrate and nitrite and resulted in an increase of 14%, 17% and 30% in average color difference (?E) when compared with 1 g/L lysozyme, 2.3 mg/L O3 and control, respectivley. Moreover, the contents of chlorophyll and VC were 66% and 35% lower in the control group than in the combined treatment group on the eighth and tenth day of storage, respectively, and percenage folic acid loss in the combined treatment group was only half of that in the control group. The accumulation of nitrate and nitrite in the combined treatment group were significantly lower than those in the three other groups (P < 0.05). Overall, it could be concluded that combined treatment with ice water and lysozyme can maintain the quality of spinach during storage and extend the shelf period so that it can be of great commocial importance.

Key words: ice water, lysozyme, combined treatment, spinach, quality, nitrate