Abstract:The effects of cold-shock treatment (CST) at 3 ℃ on fatty acids present in the membrane lipids and lipoxygenase of cold-stored banana fruits and the related physiological mechanisms were investigated. Banana fruits were treated with cold air at 3 ℃ for 6 h and then stored at 8 ℃ ± 0.5 ℃; the fruits without CST were directly stored at 8 ℃ ± 0.5 ℃ and were used as the control group. The chilling injury index, cell membrane permeability, lipoxygenase activity, and membrane fatty acid composition of banana fruits were measured regularly during the period of storage at 8 ℃ ± 0.5 ℃. After the fruits were stored in a constant temperature oven at 20 ℃ ± 0.5 ℃ for 30 days to accelerate fruit ripening, the conditions of chilling injury and fruit after ripening were observed. Eight fatty acids were identified in the pulp of banana, that is, tridecylic acid, heptadecanoic acid, arachidic acid, cis-10-heptadecenoic acid, trans-linoleic acid, linoleic acid, γ-linolenic acid, and α-linolenic acid. CST at 3 ℃ for 6 h could decrease the chilling injury index, relative conductivity, lipoxygenase activity, and the content of tridecylic acid, heptadecanoic acid, arachidic acid, and other saturated fatty acids (SFAs). Besides, it effectively prevent the decrease in the content of cis-10-heptadecenoic acid, trans-linoleic acid, linoleic acid, γ-linolenic acid, α-linolenic acid and other unsaturated fatty acids (UFSAs). It can also maintain relatively high SFA and UFSA indexes in membrane lipids. Thus, CST enhanced the chilling resistance of banana fruits, reduced the incidence of cold damage, and improved the after-ripening quality of banana fruits.
