Sucrose and brassinolide alleviated nitrite accumulation, oxidative stress and the reduction of phytochemicals in kale sprouts stored at low temperature

Abstract

Browning, nitrite accumulation, oxidative stress, and loss of nutrients in postharvest sprout during low-temperature storage are important issues that affect storage quality of sprouts. This study evaluated the effects of sucrose, brassinolide (BR), and their combination on the growth and development of fresh kale sprouts, and reactive oxygen metabolism, ascorbate-glutathione (AsA-GSH) cycle, browning, nitrite content, and bioactive ingredients of kale sprouts stored at low temperature, in order to improve the physiological traits of postharvest sprouts, resist the oxidative stress in sprouts during low-temperature storage and inhibit the loss of plant nutrients. Compared with sucrose or BR alone, the combined treatment increased fresh weight, hypocotyl length, AsA/DHA ratio, glutathione reductase activity, riboflavin, cellulose, and free amino acid contents, and decreased weight loss rate, browning index (BI), malondialdehyde (MDA) and dehydroascorbic acid content, ascorbate peroxidase and dehydroascorbate reductase activities in sprouts stored at low temperature. The riboflavin, cellulose, and free amino acid contents in the combined-treated group were higher 57.5%, 119.9%, and 66.7% than those in the control group of fresh samples (CK0), respectively, and there were no significant differences in BI and MDA content between CK0 and the combined-treated groups. These results indicated that the combination of sucrose and BR could better alleviate the reduced quality of kale sprouts stored at low temperature by regulating the weight loss rate and AsA-GSH cycle, so as to maintain the nutrients and antioxidant capacity of kale sprouts to the maximum extent.