Physiological and biochemical responses of grapefruit seed extract dip on 'Redglobe' grape

Table grapes (Vitis vinifera cv. Redglobe) were immersed in 1 g L-1 grapefruit seed extract (GSE) for 60 s at 15 degrees C and then stored at 2 +/- 1 degrees C, and the related physiological effects were investigated. The results showed that GSE treatment lowered the respiration rate and ethylene evolution in the whole cluster. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) were increased and extended by GSE treatment, however, polyphenol oxidase (PPO) activity was suppressed. Furthermore, increase of malondialdehyde (MDA) as well as membrane permeability was delayed in GSE-treated grapes. Total phenolic compounds degradation was substantially lower in GSE-treated grapes than in control. The soluble solids content (SSC) in GSE-treated grapes was always higher than in control, although there was no significant difference at the level of P < 0.05. Our study suggests that GSE might be a promising candidate for extending the postharvest storage time of table grapes. (C) 2008 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.