Enhancement of quality and antioxidant metabolism of sweet cherry fruit by near-freezing temperature storage

摘要

Near-freezing temperature storage (NFTS) is a novel method to inhibit quality loss of fresh fruit. However, little information is available on NFTS delaying the onset of senescence in sweet cherry (Prunus avium L.) fruit and regulating the changes on antioxidative enzymes participated in the balancing of reactive oxygen system (ROS). Fruits were stored at NFT (between super-cooling point and freezing point), 0 degrees C and 5 degrees C, respectively, until fruits exhibited visually rot (sampled every twenty days). NFTS effectively slowed senescence process in sweet cherry fruit, as indicated by extending storage duration and improving the changes of firmness, anthocyanins, ion leakage, peel color and sugars content. Moreover, fruit stored at NFT had higher levels of ascorbic acid, phenolics and organic acids and lower accumulation of carotenoids, malondiadehyde, hydrogen peroxide (H2O2) and superoxide radical (O-2(center dot-)). Additionally, NFTS maintained membrane integrity and prevented fresh browning of fruit by enhancing the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and gluta thione reductase (GR) and inhibiting the activities of guaiacol peroxidase (POD), polyphenol oxidase (PPO) and lipoxygenase (LOX). Furthermore, NFTS fruit exhibited higher level of antioxidant capacity as measured by radical scavenging activity and reducing power at the end of storage. These results indicate that the activities of antioxidant enzymes to scavenge superoxide anions and H2O2 during NFTS was implicated in the maintenance of membrane integrity, which might be a part of the mechanism associated with the delay of senescence in sweet cherry fruit.