Comparison between 'Fuyan' and 'Dongbi' longans in aril breakdown and respiration metabolism
POSTHARVEST BIOLOGY AND TECHNOLOGY
Authors: Lin, Lijuan; Lin, Yixiong; Lin, Hetong; Lin, Mengshi; Ritenour, Mark A.; Chen, Yihui; Wang, Hui; Hung, Yen-Con; Lin, Yifen
Abstract
This study aimed to investigate the difference between 'Fuyan' longan (Dimocarpus longan Lour. cv. Fuyan) fruit and 'Dongbi' longan (Dimocarpus longan Lour. cv. Dongbi) fruit in term of their aril breakdown and respiratory metabolism. As compared to 'Fuyan' longans, the 'Dongbi' longans exhibited lower fruit respiration rate, lower aril breakdown index, higher NADK activity, higher total activities of G-6-PDH and 6-PGDH, higher contents of NADP and NADPH, lower activities of AAO, CCO, PPO, PGI, and SDH, and lower contents of NAD and NADH in aril. These findings suggest that better storability and lower aril breakdown index in 'Dongbi' longans than 'Fuyan' longans might be due to lower activities of respiratory terminal oxidases, and lower respiratory metabolic pathways of EMP-TCA cycle related-enzymes in 'Dongbi' longan aril, which decreased respiratory rate and reduced the consumption of substrates, and subsequently maintained the integrity of the aril of 'Dongbi' longans during storage.
The role of ROS-induced change of respiratory metabolism in pulp breakdown development of longan fruit during storage
FOOD CHEMISTRY
Authors: Lin, Yixiong; Lin, Hetong; Chen, Yihui; Wang, Hui; Lin, Mengshi; Ritenour, Mark A.; Lin, Yifen
Abstract
Compared to the control longans, hydrogen peroxide (H2O2)-treated longans exhibited higher index of pulp breakdown, higher fruit respiration rate, higher activities of pulp phosphohexose isomerase (PGI), succinate dehydrogenase (SDH), cytochrome C oxidase (CCO), ascorbic acid oxidase (AAO) and polyphenol oxidase (PPO), but lower activity of pulp nicotinamide adenine dinucleotide kinase (NADK). H2O2-treated longans also exhibited lower total activities of pulp glucose-6-phosphate dehydrogenase (G-6-PDH) and 6-phosphogluconate dehydrogenase (6-PGDH), lower levels of pulp NADP(H), but higher levels of pulp NAD(H). These data indicated that H2O2-stimulated longan pulp breakdown was owing to a decreased proportion of pentose phosphate pathway (PPP), the increased proportions of Embden-Meyerhof-Parnas pathway (EMP), tricarboxylic acid (TCA) cycle and cytochrome pathway (CCP) in total respiratory pathways. These findings further revealed that H2O2 could enhance respiration rate, and thus accelerate pulp breakdown occurrence and shorten the shelf life of longan fruit.