Acidic electrolyzed water (AEW) is a novel agent that can be used for postharvest preservation of fruits and vegetables. The effect of AEW treatment on reactive oxygen species (ROS) metabolism in longan fruits during postharvest storage was investigated. The results showed that compared with the control (distilled water), soaking for 10 min in AEW with effective chlorine concentration of 80 mg/L and redox potential (ROP) of 1512 mV at pH 2.5 significantly increased the activity of antioxidant enzymes (e.g. ascorbate peroxidase (APX), catalase (CAT), and superoxide dismutase (SOD)), and maintained a higher level of non-enzymatic antioxidant substances (e.g. glutathione and ascorbic acid) and higher levels of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and reducing power in longan pulp during storage.In addition, AEW treatment significantly reduced the production rate of superoxide anion (O₂^-·) and H₂O₂ content and consequently inhibited the increase in malondialdehyde (MDA) content in longan pulp. Therefore, it can be inferred that AEW can enhance the storability of longan fruits, which may be related to improved ROS scavenging capacity of longan pulp during postharvest storage.

The effect of pre-harvest spray application of diethyl aminoethyl hexanoate (DA-6) at a concentration of 10 mg/kg on the energy metabolism in the fruit pericarp of postharvest ‘Fuyan’ longan (Dimocarpus longan Lour. cv. Fuyan) during storage was investigated by measuring the contents of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), energy charge, the activities of adenosine triphosphatase (ATPase) and nicotinamide adenine dinucleotide kinase (NADK), and the contents of nicotinamide adenine dinucleotide (NAD), reduced nicotinamide adenine dinucleotide (NADH), oxidized nicotinamide adenine dinucleotide phosphate (NADP) and reduced nicotinamide adenine dinucleotide phosphate (NADPH). The results demonstrated that compared with the control group, pre-harvest spray application of DA-6 displayed higher levels of ATP, ADP and energy charge, higher activities of H⁺-ATPase, Ca²⁺-ATPase and Mg²⁺-ATPase in pericarp plasma membrane, vacuolar membrane and mitochondrial membrane, higher activity of NADK, higher contents of NADPH and NADP, and lower amounts of AMP, NADH and NAD. These data indicated that pre-harvest spray application of DA-6 could maintain the energy requirement for normal physiological metabolism of postharvest longan fruit, keep the balance between intracellular and extracellular ion concentrations to maintain the structural integrity and the function of plasma membrane, vacuolar membrane and mitochondrial membrane, and eventually delay pericarp browning of longan fruit.

In order to explore the microfloral succession in Takifugu flavidus during storage at 0 ℃, the spoilage bacteria were detected by 16S rDNA sequencing, the dominant spoilage bacteria in the late stage of storage were identified, and the changes in the microbial flora and the spoilage capacity of the dominant spoilage bacteria were analyzed. The results showed that the refrigerated shelf life of T. flavidus was about 5 days. In the early stage of storage (0–3 days), T. flavidus had the highest number of species of bacteria, including Pseudomonas, Streptophyta, and Shewanella, while in the late stage (6–15 days), the bacterial species were concentrated mainly in Pseudomonas and Shewanella. Ten dominant spoilage bacteria were isolated and identified, Shewanella and Pseudomonas accounting for a high proportion. Moreover, the spoilage capacity of several common dominant spoilage bacteria was analyzed, revealing that the decreasing order of the spoilage capacity was Pseudomonas fluorescent > P. azotoformans > Shewanella hafniensis > S. baltica. The results of this study provide a reference for understanding the spoilage mechanism of T. flavidus during cold storage and extending its shelf life.