Effects of Four Bactericidal Preservatives Combined with Different Temperatures on the Quality and Physiology Characteristics of Fresh Bayberry

The regulatory effects of various fungicide preservatives on the postharvest storage quality and physiological metabolism of bayberry were systematically investigated. Using 'Biqi' bayberries as the experimental material, bayberry fruits were treated with different concentrations of dehydroacetic acid (0.15, 0.3, 0.6 mmol/L), prochloraz (45, 90, 180 mg/L), sodium dichloroisocyanurate (15, 30, 60 mg/L), and 1-methylcyclopropene (2, 4, 6 g). The changes in storage quality, physiological and biochemical properties, and nutritional quality during cold storage and normal temperature storage were studied. Under refrigerated conditions, prochloraz treatment was found to significantly reduce the decay rate (reduce 80%), ethylene release, and delay softening of bayberry fruits (P<0.05), while malondialdehyde (MDA) content was inhibited. At ambient temperature, prochloraz could effectively delay fruit softening, inhibit ethylene release, and suppressed the increase in polyphenol oxidase (PPO) activity (P<0.05). Sodium dichloroisocyanurate (60 mg/L) under refrigeration was observed to reduce the decay rate (by 25%) and enhance peroxidase (POD) activity (P<0.05). During room temperature storage, sodium dichloroisocyanurate (15 mg/L) could delay fruit softening, reduce ethylene content, and suppresse the increase in PPO activity (P<0.05). 1-Methylcyclopropene treatment under both refrigeration and ambient temperature storage condition was demonstrated to reduce fruit firmness and ethylene content. Moreover, under room temperature conditions, fruit decay was effectively inhibited by 1-MCP with an active ingredient concentration of 0.03% (2 g) (P<0.05). Dehydroacetic acid (0.15 mmol/L) under refrigeration could only transiently enhance the POD activity of Chinese bayberry fruits (P<0.05), amd increased the decay rate and ethylene content to varying degrees. In contrast, under ambient temperature storage, it significantly increased fruit firmness and total soluble solids (TSS) content (P<0.05), while showing no significant effects on enzyme activity or titratable acidity (TA) content (P>0.05). In conclusion, prochloraz (90 mg/L) and sodium dichloroisocyanurate (60 mg/L) at relatively high concentrations were determined to exhibit preservative effects. The 1-MCP treatment (2 g, 0.03% active ingredient) effectively maintained postharvest fruit quality and extended the preservation period, while dehydroacetic acid showed insignificant preservative efficacy. The research results provide a theoretical basis for the precise post-harvest fresh-keeping of bayberries.