The purification of dominant spoilage fungi on Lonicera Caeruleum and the inhibitory effects of composite essential oils against these fungi

The fungal inhibitory and preservative effects of essential oils(EOs)on the dominant spoilage fungi of blue honeysuckle were investigated.First,the dominant spoilage fungi(CW1,CW3,and W53)were isolated from naturally infected blue honeysuckle and identified through morphological features,inoculation study,and rDNA-ITS analysis were matched to Alternaria alternata,Metuloidea reniformis,and Rhizopus microsporus,respectively.Next,the filter paper method determined the sensitivity of EOs to the dominant spoilage fungi,and four kinds with better antifungal effects were screened out.Two or three combinations of four EOs were evaluated using a checkerboard analysis method.The fractional inhibitory concentration index(FICI)was used to assess the in-teractions between the combinations.The combinations of cinnamon/oregano,cinnamon/clove,oregano/clove,and cinnamon/oregano/clove showed synergistic effects(FICI≤0.5).The best three-oil combination had a volume ratio of 31:8:8 compared to a single oil.Finally,in vivo,experiments showed that combining triple groups of EOs could prevent the spoilage of postharvest honeysuckle.Compared with the control group,the triple groups of essential oil combination maintained the best color,quality,and flavor of blue honeysuckle berries.At the same time,the spoilage rate and the weight loss rate were reduced by 38.50%and 40.71%,respectively.Delayed spoilage time to 3-5 days and the preservation effect of blue honeysuckle was extended to 16 days.Therefore,this study provides a theoretical basis for substituting chemical preservatives and highlights the po-tential of using complex EOs to prolong the freshness of blue honeysuckle.

Effects of hexanal fumigation on fungal spoilage and grain quality of stored wheat

The prevention of fungal spoilage is an essential consideration in wheat storage.Recent studies have revealed that volatile organic compounds(VOCs),possibly with natural fungicidal properties,could be produced from stored wheat grains.In this study,the antifungal effect of hexanal,a main component of VOCs from stored wheat,against spoilage fungi on agar plate and in high-moisture wheat grains were investigated via the gas fumigation method.And the impact of hexanal fumigation on grain quality was evaluated through analysis of the malondialdehyde content,fatty acid values,germination percentages and vigor of 16%and 18%moisture wheat grains fumigated with 1.66,2.49,and 3.31 mmol/L hexanal vapor.The results of in vitro antifungal experiments on agar plates revealed that the minimum inhibitory concentration and minimum fungicidal(fatal)concentration of hexanal against the five fungi were 4–14 folds and 4–7 folds lower than those of propionic acid,respectively.The fungal spoilage of high-moisture wheat grains inoculated with pure fungal spores and with naturally occurring fungi could be completely inhibited by 1.66 mmol/L hexanal vapor.During 5-week storage of high-moisture wheat grains fumigated with 1.66,2.49,and 3.31 mmol/L hexanal vapor,the malondialdehyde content in high-moisture wheat grains did not change significantly in all samples,and fatty acid values were slightly higher in 18%moisture wheat than in 16%moisture wheat.The germination percentages and vigor of wheat samples decreased with increased hexanal vapor concentrations and moisture content.These results indicated that hexanal fumigation could be used as an alternative chemical control method to prevent the fungal spoilage of postharvest wheat.