Postharvest Propionic Acid and Hot Water Treatment for the Control of Black Spot Disease in Chinese Ya Pears

摘要

Black spot disease caused by Alternaria alternata (Fr.) is one of the main postharvest diseases of Chinese Ya pears and causes serious economic loss during storage. The fungi-toxicity of postharvest propionic acid and hot water treatment at different concentrations and temperatures was investigated in vitro and directly on Ya pears. The in vitro results showed that A. alternata was susceptible to propionic acid solutions at all tested temperatures. The toxicity of propionic acid increased linearly and the LC 99 decreased from 13.43 to 4.31 g/L with an increase in temperature from 20 to 45℃. The results in Ya pears showed that propionic acid and hot water treatment dramatically controlled black spot disease and 99% inhibition was achieved upon treatment with 9 g/L propionic acid solution for 30 min at 45℃. Furthermore, the treatment inhibited the respiration of fruits and did not cause any adverse effects on other quality parameters; however, slight surface injury was noted at 9 g/L. The safety of propionic acid treatment was further confirmed by residue analysis. The results of this study suggest that postharvest propionic acid and hot water treatment is an alternative method for the control of black spot disease in Ya pears.