Effects of exogenous oxalic acid on Penicillium expansum growth and patulin accumulation in harvest kiwifruit

【Objective】The effects of oxalic acid on controlling Penicillium expansum growth and patulinaccumulation were investigated by both in vitro and in vivo.【Methods】Effects of different oxalic acid con-centrations on spore germination and colony diameter of Penicillium expansum as well as patulin accumu-lation were studied in vitro. In addition,effects of pre-harvest spraying with 5 mmol·L-1oxalic acid andpostharvest dipping in 50 mmol·L- 1oxalic acid on controlling disease and patulin accumulation of kiwi-fruit(Actinidia deliciosa‘Bruno')inoculated with P. expansum were investigated,and changes in fruitquality were also measured.【Results】The spore germination and colony diameter of P. expansum and pat-ulin accumulation were significantly reduced on PDB or PDA containing 1-10 mmol·L-1oxalic acid at na-tive p H values or after adjustment of all to p H 7.0. Pre-harvest or postharvest oxalic acid treatment signifi-cantly decreased the lesion diameter of kiwifruit during storage. In addition,pre-harvest application ofoxalic acid inhibited patulin accumulation in the decayed flesh of kiwifruit during the whole storage afterinoculation of P. expansum. The fruits dipped with oxalic acid had lower patulin content during the earlierperiod after inoculation of P. expansum.【Conclusion】The results indicated that oxalic acid significantly inhibited spore germination and growth of P. expansum(in vitro),and pre-harvest or postharvest oxalicacid treatment decreased blue mold decay and patulin accumulation in kiwifruit,which might contributedto maintaining good quality of kiwifruit during storage.