The Effects Of Ultrasound Combined With Salicylic Acid Or Combined With Heat Treatment On Postharvest Disease Of Ya Pear

This paper explores the potentials of using ultrasonic waves to preserve fruits after harvest. By using Ya pear as the material, the effects of ultrasound treatment, ultrasound combined with salicylic acid treatment or ultrasound plus heat treatment on postharvest disease of Ya pear had been researched. Also we evaluated the effect of these treatments on the edible property of Ya pear. This is a pioneering effort in using ultrasound and ultrasound combined with other preservation methods to treat fruits after harvest.It showed that there wasn't any difference between the Ya pear treated by ultrasound at frequency 40-60KHz and control fruit in fruit firmness, in soluble solid content and in titratable acidity during storage at room temperature. There was no difference of lesion diameter size in ultrasound treated fruit and in control fruit.Treatment with ultrasound combined with 1 mM and 5 mM salicylic acid for 15 to 20 minutes respectively could: distinctly reduce incidence of the disease penicillim expansum and the lesion area by inoculation and increased the activity of peroxidase. And the effect of inhibition increased with increasing the time of treatment with ultrasound in combination with salicylic acid. No significant difference appears between the Ya pear treated by ultrasound combined with salicylic acid and the control one in fruit firmness and in the content of soluble solids and titratable acid during storage at room temperature.Ultrasound combined with heat at 50+2℃ for 5 mins had good effects on inhibiting the development of the disease caused by Penicillim expansum or Alternaria alternate. It was far more effective than heat treatment alone. The lesion incidence and lesion diameter could be decreased significantly and POD or PPO activity was enhanced by ultrasound combined with heat treatment. It was able to control the pathogen and prevent the formation of lesions before infection has occurred and stop the spread of lesions after infection has occurred.Ultrasound combined with 50℃ hot water treatment neither caused surface damage to fruits nor impaired quality parameters of fruit. It increased the ratio between soluble solids and titratable acid and the edibility of the fruit by storing under room temperature without changing the normal ripening of the fruit.