ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Effect of Irradiated Chitosan compared to Other Recommended Postharvest Treatments to Control Anthracnos Disease in Papaya

I. G. N. Hewajulige, M. G. D. S. Perera and R. S. Wilson Wijeratnam

Book of Abstracts, Asia-Pacific Symposium on Assuring Quality and Safety of Agri-Foods, August 4-6, 2008, Radisson Hotel, Bangkok, Thailand.

2008

บทคัดย่อ

Effect of irradiated chitosan treatment was investigated and compared with other recommended postharvest treatments such as wax application, salicylic acid and hot water dip treatments. Chitin extracted from locally available prawn waste was converted to chitosan by deacetylation process. A solution of 1% chitosan was selected as an effective concentration to reduce the symptoms of anthracnose disease in papaya from a series of in vitro and in vivo experiments. A 1% of chitosan solution was subjected to irradiation dosages ranging from 5 – 100 k Gy at a dose rate of 5 k Gy / hr. Chitosan solution irradiated at 5 k Gy was selected as the suitable dosage to control the growth of the fungus via in vitro experiments. Papaya var. Rathna harvested at 10% yellow stage of maturity was subjected to dipping treatments of chitosan (1%) – irradiated (at 5 k Gy), chitosan (1%) – non irradiated, salicylic acid (1%), a solution of wax (formulated at ITI), and hot water treatment at 52°C for 2 min.

Fruit treated with both irradiated and non irradiated chitosan (1%) and the hot water treatment significantly reduced the disease severity and maintained higher firmness after 2 weeks storage at 13.5°C and 95 % RH followed by two days at ambient temperature (28±2°C). However, the percentage weight loss was higher in papaya subjected to hot water treatment. Fruits treated with irradiated chitosan showed 80 % marketable quality while non irradiated chitosan treated fruit showed 70 % marketability after storage. The control fruit and the salicylic acid treated fruit were seriously affected by the disease and were not of marketable quality while 60 % marketable quality fruit was observed with wax and hot water treatments. Both irradiated (1% solution at 5 k Gy) and non irradiated chitosan (1%) could be used as postharvest dip treatments to control or protect the papaya from anthracnose disease during storage and transportation.