HOT AIR AND SALICYLIC ACID POSTHARVEST TREATMENTS ALTERNATIVE TO FUNGICIDE IN NAVEL ORANGES DURING SHELF LIFE

Abstract

Navel oranges were treated either with hot air at 45 oC for 30 min or dipped in salicylic acid solutions at 1000 and 2000 ppm concentrations for 15 min, whereas controlled fruits treated with 1400 ppm thiabendazol + 375 ppm imazalil fungicides. Fruits were held at 15 ± 2 oC and 80-85 % RH for 4 weeks; simulating shelf life period to examine the potential use of hot air as an environmentally benign and or salicylic acid as a natural and safe phenolic compound for maintaining oranges quality characteristics of fruits during their shelf life period. Salicylic acid at 2000 ppm showed the highest marketable fruit percentage and lowest decayed percentage, after 4 weeks of shelf life period, without significant difference comparing with fungicide treatment. Marketable fruit percentage was decreased, however decayed fruits were increased by advancing shelf life period and heat treatment applied. Soluble solid content: acid ratio was significantly increased by 32.71 and 31.25 % after 4 weeks compared with 2 weeks shelf life period, but it was significantly decreased by 20.64 and 14.76 % as affected by heat treatment. Salicylic acid at 2000 ppm significantly decreased soluble solid content: acid ratio as a result of maintaining titratable acidity values. Electrolytic leakage percentage of fruit's peel was significantly decreased as affected by prolonging shelf life period and heat treatment. Salicylic acid (1000 & 2000 ppm) did not reduce either spore germination or mycelial radial growth of Penicilium Digitatum Sacc in vitro compared with postharvest fungicides (thiabendazole and imazalil) treatment. However, salicylic acid had almost the same protective action against postharvest decay of Navel oranges caused by Penicilium digitatum.