Air-Oven Drying of Pre-Treated Fruit Slices: A Promising Solution to Post-Harvest Losses

Abstract

Reports have shown that over 25% of fruit are lost during their season and virtually out of the market during off season due to their high moisture content couple with poor preservation methods practiced in Nigeria. Smooth cayenne pineapple specie obtained from Ajanla Farms, Ibadan was used for the study. A two factor-factorial experimental design of 3-levels of 3 pre-treatment methods (sucrose, blanching and sulphiting) and 3-levels of drying conditions (80 C/8 h, 70 C/10 h and 50 C/16 h) resulting into 81 treatments o o o was used. The treatments were reduced to 18 by stratified sampling method from the results of the moisture and ascorbic acid content obtained from the pre-treated slices before drying. The slices were dried in a cabinet dryer; the moisture and ascorbic acid content of the dried slices were monitored during drying and after. All the samples exhibited combinations of falling and increase in drying with increasing in drying time. The dried slices were stored for 18 weeks, at which they were analyzed at 3 week intervals. The results obtained revealed that there were significant effects (p<0.05) of the pre-treatments on the ascorbic acid and moisture content of the dried slices. The 60%S/60 CB/2500ppm SO at 70 C/10 h had the least value of o o 2 moisture content of 8.75% and 25.16 mg/100 g of ascorbic acid. Furthermore, the results indicated that drying at 70 C/10 h is suitable for drying of pineapple slices than other drying conditions. During storage, o there was continuous reduction in moisture content during the early weeks of storage. However, after 9 weeks of storage the moisture content of the samples increased showing significant differences between the mean values of the samples at different weeks of storage. Though, the samples pretreated with SO2 showed a little variation over the storage period. Drying condition of 70 C/10 h and pre-treatment of 2500 ppm o SO /60% sucrose was found to have minimal reduction of quality and thus the most appropriate treatment 2 for air-oven drying of pineapple slices. The study therefore, recommends that production of pre-treated dried fruit slices could be used to reduce the enormous post-harvest losses of fruits.