EFFECT OF SELECTED PRETREATMENTS AND DRYING METHODS ON THE QUALITY OF DRIED MANGO (Mangifera Indica L.) SLICES

Abstract

The present study was conducted to assess the effect of various pretreatments and drying methods on the qualities of dried mango slices. Four drying methods (solar, tray, freeze and fluidized bed drying) and four pretreatments (lemon juice, salt solution dips, hot water blanching and control) were considered and arranged in factorial experimental design. The proximate composition, physicochemical properties, antioxidants, rehydration ratio, microbial loads and sensorial acceptance were evaluated. The result showed that the pretreatments and drying methods showed significant effects on the proximate composition, physicochemical properties, colour, antioxidants, rehydration ratio, microbial load and sensory acceptance of the dried mango slices. The nutrient analysis showed that mango slices had respective ranges for moisture, protein, fat, fibre, ash and carbohydrate contents (5.63-9.91%, 2.49-2.71%, 2.89- 3.16%, 6.51-6.56%, 2.66-2.73% and 75.51-79.35%). The pH, TSS, TA and hardness of the dried mango slices, respectively were 3.17-3.68, 69.36-86.29ºBrix, 2.20-2.54 g/100g and 7.27- 15.63N. Regarding the colour of dried mango slices, the values ranged from 55.28-57.00, 11.85- 12.84, 32.99-48.58 and 5.15-20.02 for L*, a*, b* and ΔE colour values, respectively and were significantly affected by the treatments. The ascorbic acid and phenol contents were affected by drying methods and had respective values of 33.18-41.24 mg/100 g and 131.13-251.12 mg/100 g. As far as the rehydration ratio is concerned, better rehydration performance was observed for the samples dried by the freeze and fluidized bed driers after subjected to the four different pretreatments. It could be inferred that the total plate count of dried mango slices ranged from 1.4*102 -9.6*103 CFU/g while yeast and mould were 4.2*101 -8.2*101 CFU/g. Generally, the overall acceptance of dried mango slice was good during three months of storage periods. Mango peels were good sources of nutrition and phenolic content (564.54 mg/100g), and no microbial loads have been detected during the storage period of three months.