EFFECT OF PRE-TREATMENTS AND DRYING METHODS ON THE DRYING CHARACTERISTICS AND QUALITY OF PAPAYA (Carica Papaya L.) SLICES

Abstract

The present study was conducted to evaluate the effect of various pretreatments and drying methods on the drying characteristics and quality of dried papaya (Carica papaya l.) slices. The experiment was planned with two factors: drying methods and pretreatments. It consisted of sixteen combinations of treatments executed in factorial experimental design. All samples were analyzed in triplicates. The drying methods were refractance window dryer, oven dryer, solar dryer, and sun, while the pretreatments were hot water blanching, corn starch coating, lemon juice dip, and control. The drying characteristics, physicochemical properties, proximate composition, antioxidants, total carotenoid, color, microbial loads, and sensory acceptance were evaluated. The drying characteristics of the papaya slice such as coefficient of regression (R2 ) and chi-square (χ2 ), resulted in values within the range of 0.962 to 0.998 and 0.000238 to 0.00561), respectively. The Page model gave a higher R2 value 0.9666 to 0.9988 over the other models. The results showed that the pretreatments and drying methods significantly affected the physicochemical properties, proximate composition, antioxidants, total carotenoids, colour, microbial load, and sensory acceptance of the dried papaya slices. The nutrient analysis showed that papaya slices ranged from 4.68 to 5.29, 31.11 to 49.74ºBrix, 0.63 to 0.92 g/100g, and 9.09 to 19.83 N for pH, TSS, TA, and hardness, respectively. Similarly, papaya slices' moisture, fat, fibre, protein, ash, and carbohydrate contents were found to be 6.50 to 9.77%, 1.25 to 1.98%, 4.99 to 5.68%, 2.16 to 2.60%, 2.11 to2.21%, and 78.96 to 82.46%, respectively. The ascorbic acid and total carotenoid contents were affected by drying methods and had respective values of 28.16 to 42.19mg/100 g, and 41.67 to 92.88 µg/g. Regarding the color of dried papaya slices, the values ranged from 49.22 to 53.87, 20.57 to 23.66, 54.86 to 61.21, and 4.07 to 11.29 for L*, a*, b*, and ΔE color values, respectively. It could be inferred that the total plate count of dried papaya slices ranged from 2.3102 to 5.9103CFU/g, while yeast and mold counts were 1.3101 to 3.9 101CFU/g. It can be concluded that the overall acceptance of dried papaya slices was good during the three months of storage periods.