Biochemical changes in watermelon and pineapple juice blend during storage

A water melon: pineapple juice has been produced in a ratio 9:1 respectively. However, its biochemical changes on storage to establish its keeping quality is yet to be establish and so this research work is on the biochemical changes accompanying water melon-pineapple juice blends during storage for establishing the storage life. Samples of water melonpineapple juice in 9:1 ratio respectively were produced using standard methods. The produced juice blends were subjected to chemical, microbiological and sensory evaluation at one week interval for six weeks storage time. The chemical analysis showed that, there is a gradual and minimal decrease in the specific gravity (78 80%), total sugar / brix (68 78%) and total titratable acidity (18 20%) of the juice along the storage period. This consequently indicates that the biochemical reactions that could lead to spoilage of the juice are at the minimum. The ascorbic acid and the pH values of the juice are almost constant throughout the storage period. The microbial analysis showed that the counts in total plate, coliform, yeast and mould were 5.2 x 10 6 , 4.2 x 10 5 . 1.0 x 10 6 and 4.7 x 10 6 , respectively which are values with acceptable change along the storage period. For the sensory evaluation, there were significant differences in all the quality attributes (colour, flavor, taste, and overall acceptability) starting from week 2. These changes though with very close mean difference, were noticed from week 2 till the fifth week of the storage period. From all the analysis, it can be observed that the juice blend (water melon and pineapple) at 9: 1 ratio respectively can be kept conveniently for five (5) weeks.