Influence of processing methods and storage on physico-chemical and antioxidant properties of guava jam

The present research was conducted to investigate the influence of different processing methods and ingredient mixing techniques to judge storage stability and consumer acceptability of guava jam. In the present study four treatments of guava jam were prepared at laboratory scale using two processing methods (open kettle, T-1 and T-2; double jacketed steam kettle, T-3 and T-4) and different ingredient mixing technique (dry mixing, T-1 and T-3; wet mixing or pre solution, T-2 and T-4). After preliminary analysis of guava fruit, all the four treatments were analyzed for physico-chemical, phytochemical and sensory analysis for an interval of 15 days during 2 month storage period. The results indicated that pH, water activity, color, firmness, ascorbic acid, non-reducing sugars, total phenolic contents, antioxidant activity and overall acceptability (sensory evaluation) showed a decreasing trend during storage. Opposite is the case with acidity, total soluble solids, total sugars as well as reducing sugars. Sensory analysis indicated that the order of preference for guava jam treatments was T-4>T-3>T-2>T-1. There was no significant effect of adding sugar and pectin in dry form or by making their pre solution for all the studied traits except for sensory parameters. As good sensory characteristics were shown by the treatments in which pectin and sugar was added by making their pre-solution, so it is recommended that for having superior sensory characteristics pectin and sugar should be added in pre-solution form. Study suggests that losses in fresh guava fruit can be curtailed by processing it into jam. It further suggests that losses in vitamin C, antioxidants and total phenolic contents during processing can be minimized by giving preference to double jacketed steam kettle over open kettle. (c) All Rights Reserved