Effect of Potassium Metabisulphite and Storage Conditions on Physico-chemical and Microbiological Changes in Whey-based Kinnow Juice Concentrate

The influence of three levels (250, 350 and 600 ppm) of potassium metabisulphite (KMS), and refrigerated (4(PLUS-MINUS)1°C, 80% RH) and ambient (15-35°C, 66-85% RH) storage conditions on the physico-chemical and microbiological changes of whey-based Kinnow juice concentrate (WKJC) packed in polyethylene terephthalate (PET, 150 g capacity) containers was studied. A steady increase in titrarable acidity, decrease in pH and cloudiness was observed in all the WKJC samples at both the storage conditions. Overall, the deteriorative changes were faster in samples with lower levels of KMS and ambient conditions. The standard plate count and total spore count decreased in all the samples, more prominently in case of refrigerated storage conditions and added with higher levels of KMS. The yeast and mould counts increased during storage, with a faster rate in samples stored at ambient condition and with lower levels of KMS. Addition of KMS (350 ppm) was found to preserve the physico-chemical attributes and retarded the microbial growth of WKIC for 9 months at refrigerated, and 4 months at ambient storage conditions.