Abstract

The objective of this study was to estimate shelf life of mango juice produced using small-scale processing techniques. Juice was processed and packaged in 80 plastic bottles and stored at 13 oC and 30 oC. At each temperature, 20 bottles had preservative (0.5 mg/l sodium benzoate) and 20 bottles had no preservative. The juices were analyzed for pH, vitamin C, sensory attributes and microbial load at two week intervals for six weeks. From week 2 to week 6, juices stored at 30 ^oC had lower pH values (3.15 – 2.80 with preservative, 3.60 – 2.6 without preservative) than juices stored at 13 ^oC (4.20 - 3.80 with preservative, 4.15 - 3.70 without preservative ) and the differences were significant (p<0.05). At 6 weeks, vitamin C loss was highest (79%) in juice without preservative stored at 30 ^oC, followed by juice stored at 30 ^oC with preservative (71.43%). The loss was lowest (26.98%) in juice with preservative stored at 13 ^oC. Significant differences (p<0.05) in color were observed at week 6 between juices stored at 13 ^oC (4.5 with preservative and 4.66 without preservative) and 30 ^oC (5.02 with preservative and 7.00 without preservative). Juices stored at 30 ^oC were rated ‘bad’ from week 2, in smell (5.91 and 6.25) and taste (5.66 and 6.91) while at that time, juices stored at 13 ^oC were rated ‘almost similar’ to fresh juice in smell (4.25) and taste (4.25 and 4.58). Storage at 13 ^oC with preservative resulted in lowest bacteria (2.04 x 10⁴ CFU/ml) and yeast and mold (1.72 x 10⁴ CFU/ml) counts whilst highest bacteria (2.10 x 10⁸ CFU/ml) and yeast and mold (1.96 x 10⁸ CFU/ml) counts were observed in juices stored at 30 ^oC without preservative. The shelf life was estimated based on taste and smell as 2 weeks and 4 weeks for juices stored at 30 ^oC and 13 ^oC, respectively. Chilling combined with use of preservative slowed down rate of vitamin C loss, deterioration of sensory attributes and microbial growth.

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