Microbiological, Nutritional and Sensorial Changes in Fresh Carrot Juice Preserved by Irradiation

Abstract

Fresh carrot juice has perishable nature and very limited shelf life, and may pose a microbiological hazard. Gamma irradiation (1.5, 3.0 and 4.0 kGy) as non-thermal processing was performed to improve microbial quality, ensure safety and extending the refrigerated shelf life of fresh carrot juice. Irradiation dose of 3.0 kGy greatly reduced total aerobic bacterial counts, lactic acid bacteria and total molds and yeasts. While, it completely eliminated coliform bacteria, Escherishia coli and Enterococcus faecalis. Irradiation dose of 1.5 kGy had no significant effect on ascorbic acid content of the juice, while irradiation doses of 3.0 and 4.0 kGy significantly decreased ascorbic acid content. However, there was no significant difference in total carotene content between all irradiated samples and non-irradiated control. It was found that immediately after irradiation the sensory scores of irradiated (1.5 and 3.0 kGy) and non-irradiated samples were not significantly different. Irradiation dose of 4.0 kGy significantly reduced the sensory quality attributes of the juice. Thus, irradiation dose of 3.0 kGy can be successfully used to improve the microbial quality and extend the refrigerated shelf-life of fresh carrot juice, where it extended the shelf-life to 8 days against only 2 day for non-irradiated control.

Key words: Fresh carrot juice, Gamma irradiation, Microbial quality, Nutritional quality.