COMBINED EFFECT OF IRRADIATION AND LOW TEMPERATURE STORAGE ON THE MICROBIAL, BIOCHEMICAL QUALITY AND SHELFLIFE OF GIFT TILAPIA (OREOCHROMIS NILOTICUS
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Date
2021
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KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR
Abstract
Irradiation is considered as an efficient and novel method for the preservation of food
stuffs and reduction of microorganisms. It has been used to improve the safety, quarantine
and shelf life of food products. The present study was aimed at studying the influence of
irradiation (1 and 3 kGy) and storage at ice (0oC) and frozen temperatures (-18±2 oC) on the
microbial, biochemical qualities, and extended shelf life of GIFT (Oreochromis niloticus).
The quality changes and shelf life were assessed by evaluating the changes in biochemical,
microbial and sensory attributes during different storage conditions. The results obtained
from the study revealed that the biochemical quality indices like pH, TVBN, PV and TBARS
were within the acceptable range. The total volatile base nitrogen (TVBN) of the irradiated
GIFT fish samples significantly (p< 0.05) decreased in comparison with the control (nonirradiated)
throughout the storage period. Thiobarbituric acid values for irradiated (1 and 3
kGy) samples were significantly (p< 0.05) higher than control sample. The non-irradiated
samples showed a higher pH than the irradiated ones but there was no significant difference
in pH (p< 0.05) between the samples. The effect of irradiation was noticed as the total
mesophilic counts, total psychrophilic counts, total coliforms and faecal coliforms counts
showed gradual reduction as the irradiation dose increased. Sensory evaluation showed a
good correlation with bacterial populations with storage time. The results obtained from the
present investigation elucidated that 3 kGy is the safest irradiation dose as it has eliminated
the microbial growth and extended the shelf life of GIFT fish to 18 days at ice (0oC) storage
and 90 days at frozen (-18±2 oC) storage without affecting the biochemical characteristics