Inhibition of melanosis in white shrimp Penaeus vannamei using beetroot extract during iced and room temperature storage

Effect of beetroot extract in inhibition of melanosis formation and quality of white shrimp Penaeus vannamei was evaluated in iced and room temperature storage. Shrimps were treated with beetroot extract (BT) at 1 and 4% and compared with control and commercial anti-melanosis agent, 1.25% sodium metabisulfite (SMS) and stored in ice. The effect of BT4% treatment at room temperature was also evaluated. There was no significant difference (p>0.05) in the melanosis score of SMS and BT4% till 7th day of iced storage while BT1% was not effective in retarding the melanosis from 5th day of storage. In room temperature storage, melanosis formation was similar both in the case of SMS and BT4% till 6th hour of storage. Total volatile base nitrogen (TVBN) value and aerobic plate count (APC) of BT treated samples were significantly lower than control and SMS (p<0.05) in both storage conditions and lower thiobarbituric acid reactive substances (TBARS) values indicated the antioxidant activity of beetroot extract. BT4% treatment inhibited growth of H2S producing organisms (1.3-2.1 log cycles) and Pseudomonas spp. (0.3-1 log cycles) compared to control and SMS. BT4% treatment resulted in a storage life of 9 days in iced condition and eight hours at room temperature. Beetroot extract treatment at 4% level was found as effective as sodium metabisulfite in preventing melanosis till 7th day of iced storage and 6th hour of room temperature storage.