Abstract:

In the present study, we formulated 4-hexylresorcinol, citric acid and ascorbic acid to provide a preservative for inhibiting the darkening of Pacific white shrimps. The formulation was optimized using orthogonal array design. Pacific white shrimps treated with the optimized blend of 4-hexylresorcinol, citric acid and ascorbic acid were kept cold-stored or superchilled for 10 days and the polyphenol oxidase (PPO) activity, total volatile base nitrogen (TVB-N), pH and total bacterial count (TBC) of the shrimps were periodically measured during storage. The results showed that the temperature of super-chilling ranged from 0 to －2.2 ℃, and the temperature fluctuation of a common refrigerator met the requirements of super-chilling. A blend containing 0.01% 4-hexylresorcinol, 1.5% citric acid and 1% ascorbic acid provided an optimal inhibitory effect against the darkening of Pacific white shrimps and could effectively inactivate PPO activity. Super-chilling could make the growth of TVBN, pH and TBC slow down significantly. The combination of super-chilling with the optimized blend gave a mutual complement between them, presented a more significant inhibitory effect against the darkening of Pacific white shrimps and the growth of PPO activity, TVB-N, pH and TBC, and resulted in a 2-fold prolongation of shelf-life when compared with cold storage at (4 ± 1) ℃. These results suggest that super-chilling provides a promising technique for delaying the darkening and prolonging the shelf-life of Pacific white shrimps.

Key words: Pacific white shrimp, super-chilling, preservatives, darkening, preservation