Formula optimization for melanosis-inhibitors of Pacific white shrimp (Litopenaeus vannamei) by response surface...

Melanosis is major problem of crustaceans during their rigor mortis storage. This study for the first time was designed to optimize the formula of preservatives to maintain the color feature of Pacific white shrimp using response surface methodology. A three-factors-three-levels Box-Behnken design was applied to evaluate the effect of chitosan, citric acid and l-cysteine on color features (L*, a*, b* and ΔE) of Pacific white shrimp. It was found that the increasing rate of ΔE was retarded by the higher concentrations of chitosan, citric acid and l-cysteine in a certain range. The optimal formula for inhibiting the increase of ΔE was 1.36% chitosan, 0.47% citric acid and 0.31% l-cysteine. Under the optimal pretreated conditions, the predicted ΔE of shrimp after 8 days of storage was 14.59, close to the measured values (14.49). These results indicated that the optimal combined preservatives could retard the decrease of lightness and the aggregation of ΔE and melanosis effectively, and might be a potential application for retarding melanosis and extending shelf life of Pacific white shrimp.