The Effect of Nisin on the Quality of Shrimp during Refrigerated Storage

Introduction: Shelf life of shrimp during refrigerated storage is deeply influenced by both endogenous and microbiological enzymatic activity, for example melanosis. Melanosis in crustaceans is normally controlled by sulphite derivatives. However these derivatives are known to produce allergic reactions and severe disorders in asthmatic patients. Therefore, finding new substitutes for sulphites is an important issue.

Purpose: The goal of this study was to investigate the effect of nisin on the enzymatic oxidation and quality of white shrimp during refrigerated storage of seven days.

Methods: Five experiment groups were designed and compared: control, flake ice, sodium metabisulphite, nisin and mix. In each experiment group, pH, total viable count (TVC), mesophilic, psychrophilic, lactic acid bacteria (LAB) and Enterobacteriaceae, total volatile base nitrogen (TVBN), and color changes were measured

Results: Preliminary results indicated control group contributed no inhibition of melanosis and total viable count. Sodium metabisulphite showed better control for melanosis than flake ice group. The inhibitory activity of nisin seemed to follow a dose-dependent manner. With storage, treating the shrimp with either 75 μg/g could appreciably retard the total viable count and prevent melanosis.

Significance: The findings could be used by the food industry to substitute for sodium metabisulfite as a melanosis inhibitor of shrimp.