Efficacy of heat treatment of salt contaminated with Salinicoccus roseus on shelf life of cured ribbon fish (Trichiurus upturns) Linnaeus 1758

Abstract

In the present study, the quality and shelf life of salt cured ribbonfish (Trichiurus lepturus) using heat-treated salt artificially contaminated with known density of Salinicoccus roseus was carried out. To determine whether crystal size of the salt had any effect on the quality of cured fish, semi-ground salt was used along with crystalline (natural) salt. Salinicoccus roseus, a dominant halophilic bacteria among red halophiles isolated from the commercial salt-cured fish showing red discoloration, was used to contaminate the sterile crystalline and semi-ground salts. The salts were further heat treated to test the efficacy of heat treatment of the salt on the bacteria. Shelf life studies were carried till signs of spoilage were evident. During the storage period, total bacterial count, moisture, total volatile nitrogen (TVN), peroxide value (PV) and free fatty acids (FFA) were monitored at three months intervals for one year. During three months of storage, TVN in ribbon fish cured with crystalline salt (control) reached 416.7 mg N% from an initial value of 25.33 mg N%. On the contrary, ribbon fish cured with heat treated crystalline salt (CS) and semi-ground (SS) salt had TVN 204.82 and 168.48 mg N% after 6 and 12 months storage periods respectively. The treatment effect in terms of TVN was 0.62 and 0.65 for CS and SS cured ribbon fish. The peroxide values (PV) increased in crystalline salt cured (control) samples from an initial value of 31.46 to 235 milliequivalents of O sub(2) per Kg of fat at the end of three month storage period. However, these values were 288.46 and 127 milliequivalents of O sub(2) per Kg of fat for heat treated CS and SS cured ribbon fish after 6 and 12 months storage period, respectively. The treatment effect in relation to PV was 0.60 and 0.90 for CS and SS cured ribbon fish. The present study revealed that heat treatment of solar salt used for curing of fish enhanced the shelf life of cured fish from 6 to 12 months when compared to the control. The use of semi-ground salt for curing of fish has the added advantage of superior quality, treatment effectiveness and longer shelf life than that of crystalline salt cured fishes.