Application of sodium alginate cover in frozen and cleaned common kilka and its quality evaluation by bacterial,chemical and sensory tests

Abstract

This project was carried out to increase shelf life of kilka and prevent color changes during cold storage. Edible film made by sodium alginate (0.5% concentration) was used for fish packaging at time zero. The covered samples were kept at -18oC. Examination were carried out for a period of six months. Coliform, Escherichia coli and Pseudomonas bacteria contamination were negative until the end of storage period in the covered samples. Total bacterial counts and Acetaphylococcus bacteria count were lower in the treated samples (2.93 and 1.46log cfu/g, respectively) compared with the control specimens (3.21 and 2.28log cfu/g, respectively). Chemical factors consisting of humidity, protein, lipid, ash and calorie were higher in the treated samples (73.34%, 18.96%, 4.62%, 2.88% and 134. 63% kcal/kg, respectively) compared with the control samples (59.43%, 18.04%, 4.03%, 2.87% and 108.43% kcal/kg, respectively) and fresh fish samples (73.93%, 18.91%, 4.59%, 2.87% and 117.28% kcal/kg, respectively). Free fatty acids (0.77 and 9.21g/100), thiobarbitoric acid (0.001 and 0.15mg/kg), peroxide value (0.06 and 3.75meq/kg oil), TVN (6.92 and 16.28mg/100g) and pH (6.34 and 6.91) were lower in the treated samples compared with the control samples. However, no statistically significant decreases were observed in chemical factors including moisture, peroxide value, TVN and pH in the covered samples compared with the control samples during cold storage (P>0.05). According to the statistical analyses of sensory specifications including taste, odor, color, tissue and total acceptance, there was a significant difference between the covered samples and the control ones (P<0.05). Using the results of bacterial, chemical and sensory tests and statistical analyses, the covered samples had a favorable quality until the end of storage period. Also, based on the results of sensory analyses and moisture test, the control samples had a favorable quality for a period of three months.