Effect of sodium lactate and thymol on some microbiological, chemical and sensory attributes of fish balls made from carp meat (cyprinus carpio L.)

The present study was carried out to investigate the effects of thymol and sodium lactate, alone or in combination, on some microbiological, chemical and sensory attributes of fish ball made from common carp meat. Fish ball samples were separated into 6 groups. The groups were assigned as control, 1% sodium lactate, 0.1% thymol, 0.25% thymol, 1% sodium lactate + 0.1% thymol and, 1% sodium lactate + 0.25% thymol. The fish ball samples were placed in foam plates, wrapped with plastic wrap and stored at 4oC, and then, they were analyzed for microbiological (total mesophilic aerobic microorganisms, total psychrophilic aerobic microorganisms, total coliforms, pseudomonas spp., yeast and mold), chemical (pH, total volatile basic nitrogen and thiobarbuturic acid) and sensory (taste, odor and color) attributes on days 0, 4, 6, 8 and 10. Results of the microbiological analysis indicated that the fish ball samples treated with 1% sodium lactate and 1% sodium lactate + 0.25% thymol have longer shelf-life compared to the other groups (p<0.05), and there was no significant difference among the other groups from microbiological and shelf-life points of view (p>0.05). Results of the chemical analysis pointed out that there were no significant differences between all the fish ball groups including control group in terms of total volatile basic nitrogen (TVB-N) and thiobarbuturic acid (TBA) values (p>0.05). With regard to pH value, it was observed that the fish ball samples treated with 0.1% thymol and 1% sodium lactate + 0.1% thymol were different from the other groups due to a slight decrease in their pH (p<0.05). Results of the sensory evaluations showed that there were no significant differences between all the fish ball groups including control group in terms of color (p>0.05), and there were differences between the groups depending on the storage days (p<0.05). In point of taste, it was observed that there were differences between the groups, and some groups have an unacceptable aroma depending on the increase in the thymol concentration. As a result, it was concluded that addition of thymol into the fish ball did not show significant effect on the microbiological quality and shelf-life of the product; however it has a negative effect on the sensory attributes of the product.