Effects of Table Salt and Thymol Oil on Shelf Life of Common Carp (Cyprinus carpio) Fillets during Iced Storage

Abstract

The study evaluated the effects of table salt and thymol oil used as natural preservatives on the quality and shelf life of the common carp (Cyprinus carpio) fillets exposed to different treatments during iced storage. The effects were investigated by measuring of microbiological, chemical and sensory parameters for 21 days at 3 day intervals. Treatments included the following: S1 (control sample) and dip treatments for S2 (12% salt solution, w/v), S3 (0.7% thymol oil solution, v/v) and S4 (salt 12%, w/v + thymol oil 0.7%, v/v). The S3 and S4 produced significantly lower (p<0.05) total viable count of bacteria (TVC), pH, total volatile basic nitrogen (TVB-N) and trimethylamine nitrogen (TMA-N) values as compared to S1 and S2 samples after day 6 up to the end of the storage period. TVC of fillets dipped in S1 and S2 was significantly higher than those of fillets dipped in S3 and S4. TVB-N of fillets in S1 was significantly higher than that of fillets in S3 and S4. However, no significant difference was observed among TVB-N of fillets in S2 and S3; and among S3 and S4. TMA-N of fillets in S2, S3 and S4 was significantly lower than that of fillets in S1. However, no significant difference was found among the fillets in S2, S3 and S4. Positive significant correlations were established within and between microbial and chemical parameters. According to the results of TVC, pH, TVB-N, TMA-N and sensory parameters, the shelf life of the common carp (C. carpio) fillets has extended upto 9, 18 and more than 21 days in S1, S2, S3 and S4 respectively. However, no significant difference (p>0.05) was observed among S3 (0.7% thymol oil solution, v/v) and S4 (salt 12%, w/v + thymol oil 0.7%, v/v). Therefore, for extending the shelf life of the fillets thymol oil could be the effective treatment.