Abstract:The effects of storage temperature and duration on the freshness of three kinds of freshwater fish (grass carp, tilapia, and bighead carp) were analyzed. The changes in several physicochemical indicators [including color, pH, and thiobarbituric acid reactive substances (TBARS) and total volatile basic nitrogen (TVB-N) contents] during storage at 25 ℃ and 4 ℃ were monitored, and sample freshness was evaluated on the basis of electronic nose measurements and biogenic amine (BA) contents. The results showed that with increasing storage time at 25 ℃ and 4 ℃, the b* and total chromatic aberration (ΔE) values and BA, TVB-N, and TBARS contents gradually increased, whereas the L* and a* values decreased, and the pH value first decreased and then increased. The TVB-N amount in all three types of fish exceeded 15 mg N/100 g after storage at 25 ℃ for 12 h and 4 ℃ for 6 days. Putrescine and cadaverine were detected, indicating that the fish had begun to deteriorate. Notably, the electronic nose response signals could accurately distinguish the freshness of all fish samples. In conclusion, storage temperature and time are key factors influencing the freshness of freshwater fish, the quality changes of which can be accurately determined by evaluating characteristic BAs and electronic nose response signals. In addition to verifying the feasibility of these evaluation methods, the results provide a theoretical basis for the freshness evaluation of freshwater fish products.
