Influence of Nisin and Lysozyme on the Shelf Life of Hot-Smoked Rainbow Trout Fillets (Oncorhynchus Mykiss) During Storage at 4 °C

Abstract

Hot-smoked rainbow trout (Oncorhynchus mykiss) fillets with vacuum packaging are an important export source and the manufacturers recommend a shelf life of 21 d at 4 °C. This time is very short in terms of the shelf life of packaged foods. In this study, nisin and lysozyme (0.5 and 1% w/v, respectively) were used in order to prolong the shelf life of hot-smoked rainbow trout by adding them to the brine (8–10 ˚C, 10 h). Five treatment groups were formed, including the control group. Samples (105) were hot-smoked at 72 ˚C and vacuum-packaged. The effect of nisin and lysozyme (0.5 and 1% w/v) on the chemical [(pH, total volatile basic nitrogen (TVB-N), peroxide, thiobarbituric acid reactive substances (TBARS), free fatty acids (FFAs)], microbiological [total number of aerobic mesophilic bacteria (TMAB), number of lactic acid bacteria (LAB), total number of coliform bacteria (TCB), total number of psychrophilic bacteria (TPB)], and sensorial properties were investigated during storage at 4 °C for 42 d. TVB-N, TBARS, and FFA values were evaluated. The most favorable results among the treatment groups for the chemical analysis were observed in groups treated with nisin (1 and 0.5%, respectively) followed by lysozyme-treated groups (1 and 0.5%, respectively), and the control group. Nisin and lysozyme showed the most important effect microbiologically and extended the shelf life of the samples from 21 d to 42 d at 4-˚C storage. The sensory analyses suggested that nisin and lysozyme treatments did not have a negative impact on the organoleptic properties of samples. Natural antimicrobials (nisin and lysozyme) reduced the TMAB, TCB, and TPB. As a result, it was determined that nisin and lysozyme can be used to increase the quality characteristics and shelf life of hot-smoked rainbow trout fillets instead of synthetic antioxidants and additives. © 2021, Department of Science and Technology. All rights reserved.