Application of ice nucleation-active bacteria to unwashed mince of greater lizardfish and Indian mackerel subjected to freeze-thaw cycles: Comparative study of low-fat and high-fat fish

Ice nucleation-active bacteria have demonstrated a potential to improve food freezing. However, interaction between fish fat content and INB concentration has not been studied yet. This study explored how this bacterium impacted the freezing process between greater lizardfish and Indian mackerel, representing low- and high-fat species, respectively. Greater lizardfish and Indian mackerel showed distinct freezing behavior, phase transition, and freezing time governed by the concentrations of ice nucleation bacteria (INB). After six freeze-thaw cycles, the lower bacterial concentration (INB-3) resulted in higher absolute zeta potential in greater lizardfish mince. In contrast, the effects of higher concentrations were more significant in Indian mackerel ( P < 0.05). In lizardfish, INB-3 and INB-5 led to the lowest root-mean-square roughness (Rq), showing a lower aggregation rate. At the same time, in Indian mackerel, INB-3 was more effective in maintaining a more stable MP structure, as evidenced by lower Rq and average roughness after six freeze-thaw cycles. In mackerel, INB-5 was more effective at protecting proteins against oxidation, whereas INB-3 and INB-4 decreased protein carbonyls and maintained total sulfhydryl groups in lizardfish, respectively (P < 0.05). Results showed that fish fat content could affect the ability of ice nucleation-active bacteria in the freezing process of unwashed mince. • INB caused distinct freezing processes in greater lizardfish and Indian mackerel mince. • Surface roughness and aggregation was influenced by species and bacterial concentrations. • Protein and lipid oxidation was affected by the fat content in the presence of INB. • MP from both species had smaller size depending on the concentrations of INB.