Protective effects of gamma-irradiated ice-nucleating Pseudomonas syringae on quality loss in rainbow trout during freeze-thaw cycles.

This study investigated the protective effects of gamma-irradiated ice-nucleating Pseudomonas syringae, known as P. syringae parabiotics (PBs), on the freezing behavior, physicochemical quality, and microstructural integrity of rainbow trout mince during six freeze-thaw (F-T) cycles. PBs were added to the mince at levels of 2 × 102 to 2 × 104 inactivated cells/g and compared with the viable cell treatment (2 × 103 CFU/g). The results demonstrated a pronounced protective effect of 2 × 102 inactivated cells/g (PBs-2) and 2 × 103 inactivated cells/g (PBs-3) during repeated F-T cycles. PBs-2 exhibited the lowest thawing loss, delayed color deterioration, reduced particle size, and the highest absolute negative zeta potential (-32.45 mV). While PBs-3 reduced loss of total sulfhydryl groups (35.10%), mitigated formation of protein carbonyls (1.92 nmol/mg protein), and decreased centrifugal loss (39.00%). The use of P. syringae PBs may be a non-viable biotic-based strategy for protecting fish myofibrillar proteins from freeze-thaw-induced damage.