Non-thermal preservation of traditional fermented Pla-som: Effects of UV-C, pulsed electric field, and gamma irradiation on safety and quality

This study compared the immediate post-treatment effects of ultraviolet-C (UV-C), pulsed electric field (PEF), and gamma irradiation on Pla-som , a Thai fermented fish product. Samples were treated with UV-C (2.0 kJ/m 2 ), PEF (20 kV/cm, 100 pulses, 60 μs), or gamma irradiation (1 and 3 kGy). Gamma irradiation achieved the greatest microbial inactivation, with 3 kGy reducing total plate counts (TPC) from 4.25 × 10 7 to 1.66 × 10 3 CFU/g (approximately a 4.41-log reduction), but was associated with higher lipid oxidation indices and lower concentrations of several quality-related metabolites. PEF reduced TPC to 8.32 × 10 4 CFU/g while maintaining the measured physicochemical properties and organic acid profile immediately after treatment. PEF-treated samples contained glutamic acid (188.67 mg/100 g), γ-aminobutyric acid (24.66 mg/100 g), inosine-5′-monophosphate (36.64 mg/kg), creatine (536.19 mg/kg), and carnosine (284.26 mg/kg). Targeted metabolite profiling further showed higher residual concentrations of several quality-related metabolites following PEF than following gamma irradiation. Overall, under the specific conditions evaluated, PEF provided a favorable compromise between immediate microbial reduction and retention of the measured physicochemical and biochemical attributes, supporting its potential as a non-thermal post-fermentation treatment for Pla-som .