Effects of gamma irradiation on the physical and sensory quality and inactivation of Listeria monocytogenes in blue swimming crab meat (Portunas pelagicus)

• γ-irradiation up to 6 kGy caused no changes in fresh crab meat textural properties.
• γ-irradiation increased safety of ready-to-eat product i.e. fresh crab meat.
• γ-irradiation had either listericidal or listeristatic effect on L. monocytogenes.
• L. monocytogenes were completely inactivated by 4 kGy and 6 kGy γ-irradiation.
• 1–2 kGy lethally injured L. monocytogenes but survivors increased during storage.

Blue swimming crab lump (backfin) meat were exposed to 2, 4, and 6 kGy doses of Co60 irradiation and evaluated for changes in physical, sensory properties, and Listeria monocytogenes inactivation. Irradiation up to 6 kGy resulted in no textural changes (p>0.05) in maximum shear forces; however, these exposures resulted in sensory quality changes (p<0.05) as determined by a triangle overall difference test (n=50) at each irradiation level. Irradiation had no effect (p>0.05) on L⁎ color value. Irradiation at 4 and 6 kGy resulted in listericidal reductions greater than 6.65 (Department of Medical Science, Ministry of Health, Thailand, [DMST] 1783) and 7.56 logs (DMST 4553). Irradiation doses of 1 and 2 kGy resulted in a reduction of 2.10 and 5.35 logs respectively of L. monocytogenes DMST 1783 and 1.56 and 4.19 logs respectively of L. monocytogenes DMST 4553. The D10 values of L. monocytogenes DMST 1783 and 4553 were 0.35 and 0.45 kGy. The study indicated that low-dose gamma irradiation would increase the safety of blue swimming crab meat without unacceptable changes in texture and L⁎ color value.