Preservation of Grass Prawns by Ionizing Radiation

Abstract

The purpose of this study was to evaluate the feasibility of preserving grass prawns (Penaeus monodon) by ionizing radiation. Frozen prawns were irradiated with different doses at −10 ± 2°C. The threshold dose for detecting irradiation flavor was 4.5 kGy. The D10 values for Vibrio cholera, Staphylococcus aureus, Escherichia coli, and Salmonella enteritidis were 0.11, 0.29, 0.39, and 0.48 kGy, respectively. Irradiation with doses of 2.5, 5.0, and 7.5 kGy reduced the total bacterial counts from 105 CFU/g to 4.0 × 103, 1.6 × 103, and 3.2 × 102 CFU/g, respectively. The bacterial counts of the irradiated samples were below 105 CFU/g throughout the storage periods studied. In contrast, the total bacterial counts of the unirradiated samples exceeded the marginal quality index (106 CFU/g) after 48 d of storage at −10°C. The most significant changes in nutrients of irradiated frozen prawns were C20:5, C22:6, and thiamine, which decreased by 22, 25, and 32%, respectively. Other nutrients such as amino acids, saturated fatty acids, riboflavin, and niacin were relatively resistant to γ-irradiation within a dose range of 10 kGy. In summary, ionizing radiation can effectively reduce the number of microorganisms and preserve the quality of frozen grass prawns.