Effect of Electron Beam Irradiation on Microbial and Sensorial Qualities of Frozen Vacuum-Packed Ground Beef Burger Patties

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Introduction

Radiation technology using gamma ray or electron beam has been known to be an effective method to improve food safety. This study aimed to determine the effects of electron beam irradiation on the microbial and sensorial qualities of frozen ground beef burger patties.

Materials and Methods

Beef burger patties were prepared, molded, vacuum packed and stored at -18⁰C and were irradiated at 2, 4, and 6 kGy. Monthly analysis for Aerobic Plate Count (APC), Molds Yeast Count (MYC) and Total coliform counts were done. Cooked patties were evaluated monthly for 6 months for color, juiciness, texture, flavor/taste and overall acceptability fifteen untrained panelists. Statistical analysis was done.

Results and Discussion

At 2 kGy APC & MYC were significantly lower compared to non-irradiated (2.8 ± 0.009 log cfu/g vs. 5.0 ± 0.015 log cfu/g and 2.0± 0.0 log cfu/g vs. 3.4 ± 0.043 log cfu/g, respectively), at 6 months of storage (Figs 1 & 2). Statistical analysis showed that APC means of 2 kGy patties were significantly higher than 4 kGy and 6 kGy throughout the storage. APC of 4kGy and 6kGy-irradiated patties have no difference. 4 kGy and 6 kGy further reduced APC to 2.4 ± 0.0 log cfu/g. Dose of 6 kGy further reduced MYC to 1.0 ± 0.0 log cfu/g, from 0 to 6 months of storage. Total coliform counts of all irradiated groups were also decreased compared to non-irradiated controls at 1.0 ± 0 log cfu/g vs. 2.37± 0.87 log cfu/g at 6th months. No significant differences in total coliform count were observed between 2 kGy, 4 kGy and 6 kGy. There was no significant difference in overall sensorial acceptability of cooked beef patties between irradiated and non-irradiated control until 4th month storage (mean score: 4.66 to 5.66(p>0.05)). At 5th month of storage, mean score for flavor attribute for 2 kGy and 6 kGy irradiated beef patties were 5.2 and 5.73, respectively. There were no significant differences between 2 kGy and 6 kGy for flavor attribute. At 6 th month of storage, irradiated beef patties showed significantly higher mean scores than control in terms of flavor and juiciness.

Conclusion

Electron beam irradiation is effective in reducing the microbial load of frozen vacuum-packed ground beef patties with a dose as low as 2 kGy, from 0 to 6 months of storage 2 kGy maintained the sensorial attributes of beef burger patties throughout 6 th month storage. These results are comparable with APC acceptable limit on meat pate (heat treated), which is 10⁴ cfu/g and coliform counts of 10 cfu/g, based on FDA Circular 2013. The recommended dose is within the limits applicable for meat, which is 1 to 7 kGy, based on the Philippine National Standard on Code of Hygienic Practice for Radiation Processing of Food.