The influence of electron beam irradiation on the effectiveness of trans-cinnamaldehyde-coated LDPE/polyamide films

We have evaluated the effect of electron beam irradiation (up to 20 kGy) on the functional and barrier properties of trans-cinnamaldehyde-coated low-density polyethylene (LDPE)/polyamide films. Irradiation did not affect the tensile strength and toughness of the films, but the 20 kGy treatment increased the percent elongation-at-break significantly. The barrier properties were also enhanced (approximately 18.8%) when the films were exposed to 20 kGy. Addition of trans-cinnamaldehyde with 3% of polyamide coating solution (w/w) did not affect the tensile strength and barrier properties of the films, but significantly decreased the percent elongation-at-break and toughness. Films with 3% and 10% coating were used to wrap fresh-cut romaine lettuce samples to determine their antimicrobial activity. Total aerobic plate count (APC) and yeast and mold growth were determined as a function of dose (0, 0.5, and 1.0 kGy) for 14 d of storage at 4 °C. Irradiation reduced the total APC and yeast and mold counts (YMC) as dose increased. The 0.5- and 1.0-kGy treatments decreased initial APCs by 1.2- and 1.5-logs, and no YMCs were observed in the 1.0-kGy treated samples at day 0. Irradiation exposure significantly lowered APCs of lettuce samples by almost 1-log colony-forming unit (CFU)/g compared to the nonirradiated controls, though it only slightly reduced YMCs. The effectiveness of using irradiation with antimicrobial films was enhanced with increased radiation dose and trans-cinnamaldehyde concentration (3% to 10%).