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Modified atmosphere packaging pre-storage treatment for thermal control of E. coli ATCC 25922 in almond kernels assisted by radio frequency energy
- Cheng, Teng, Wang, Shaojin
- Journal of food engineering 2019 v.246 pp. 253-260
- Escherichia coli, air, almonds, color, energy, fatty acids, heat tolerance, heating systems, modified atmosphere packaging, pasteurization, peroxide value, radio waves, seeds, sustainable technology
- The purposes of this study were to validate modified atmosphere packaging (MAP) pre-storage for reducing surviving populations and thermal resistance of E. coli ATCC 25922 in almond kernels. A 6 kW, 27.12 MHz radio frequency (RF) assisted hot air heating system was used to conduct thermal treatments of 1.5 kg MAP pre-storage samples. Surviving populations of E. coli ATCC 25922 in almond kernels with 8.0% wet basis were determined weekly for 12-week pre-storage and samples were removed at five different time intervals during thermal treatments to achieve at least 4-log reduction. The results showed that reduction levels of E. coli for MAP and regular atmosphere packaging (RAP) were 1.47 ± 0.08 and 0.61 ± 0.05 log CFU/g after 12-week pre-storage. The 4-log reduction time of E. coli in MAP was 18 ± 1 min holding after RF assisted heating to 75 ± 2 °C, reducing 40% pasteurization time as compared with RAP pre-storage. Fatty acid and peroxide values remained within acceptable range (FA < 0.6% and PV < 1.0 meq/kg), and color values of treated samples were not significantly (p > 0.05) different from those of untreated ones. MAP pre-storage assisted thermal treatments induced by RF energy may hold potential as an effective and environmentally friendly method to control E. coli ATCC 25922 in almond kernels.