Table 2.
The antimicrobial efficacy of LED in solid foods
Tested food product | LED used | Tested microorganisms | Quality and mode of action | Major findings | References |
---|---|---|---|---|---|
Sliced camembert cheese | UV emitting peak wavelengths 266, 270, 275, and 279 nm; dose, 1, 2, and 3 mJ/cm2, respectively; radiation intensity, about 4 W/cm2 | E. coli O157:H7, S. Typhimurium and L. monocytogenes | The 3 mJ/cm2 dose resulted in 4 to 5 log reduction in E. coli, S. Typhimurium and L. monocytogenes | Kim et al. [56], | |
Shelled almonds | 405 nm MBL LED lights; working distance, 7 cm; treatment time, 0, 1, 2, 4, 6, 8, and 10 min | Pathogenic E. coli O157:H7, non-pathogenic E. coli K12, pathogenic S. Enteritidis (PT30, Stanley and Anatum) and non-pathogenic S. Typhimurium strain Chi3985 with 8 or 5 CFU/g inoculum levels |
Following log reductions for higher and lower inoculum levels, respectively: E. coli O157:H7, 2.44 and 1.44 log CFU/g E. coli K12, 1.85 and 1.63 log CFU/g S. Enteritidis, 0.7 and 0.55 log CFU/g S. Typhimurium, 0.54 and 0.97 log CFU/g |
Lacombe et al. [66] | |
Fresh-cut papaya | 405 ± 5 nm LED treatment with 0.9–1.7 kJ/cm2 (24–28 h), 10 ± 1 mW/cm2; working distance 4.5 cm in the temperature-controlled incubator (4, 10, or 20 °C) | S. Agona, S. Newport, S. Saintpaul and S. Typhimurium | No significant cellular lipid oxidation, significant DNA oxidation, no significant color change and antioxidant capacity, 1.5–1.9 times higher total flavonoid content, no significant change in the ascorbic acid, β-carotene and lycopene content | 0.3–1.3 log CFU/cm2 reduction in Salmonella cells at 1.3–1.7 kJ/cm2 dose | Kim et al. [58] |
Fresh-cut mango | 405 ± 5 nm LED; irradiance, 20 ± 2 mW/cm2; at 4, 10, or 20 °C illumination temperature; treatment times, 24–48 h; total dose, 1.7–3.5 kJ/cm2 in a temperature-controlled incubator | Three strains of E. coli O157:H7, 3 serotypes of L. monocytogenes and 5 serotypes of Salmonella | No significant changes in the color, antioxidant capacity, total flavonoid content, ascorbic acid content, and β-carotene of the LED treated mangoes | 2.6–3.5 kJ/cm2 of LED light resulted in 1–1.6 log CFU/cm2 at 4 and 10 °C in all the bacterial species and; 1.2 log CFU/cm2 reduction in Salmonella at 20 °C with 1.7 kJ/cm2 dose | Kim et al. [59] |
Fresh-cut pineapples | 460 nm LED with irradiance of 92.0, 147.7 or 254.7 mW/cm2, corresponding to the working distances (4.5, 3.5 and 2.5 cm, respectively); illumination times (24, 13.91 and 8.66 h) to produce the same dose of 7950 J/cm2 to the slices. | A cocktail of five serovars of Salmonella enterica Gaminara, Montevideo, Newport, Saintpaul, and Typhimurium | Discolouration of treated pineapple slices | Significant effect of illumination temperature on the antibacterial efficacy; inactivation ranged from 0.61 to 1.72 log CFU/g | Ghate et al. [36] |
Satsuma mandarin fruits | 465 nm blue LEDs with low (8 μmol/m2/s) and high (80 μmol/m2/s) fluency | Penicillium italicum | Radial growth of sporulation zone was found to be 0.3 and 3 mm/day for high and low fluency, respectively. LED-80 produced suppression of sporulation till day 6 after inoculation | Yamaga et al. [132] | |
Blueberries | Green, red, blue, and white LEDs; working distance, 30 cm | Bacillus amyloliquefaciens and Lactobacillus brevis for fermentation and Propionibacterium acnes and Staphylococcus epidermis for antimicrobial study | Green and white LED increased the total phenolic content and total flavonoid content in fermented blueberry extract | White and green LED effective in improved fermentation for 72 h and improved antibacterial activity | Jeong et al. [46] |
White mushrooms and commercial ready-to-eat (fully cooked) sausages | Three UV-C LEDs (280 nm) were combined; working distance-3 cm; varied duty cycle; irradiance, 1 to 5 J/cm2, continuous and pulsed irradiation | E. coli O157:H7 (ATCC 35150, ATCC 43889, and ATCC 43890), Salmonella enterica serovar Typhimurium (ATCC 19585, ATCC 43971 and DT 104), and Listeria monocytogenes (ATCC 19111, ATCC 19115, and ATCC 15313) | LED treatment reduced formazan formation levels in E. coli and Listeria; pulsed LED produced more ROS and membrane lipid peroxidation compared to continuous irradiation; no significant effect on membrane damage but effect on membrane potential of E. coli and Listeria |
Continuous and pulsed irradiation resulted in the following inactivation, respectively: White mushrooms: E. coli, 2 and 2 log CFU/g; Salmonella, 1 and 1.5 log CFU/g; Listeria- 1 and 1.8 log CFU/g RTE sausages: E. coli, 2 and 3 log CFU/g; Salmonella, 1.5 and 4 log CFU/g; Listeria, 2 and 4 log CFU/g |
Kim and Kang [50] |
Cooked chicken | 405 ± 5 nm LED; working distance, 3 cm; surface intensity on cooked chicken 22.0 ± 1.1 mW/cm2; dose, 1.58-3.80 kJ/cm2; treatment times, 20-48 h; illumination temperature, 4, 10, and 20 °C | Salmonella enterica Enteritidis (124, 125, and 130) | Salmonella cells incapable of cellular repair at 4 °C | 0.8–0.9 log CFU/cm2 reduction on cooked chicken in all Salmonella spp. with 3.8 kJ/cm2 dose at 4 °C; growth delays observed at 10 and 20 °C | Kim et al. [57] |
Smoked salmon | 460 nm LEDs; working distance, 9 cm (intensity of 15 mW/cm2) to 5.4 cm (intensity of 58 mW/cm2); dose maintained at 2400 J/cm2 | Four serotypes of Listeria monocytogenes | 0.7–1.2 log CFU/cm2 reduction with LED treatment in combination with riboflavin (25, 50, and 100 mM) | Josewin et al. [47] | |
Ready-to-eat fresh Salmon | 405 nm LEDs; radiation intensity, 26 ± 2 mW/cm2; working distance- 4.5 cm | Listeria monocytogenes inoculated on salmon exudates | LED treatments effective in reduction of Listeria during the biofilm formation | LED treatment produced 2–2.8 log reduction in planktonic cells on stainless steel or acrylic coupons in salmon exudates during 8 h storage | Li et al. [72] |
405 nm LED; intensity, 16 ± 2 mW/cm2; treatment time, 8 h; illumination temperature, 4 and 12 °C; working distance −7.9 cm | Listeria monocytogenes and Salmonella enterica serotype Enteritidis, Typhimurium and Newport | LED treatment produced insignificant color change; it improved the sensitivity of the bacteria to simulated gastric fluid | Reduction of 0.4 and 0.3 log CFU/cm2 in L. monocytogenes; reduction of 0.5 and 0.4 log CFU/cm2 in Salmonella at 4 and 12 °C, respectively | Li et al. [73] |