The effect of ultraviolet radiation on pathogenic microorganisms in milk, traditional fruit juice, and drinking water

Subject Areas : Food Hygiene

Reza Nooshabadi ¹ , seyed majid hashemi ^{2 *}

1 - Graduated in food hygiene, Department of Food Hygiene, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran
2 - Research Center of Nutrition and Organic Products (R.C.N.O.P), Shahrekord Branch, Islamic Azad University, Shahrekord, Iran

Received: 2024-08-11 Accepted : 2024-12-11 Published : 2024-08-20

Keywords: Escherichia coli, Salmonella, Staphylococcus aureus, Listeria monocytogenes, Ultraviolet radiation,

Abstract :

Due to the growing demand for healthier products, non-thermal technologies, such as ultraviolet (UV) radiation, have been studied as alternative methods for food and water treatment. The present research investigated the effect of UV rays on bacteria inoculated into milk, fruit juice, and drinking water. The samples were sterilized before inoculating Escherichia coli, Salmonella, Staphylococcus aureus, and Listeria monocytogenes. The inoculated samples were then exposed to UV radiation. Treatment durations of 30, 60, and 120 seconds were applied. Statistically significant (p < 0.05) differences in bacterial reductions were observed across the different exposure times. The highest contamination was found in the first dilution of apple juice for E. coli (13.66 ± 1.11 log CFU/ml), while the lowest contamination was found in the fourth dilution of milk for S. aureus (0.26 ± 0.01 log CFU/ml). The 30-second UV treatment for milk, water, and apple juice reduced E. coli by 30-40%; the 60-second treatment reduced E. coli by 60-70%; and the 120-second treatment reduced E. coli by 100% in water and milk. In apple juice (first dilution), the 120-second UV exposure reduced E. coli by 97%, with a 100% reduction observed in the remaining dilutions. The 30-second UV treatment reduced Salmonella by 30% in milk, water, and apple juice; the 60-second treatment resulted in a 75% reduction; and the 120-second treatment achieved a 100% reduction. Similarly, the 30-second UV exposure caused a 40% reduction in Listeria monocytogenes; in 60 seconds, the reduction was 80%, and in 120 seconds, it reached 100%. For S. aureus, the 30-second treatment caused a 70% reduction in milk, water, and apple juice, while 60 and 120 seconds of exposure resulted in a 100% reduction. In conclusion, the results indicate that UV radiation, when accurately directed at liquids, effectively reduces bacterial contamination in milk, fruit juice, and drinking water.