The effect of different ultraviolet-C light doses on microbial reduction and the components of camel milk

Authors: DHAHIR, NAMARIQ - Southern Illinois University; FEUGANG, JEAN - Mississippi State University; WITRICK, KATHERINE - Southern Illinois University; PARK, SEONGBIN - Mississippi State University; WHITE, SHECOYA - Mississippi State University; ABUGHAZALEH, AMER - Southern Illinois University

Submitted to: Food Science and Technology International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2020
Publication Date: 6/24/2020
Citation: Dhahir, N., Feugang, J., Witrick, K., Park, S., White, S., Abughazaleh, A. 2020. The effect of different ultraviolet-C light doses on microbial reduction and the components of camel milk. Food Science and Technology International. 27, 99-111, issue 2. https://doi.org/10.1177/1082013220935230.
DOI: https://doi.org/10.1177/1082013220935230

Interpretive Summary: The global market for camel dairy products is currently developed because of its reported health benefits. It has the same essential nutrients as bovine milk, but higher biological values for antimicrobial factors such as lactoferrin, lysozyme, and immunoglobulins. In addition, camel milk has extraordinary medicinal properties against diseases such as hepatitis, diabetes, and lactose intolerance. Numerous pathogens such as E. coli and Salmonella can contaminate milk and cause illness or death. In the dairy industry, heat treatments, such as pasteurization and sterilization are the most common processing technologies used to inactivate milk-borne pathogens and to extend the shelf life of the product. However, heat treatments have direct effects on the biological, functional, and nutritional properties of milk proteins, lipase enzymes, and vitamins. Here we investigated the potential of a non-thermal approach, the ultraviolet_C light, to inactivate pathogenic bacterial in camel milk samples.

Technical Abstract: There is a need to develop non-thermal technologies as possible alternatives or complementary to milk pasteurization processing. The objectives of this study were to determine the effects of different ultraviolet-C light doses on the viability of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium and chemical changes to camel milk components. Pasteurized and inoculated camel milk samples were ultraviolet-C treated in a continuous flow system. The viability of E. coli O157:H7 and S. Typhimurium was evaluated with both in vivo imaging system and traditional plate count agar method. Samples subjected to the 4.15, 8.30, and 12.45'mJ/cm2 of ultraviolet-C treatment resulted in 1.9, 3.3, and 3.9-log reductions in E. coli O157:H7 and 0.9, 3, and 3.9-log reductions in S. Typhimurium, respectively. The measurement of secondary lipid peroxidation products (or ThioBarbituric Acid Reactive Substance values) showed no significant (P'>'0.05) differences between the raw and ultraviolet-C treated milk samples. Additionally, no changes (P'>'0.05) in the protein profiles of as1-casein, a-lactalbumin, and lactoferrin were observed between both samples. Compared to the untreated raw milk, c9t11 conjugated linoleic acid decreased (P'<'0.01) while t10c12 conjugated linoleic acid increased (P'<'0.01) in the ultraviolet-C treated milk. Furthermore, three new volatile compounds were identified in the ultraviolet-C treated milk compared to the control. In conclusion, milk treated with the ultraviolet-C light at a dose of 12.45'mJ/cm2 did not meet the Food and Drug Administration (FDA) requirements for the 5-log pathogen reduction. The ultraviolet-C treatment, on the other hand, had minimal effects on camel milk components.