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

Abstract

As a result of increasing interest in non-thermal technologies as a possible alternative 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 αs1-casein, α-lactalbumin, and lactoferrin were observed between both samples. Compared to the untreated raw milk, c9 t11 conjugated linoleic acid decreased (P < 0.01) while t10 c12 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.

Nonthermal turbulent flow ultraviolet‐C (UV‐C) radiation processing for cheese whey‐brines purification

“…Moreover, authors observed that the higher the number of whey passages through the UV-C apparatus, the higher the microbial reduction. Dhahir et al 2021 reported that camel milk samples subjected to the 4.15, 8.30 and 12.45 mJ/cm 2 of UV-C treatment resulted in 1.9, 3.3 and 3.9-log reductions in E. coli and 0.9, 3 and 3.9-log reductions in Salmonella typhimurium, respectively. The findings on higher bacterial reduction obtained with higher dosage are consistent with our results.…”

“…Ultraviolet-C treatment can be performed under continuous or pulsed light where the liquid passes through a chamber and light photons are being absorbed by the product (Rodriguez-Gonzalez et al 2015). The UV-C spectrum has been proven to efficiently kill microorganisms in different liquids including different types of milk, while preserving nutritional and organoleptic characteristics (Dhahir et al 2021;Papademas et al 2021).…”

“…The UV‐C spectrum has been proven to efficiently kill microorganisms in different liquids including different types of milk, while preserving nutritional and organoleptic characteristics (Dhahir et al . 2021; Papademas et al . 2021).…”

Current progress of emerging technologies in human and animals’ milk processing: Retention of immune‐active components and microbial safety

“…Camel milk has gained attention and popularity due to its specific bioactivities, such as potential antidiabetic (Han et al, 2022) and autism prevention functionality (Deshwal et al, 2020). Dhahir et al (2020b) 1.…”

“…Dhahir et al. (2020b) investigated the effects of UV‐C dosage on the viability of E. coli O157:H7 and S. Typhimurium and changes to camel milk components and found that UV‐C treatment at 12.45 mJ/cm 2 resulted in a 3.9 log reduction in E. coli and S. Typhimurium , and this dosage did not change the main protein profile or induce lipid oxidization, as determined by secondary lipid peroxidation products.…”