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

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 ofEscherichia coli O157:H7 andSalmonella entericaserovar 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 ofE. coli O157:H7 andS. 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/cm(2)of ultraviolet-C treatment resulted in 1.9, 3.3, and 3.9-log reductions inE. coli O157:H7 and 0.9, 3, and 3.9-log reductions inS. 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 alpha(s1)-casein, alpha-lactalbumin, and lactoferrin were observed between both samples. Compared to the untreated raw milk,c9t11 conjugated linoleic acid decreased (P < 0.01) whilet10c12 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/cm(2) 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.

Automated summary

This study investigated the effects of different ultraviolet-C light doses on the viability of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium, as well as the chemical changes to camel milk components. The results showed reductions in bacterial counts and minimal impact on camel milk components after ultraviolet-C treatment.