Effect of the Application of Cold Plasma Energy on the Inactivation of Microorganisms, Proteins, and Lipids Deterioration in Adobera Cheese

Abstract

Cheeses are perishable foods that must fulfill sanitary and quality requirements according to the parameters established globally. Plasma as a nonthermal inactivation technique has been a current research topic for food preservation, so the objective of this work was to study the effect of plasma energy against microorganisms in Adobera cheese (traditional Mexican cheese) as well as evaluate the possible degradation of lipids and protein. 108 CFU/mL of Escherichia coli ATCC 25922, Salmonella ATCC13076, and Staphylococcus aureus ATCC 6538 were inoculated at 0.5 g of Adobera cheese and were subjected to an energy of 30 volts, in a dielectric barrier discharge reactor (DBDR) at intervals of times 1, 3, 5, 7, 10, and 15 min. A flow of a mixture of air and helium at 96% purity was used. The decimal reduction time (D) was determined, and the oxidation of proteins and lipids was analyzed after each treatment. The results showed an annihilating effect of plasma on the indicator bacteria under study, and a reduction of 5 logarithmic cycles was obtained. The maximum degree of lipid oxidation was 23 acid degree values (ADV) after 7 min of exposure to plasma. The oxidation of proteins showed a direct and proportional relationship between the formation of carbonyl groups with the percentage significant loss to the concentration of carbonyl groups with the concentration of protein oxidation, after 3 min of exposure to cold plasma levels of 82% and 99% oxidation of Adobera cheese protein and free casein, respectively. We conclude that the plasma energy applied to Adobera cheese is an effective treatment to inactivate bacteria. However, there is the possibility of causing changes in taste and odor, due to the release of fatty acids and the oxidation of proteins.