EFFECT OF ANTIMICROBIAL SOLUTIONS ON Salmonella POPULATIONS AND COLOR OF CLADODES OF NOPAL VEGETABLE

Abstract

During the production and post-harvest handling of the nopal vegetable (Opuntia ficus-indica) there is a risk of contaminating this product with pathogenic microorganisms such as Salmonella. Currently, there is no effective product to eliminate Salmonella from fresh nopal vegetable. To prevent illnesses to consumers of this fresh product, it is important to have an effective disinfectant that eliminates the bacteria without affecting the color of the cladode. This research aimed to evaluate the effect of organic compounds such as hibiscus (Hibiscus sabdariffa) calyx extracts, a mixture of white vinegar and lemon (Citrus × latifolia) juice 1:1 (v/v), and 1.5 % lactic acid solution on Salmonella cultures, as well as identify their effect on the color of fresh vegetable nopal tissue, without thorns. Nopal cladodes of the Atlixco, Copena V1, Milpa alta and Villanueva varieties were used for the tests, inoculated with a mixture (7.6 log10 CFU) of strains of the serotypes S. Javiana and S. Typhimurium, resistant to Kanamycin (Km50). After the incubation time, cladodes were put in contact with the disinfectant solution for 10 min, they were immediately washed with sterile distilled water and the bacterial count was performed by inoculating the previously treated samples in boxes with Hektoen enteric agar added with Km50. Results obtained showed a significant reduction (P ≤ 0.05) of 2.4 log10 mL-1 in the Salmonella population with all the solutions evaluated (extracts of hibiscus calyces, a mixture of white vinegar and lemon juice, and lactic acid). The luminosity of the tissue was affected (P ≤ 0.05) only with the mixture of vinegar and lemon juice; thus, it is concluded that all the disinfectants tested are suitable to maintain the safety and quality of the nopal vegetable.