Evaluación microbiológica comparativa del queso de hoja tradicional elaborado en una planta industrial y en una artesanal de la ciudad de Latacunga.

Abstract

The microbiologic comparative evaluation of the traditional leaf cheese from Latacunga city elaborated in an artisan and industrial way was carried out. The samples were collected at random periods. The microbiological count was conductec to aerobic mesophilic (NTE INEN 1592-5), total coliforms, Escherichia coli, Staphylococccus aureus using 3M TM Petrifilm TM. The lactic acid bacteria count was carried out in selective media of cultivation MRS and M17 taking as a reference the methodology (PRT-712.02-047). The isolation of the lactic acid bacteria was conducted based on the macroscopic morphology, microscopic, catalase test, oxidase, and motility. The strain growth was evaluated in different conditions of temperatura (10ºC and 45ºC), NaCl concentration (6.5% and 18%), pH (4.4 and 9.6) and the formation of CO2 from glucose. Finally, the strains were stored in 30% glicerol at -20ºC for subsequent identification test. The results showed that the leaf cheese produced at the industrial level meets the microbiological requirements of the standard NTE INEN 1528, unlike the artisanal leaf cheese, therefore failed to meet the microbiological criteria. At the end of the isolation, it was selected 32 lactic acid bacteria strains, (56,25%) bacillus, and cocci (43,75%) wich were Gram positive, catalase, oxidase, and motility negative. The test of diferential characterization showed that 50% of isolated strains in MRS could belong at Lactobacillus genre and isolated strains in M17 at Enterococcus genre. However, it is necessary biochemistry and genetic test.