Physicochemical and microbiological characterization of the traditional quesillo (Pasta filata) from Oaxaca, Mexico

The quesillo de Reyes Etla, Oaxaca is considered the most important cheese in the country, but also the most imitated for the industry under the name Oaxaca cheese. The aim was to analyze the physicochemical and microbiological properties of the authentic quesillo from Reyes Etla, Oaxaca. Sixty samples from five traditional cheese factories were analyzed; four samples per year were taken in spring, summer, autumn and winter; the analyzes were carried out in accordance with Mexican regulations. A high level of microbial strains was detected: Fungi and yeasts (6.78 log CFU/g), total coliform bacteria (2.53 log CFU/g), fecal coliform bacteria (1.78 log MPN/g), Escherichia coli (7.00 log CFU/g), Lactobacillus spp. (7.35 log CFU/g), Streptococcus spp. (6.94 log CFU/g) and the total absence of Salmonella spp, while the physico-chemical properties showed an appropriate balance: fat (23.08%), moisture (47.04%), protein (23.75%), pH (5.10). The characteristics of quesillo are therefore linked to its production process, in particular the lack of standardization of the process, especially in natural acidification and melting. It is confirmed that the authenticity of the quesillo results from the characteristics of the territory and experiential knowledge.