Assessment and Relationship between Chemical Composition and Microbial Load in Corn Tortillas Sampled from Different Vending Points in Two Regions of Mexico

Abstract

During tortilla production, different heating stages help to ensure low bacterial loads that contribute to their safety. However, there is an increasing concern about these products’ stability. This work is aimed at analyzing corn tortillas collected at different vending points from two regions of the country, Nuevo Leon and Guanajuato. A total of 80 samples were analyzed, and the bacterial presence was related to the origin of the raw materials. Guanajuato region resulted with the highest concentration ( $6.04\pm 0.07$ Log UFC/g). Tortillas made with nixtamalized corn masa flour (NMF) had significantly lower microbial loads ( $p<0.05$ ) than those made with 100% nixtamal masa or mixtures of NMF/nixtamal masa. In all samples, there were no pathogenic bacteria. On 28 selected samples, through PCA analysis, a strong influence of the microbial loads (which include foodborne bacteria) and their changes in chemical composition being reflected in the free sugars, free amino nitrogen (FAN), and peroxides contents, respectively, could be related with the vending point good manufacturing practices.