Many Mexican women consume inadequate amounts of folic acid. Fortification of the corn tortilla could be an effective way to help increase the folic acid levels among the Mexican population. Previous studies have shown significant folic acid losses in fortified tortilla dough (masa) as it is held before baking. This loss in folic acid could be due to degradation by lactic acid bacteria naturally present in the masa. The microflora of traditionally made nixtamalized corn masa from six tortilla mills in Guadalajara, Mexico were isolated and characterized, and their effect on folic acid content was evaluated. Isolated bacteria were identified using whole cell fatty acid analysis via MIDI Inc.'s Microbial Identification System. Twenty-two unique bacterial species were identified, primarily belonging to the Streptococcus and Lactobacillus genera. Lactic acid bacteria were the predominant microorganisms, with counts ranging from 10^4 to 10^7 cfu/g. Aerobic mesophilic bacteria also ranged from 10^4 to 10^7 cfu/g. Coliforms and yeasts and mold were present at significantly lower levels. Masa samples, prepared from sterile fortified corn masa flour, were inoculated with a cocktail of bacteria isolated from the individual mills. Control samples were prepared using sterile media. Inoculated and uninoculated control samples were held at 56°C for 0, 3 and 6 hours, mimicking the elevated temperature of the masa as it is held before baking. The loss of folic acid in the sterile control was not different from the inoculated samples, indicating that the decline in folic acid is not due to bacteria present in the masa, but appears to be a chemical degradation related to time and temperature.



College and Department

Life Sciences; Nutrition, Dietetics, and Food Science



Date Submitted


Document Type





microflora, masa, corn, folate