Revising the role of pH and thermal treatments in aflatoxin content reduction during the tortilla and deep frying processes

Naturally aflatoxin-contaminated corn (Zea mays L.) was made into tortillas , tortilla chips, and corn chips by the traditional and commercial alkaline cooking processes. The traditional nixtamalization (alkaline-cooking) proc ess involved cooking and steeping the corn, whereas the commercial nixtamal ization process only steeps the corn in a hot alkaline solution (initially boiling). A pilot plant that includes the cooker, stone grinder, celorio cu tter, and oven was used for the experiments. The traditional process elimin ated 51.7, 84.5, and 78.8% of the aflatoxins content in tortilla, tortilla chips, and corn chips, respectively. The commercial process was less effect ive: it removed 29.5, 71.2, and 71.2 of the aflatoxin in the same products. Intermediate and final products did not reach a high enough pH to allow pe rmanent aflatoxin reduction during thermal processing. The cooking or steep ing liquor (nejayote) is the only component of the system with a sufficient ly high pH (10.2-10.7) to allow modification and detoxification of aflatoxi ns present in the corn grain. The importance of removal of tip, pericarp, a nd germ during nixtamalization for aflatoxin reduction in tortilla is evide nt.