Hurdle technologies for the preservation of nixtamalized tortillas: application of sous vide processing and refrigerated storage

The short shelf life of nixtamalized tortillas, caused by textural changes and microbial spoilage, represents a critical challenge for their industrial commercialization. This study was the first to evaluate the effect of sous vide treatment as a novel alternative for extending shelf life without chemical preservatives. All tortilla formulations, including control, were supplemented with 0.4% carboxymethyl cellulose (CMC) and vacuum-sealed in polyamide films. Tortillas were thermally processed in a circulating water bath at 65 °C for 30 min, then stored at 25 °C and 4 °C. Control samples (vacuum-sealed without thermal treatment) exhibited rapid proliferation of lactic acid bacteria and coliforms, losing flexibility and reaching critical rollability limits (>3) after only 5 days of storage. In contrast, the sous vide treatment significantly reduced the initial vegetative microbial load. At 25 °C, treated tortillas remained stable for two months before rejection due to visible fungal growth. The combination of sous vide processing and refrigerated storage at 4 °C proved to be the most effective strategy, controlling microbial metabolic activity, maintaining moisture content above 42%, delaying increases in cutting force and textural tension, and preserving adequate rollability (<3) for up to 4 months. These results demonstrate that sous vide and refrigeration are a promising preservative-free strategy for extending the shelf life of nixtamalized tortillas, and this approach may promote the development of clean-label products.