[Shelf-life and sensorial evaluation of corn tortillas, made with preservatives and texture conditioners]

With the objective of producing packaged tortillas with a longer shelf-life which, at the same time, have the qualities of fresh tortillas, the effects of preservatives and texture conditioners on rheologic and sensory characteristics and shelf-life of tortillas made with nixtamalized corn flour were studied. The preservatives evaluated were potassium sorbate (SK) and calcium propionate (PCa). The texture conditioners used were carboxymethylcellulose (CMC) and sodium stearyl-2 lactilate (SS2L). Fresh tortillas were evaluated for pH, yield, texture, elasticity, and sensory quality. The packaged tortillas were packed in polyethylene bags and stored at 4 degrees C. The tortillas with 0.1% SK, 0.1% PCa, and 0.25% SS2L were the most acid (pH = 5.12), had the longest shelf-life (53 days with no microorganism growth), and the lowest total count of aerobic mesophylls (23 colony forming units). The highest yields resulted from the treatment with 0.5% CMC, producing the most elastic tortillas but those with the shortest shelf-life (18 and 24 days). The sensory evaluation, done ten days after packing by five trained panel members, judged that best treatment was that which contained 0.1% SK, 0.1% PCa, and 0.5% CMC. These tortillas were judged to be the softest and most elastic. For the remaining attributes, the best tortillas were those processed by the traditional method (fresh). In the pleasure test, the opinion of the consumers was that the tortilla with the best flavor was the traditionally prepared tortilla. Nevertheless, the treatments with mixtures of preservatives and texture conditioners were graded with scores similar to those obtained by two commercial packaged tortillas.