[Effect of packing material and temperature of storage on the quality of maize tortilla]. / Efecto del material de empaque y temperatura de almacenamiento en la calidad de la tortilla de maíz.

Three packaging materials (tortilla-packing paper, low-density polyethylene and high density polyethylene) were used to evaluate tortilla shelf-life at two different temperatures (-10 degrees C and 5 degrees C). Tortilla quality changes upon storage were evaluated by measuring pH, total moisture, texture (puncture and cutting resistance) and sensory characteristics. Results were analyzed by means of covariance analysis and slope contrast between treatments with a 0.05 level of significance. At -10 degrees C, the quality of tortillas did not change significantly during 11 days of storage, and the influence of the packaging material was negligible. Tortilla kept at 5 degrees C in high or low-density polyethylenes, had significantly better quality than the paper-packaged product. Textural changes were best shown by the Instron puncture resistance test than by the cutting resistance test. At 5 degrees C, packaged tortillas had a microbiologically stable level for up to seven days, while that at -10 degrees C significantly improved over the storage period.