RESUMEN
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.
Asunto(s)
Grano Comestible/química , Aditivos Alimentarios/análisis , Conservación de Alimentos/métodos , Harina , Conservantes de Alimentos/análisis , Factores de TiempoRESUMEN
In Mexico, some varieties of beans become hard during storage, and required a longer time for cooking. Beans which need more than four hours to cook are deemed unsuitable for human consumption by the government agency CONASUPO even though their nutritional value is unaltered. The objective of this study was to evaluate the nixtamal-tortilla-making quality of mixtures of maize and hard beans, protein, sensory evaluation, and shelf life of the tortillas. The tortillas were made from mixtures of maize with 5% and 10% hard beans without the seed coat and compared with tortillas made with 100% maize. The mixtures and the control were nixtamalized for 20, 30 and 40 minutes with 1% lime (CaO). The maximum viscosity of the mass were statistically equal to that of the control. The mixture with 10% beans, 90% maize, and 30 min of nixtamalization produced tortillas with 26.3% more protein than the control. The texture evaluated in the Instron showed that the tortillas with 10% beans were harder than the control; however, in the sensory evaluation, the recently-made tortillas with 30 min nixtamalization were judged the best, with no significant differences between the control and the mixtures of maize with hard beans. The analysis of fungi, yeasts, and bacteria at room temperature and with refrigeration (4 degrees C), showed that the growth of microorganisms was directly proportional to the percentage of beans added and the duration of storage. The largest number of microorganisms was found at room temperature after 48 h of storage.