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ResumenSe estudió el efecto del secado con aire previo al freído, en la disminución de grasa y en otras propiedades de tortillas tostadas. En el secado, se manejaron tres temperaturas (35, 48 y 68 °C) y tres velocidades de aire (2, 4 y 6 m/s), obteniendo una humedad en la tortilla de 6 a 12%. En el proceso de freído, se analizaron tres temperaturas de aceite (140, 160 y 180 °C) y cuatro tiempos de proceso (30, 60, 90 y 120 s), partiendo de tortilla con 10% de humedad. Se determinó que una pérdida acelerada de humedad durante el secado resultó en una pérdida lenta de humedad en el freído y viceversa, y que el secado tuvo un efecto significativo sobre el freído. Las tostadas tuvieron un contenido de grasa más bajo que los productos comerciales, y atributos sensoriales semejantes. Se realizó una optimización del proceso mediante un programa computacional, basado en el modelo Box-Behnken y los resultados se compararon con datos experimentales. Palabras clave: tortillas tostadas, secado, freído, combinación de procesos Study of the Combined Effect of Drying and Frying on Toasted Tortillas Properties AbstractA study of the combination of air drying and immersion frying, and their effect on decreasing fat content and other properties of toasted tortillas was done. Drying with hot air (35, 48 and 68 °C) at 2, 4 and 6 m/s was utilized to dry the tortillas, in which the final moisture content was in a range of 6-12%. Frying was conducted with initial moisture of 10% in the tortillas, at 140, 160 and 180 °C and process times of 30, 60, 90 and 120 s to get the toasted tortillas. Faster moisture loss during drying determined lower evaporation rates through the frying and vice versa. There was a significant effect of the drying conditions on the fried product. The toasted product had fat content lower than commercial products and similar quality attributes. Optimization of the process was carried out using a computer program and the Box-Behnken approach. Model results were compared with experimental data.

The purpose of this study was to combine advantages of two processes: air drying and frying to produce toasted tortillas with lower fat content in comparison with those commercial items existing in the market. Product characterization of four commercial brands was carried out; characteristics, such as moisture (1.8-6.7%) and fat percentages (22-28%), color parameters (L: 23-25, a: 0.04-0.18, b: 1.3-2.5) and texture (5.8-7.6 N) were measured in order to establish a reference frame. Drying with hot air (35, 48 and 68°C) at 2, 4 and 6 m/s were applied to dry tortillas, in which the final moisture contents were in the range of 6-12% and taking 30-200 min of treatment, as a function of the variables, to reach 10% of moisture. While frying was conducted with a standardized initial moisture of 10% at 140, 160 and 180°C, in which only two minutes were utilized to get the toasted tortillas. In general terms, at a given temperature lower moisture and higher fat contents were measured for longer frying times, and finding that tortillas dried at 4 m/s resulted in better product attributes. There was significant effect of the drying conditions on the fried product. The toasted product had 2-4% moisture, 10-12% fat, which is lower than commercial products; and it developed similar quality attributes to those of commercial "tostadas". Mass transfer parameters were computed for processes, drying and frying. Finally an optimization was carried out, with the Design Expert software and experimentally as well.