Estudio del calentamiento óhmico para la obtención de masa y harinas de maíz nixtamalizado

Abstract

The corn tortilla is the staple diet in Mexico and part of Central America. These are prepared using the alkaline thermal process which gives masa or corn flour. The corn flour nixtamalized has been an improvement of the ancient method, however is has several problems, such as: generates a large volume of effluent contaminants, loss of solids and nutrients, long times and low energy efficiency. The objective of the present work was to develop an efficient technology designed to produce corn flour to make tortilla using the ohmic heating as a method of cooking. In the first part, we studied the effect of temperature (70, 80 and 90°C), the average particle size (270, 320, 390 μm) and the moisture (45, 52.5 and 60%) of the process in the physicochemical, rheological and functional properties of the corn flour nixtamalized by ohmic heating. For this, we used a design of experiments 33. The results obtained show that the temperature was the parameter determining the quality of the product and in conjunction with the humidity controls the degree of gelatinization of the flours. The flours obtained by ohmic heating, may be destined for different nixtamalized products when controlling the average particle size. On this basis, the flour processed with mean particle size of 270 μm when processed at a temperature of 90°C and humidity of 52.5% and 60% were low viscosities and high solubility rate in water, so that this suggests that can be destined to the manufacture of beverages snapshot type “atoles”. The flour with average particle size of 390 μm, showed high percentages of weight loss and thicker particle size, having appropriated characteristics for the development of snacks or dried corn tortilla. In both that corn flour of ohmic heating with particle size 320 μm showed good performance and an appropriated texture for tortilla, so these flours had the more appropriated characteristics for the preparation of tortillas. In the second part, we compared the flour nixtamalized by ohmic heating with particle size of 320 μm, a corn flour obtained with the traditional process and a commercial corn flour, in its chemical composition, capacity and rate of absorption and solubility in water, viscosity; the yield, humidity and texture of the dough and tortillas. The corn flour processed with the ohmic technology had different degrees of gelatinization according with the results of absorption and solubility in water, as well as in the viscosity profile. The masa obtained from the corn flour by ohmic heating, showed greater moisture (53.62% to 58.25%) that the flour obtained by the traditional process (52.67%), resulting in a higher tortilla yield, with good texture. With regard to the chemical composition of the flours obtained by ohmic heating, these shows higher fiber content, there are not fat and protein losses because is a closed system and the loss of dry matter is null. Calcium content of corn flour by ohmic heating was higher than commercial corn flour ; an important aspect of the ohmic heating process is that allows, in a very controlled way, vary the calcium content of the corn flour. The variable that had the greatest effect on the ohmic heating was the moisture, changing the electrical conductivity, time and power consumed during the process. We can therefore say that the ohmic heating presents a great potential to be used in the processing of corn flour nixtamalized, in addition to not generate pollution effluent and use of grain integral, so it could be used as an alternative technology to give a solution to the problems associated with this industry.