Determination of the heat transfer parameters during cooking maize buns yellow

Abstract

The buns are indigenous foods prepared from corn dough, these are wrapped in the corn leaves and cooked by boiling. In this research were determined the parameters of the heat transfer during the process of cooking of buns of maize of the variety cariaco yellow, The cooking was performed in an automated system with the control of temperature and time. The thermophysical properties were calculated according to the chemical composition and temperature. The heat transfer coefficient was calculated by linear regression from the dimensionless temperature vs time data. The results indicated that the thermal center of the product reached 75 ± 1 °C in 25 minutes. The composition of cooked buns was (moisture = 29.54 ± 1.07, fat = 6.51 ± 0.49, ash = 0.48 ± 0.05, protein = 7.59 ± 0.29, fiber = 9.65 ± 0.77, carbohydrates = 45.89 ± 3.22 % and calories = 373.36 ± 9.36 kcal / 100 g). The coefficients of conductivity and thermal diffusivity increased significantly with the processing temperature, obtaining maximum values in the final product of 0.68 ± 0.07 W/m° C and 1.98 ± 0.02 x 10-7 m2/s. The heat capacity and the density in the cooked product were 3145.36 ± 88.45 J/kg °C and 1254.49 ± 30.47 respectively. The convective coefficient was 118.29 W/m2 ºC, which was within the range reported for similar starch products. The understanding of the parameters of heat transfer during the cooking of corn bun is important for the optimization of thermal processes applied in this food.