EVALUATION OF THE RHEOLOGICAL PROPERTIES OF FRESH CORN MASA USING SQUEEZING FLOW VISCOMETRY - BIAXIAL EXTENSIONAL VISCOSITY

Alkaline corn was cooked for 20, 55 or 80 min, and the nixtamal was gr ound into masas with medium or coarse particle size distributions. Wat er was added to each corn masas in order to obtain the same adhesivene ss. Rheological properties of these masas were evaluated with the sque ezing flow viscometry technique with lubrication at crosshead speeds o f 0.05, 0.2 and 0.5 cm/min, respectively. From the data collected, str ess-strain and biaxial elongational viscosity-radial extension rate cu rves were obtained. All the fresh corn masas gave the same stress and elongational viscosity at any given specific strain and radial extensi on rate, respectively, regardless of the cooking time and degree of gr inding. The elongational viscosity could be useful to predict fresh co rn masa behavior during molding and cutting steps in the tortilla-maki ng process.