Factors influencing anthocyanin loss during nixtamalization of blue purple maize grain

Blue purple maize grain loses a great amount of anthocyanins during the nixtamalization processing. The impact of the process factors on anthocyanins losses has not been studied in detail. The objectives of this work were to: (1) determine the step of the nixtamalization procedure where the greatest anthocyanin loss occurs and (2) study the effect of cooking time, alkali concentration, and sample size on anthocyanin losses (AL), and on the color of masa and tortilla from blue purple maize grain. Two cooking times were assayed (25 and 35 min), three alkali concentrations (0.5, 0.7, and 1.0% w/w), and two maize grain sample sizes (100 and 1000 g). Alkali concentration determines the time required to solubilize the maize grain pericarp, higher concentrations resulted in shorter maize grain pericarp solubilization times and this variable was related with AL. The greatest AL occurred during the grain cooking step, but an additional loss took place during the steeping of cooked grain. For the cooking time of 25 min, AL were of 38.3% during the cooking step, and 21.3% during the steeping of cooked grain. The cooking time had no effect (p > 0.05) on AL in masa and tortilla whereas alkali concentration and sample size significantly affected it. The greater the concentration and size, the higher the AL. The color of masa and tortilla were affected by cooking time and alkali concentration. Increasing alkali concentration during the nixtamalization procedure, reduced the brightness and chroma of masa and tortilla and made these products seem darker and dull.