Physicochemical and Rheological Changes of Starch in Nixtamalization Processes: Extrusion as an Alternative to Produce Corn Flour

Abstract

Corn tortilla is a food consumed mainly in México and Central America. It provides 50% of total calories ingestion and is a good source of fiber. Tortilla is produced by the nixtamalization process using corn, water and lime. It has been produced by alternative processes as extrusion, reducing cooking liquor, and increasing dietary fiber. The aim of this book chapter is to describe the changes in corn starch by different nixtamalization processes, also are presented the advantages and disadvantages of both processes, encouraging some aspects of producing corn flour by extrusion. The extrusion is a technology that is dependent of process variables and is reflected on quality of end product. Several factors are involved, as feed moisture and temperature, and they have a direct impact on corn starch physicochemical, textural, and rheological properties.

Innovation in Nixtamalization by Extrusion Using the Wet Process

“…The nixtamalization process involves treating corn with an alkaline solution, usually lime (calcium hydroxide). Factors, such as lime concentration, soaking time and cooking temperature play a pivotal role in the flavor and nutritional content of nixtamalized masa [28]. Extrusion involves subjecting a whole flour of corn with a variety of particle sizes mixed with the lime in concentrations from 0.1 to 0.5% w/w and from 30 to 60% of moisture.…”

“…This resting period allows for hydration and relaxation of the masa structure. This, in turn, raises the gelatinization temperature and results in a more reorganized starch molecule, contributing to a higher degree of crystallinity retrogradation, shortening, and syneresis [ 28 ].…”