Effect of process and variety on physico-chemical and rheological properties of two corn flour varieties (Atp and Kassaï)

Abstract

Corn is the world's most widely used cereal in the production of supplementary foods. This use involves several processing steps such as fermentation, roasting and dehulling. These processes are either applied alone or in combination, and are accompanied by the modification of the nutritional, functional and rheological characteristics of the flour obtained. This led us to investigate about the influence of the process and the variety on the physico-chemical and rheological properties of the flours. White and yellow corn flours used were process using three processes. Unroasted flours were obtained after dehulling and fermentation, roasted flours after fermentation and roasting and unfermented flours after soaking and grinding. The proximate chemical composition, physical, rheological properties and PCA (Principal Component Analysis) were evaluated. The results showed that treatment and variety significantly affected these properties with roasted flours who had the best contents of digestible carbohydrates, minerals and ash while unroasted flours had the highest of protein and lipid contents. The white variety had the highest levels of carbohydrates and proteins, while the yellow variety had the highest of lipid and minerals contents. The evaluation of the rheological properties shows that the pasting temperature is between 74.50 and 77.77 °C, between 490 and 1053.55 cP for the Holding viscosity and between 431.50 and 2348 cP for the peak viscosity. The rheological properties always showed that the roasted flours had the lowest pasting temperatures, retrogradation, final viscosity and peak temperatures while unfermented flours had the highest values. Principal component analysis (PCA) showed that unroasted flours are characterized by the carbohydrates, starch, amylose, amylopectin and lipids content, roasted by minerals, anti-nutrient and protein contents and the unfermented flours by rheological properties. All this shows that the combination of the process and use of these corn flours varieties could be used to prepare the infant meal and thus fight against protein energy malnutrition in children. • Variety influence physico-chemical and rheological properties of different flours. • The different process has influenced physico-chemical and rheological properties. • Yellow flour variety exhibits the best rheological properties. • Unroasted flour (process I) has present the highest proteins and lipids content.