Physicochemical Properties of Flour Obtained from Selected Traditional Corn Landraces in Sri Lanka

Abstract

In Sri Lanka, most widely grown corn varieties are local and hybrid types. Besides these, there are traditional corn landraces that are relatively overlooked. This study examined physicochemical properties (starch granular structure, colour, pH, water absorption capacity, water solubility, oil absorption capacity, swelling capacity, bulk density, foaming capacity and foaming stability) of flour obtained from 4 such traditional corn landraces (Deshiya Iringu, Kahata Iringu, Kesel Iringu and Rathu Kappal) using standard procedures. For comparative purposes the above parameters were determined in a popularly cultivated local corn variety (Ruwan) and a Hybrid corn variety (M1 Maize Hybrid 5). All tests were conducted with triplicate measurements. Statistical differences between means were determined using analysis of variance (one-way ANOVA) and Tukey's honestly significant difference test. Morphologically no difference was observed in the shapes of starch granules observed under the light microscope. All the samples displayed polygonal granular shapes. Colour was analyzed using CIELAB colour parameters, (L*, a*, b*) which represent lightness, red-green, and yellow-blue values respectively. Highest a* value was shown by Rathu Kappal landrace. Highest L* and b* values were shown by Ruwan variety. pH of corn flours varied between 5.95–6.35. Water absorption capacities and water solubilities of corn flour types ranged between 129.98%–143.47% and 1.75%–4.38% respectively. The Ruwan variety showed the highest water absorption capacity and the lowest water solubility. Oil absorption capacities of corn flours ranged from 91.98%–105.70%. Bulk densities of the corn flours varied between 0.75–0.79 kg/m-3. Statistically there was no significant difference (P>0.05) in bulk densities of flour obtained from traditional corn landraces. Flour obtained from local and hybrid varieties showed significantly high bulk densities. Swelling capacities of the corn flours ranged from 9.00–11.33 mL and Hybrid variety showed the lowest swelling capacity. Foaming capacities of the corn flour types varied between 6.10%–8.40%. The Ruwan variety showed the lowest foaming capacity and Deshiya Iringu showed the highest foaming capacity. Foaming stability of all the corn flour types were found to be 0.00% in 1 hour. Although the study revealed variations in certain physicochemical properties among the six corn flour types, similarities were observed in properties such as foaming stability.

Keywords: Corn flour, Hybrid corn, Physicochemical properties, Traditional landraces