[Comparison of methods for determining corn hardness (Zea mays L.)]

One of the most important intrinsic properties of corn kernels is hardness. Nowadays controversy exists as to which method is more accurate to measure this property. In the present study, therefore, several methods for measuring hardness in corn kernels are compared, for the purpose of finding the most appropriate one. A corn population ranking from hard to soft was tested. The methods tested were: endosperm texture (ET), pearling index (PI) floating index (FI), density (D), near infrared reflectance (NIR), test weight (Ph) and time required to grind the corn with the Brabender automatic micro-hardness (TDB) method. The floating index (FI) method was found to be the most suitable one for determining hardness of corn kernels. This method permitted determination of the differences existing in corn with hard, intermediate, and soft-textured endosperms, with low variation coefficients. The TDB and NIR methods were not appropriate to determine the hardness of corn kernels, showing high variability in the results. With the Ph and D methods it was difficult to distinguish between corn with hard, intermediate and soft texture endosperm.