Estudios de control de insectos para la preservación del maíz opaco-2 almacenado, y efectos sobre su valor nutritivo.

The present research was carried out to evaluate the effectiveness of three types of packaging materials and of six treatments on the control of insect infestation of Opaque-2 corn. The packaging materials employed were burlap sacs previously treated with 2% Malathion, untreated burlap bags, and 3-layer paper bags. The chemical treatments included the application of methyl bromide once or every two months; Phostoxin applied once or every two months; tricalcium phosphate; calcium hydroxide, thulane; and a control. The bags containing the Opaque-2 corn were stored at ambient temperature for a period of 6 months. Evaluation consisted in monthly measurements of percentage of insect damaged grains, number and kinds of insects. At the end of 6 months, the grain was also analyzed for uric acid, total protein and the zein fraction and non-protein nitrogen (NPN). The material, raw and cooked, was also evaluated for protein quality by protein efficiency ratio (PER) assays. The best protection was furnished by the burlap bags, previously treated with 2% Malathion, a method which, besides being efficient, is practical and of low cost. The effectiveness of untreated burlap bags and paper bags was poor in both cases. Other effective treatments included the application of methyl bromide and Phostoxin every two months, as well as the use of calcium salts and Lindane. It was not possible to detect losses in protein quality in the raw or processed corn. However, processed corn in the form of tortilla was consistently superior to raw corn. No relationship was found between damage and zein content, although a highly statistical significant correlation was found between uric acid and NPN.