Efeitos da radiação UV-C na qualidade nutricional e tecnológica de grãos de milho inoculados com fungos e armazenados sob diferentes umidades

Abstract

Corn (Zea mays L.) is the second most produced cereal in Brazil and its economic importance is due to the different forms of use and relevance in human and animal food. Because to the high demand of maize by the food industry, it is necessary that the grains are stored for long periods to meet the market in offseason. During storage, some species of fungi proliferate in stored grains favoring the production of mycotoxins and rendering them unfit for consumption. So, radiation can be an alternative method of fungus control and, therefore, maintenance of the quality of corn grains. Therefore, the study was divided into two chapters aimed at meeting two main objectives: i); Ii) to evaluate the effects of UV-C radiation and grain moisture on the qualitative and quantitative technological parameters of corn grains during nine months of storage; Ii) to evaluate the effects of UV-C radiation and grain moisture on the qualitative and quantitative technological parameters of corn starch extracted from grains stored during nine months of storage. Corn grains were harvested mechanically and dried to moisture of 13% and 16% . The grains were inoculated with fungi and treated with UV-C radiation at 4 and 8 KJ.m-2 doses. The UV-C radiation at the doses used did not influence the results obtained, however, moisture and storage time had a direct influence on the evaluated parameters. The association of high moisture and a long time of storage showed an increase in the incidence of fungi Aspergillus and Pennicilium, electrical conductivity, lipid acidity, moldy, arid and fermented grains, and reduction on fungi of the genre Fusarium, protein solubility, lipid content and Value L. The phenolic compounds presented higher concentration in the grains inoculated with fungi (0, 4 and 8 kJ.m-2). The mycotoxins were found in higher concentration after storage, being favored dose of 8 kJ.m-2 and the moisture of 16%. No changes were observed in the amylose and solubility of the starch. After storage, in the moiture of 16% are observed the major changes, with reductions in the extraction of starch, value of L * and increases in value b *, crude protein and lipid content. The pasta properties were most influenced at 16% moisture, with increases in pasta temperature, retrogradation and reductions in maximum viscosity and viscosity break. In all treatments, the starch presented perforations, being found in higher concentrations in the moisture of 16% and the dose of 8kJ.m-2. The radiation promoted an increase in the swelling power of the starch granules in all doses in both moistures, with the highest observed increases in moisture content of 16%.