Qualidade de grãos de milho armazenados em escala comercial: Análise dos efeitos do resfriamento artificial

Abstract

Large-scale grain storage in Brazil has been facing challenges imposed by climatic conditions that speed up deterioration and favor pests and fungi proliferation. Artificial cooling of the grain mass emerges as a technological alternative to conventional aeration. Thus, this doctoral dissertation presents an integrated analysis of the effects of artificial cooling on the quality and sanity of 12,000 tons of Zea mays L., (3,000 maize tons per silo in four commercial metallic silos), by comparing artificial cooling with conventional management (aeration and chemical control). The research evaluated the effects on the physical, hygroscopic, and nutritional quality condition of grains (Chapter 1), the population dynamics of pest insects (Chapter 2), the incidence of mycotoxins (Chapter 3), and thermal dynamics based on mathematical modeling (Chapter 4). The results revealed distinct responses dependent on context. For grain quality, cooling showed selective influence dependent on time. For pest insects, efficacy was species-dependent: Sitophilus spp. increased to 28.3 insects/trap (7 times higher than the control with 4.0 insects/trap); Tribolium spp. reached 924.8 insects/trap in the control versus 411.8 in cooling; Cryptolestes spp. presented 242 versus 156 insects/trap; Oryzaephilus spp. reached 577 insects/trap in cooling (8.2 times higher than the control). For mycotoxins, zearalenone showed lower concentrations and greater stability in cooling; while fumonisins did not reduce significantly, but temporal evolution was modulated; and deoxynivalenol increased in both treatments in November (p < 0.001). Mathematical modeling revealed radial thermal heterogeneity, with the silo center up to 7 °C warmer than the periphery from 09/03rd/2023 to 09/08th/2023, consequently, heat pockets were created. Therefore, it is concluded that artificial cooling is a powerful tool, but not universal, and should be integrated into an Integrated Pest Management (IPM) program that considers the spatial heterogeneity of temperature and the ecological characteristics of each target species.