Determinación de la flora micológica del maíz seco y su harina en la parroquía San Juan-cantón Gualaceo

Abstract

The aim of this thesis work was to evaluate the mycoflora of dried maize kernels and its flour produced at the Community of San Juan – Gualaceo canton in order to support with information about the quality of those foodstuffs. In addition, the following factors related to the mycoflora growth were evaluated: temperature, water activity, storage; as well as the growth in different media and the use of disinfection of the kernels as part of the fungi sowing technique. Detection, quantification and isolation was done according to the technique of “counting in plate by sowing in deep” for the flour and for the kernels following the direct sowing technique, with and without disinfections using MEA agar (Malt Extract Agar), PDA (Potato Dextrose Agar) and DRBC (Dichloran Rose Bengal Chloramphenicol Agar). The cultures were subjected to two thermal treatments (18°C vs 25°C). It was found that the mycoflora corresponded to the genera Penicillium, Fusarium, Rhizopus, Aspergillus and yeast. The genus Penicillium was the most prevalent in both kernels and flour. The optimal temperature for growth was 25°C, and it was better when the kernel´s surface were not disinfected. The growth also varied according to the media, and the PDA resulted to be the most optimal for Penicillium and Rhizopus, whereas for Fusarium and Aspergillus no difference was observed. At the same time, it was found that the water activity influenced proportionally to the mycoflora growth and that the controlled storage influenced positively on the decreasing growth.