Studies on Fungal Spoilage of Stored Zea mays L. (Maize) Grains in Two Markets in Lagos State, Nigeria

Maize is one of the most essential staple foods consumed and its spoilage by fungi has been a serious concern to humans since the dawn of agriculture and food storage. Therefore, this research was aimed at isolating, identifying and determining the toxicity level of fungi causing spoilage of stored maize grains. Grain samples of maize were collected from Igando and Alaba markets in (Lagos State) from the top and bottom of maize bags from both market stores. Samples were cultured on Potato Dextrose Agar for fungal isolation. All isolates were identified using morphological and microscopic features. Also, the affordable qualitative method (ammonia vapour test) was carried out in order to identify some selected isolates that are aflatoxigenic. Petri- plates containing these isolates were flipped upside down and 2ml of concentrated ammonia solution (Extra Pure AR grade) was poured into the lid of inverted culture plates and observed for 10-15 minutes inside a desiccator for proper release of ammonia vapour. The genera of fungi isolated were; Aspergillus (57.15%), Fusarium (21.43%), Penicillium (7.14%) and Rhizopus (14.29%). The dominant genus was Aspergillus. The exposure of selected isolates to ammonia vapour led to varying degrees of colour changes which included pink, red and plum red. Similarly, isolates that were moderately poisonous were pink in colour, least poisonous showed red colour and very poisonous isolates indicated plum red colour. The findings from this study indicated that Aspergillus spp. are mostly responsible for spoilage of maize grains in storage and contamination with A. flavus can lead to poison production.