[4-1445-C] Postharvest Facility

[4-1445-C-01] The Effect of Level of Fill on Nutritional Quality of Maize in an Un-aerated Clay Silos

*Mobolaji Omobowale¹, Jonathan Ogwumike¹ (1. University of Ibadan(Nigeria))

Keywords:Clay Silo, Grain Quality, Postharvest losses, Maize, Level of Fill

Silos have a fixed volume at the time of construction; harvests however vary from season to season. Arising from complaints of severe postharvest losses in grains, most especially in the humid tropics of southern Nigeria, this study investigated the effect of level of filling on the nutritional quality of stored maize. Three clay silos labelled S₁ to S₃ of the same dimension and capacity (3.5 metric tonnes) were used. The walls were painted externally with gloss paint to eliminate or reduce water absorption into the silos. The three silos were filled with shelled maize; with the first silo (S₁) was filled with 3 tonnes, the second silo (S₂) was filled with 2 tonnes while the third silo (S₃) was filled with a tonne of maize. A storage experiment was carried out for 6 months and data was collected on environmental conditions within the silo as well as grain quality with increasing time of storage. Temperature, relative humidity and equilibrium moisture content were obtained three times daily for each of the three silos, focusing on the air-space between the grains and the head-space above the grains. Temperature fluctuations within the fully filled S₁ as indicated by the statistical range of 2^oC was minimal compared with that of S₂ and S3 at 7 and 8^oC respectively. Silo S₃ showed high values of relative humidity toward the end of storage period, ranging between 65% to 80% at the top level and 76% at the bottom level. Equilibrium moisture content at the airspace above the grains in S₁ increased from 12.0% at the beginning of storage in the dry season to 15.6% at the end of storage in the rainy season compared with S₂ and S₃ which increased from 12.0 to 17% and 12.0 to 17.2% respectively within the same period. Fungal and total viable counts showed an increase in microbial activity with decreasing level of fill. Grains were found to be more prone to deterioration with decreasing level of fill and recommendations were made to farmers and grain traders on proper actions to take as the situation arises.