Investigation on compression and mildew of mixed and separated maize

This study explores the influence of different segregation configurations on the creep behaviors and mildew of maize. An inexpensive and easy-to-use system was designed, and three configurations of maize kernels distribution, i.e., uniform mixing (Md_m), alternating distribution (Md_a), and segregated state distribution (Md_s), with wet basis moisture content of 22.9%, were compressed under vertical pressure of 200 kPa through a one-dimensional oedometer. The compression and creep behaviors were investigated using the strain/settlement-time results, and aerobic plate counting (APC) was performed to study the effect of distribution configuration on the mildew effect. A finite-element model was established to simulate the temperature variation caused by physical environmental factors, and the heat production by fungi was quantified using the difference in temperature between simulation and test. The results indicate that the three-element Schiffman model can represent the creep behavior of the maize with different distribution configurations. The average temperature of Md_m, Md_a, and Md_s were 7.53%, 12.98%, and 14.76% higher than the average room temperature, respectively. The aerobic plate count of Md_m, Md_a, and Md_s were 1.0 × 10⁵, 2.2 × 10^5, and 8.8 × 10⁵ cfu g^-1 stored for 150 h, respectively. In general, the temperature and APC in segregated maize bulk are higher than uniform grain. The effectiveness of the numerical model was verified, and the heat production by maize bulk fungi was quantified using the test and numerical temperature difference. The average heat was the least in Md_m with 2.8 × 10⁶ J m^-3, and Md_a and Md_s were 1.7 and 2 times more than Md_m. And the heat was related to the segregation configurations and agreed very well with the APC and temperature results.