Synergism between methods for inhibiting the spoilage of damp maize during storage

Combinations of physical and chemical treatments were used in attempts to control mould development in maize grain containing 18% moisture. The treatments involved the use of propionic acid (0.1 or 0.2% v/w), γ-irradiation (1.0 or 2.0 kGy) and modified atmospheres (40% or 60% CO 2 in the presence of 20% oxygen) either separately or in combination. Mould colonisation during storage was assessed by dilution plating and measurements of respiratory CO 2 produced by grain samples. Spoilage was most effectively counteracted using a combination of 0.2% propionic acid with 2 kGy irradiation and 40% or 60% CO 2, and this was more successful than any single component used separately, even after 45 days of treatment. Synergistic interaction between treatments thus allows the prospect of more efficient maize storage rather than employing single techniques. This concept could be important in practice because each component is employed only at a relatively low level of intensity.