Effect of the time interval from harvesting to the pre-drying step on natural fumonisin contamination in freshly harvested corn from the State of Paraná, Brazil

Abstract

Natural mycoflora and fumonisins were analysed in 490 samples of freshly harvested corn (Zea mays L.) (2003 and 2004 crops) collected at three points in the producing chain from the Northern region of Paraná State, Brazil, and correlated to the time interval between the harvesting and the pre-drying step. The two crops showed a similar profile concerning the fungal frequency, and Fusarium sp. was the prevalent genera (100%) for the sampling sites from both crops. Fumonisins were detected in all samples from the three points of the producing chain (2003 and 2004 crops). The levels ranged from 0.11 to 15.32 µg g⁻¹in field samples, from 0.16 to 15.90 µg g⁻¹in reception samples, and from 0.02 to 18.78 µg g⁻¹in pre-drying samples (2003 crop). Samples from the 2004 crop showed lower contamination and fumonisin levels ranged from 0.07 to 4.78 µg g⁻¹in field samples, from 0.03 to 4.09 µg g⁻¹in reception samples, and from 0.11 to 11.21 µg g⁻¹in pre-drying samples. The mean fumonisin level increased gradually from ≤ 5.0 to 19.0 µg g⁻¹as the time interval between the harvesting and the pre-drying step increased from 3.22 to 8.89 h (2003 crop). The same profile was observed for samples from the 2004 crop. Fumonisin levels and the time interval (ρ = 0.96) showed positive correlation (p ≤ 0.05), indicating that delay in the drying process can increase fumonisin levels.

Keywords:

• Corn-producing chain
• fumonisins
• pre-drying step
• mycoflora

Acknowledgements

The authors thank the FINEP, CNPq (the Brazilian Government Organization for grant aid and fellowship to Brazilian researchers), the Araucária Foundation, Paraná Fund/SETI and CAPES (Coordination for Formation of High Level Professionals) for financial support. They are also grateful to ADETEC (Agency for Technological Development of Londrina city and Region) for project management, especially to Dr Maria Victoria E. Grossmann and Dr Plinio Pinto Mendonça Uchoa, Jr; as well as to Integrada Agroindustrial Cooperative for providing the corn samples and for the financial support.