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ARS Home » Southeast Area » Tifton, Georgia » Crop Genetics and Breeding Research » Research » Publications at this Location » Publication #202309

Title: Changes in Fungi and Mycotoxins in Pearl Millet Under Controlled Storage Conditions

item Wilson, Jeffrey - Jeff

Submitted to: Mycopathologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2007
Publication Date: 8/16/2007
Citation: Jurjevic, Z., Wilson, J.P., Wilson, D.M., Casper, H.H. 2007. Changes in Fungi and Mycotoxins in Pearl Millet Under Controlled Storage Conditions. Mycopathologia. 164:229-239.

Interpretive Summary: Agricultural commodities must maintain superior quality if they are to be sold into premium value markets. The challenge of maintaining superior quality can be more difficult in the absence of recommendations for proper storage. Pearl millet is increasingly being grown in the southern United States for the recreational wildlife industry. Maintenance of high quality can be a key factor in successful marketing of the product, and profitability of the enterprise. In this study we examined the effects of diverse storage conditions for pearl millet grain by varying temperature, relative humidity, and grain moisture content. Fungi that may cause problems as storage molds were identified and the potential for associated mycotoxins to develop were determined for specific environmental conditions. This information will serve to develop guidelines for proper storage practices for this commodity that is new to US production systems.

Technical Abstract: Pearl millet is increasingly being grown for grain in the southern United States, and information concerning the influence of storage conditions on grain mold development is needed for industry. Effects of production year, temperature, relative humidity, atmosphere, and grain moisture content on fungal and mycotoxin development in stored pearl millet were evaluated. In experiment 1, grain (ranging from 9-11% moisture content, m.c.) was stored for 9 weeks at 20 C or 25 C and maintained at 86 or 91% relative humidity (r.h.). In experiment 2, grain (9-11% m.c.) was stored for 9 weeks at 20 C or 25 C in either air or N2 maintained at 100% r.h. In experiment 3, grain (17-20% or 20-22% m.c.) was stored for 3 weeks at 20 C or 25 C and maintained at 100% r.h. Grain was sampled at weekly intervals and plated to determine changes in fungal frequency. Fungi isolated included Fusarium chlamydosporum (19% of plated grain), Curvularia spp. (14%), F. semitectum (16%), Alternaria spp. (9%), Aspergillus flavus (8%), “Helminthosporium” spp. (6%), and F. moniliforme sensu lato (3%). Year of grain production significantly affected isolation frequency of fungi. In experiments 1 and 2, isolation frequency was rarely affected by temperature, relative humidity, or atmosphere treatments, but was affected by storage duration for some fungi. Significant effects of grain moisture content were observed only in experiment 3 and changes in isolation of toxigenic fungi occurred. Isolation frequency of F. chlamydosporum increased in grain stored at 86 and 91% r.h. Incidence of deoxynivalenol was not affected by storage treatment. Low concentrations of nivalenol were detected in most grain incubated at 100% r.h. Zearalenone was detected only when grain moisture content was 20-22%. Incidence of A. flavus increased in the 17-20% and 20-22% grain moisture treatments, particularly at 25 C. Aflatoxin contamination averaged 174 ng g-1 over all treatments, and increased up to 798 ng g-1 in grain at 17-20% m.c. and stored at 25 C.