title: Microbial Load of Hard Red Winter Wheat Produced at Three Growing Environments across Nebraska, USA.
abstract: Post-flowering weather variables in farm fields may influence the microbial loads of wheat grain. In this study, the effects of weather variables following wheat flowering on the microbiological quality of wheat were evaluated over two consecutive growing seasons (2011 to 2012 and 2012 to 2013) in the state of Nebraska, USA. Three hard red winter wheat lines, including two commercial cultivars (Overland and McGill) and one experimental line (NW07505), were planted in three regions with contrasting key weather variables (Southeast, South Central, and Panhandle district) to ensure that developing seeds were exposed to different weather conditions. The natural microbial flora and deoxynivalenol concentrations of 54 freshly harvested wheat samples (three samples per wheat line, with a total of 9 samples per district) were analyzed to evaluate the impacts of the weather conditions prevailing from flowering to harvesting in each growing location (district) and season on the microbiological quality and safety of wheat grain. In 2012, the values for aerobic plate counts, Enterobacteriaceae, yeasts, molds, and internal mold infection levels were significantly lower in grain samples collected from the Panhandle district than in grain harvested from the South Central and Southeastern districts. No significant differences in the yeast counts were found in grain collected from all districts in 2013, but the levels of internal mold infection and mold counts were significantly higher in grain from the Southeastern district than in grain from the Panhandle district. Deoxynivalenol was detected in all districts; however, the concentrations were below the advisory level of 1 mg/kg for processed wheat. Microbial growth during grain development seems to be dependent on the existence of a threshold level of weather variables during the season. In general, the microbial loads in wheat grain tended to be lower in those areas with lower relative humidity levels (below 55%) and with temperatures lower than 13.7°C and higher than 31.5°C.
authors.affiliation: Department of Food Science and Technology, The Food Processing Center, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.
authors.forename: Luis
authors.initials: L
authors.lastname: Sabillón
authors.affiliation: Department of Food Science and Technology, The Food Processing Center, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.
authors.forename: Jayne
authors.initials: J
authors.lastname: Stratton
authors.affiliation: Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA; Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, Nebraska 68583, USA.
authors.forename: Devin J
authors.initials: DJ
authors.lastname: Rose
authors.affiliation: Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, Nebraska 68583, USA.
authors.forename: Teshome H
authors.initials: TH
authors.lastname: Regassa
authors.affiliation: Department of Food Science and Technology, The Food Processing Center, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA. abianchini2@unl.edu.
authors.forename: Andréia
authors.initials: A
authors.lastname: Bianchini
mesh_terms: D005658:Fungi / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism; D009329:Nebraska; D012621:Seasons; D014255:Trichothecenes / Q000032:analysis / Q000378:metabolism; D014908:Triticum / Q000254:growth & development / Q000382:microbiology*; D015003:Yeasts / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D014255:Trichothecenes; C007262:deoxynivalenol