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Title: Detection of internal insects in wheat using a conductive roller mill and estimation of insect fragments in the resulting flour

Author
item Brabec, Daniel - Dan
item Pearson, Thomas
item Flinn, Paul
item KATZKE, DAVE - General Mills, Inc

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2010
Publication Date: 7/1/2010
Citation: Brabec, D.L., Pearson, T.C., Flinn, P.W., Katzke, D. 2010. Detection of internal insects in wheat using a conductive roller mill and estimation of insect fragments in the resulting flour. Journal of Stored Products Research. 46(3):180-185.

Interpretive Summary: Insects reduce value of grain, cause loss of grain due to consumption by insects and extra cleaning required to remove insects and damaged kernels, and high levels of insects can indicate a general sanitation problem in the grain. However, small insects that bore into wheat kernels are extremely difficult to detect. A recently developed machine was tested for its ability to detect insects living inside of wheat kernels and estimate insect pieces in flour after milling. The machine can inspect a one kilogram sample in less than a minute with very little sample preparation. Results showed high correlation with insect counts by x-ray and with insect fragment counts in resulting flour. The machine should find widespread usefulness where grain is inspected for quality and for determining long term storability.

Technical Abstract: A laboratory roller mill that monitors the conductance of kernels that pass through it was tested for its ability to estimate the number of insect fragments in flour after milling. This system can test a kilogram of whole wheat in approximately one minute and requires little sample preparation. Hard red winter wheat samples were infested with lesser grain borers and stored at 24'C. Infestations ranged from 12 to over 2500 infested kernels per 1 kg or per 30,000 kernels. After crushing of samples in the conductance instrument, the samples were milled into flour and sub-samples were sent to two laboratories for insect fragment analysis. The insect fragments were proportional to the number of detection incidences obtained using the conductance instrument and x-ray images. Insect fragment counts per 50 g of flour ranged from 0 to over 5000. For insect fragment counts from 0-200, correlations between fragment counts and conductance mill detection were 0.92 and 0.82 from two separate cereal chemistry laboratories. For laboratories #1 and #2, the insect fragments were estimated at 1.9 and 1.3 times the number of detections obtained with the conductance mill, respectively. Therefore, the conductance mill is potentially a good method for testing incoming grain for live internally infesting insects; it is able to test 1 kg of grain in about one minute and can detect low levels (as low as one or two insects) of live internal infestations in a one or two kilogram sample.