PROJECT RESULTS

Detection of Fusarium Damaged Kernels Using High Speed Optics

Applicant: 

Dr. David A. Prystupa

Spectrum Scientific Inc.

Pinawa, Manitoba  R0E 1L0  Canada

Table of Contents:

• Objectives
• Introduction
• Results and Discussion
• Conclusions

Dr. David A. Prystupa, Spectrum Scientific and Dr. Jitendra Paliwal, Department of Biosystems Engineering, University of Manitoba

ARDI Project:

#05-654

Project Status:

Completed October, 2006

Objectives:

The primary objective for this project was to determine the rate at which wheat kernels can be reliably classified as healthy or Fusarium infected with a proprietary optical method.  The secondary objective is to establish whether the method has the potential to be economic. 

Introduction:

Fusarium head blight (FHB), commonly known as scab or tombstone, is a fungal infection that affects cereal crops in all major grain producing regions of the world.  Fusarium reduces both crop yield and crop quality.  Species of the Fusarium genus produce mycotoxins that are concentrated in, but not limited to infected kernels.  At concentrations in excess of a few parts per million, the mycotoxins produce nausea, vomiting, and reduced growth rates in livestock and humans.  The concentration of Fusarium infected kernels is thus an important factor for determining the grade, and hence the price of grains.  The value of wheat is reduced by 40% or more if 5% of the kernels are infected.  In Canada, losses to farmers are estimated at more than $100 million per year.  The ultimate objective of this research is to develop methods to reduce the economic losses caused by Fusarium by selectively removing Fusarium infected kernels from bulk grain.

Results and Discussion: 

Wheat kernels were placed in grooves in a wheel apparatus so that the kernels passed in front of an optical detection apparatus one at a time.  The same kernels were measured repeatedly, once per revolution, so that the measurement reproducibility could be assessed.  Wheat from 27 different sources was tested to verify the range of applicability of the system.  The maximum detection rate achieved was 450 kernels per second, which corresponds to approximately 50 kg per hour.  The signal from each kernel sampled repeatedly was reproducible to better than 1%.  The maximum achieved sampling rate was limited by the speed at which kernels could be presented to the detector with the motor used in the apparatus.  The optical system alone was tested up to a rate corresponding to 20,000 kernels per second without degradation of signal quality.  The minimum economic rate is estimated to be 100 kernels per second and this rate has been exceeded.  

The optical system is linked to a processor that outputs an electrical signal for each kernel based on the optical characteristics of that kernel.  The geometry and the type of lighting used have been optimized and a patent application has been filed.  Healthy and infected kernels produce a range of signals that are for the most part different, but overlap in a region containing about 10% of the kernels.  A range of cutoff values within this range can be selected which either maximize rejection of infected kernels or maximize acceptance of healthy kernels.  With one possible choice of operating parameters, approximately 94% of the Fusarium infected kernels could be rejected at a loss of 10% of the healthy kernels.  Further experiments are required to determine whether a second pass through the sorter can improve the healthy kernel recovery.

In a commercial implementation of the Fusarium detection method, all of the costs and benefits must be weighed.  Using prices posted by the Canadian Wheat Board, September 2006, a ton of wheat with 5% Fusarium is worth $133.35 per ton.  This could be separated into fractions with less than 0.5% Fusarium (86% of the total) and 33% Fusarium (14% of the total).  The low Fusarium fraction would have a value of $170.71, an excess of $37.36 per ton.  It is premature to determine what the final cost of the process for Fusarium removal will be, because the scale, labor costs for operation and utilization are unknown. 

Conclusions:

The feasibility of classifying wheat kernels as healthy or Fusarium infected at a rate of 450 kernels per second has been established.  The classification rate is high enough to form the basis of a commercial bulk grain cleaning system.

Acknowledgement:

This project was made possible due to funding from the Governments of Manitoba and Canada through the Canada-Manitoba Agri-Food Research and Development Initiative (ARDI).

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