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Removal of Aflatoxin Contaminated Peanuts from a Process Stream

Investigators
Schatzki, Thomas
Institutions
USDA - Agricultural Research Service
Start date
2000
End date
2005
Objective
  1. Develop and apply a method to obtain a training set of highly infected peanuts as well as a control set.
  2. Use this training and control set to establish the properties indicative of aflatoxin infection.
  3. Construct and test a batch bench top sorter to detect peanuts of high aflatoxin content, adequate if they were removed to bring the aflatoxin level of the lot down by a factor of 10, while removing less than 2% of all nuts.
  4. Construct and demonstrate a real-time, commercial size demonstration unit to carry out the above.
More information
The Enhancing Value and Use of Agricultural and Forest Products Division responds to the growing need to enhance the competitive value and quality of U.S. agricultural and forest products. Research in this area builds the scientific base of knowledge to use agricultural and forest materials more fully and effectively. The Division supports both fundamental and applied research on new and improved processes and on development of new uses for agricultural and forest materials. Program Areas in this Division include: Value-Added Products Research encompassing Food and Non-Food Characterization/Process/Product Research, and Improved Utilization of Wood and Wood Fiber

APPROACH: We are in the process of collecting a set of whole peanuts of high aflatoxin (HiAT) content. Whole nuts are dipped in a MeOH/water blend (commonly used for extracting ground nuts) and then dried. the 'dip fluid' is analyzed for aflatoxin, using rapid MS/MS. We have shown that HiAT nuts yield HiAT 'dip fluids'. The HiAT nuts will be investigated for properties them from LoAT nuts (these properties will almost certainly include transmission NIR). HiAT and LoAT nuts will then be used as a training set to develop aflatoxin recognition algorithms. Initially sensors for the required properties will be tested off-line. Based on such sensors and algorithms, real-time sorting equipment will be constructed to demonstrate sorting capability in commercial settings.

PROGRESS: 2001/12 TO 2002/12
The aflatoxin B1 distribution among single kernels of a non-irrigated lot of Georgia Green peanuts has been measured for each of three sublots (sm OK, medium and jumbo grades). It was established that 98% of total aflatoxin was contained in kernels containing 5000-8000 ng/g each, depending on grade. Average concentration of the sublots was established as 750, 370 and 170 ng/g respectively, approximately 20-50 times that of tree nuts. The diffuse surface reflection/emission of selected medium and jumbo kernels (chosen from kernels whose aflatoxin concentration was previously determined non-destructively) was determined by NIR and synchronous fluorescence. A number of other spectral properties (Raman imaging, fluorescence imaging, a.o.) were measured, but poroved not promising. These efforts caused slippage of about one year. Four spectral features could be established of which three could be normalized without difficulty. A preliminary discriminant function was established. Although the sample set was exceedingly small (17 kernels c<20 ng/g, 28>20 ng/g) and the error rate too high (3 false pos., 3 false neg.), the results are promising enough to continue along that line. Further work in adding more samples and adding the blanched nut color as a discriminator is being worked on.

IMPACT: 2001/12 TO 2002/12
This is the first measure of individual kernel aflatoxin distribution in peanuts, although much has been done by us in tree nuts. This information and the preliminary results on finding a sensor suitable for sorting are essential in guiding the development of a peanut sorter. Additional distribution work needs to be carried out for lot which are less contaminated than the ones considered so far to allow application to irrigated lot, particularly to sublots which have been color sorted. Some additional samples and possibly additional features will be added to the sorting discriminant. However, the bulk of the work outlined as stage 2 in the original proposal has now been carried out and stage 3, constructing a demo sorter, will commence shortly. Optimization will form part of that stage.

Project number
CALR-2000-01614
Accession number
186324
Categories
Mycotoxins
Bacterial Pathogens
Commodities
Nuts, Seeds