here - Iowa State University

Report
Mycotoxins in Grain and Feed Industries
II. Best Practices in Handling and Testing
Erin Bowers, Iowa State University, Agricultural Engineering
Charles Hurburgh, Iowa State University, Agricultural Engineering
Alison Robertson, Iowa State University, Plant Pathology
page 1
Learning Objectives
• This learning module will focus on the sampling, testing,
and storage of grains containing mycotoxins
• Module Objectives:
• Learn BMP for testing for mycotoxin contamination and
for consignment of inbound ingredients (grains) that
potentially contain toxins.
• Learn BMP for preventing the production of mycotoxins
in grain or grain sample storage.
**BMP=Best Management Practices
Basics:
Agriculturally Important
Mycotoxins
• Fungi contaminate grains, food, and
feed worldwide
• Mycotoxins are chemical compounds
produced by some fungi
• More than 400 mycotoxins identified
worldwide, 30 concerning for human or
animal health
• 5 principle mycotoxins affect cereal
grains (corn, wheat, rye, barley, oats)
• aflatoxins, fumonisins, deoxynivalenol
(vomitoxin), zearalenone, and ochratoxin A
Gibberella Ear Rot caused
by Gibberella zeae
Wheat Scab
Developing Fungus is Dependent on the
Environmental Conditions During
Pollination and Early Grain Development
Mycotoxin(s)
Fungi
Primary
Grains
Hot and dry,
drought
Corn, Durum
(in EU)
Deoxynivalenol
Fusarium graminearum
(Vomitoxin)
Fusarium culmorum
Zearalenone
Cool, wet, humid at
grain fill
Corn, Wheat,
Oats, Rye,
Barley, Durum
Fusarium verticillioides
Fusarium proliferatum
Warm to hot, dry at
and after flowering
Corn
Penicillium verrucosum
Harvest conditions
determine
Corn
Aflatoxins
Fumonisins
Ochratoxin A
Aspergillus flavus
Aspergillus parasiticus
Favorable
Conditions
page 4
Basics:
Mycotoxins in Grain and Feed
• Environmental stresses increase susceptibility
• Planting, harvest, and storage practices also
contribute to mycotoxin risk
• Most mycotoxins remain intact after cooking,
drying, freezing or storage conditions.
• Mycotoxins at very low concentrations (ppm or
ppb) are capable of causing serious health
problems for humans as well as animals.
• There is usually no treatment for mycotoxin
poisoning (mycotoxicosis).
ppm: parts per million
ppb: parts per billion
Poisonous Ingredients in Food
Federal Food, Drug, and Cosmetic Act
§402 [21 U.S.C. 342]
A food shall be deemed adulterated—(a)(1) If it bears or contains
any poisonous of deleterious substance which may render it
injurious to health; but in case the substance is not an added
substance such food shall not be considered adulterated under
this clause if the quantity of such substance does not ordinarily
render it injurious to health.
Mycotoxin Management Plan
• Most mycotoxin contamination happens in the field
• Prevent contaminated grain from entering the facility
• Pre-harvest preventative controls
• Scouting and pre-harvest observations
• Climate and weather conditions
• At-receiving mycotoxin testing procedure
Mycotoxin testing procedure
Procedural component
Output
1) Sampling
 Laboratory Sample
• Sample size reduction
(if necessary)
2) Sample Preparation
 Analysis Sample
• Grinding
• Mixing
• Subdividing
3) Analysis
 Mycotoxin Result
An example of a
grinder that would be
used to grind a
laboratory sample.
Heterogeneous distribution
• Mycotoxins are not distributed uniformly
throughout fields, bins, or transportation
containers
• Localization of moldy grain
• High variability among individual kernels
• A few mycotoxin-affected kernels can limit grain use
• Misclassification of grain
0 ppb 0 ppb 0 ppb 0 ppb 0 ppb
0 ppb 0 ppb 0 ppb 0 ppb
100
ppb
Hypothetical distribution of an incoming load of corn with
an average aflatoxin level of 10 parts-per-billion (ppb)
Sampling (the laboratory sample)
• The process of acquiring a sample of grain (laboratory
sample) that is representative of the lot
• Subject to sampling bias
• Sample representativeness is increased by taking
incremental samples
• This is a time-consuming practice
• Not practical to use for every load of grain entering a facility
• Prescribed for compliance sampling (aflatoxin)
• Incremental samples are aggregated and mixed to form
the laboratory sample
Sampling Equipment
x
x
x
Hand grain probe (trier)
x
x
x
x
Above: An example of a probing
pattern to be used for sampling a
flat-bottom truck or trailer.
Receptacle
Grain
flow
Mechanical grain probe
sampling a truckload of
grain at a receiving point
Sample
An Ellis sampler can
be used to manually
sample grain on a
conveyor
Bottom right: An
illustration of the action
of a diverter-type
sampler. At set
intervals a portion of
the moving grain is
captured and diverted
to a sample receiving
container by a moving
receptacle.
Corn
shelled, whole kernel
meal
flour
snack foods
popcorn
cleaned, for masa production
dry milled bran
grits or flaking grits
cereals
baby cereals
Cottonseed
whole grain
meal
Rice
cultivated, whole grain
wild, whole grain
cereals
baby cereals
Wheat
whole kernel
whole wheat flour
white flour
bran, for human consumption
cereals
baby cereals
Oats
whole
cereals
baby cereals
Barley
whole
malt
cereals
baby cereals
Rye flour
soya-based baby food products
Products for Surveillance Sampling
Aflatoxin
Fumonisin
Ochratoxin A
x x x x
x x x
x
x x
x x
x x
x x
Deoxynivalenol
x x x x
x x x x
x x
x x x
x x
x x x
x x x x x x
Abbreviated list adapted from CPG 7307.001 Attachment A
Aflatoxin Compliance Sampling
Commodity
Corn
Shelled, meal,
flour, grits
Oilseed meal
e.g., cottonseed
Small grains
e.g., wheat,
barley, sorghum
Lot type
Number of
incremental
samples
Incremental
sample size
(lbs)
Laboratory
sample size
(lbs)
Bulk and
consumer
10
1
10
Bulk
20
1
20
Bulk
10
1
10
Adapted from FDA Investigations Operations Manual, 2013, Ch. 4, Chart 6
Sample preparation
• Preparing the laboratory sample for analysis
1. Grinding the entire laboratory sample
•
The smaller the laboratory sample, the higher the
uncertainty in the final analytical result
2. Mixing
•
Homogenize
3. Selecting analysis sample
An example of a
grinder that would be
used to grind a
laboratory sample.
Operating characteristics of
mycotoxin sampling plans
Probability of Accepting Lot (%)
What is the probability that
a grain lot will be correctly
quantified using a given
sampling plan?
All parameters the same
except
Lot Aflatoxin Concentration (ppb)
www.fstools.org/mycotoxins/
• Green=1 lb laboratory sample
• Blue=5 lb laboratory sample
• Orange=10 lb laboratory
sample
Operating characteristics of
mycotoxin sampling plans
Probability of Accepting Lot (%)
Seller’s Risk
Buyer’s Risk
Lot Aflatoxin Concentration (ppb)
www.fstools.org/mycotoxins/
Seller’s risk
Commercial-false rejection of
good quality grain
Regulatory-false sanctions
Buyer’s risk
Commercial-false acceptance
of poor quality grain
Regulatory-compromises food
and feed safety
Analysis
• Using an appropriate method to determine the quantity or
confirm the presence or absence of mycotoxins in the
analysis sample
• Qualitative or Quantitative
• Rapid test or analytical laboratory
• The choice of detection method will depend on the user’s
needs and resources, the commodity being tested, and the
decisions which will be made using the analytical result.
Analysis
• High Performance Liquid
Chromatography (HPLC)
• Require trained personnel to maintain and
operate
• Produces results with high
• Precision
• Accuracy
• Repeatability
• Sensitivity
• Standard for mycotoxin confirmation analysis
in compliance samples
The image below
shows an example of
an HPLC instrument
set up in a lab
Analysis
• Rapid test methods
• Rapid relative to analytical chemistry methods
• Common on-site analysis methods
• Examples of rapid test methods
• Enzyme-linked immunosorbent assay (ELISA)
• Lateral flow assay
• Flow through assay
Left: an example of an
ELISA test
Right: examples of lateral
flow assays
Analysis
GIPSA provides outside laboratory validation of
rapid test kits submitted by manufacturers
•Not mandatory to use a GIPSA-approved kit
•More information,
http://www.gipsa.usda.gov/fgis/insp_weigh/raptestkit.html
Left: an example of an
ELISA test
Right: examples of lateral
flow assays
Analysis
• Blacklighting (IOM 427.04g)
• Screening purposes
(aflatoxin only)
• Few false negatives, but
many false positives
• Direct quantitative testing to
at-risk-loads
• Thin-Layer Chromatography
(TLC)
Above: an example of bright
greenish-yellow fluorescence
produced when Aspergillus flavusinfected corn is viewed under
blacklight
Analysis
• Benefits of rapid tests vs HPLC
•
•
•
•
•
•
Ease of use
Cost
Compact (size)
Minimal calibration
Less equipment maintenance/upkeep
Faster
• Downfalls of rapid tests
•
•
•
•
Reduced sensitivity
Narrow operating range
Higher limits of detection
Not approved for regulatory decision-making
• Confirmation analysis necessary by accepted analytical method
• Compliance Policy Guide Manual, section 555.400
Analysis
• FSMA: Industry action required based upon reasonable
suspicion of food/feed safety threat
• Documentation to verify safe handling, processing, storage, and end
use
• Performance Monitoring: Check-samples ensure
appropriateness of mycotoxin management (best practice)
• Especially in facilities producing finished feed or food products
Practical Considerations
• Time requirement for testing is significant
• Can’t test/sample every load
• Can’t test for every mycotoxin
• Know the risks and be strategic
• Weather and climate are good indicators of mycotoxin risk
• Cool, wet conditions- risk of deoxynivalenol and zearalenone
• Hot, drought conditions- risk of aflatoxins
• Warm, drought conditions-risk of fumonisins
• Use this as a predictive tool to direct sampling and testing
• Composite testing is good practice to monitor overall quality
of incoming grain and of that which has been accepted
Storage and Handling
• Reduce the ability of fungi to survive and grow
• Shelf life of grain is impacted by
• Quality of stored grain
• Water availability
• Grain moisture
• Grain temperature
• Drying: Reduce grain moisture to stop fungal growth and
mycotoxin production
• Dry promptly: minimize time between harvest and drying to maximize
shelf life of grain
• Dry carefully: prevent stress cracks and reduce breakage
• Kernel temperature ≤110°F
• Grain moisture in equilibrium with 65% RH will prevent fungal activity
Storage and Handling
• Temperature is an important factor for grain storage
• Cool temperatures (<60°F) minimize fungal growth
• Aeration can be used to facilitate temperature control
• Temperature
uniformity
• Minimize moisture
movement
• Monitor grain for changes in quality
Blending
• Aflatoxin is a food/feed adulterant
• Grain >20 ppb cannot be deliberately blended
• FDA blending dispensations have been allowed in rare
instances when a large portion of the U.S. corn supply is
affected
• State by state basis
• Resultant grain used only for specific livestock feed
• >500 ppb aflatoxin grain has never been allowed to be blended
page 27
Mycotoxins in grain handling facilities
• Mycotoxin management can be accomplished using
proper storage and handling practices, and through
preventing contaminated grain from entering a facility
• Testing domestic grain for mycotoxins is discretionary,
export is mandatory for aflatoxin only
• Each facility will likely handle mycotoxin management
uniquely, depending on their individual structure,
capabilities, and contract requirements
• Look for evidence of proactive action
• Strategic, informed plans and actions
Proactive approaches
•
•
•
•
Contract terms for suppliers
Attention to growing conditions in the area
Pre-harvest scouting/survey
A mycotoxin sampling plan
}
• Sampling
• Sample preparation
• Analysis
in combination with a threshold for
acceptance
• Monitoring the effectiveness of the sampling plan
• Finished product checks and verification
• Check sample analysis (third party laboratory)
• Composite sample testing
This training was a joint effort of
www.iowagrain.org
www.grains.ksu.edu
*Funding for this Grain and Feed Mill Operations course was made
possible, in part, by the Food and Drug Administration through grant
(1U54FD004333-01), views expressed in written materials or publications
and by speakers and moderators do not necessarily reflect the official
policies of the Department of Health and Human Services; nor does any
mention of trade names, commercial practices, or organization imply
endorsement by the United States Government.*

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