United States Department of Agriculture

Agricultural Marketing Service

Federal Grain Inspection Service

Directive 9180.82 March 14, 2022

Distribution: FGIS, OSP, Industry Originating Office: FMD PPMAB

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TDD).

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Washington, DC 20250-9410, or call (202) 720-5964 (voice and TDD). USDA is an equal employment opportunity 

employer.

INSPECTION OF SPECIALTY TYPE CORN

Contents

INSPECTION OF SPECIALTY TYPE CORN �������������������������������������������������������������������������1

1. PURPOSE����������������������������������������������������������������������������������������������������������������������������

2. REPLACEMENT HIGHLIGHTS��������������������������������������������������������������������������������������������

3. GENERAL INFORMATION���������������������������������������������������������������������������������������������������

4. BACKGROUND��������������������������������������������������������������������������������������������������������������������

5. DEFINITION OF SPECIALTY TYPE CORN�������������������������������������������������������������������������

6. BASIS OF DETERMINATION ����������������������������������������������������������������������������������������������

7. ODOR�����������������������������������������������������������������������������������������������������������������������������������

8. TEST WEIGHT PER BUSHEL ���������������������������������������������������������������������������������������������

9. MOISTURE���������������������������������������������������������������������������������������������������������������������������

10. INFESTED SPECIALTY TYPE CORN �������������������������������������������������������������������������������

11. DISTINCTLY LOW QUALITY����������������������������������������������������������������������������������������������

12. ACTIONABLE CRITERIA���������������������������������������������������������������������������������������������������

13. BROKEN CORN AND FOREIGN MATERIAL ��������������������������������������������������������������������

14. DAMAGED AND HEAT-DAMAGED KERNELS ���������������������������������������������������������������1

15. PURITY ����������������������������������������������������������������������������������������������������������������������������1

16. COLOR�����������������������������������������������������������������������������������������������������������������������������1

17. AFLATOXIN TESTING �����������������������������������������������������������������������������������������������������1

18. CERTIFICATION ��������������������������������������������������������������������������������������������������������������1

21. QUESTIONS ��������������������������������������������������������������������������������������������������������������������1
FGIS Directive 9180.82 March 14, 2022

Page 2

1. PURPOSE

This directive establishes uniform procedures for the analysis of Specialty Type Corn

(e. g. Blue Corn Zea mays L. subsp. Amylacea (Sturtev.) Zhuk.) under the U. S

Standards Act (USGSA)

2. REPLACEMENT HIGHLIGHTS

This directive is revised to specify that any moisture meter listed as approved in 

the Moisture Handbook can be used to determine moisture content. This directive

supersedes FGIS Program Directive 9180.82, dated 5/01/1

3. GENERAL INFORMATION

a. Inspection of Specialty Type Corn is upon request and on a factor only basi

b. All quantities referenced in this directive are approximate unless otherwise specifie

c. There are no classes, subclasses, or numerical grades for Specialty Type Cor

d. An applicant may request an analysis for quality factors such as moisture, tes

weight per bushel, damaged kernels, heat-damaged kernels, and aflatoxin.

e. Use an approved divider to obtain sub portions of a sample for analysis unless

otherwise specified.

f. Official inspection personnel shall document inspection information during 

sampling and inspection

g. Four inspection levels (original, reinspection, appeal, and board appeal) are

available under USGSA regulations for single lot and composite lot inspections

For shiplots and unit trains loaded to specific contract requirements, only three 

levels of inspection (original, review (reinspection or appeal inspection), and board 

appeal) inspection are available

4. BACKGROUND

Blue corn (Zea mays L. subsp. Amylacea (Sturtev.) Zhuk.) is of the same genus 

species as flint (Zea mays induata) and dent (Zea mays indentata) type of corn, which 

are presently defined in the U.S. Standards for corn and are classified into two primary 

classes, Yellow and White corn. However, in contrast, the majority of blue corn is a flour 

type of corn, which has a soft, floury endosperm covered by a thin, evenly distributed 

layer of hard, corneous endosperm. The outer endosperm is comprised of a single

layer of cells containing blue pigment called the aleurone layer and the pericarp is a 

thin, transparent layer of crushed cells that cover the entire kernel and serves as the 

seed coat. The shape of kernels can range from small, flint-type kernels to large hominy 

types
FGIS Directive 9180.82 March 14, 2022

Page 3

5. DEFINITION OF SPECIALTY TYPE CORN

a. Specialty Type Corn, as described in this directive, is grain that before the removal

of broken corn and foreign material consists of 50 percent or more shelled whole 

kernels of the species Zea mays L. subsp. Amylacea (Sturtev.) Zhuk. Specia

Type Corn typically has floury endosperm, but may include hard endosperm 

kernels, and the pericarp color of this subspecies may include blue, red, and 

purple

b. The sample must not meet the definition of white or yellow shelled dent or flint corn 

(Zea mays L.

c. Visually examine the sample to determine if it meets the definition of corn or 

Specialty Type Corn. If an analysis is necessary, make the determination on a

250-gram representative portion on the basis of the sample as a whole. From

the 250-gram portion remove all whole kernels (i.e., kernels with less than on

fourth broken off) of corn, other standardized grains, and Specialty Type Corn, and 

calculate the percentage of specialty type corn

6. BASIS OF DETERMINATION

All determinations, except for kernel color, heat-damaged kernels, and damaged 

kernels, are based on the sample as a whole. Kernel color, heat-damaged kernels, and

damaged kernels analyses are performed on the basis of the corn after the removal of 

broken corn and foreign material

BASIS OF DETERMINATION

Lot as a whole

Factors Determined Before the 

Removal of Broken Corn and 

Foreign Material

Factors Determined After the

Removal of Broken Corn and

Foreign Material

Heating

Odor

Heating

Moisture

Odor

Test Weight

Damaged kernels total

Heat-damaged kernels

Kernel color

Odor

Purity
FGIS Directive 9180.82 March 14, 2022

Page 4

7. ODOR

a. Basis of Determination. Determine odor on evidence obtained at the time o

sampling or on the sample either before or after the removal of broken corn and 

foreign material

Odor Classification Examples

Sour Musty

Commercially

Objectionable

Foreign Odors

Boot

Fermenting

Insect (acrid)

Pigpen

Ground

Insect

Moldy

Animal hides

Decaying animal and vegetable 

matter

Fertilizer

Fumigant

Insecticide

Oil products

Skunk

Smoke

Strong weed

b. Commercially Objectionable Foreign Odors. Commercially objectionable foreig

odors are odors foreign to grain that render it unfit for normal commercial usage.

Fumigant or insecticide odors are considered commercially objectionable foreign 

odors if they linger and do not dissipate. When a sample of corn contains a

fumigant or insecticide odor that prevents a determination as to whether any other 

odor(s) exists, apply the following guidelines:

(1) Original Inspections. Allow the work portion to aerate in an open container for

4 hours, or less, if the odor dissipates in less time

(2) Reinspections, Appeal, and Board Appeal Inspections. Allow unworked file 

samples and new samples to aerate in an open container for 4 hours, or less, 

if the odor dissipates in less time. The 4-hour aeration requirement does not

apply when the original work portion was aerated and retained as the final file.

Consider the sample as having a commercially objectionable foreign odor if the 

fumigant or insecticide odor persists based on the above criteria

Final Determination. The inspector(s) is responsible for making the final 

determination for all odors. A consensus of experienced inspectors is used,

whenever possible, on samples containing marginal odors. The consensus

approach is not required if no odor or a distinct odor is detected

c. Record the words “Musty,” “Sour”, or “Commercially Objectionable Foreign Odor

in the “Results” section of the certificate. If samples have no odor, enter “OK” on 

the work record
FGIS Directive 9180.82 March 14, 2022

Page 5

8. TEST WEIGHT PER BUSHEL

a. Test weight per Winchester bushel (2,150.42 cubic inches) is determined usin

an approved device according to procedures prescribed in Federal Grain 

Inspection Service (FGIS) instructions

b. Determine test weight on a representative portion of the original sample with a

quantity sufficient to overflow the kettle. Record test weight results on the work 

record as displayed on the electronic scale or in whole and tenth pounds to the 

nearest tenth pound. Record the test weight on the certificate in whole and tenth 

pounds

c. If requested, convert the pounds per bushel (lbs. /Bu) result to kilograms pe

hectoliter (kg/hl) using the following formula: lbs. /Bu x 1.287 = kg/hl and record i

the “Remarks” section in whole and tenths

9. MOISTURE

a. Moisture is determined by using approved moisture instruments listed in the

Moisture Handbook utilizing the approved corn calibration (see FGIS Directive 

9180.61

b. Determine moisture on a representative portion of approximately 650 grams before

the removal of Broken Corn and Foreign Material (BCFM)

c. Record the percentage of moisture on the work record and certificate to the 

nearest tenth percent

10. INFESTED SPECIALTY TYPE CORN

Infested Specialty Type Corn is a specialty type corn that is infested with live weevils or 

other live insects injurious to stored grain

The presence of any live weevil or other live insects injurious to stored grain found in 

the work sample indicates the probability of infestation and warns that the corn must 

be carefully examined to determine if it is infested. In such cases, examine the work

sample and the file sample before reaching a conclusion as to whether or not the corn is 

infested. Do not examine the file sample if the work sample is insect free.

Live weevils include rice weevils, granary weevils, maize weevils, cowpea weevils, 

and lesser grain borers. Other live insects injurious to stored grain shall include grain

beetles, grain moths, and larvae

Basis of Determination. Determine infestation on the lot as a whole or the sample as a

whole
FGIS Directive 9180.82 March 14, 2022

Page 6

INSECT INFESTATION

Samples meeting or exceeding any one of these tolerances are infested:

2 lw, or 1 lw + 5 oli, or 10 oli

1,000-gram

representative sample 1

(+ file sample if needed)

Lot as a Whole (Stationary) Online Sample (In-Motion) 2

Submitted samples

Probed lots

D/T sampled land carriers

Probed lots (at time of sampling) Railcars under the Cu-sum

Subsamples for Sacked Grain lots

Components for Bargelots 3

Components for Shiplots 3

1 Examine work portion and file sample if necessary. Do not examine file sample if work portion is insect free.

2 Minimum sampling rate is 500 grams per 2,000 bushels

3

 Minimum component size is 10,000 bushels.

Key: lw = live weevil, oli = other live insects injurious to stored grain

Certification. Record the number of insects in the “Results” section of the certificate.

11. DISTINCTLY LOW QUALITY

Consider Specialty Type Corn as distinctly low quality when it is obviously of inferior 

quality and the existing grade factors or guidelines do not accurately reflect the inferior 

condition

Basis of Determination. Use all available information to determine whether the corn is

of distinctly low quality. This includes a general examination of the corn during sampling

and an analysis of the obtained sample(s)

Large Debris. Specialty Type Corn containing two or more stones, pieces of glass,

pieces of concrete, or other pieces of wreckage or debris which are visible to the 

sampler but are too large to enter the sampling device is considered distinctly low 

quality

Other Unusual Conditions. Specialty Type Corn that is obviously affected by other 

unusual conditions which adversely affect the quality of the corn and cannot be properly 

graded by use of the grading factors specified or defined in the standards is considered 

distinctly low quality

Specialty Type Corn suspected of containing diatomaceous earth is considered 

distinctly low quality unless the applicant specifically requests an examination to verify 

the presence of diatomaceous earth. If the laboratory examination verifies that the 

corn contains diatomaceous earth, then the corn is not considered distinctly low quality 

due to diatomaceous earth. Refer to FGIS Program Directive 9180.49, “Grading an

Certification of Grain Containing Diatomaceous Earth and Silica Gel,” for additional 

information regarding the testing of corn for diatomaceous earth

Certification. Record the words “Distinctly Low Quality” and the reason(s) why in the

“Results” section of the certificate.
FGIS Directive 9180.82 March 14, 2022

Page 7

12. ACTIONABLE CRITERIA

Lots that exceeds Food and Drug Administration (FDA) limits for certain harmful or toxic 

substances (e.g., castor beans) must be reported to the local FDA office.

Basis of Determination. Determine Actionable Criteria before the removal of broken

corn and foreign material based on a work portion of 1,000 to 1,050 grams. The

Actionable Criteria Table provides the criteria and corresponding Visual Reference 

Images, tolerance limits, and the appropriate basis of determination. Consider

identifiable pieces of grain, processed grain products (e.g., soybean meal, sorghum 

grits, corn meal, bulgur, etc.), or feed pellets in grain as foreign material. Unidentifiable 

materials or material unrelated to grain shall function as “unknown foreign substance.

ACTIONABLE CRITERIA

Criteria Reference

Image

Number/Weight 1

Sample Basis Lot Basis 2

Animal filth

Castor Beans

Cockleburs

Crotalaria seeds

Glass

Commercially Objectionable 

Foreign Odor

Stones

Unknown foreign substances 3

Heating

Large Debris *

Other unusual conditions *

Animal filth

Castor Beans

Cockleburs

Crotalaria

Fertilizer

Excess of 0.20

2 or more

8 or more

3 or more

2 or more

Presence

Excess of 0.1% by weight

4 or more

Presence

N/A

Presence

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

Presence

2 or more

Presence

1

 Record count factors to the nearest whole number

2

 Consider feed pellets and processed grain products as foreign material, not unknown foreign substance

* For Distinctly Low Quality, see section 10

Certification. Report Actionable Criteria on the work record and in the “Results” section

of the certificate. Record count factors to the nearest whole number.
FGIS Directive 9180.82 March 14, 2022

Page 8

13. BROKEN CORN AND FOREIGN MATERIAL

Broken Corn. All matter that passes readily through a 12/64 round-hole sieve and over a

6/64 round-hole sieve according to procedures prescribed in FGIS instructions

Foreign Material. All matter that passes readily through a 6/64 round-hole sieve and all

matter other than Specialty Type Corn that remains on top of the 12/64 round-hole sieve 

after sieving according to procedures prescribed in FGIS instructions. Shelled flint and/

or dent corn (Zea mays, L.) as defined in the U.S. Standards for Corn, is considered as 

foreign material

Broken Corn and Foreign Material. All matter that passes readily through a 12/64 roundhole sieve and all matter other than corn that remains in the sieved sample after sieving

according to procedures prescribed in FGIS instructions

Basis of Determination. Determine the factor broken corn and foreign material (BCFM)

on a portion of 1,000 to 1,050 grams

Procedure. The approved methods for determining the factor BCFM are the methods

described in this section

The procedure is performed in two steps: A mechanical separation of BCFM is made 

using a Carter Dockage Tester to remove the larger and finer particulate matter from the 

sample. The mechanically cleaned sample is then handpicked to remove any remaining

similarly sized foreign material from the sample. To avoid repeating operations, check 

the material found in the BCFM sieve catch pans for live weevils and other live insects 

injurious to stored grain, stones, distinctly low quality, and other actionable criteria 

factors
FGIS Directive 9180.82 March 14, 2022

Page 9

PROCEDURE FOR DETERMINING BCFM

STEP 1. Carter Dockage Tester.

a. Set the air control to 1 and th

feed control to 10

b. Insert the No. 3 sieve in the t

sieve carriage

c. Run 1,000 – 1,050 grams throug

the dockage tester

STEP 2. Handpick (foreign material)

a. Remove all matter othe

than corn, including sweet corn, 

standardized shelled flint and/

or dent corn (Zea mays, L.), and

popcorn. (Reference: Visual

Reference Image No. OF-Sweet

Corn & Popcorn), from the 

mechanically cleaned portion

b. Combine the mechanicall

separated and handpicked 

BCFM

Certification. Record the percentage of BCFM on the work record and certificate to the 

nearest tenth percent. Upon request, use the following alternate procedure which allows for

the separation of BC and FM
FGIS Directive 9180.82 March 14, 2022

Page 10

ALTERNATE PROCEDURE FOR DETERMINING BC AND FM

STEP 1. Carter Dockage Tester.

a. Set the air control to 1 and the fe

control to 10

b. Insert the combination 12/64 inc

and 6/64 inch No. 3 sieve in the top

sieve carriage

c. Run 1,000 – 1,050 grams throug

the dockage tester

d. BC consists of all material passi

through the 12/64 inch sieve and 

over the 6/64 inch sieve (collected 

in the middle sieve collection pan)

e. FM consists of all material passin

through the 6/64 inch sieve 

(collected in the bottom collection 

pan)

STEP 2. Handpick (foreign material)

a. Remove all matter other than cor

 including sweet corn, standardized 

shelled flint and/or dent corn (Zea 

mays, L.), and popcorn from the

mechanically cleaned portion

b. Combine the mechanicall

separated and handpicked FM
FGIS Directive 9180.82 March 14, 2022

Page 11

Alternate Procedure for Determining BCFM (Hand Sieve Method). Official personnel 

have the option of manually hand-sieving or mechanically sieving (using a sizer shaker) 

the BCFM portion

Follow the procedures listed below to separate the components BC and FM from 

machine (Carter Dockage Tester) separated BCFM

a. Mechanically Sieving Metho

1. Mount a 6/64 round-hole hand sieve and a bottom collection pan on a

mechanical sieve shaker

2. Set the stroke counter to 

3. Remove the BCFM collection pan from the Carter Dockage Tester and pour

the contents into the center of the 6/64 round-hole sieve

4. Turn the sieve shaker o

5. After the sieve shaker has stopped carefully remove the sieve and bottom

collection pan

6. Combine the material that lodged in the perforations with the material that

remained on top of the sieve. Consider this material as broken cor

7. Consider the material in the bottom collection pan as foreign materia

8. Remove all matter other than corn, including sweet corn, standardized shelled 

flint and/or dent corn (Zea mays, L.), and popcorn from the mechanically 

(Carter Dockage Tester) cleaned portion and combine with the foreign 

material in step 7 above. This combination of mechanically separated FM and

hand-picked FM functions as foreign material

9. Calculate the percentages of BC and FM separatel

b. Hand Sieving Metho

1. Mount a 6/64 round-hole hand sieve to a bottom collection pa

2. Remove the BCFM collection pan from the Carter Dockage Tester and pour

the contents into the center of the 6/64 round-hole sieve

3. Hold the sieve level in both hands with elbows close to the bod

4. In a steady motion, move the sieve from left to right approximately 10 inches

and then return from right to left

5.  Repeat this operation 5 tim
FGIS Directive 9180.82 March 14, 2022

Page 12

6. Combine the material that lodged in the perforations with the material that

remained on top of the sieve. Consider this material as broken cor

7. Consider the material in the bottom collection pan as foreign materia

8. Remove all matter other than corn, including sweet corn, standardized shelled 

flint and/or dent corn (Zea mays, L.), and popcorn from the mechanically 

(Carter Dockage Tester) cleaned portion and combine with the foreign 

material in step 7 above. This combination of mechanically separated fm and

hand-picked FM functions as foreign material

9. Calculate the percentages of BC and FM separate

Adjustment of Factors. In certain instances, when using the alternate procedure, the

sum of BC and FM in corn, due to rounding, will not equal the percentage of BCFM 

recorded on the certificate. When this occurs, it is necessary to adjust the component 

nearest a midpoint (e.g.; .05, .15, .25, .35, etc.) by adding or subtrac

Example

Original sample weight 1,012 grams

Weight of BC 38.34 gram

Weight of FM 2.64 gram

Weight of BCFM 40.98 gram

STEP 1 (38.34 ÷ 1,012) x 100 = 3.78% BC (rounded 3.

STEP 2 (2.64 ÷ 1,012) x 100 = 0.26% FM (rounded 0.

STEP 3 (40.98 ÷ 1,012) = 4.04% BCFM (rounded 4.

Since the sum of the rounded BC and FM results (3.8% BC + 0.3% FM = 4.1%) do

not equal the rounded BCFM results (4.0% BCFM), an adjustment of -0.1 is needed. 

this instance, the rounded result for FM (0.3%) is adjusted downward to 0.2% becaus

the unrounded result (0.26%) is nearer to a midpoint (0.25) than the unrounded resul

for BC

Certification. Record the percentage of BC and the percentage of FM separately to the

nearest tenth in the “Results” section of the certificate. Record the total percentage of 

BCFM to the nearest tenth percent
FGIS Directive 9180.82 March 14, 2022

Page 13

14. DAMAGED AND HEAT-DAMAGED KERNELS

a. Damaged kernels are whole kernels or pieces of corn kernels that are badly

ground-damaged, badly weather-damaged, diseased, frost-damaged, germdamaged, heat-damaged, insect-bored, mold-damaged, sprout-damaged, or 

otherwise materially damaged

b. Heat-damaged kernels are whole kernels or pieces of corn kernels that are

materially discolored and damaged by heat

c. Determine total damaged kernels and heat-damaged kernels on the basis of a

250-gram portion that is free from broken corn and foreign material (BCFM)

d. Report the percentage of total damaged kernels and heat-damaged kernels to the

nearest tenth percent on the work record and certificate.

15. PURITY

Purity refers to the total percentage of specialty corn minus the percentage of BCFM 

(standardized corn, popcorn, and sweet corn function as BCFM).

Basis of Determination. Determine Purity on a portion of 1,000 to 1,050 gram

Procedure: Calculate the percentage of BCFM in the sample. Subtract the percentage

of BCFM from 100 percent. The resulting difference is the actual percent of Specialty 

Type Corn in the sample

For example a sample contains 3.2 percent of BCFM, the purity is equal to 96.8 perce

(100.0 – 3.

Certification. Certify purity on the work record and certificate to the nearest tenth 

percent

16. COLOR

Determine kernel color on the pericarp color of the kernels. Pericarp colors may include

blue, red, and purple kernels

Basis of Determination. Determine the color of Specialty Type Corn by the color

characteristics of the kernels. Use a 250-gram portion of BCFM-free corn and consider

all kernels and pieces of corn kernels for the determination

Certification. Record the percentage of the color(s) of Specialty Type Corn in the

sample to the nearest tenth percent on the work record and in the “Results” section of 

the certificate. For example: Blue Kernels 98.2 percent, Red Kernels 1.8 percent.
FGIS Directive 9180.82 March 14, 2022

Page 14

17. AFLATOXIN TESTING

a. Samples may be tested for aflatoxin using only FGIS-approved quantitative or 

qualitative test kits

b. The minimum sample size is based on the type of lot. Applicants may request a 

sample size larger than the minimum sample size.

Lot Type Minimum Sample Size (lbs.)/ grams

Trucks 2 pounds / approximately 908 grams

Railcars 3 pounds / approximately 1,362 grams

Barges/Sublots 10 pounds / approximately 4,540 grams

Submitted Samples 10 pounds / approximately 4,540 grams (recommended)

Note: A minimum sample size of 10 pounds is required for composite type 

samples (e.g., a single sample representing multiple carriers). A 10-pound sample 

size is also recommended, but not required, for submitted samples.

Testing locations that receive submitted samples that contain less than the 

recommended 10-pound sample size must grind the entire sample as submitted. 

For submitted samples that are 10-pounds or more, a minimum of 10-pounds 

must be ground for testing purposes.

c. Perform aflatoxin testing and certification in accordance with the applicable 

instructions in the Aflatoxin Handbook.

18. CERTIFICATION

a. Certify lots/samples of Specialty Type Corn as “Not Standardized Grain” on the 

gradeline of the certificate. Delete the word “Grade” on the grade line of the 

certificate and enter the words “Not Standardized Grain.”

b. In the “Remarks” section of the certificate enter “Specialty Type Corn.”

c. Enter the test results of all factors determined in the “Results” section of the

certificate.

21. QUESTIONS

Direct any questions concerning this directive to the Policies, Procedures, and Market 

Analysis Branch at (202) 720-0228