Wisconsin Administrative Code
Department of Agriculture, Trade and Consumer Protection
ATCP 55-89 - Food, Lodging, and Recreation Safety
Chapter ATCP 65 - Milk And Milk Products
Subchapter V - Safety and Quality Standards
Section ATCP 65.86 - Milk component test methods
Universal Citation: WI Admin Code ยง ATCP 65.86
Current through August 26, 2024
(1) GENERAL. Milk component tests shall be performed using any of the following methods, subject to additional requirements under sub. (2) and (3):
(a) A method described in the American Public
Health Association., Standard Methods for the Examination of "Dairy Products,"
17th edition (2004).
(b) A method
described in the Official Methods of Analysis of AOAC International," 18th
edition (2005).
(c) A method
approved in writing by the division.
Note: "A milk component test," as defined under s. ATCP 65.01(35), means a test that determines the amount of milkfat, protein, total solids, solids-not-fat, or other valuable components in milk, and that may affect the price that a dairy plant operator or milk contractor pays a milk producer for milk.
The American Public Health Association's "Standard Methods for the Examination of Dairy Products," 17th edition (2004), is on file with the division and the legislative reference bureau. Copies may be obtained from the American Public Health Association, 800 I Street, NW, Washington, D.C. 20001, telephone 202-777-2742, website www.apha.org.
The "Official Methods of Analysis of AOAC International,"
18th Edition (2005), is on file with the division and the legislative reference
bureau. Copies may be obtained from AOAC International, 2275 Research Blvd.,
Rockville, MD 20850, telephone 800-379-2622, website
(2) MILKFAT TEST METHODS.
(a) Milkfat tests shall be performed
using the Babcock method, the ether extraction method, or another test method
approved by the division. Babcock and ether extraction tests shall be conducted
according to the Official Methods of Analysis of the Association of "Official
Analytical Chemists (AOAC) International," 17th edition (2000), except as
provided under par. (b).
(b) Each
milk sample tested by the Babcock method shall be agitated for at least 3
minutes by the use of a mechanical agitator after pipetting the sample and
adding sulfuric acid according to the procedure prescribed under par. (a). A
reading device, such as a needlepoint divider or other mechanical divider, that
accurately determines milkfat level in a test bottle shall be used in reading
all Babcock tests. All Babcock test readings shall be made against a
light-colored surface with adequate natural or artificial light. The Babcock
test shall be read to the nearest 0.05% by weight.
(3) AUTOMATED MILK COMPONENT TESTING DEVICES.
(a)
General calibration
requirements. If an automated testing device is used to perform a milk
component test for any milk component, that device shall be calibrated and
regularly checked to ensure that it accurately tests for that milk
component.
(b)
Specific
calibration requirements. If an automated testing device is used to
test for milkfat, protein, total solids, or solids-not-fat in milk, and if the
test results may affect the price paid to a milk producer, the testing device
shall be calibrated according to this paragraph. The testing device shall be
calibrated, for each relevant milk component, by a tester who is licensed under
s.
97.17 or
98.145,
Stats., to operate that device.
Note: See s. ATCP 65.78(2).
1. 'Calibration frequency'. A milk component
testing device under par. (b) shall be calibrated at all of the following
times:
a. Upon installation.
b. At regular 3 month intervals after
installation.
c. Immediately after
every significant repair or alteration to the testing device.
d. Whenever the mean difference on a daily
performance check under par. (c) exceeds plus or minus 0.044% for milkfat or
protein or plus or minus 0.084% for total solids or solids-not-fat.
2. 'Calibration procedure'. To
calibrate a milk component testing device under par. (b), a tester shall use
the device to test a set of calibration samples under subd. 3. The milk
component testing device shall be adjusted, as necessary, to satisfy all of the
following requirements:
a. The performance
error on each calibration sample shall be as near as practicable to zero. The
performance error is the difference between the known percentage content of
each milk component in the calibration sample, as determined by the sample
provider, and the percentage content measured by the testing device.
b. The mean difference for the entire set of
calibration samples shall be as near as practicable to zero and shall not
exceed plus or minus 0.044% for milkfat or protein or plus or minus 0.084% for
total solids or solids-not-fat. The mean difference is the sum of the
performance errors for the individual calibration samples divided by the number
of samples in the set.
c. The
standard deviation of test results, calculated for the set of calibration
samples according to the formula set forth in the Official Methods of "Analysis
of AOAC International," 18th edition (2005), section 969.16, shall not exceed
0.044% for milkfat or protein, or 0.084% for total solids or solids-not-fat.
Note: The Official Methods of "Analysis of
AOAC International," 18th edition (2005), is on file with the division and the
legislative reference bureau, and may be obtained from AOAC International, 2275
Research Blvd., Rockville, MD 20850, website
3. 'Calibration samples'. A set of
calibration samples shall be obtained from a sample provider approved by the
division. A set of calibration samples shall consist of at least 12 individual
samples, each of which complies with all of the following requirements:
a. Each sample shall be not more than 21 days
old.
b. Each sample shall be a
fresh milk sample preserved with bronopol (2-bromo-2-nitro-1, 3-propanediol) or
another approved preservative. Preservative methods, formulations, and
concentrations shall be approved by the division.
c. Each sample shall have a known percentage
content of each relevant milk component determined by the sample provider under
pars. (e) to (h).
(c)
Daily performance check.
1. If an automated testing device is used to
test for milkfat, protein, total solids, or solids-not-fat in milk, and if the
test results may affect the price paid to a milk producer, the device shall be
subjected to a daily performance check before each day's testing. The daily
performance check shall be conducted, for each relevant milk component, by a
tester who is licensed under s.
97.17 or
98.145,
Stats., to operate the testing device.
2. To conduct a daily performance check under
subd. 1., a tester shall test a set of daily performance check samples under
subd. 4. Based on the daily performance check, the tester shall do all of the
following:
a. Determine the performance error
of the testing device with respect to each daily performance check sample. The
performance error is the difference between the known percentage content of
each milk component in that sample, as determined by the sample provider, and
the percentage content measured by the testing device.
b. Based on the performance errors for the
individual samples under subdivision paragraph a, calculate the mean difference
for the set of daily performance check samples. The mean difference is the sum
of the performance errors for the individual samples, divided by the number of
samples in the set.
3.
If, on a daily performance check under subd. 1., the mean difference calculated
under sub. (2) (b) exceeds plus or minus 0.044% for milkfat or protein or plus
or minus 0.084% for total solids or solids-not-fat the testing device shall not
be used until it is recalibrated under par. (b).
4. A set of daily performance check samples
shall be obtained from a sample provider approved by the division. A set shall
consist of at least 5 individual samples, each of which complies with all of
the following requirements:
a. Each sample
shall be not more than 21 days old.
b. Each sample shall be a fresh milk sample
preserved with bronopol (2-bromo-2-nitro-1, 3-propanediol) or another approved
preservative. Preservative methods, formulations, and concentrations shall be
approved by the department.
c. Each
sample shall have a known percentage content of each relevant milk component,
determined by the sample provider under pars. (e) to (h).
(d)
Reference
checks.
1. If an automated testing
device is used to test for milkfat, protein, total solids, or solids-not-fat in
milk, and if the test results may affect the price paid to a milk producer,
that device shall be subjected to a daily reference check under subd. 2 and
hourly reference checks under subd. 3.
2. A daily reference check required under
subd. 1 shall be done in accordance with all of the following requirements:
a. A daily reference check shall be conducted
before each day's testing, at the same time that the dairy plant operator
conducts the daily performance check under par. (c). The daily reference check
shall be conducted, for each relevant milk component by a tester who is
licensed under s.
97.17 or
98.145,
Stats., to operate the testing device.
b. To perform a daily reference check, a
tester shall perform 10 tests on a reference sample. The reference sample may
be a homogenized milk sample prepared by the dairy plant operator, or it may be
a daily performance check sample obtained from a sample provider approved by
the department under par. (c) 4. The 10 test results shall be averaged and the
average result shall be used as a comparison value for the hourly reference
checks under subd. 3.
3.
An hourly reference check required under subd. 1 shall be done in accordance
with all of the following requirements:
a. An
hourly reference check shall be conducted for each milk component before each
hour's testing for that component. To conduct an hourly reference check, a
tester shall test the same reference sample used for the daily reference check
under subd. 2.
b. For each relevant
milk component the hourly reference check result shall be compared to the
average result obtained on the daily reference check under subd. 2. If an
hourly reference check result differs from the average result on the daily
reference check by more than 0.034 % for milkfat or protein or 0.064% for total
solids or solids-not-fat, the testing device shall not be used until the
condition causing the difference is found and corrected. Test results obtained
before the device is corrected, and after the last previous conforming
reference check, shall not be used in determining the amount paid to milk
producers.
(e)
Calibration and daily performance
check samples; milkfat contents.
1.
The provider of a calibration sample under par. (b) or a daily performance
check sample under par. (c) shall determine the known percentage content of
milkfat in that sample by averaging the results of 3 milkfat tests using a
method specified under subd. 4. The percentage milkfat results from those 3
milkfat tests shall not vary by more than 0.034 percentage points.
2. The known milkfat content of a calibration
sample, expressed as a percentage of the sample weight, shall be at least 2.5%.
Within a set of calibration samples, the difference in known milkfat content
between the lowest milkfat sample and the highest milkfat sample, expressed as
a percentage of average sample weight, shall be at least 2.5%.
3. The known milkfat content of a daily
performance check sample, expressed as a percentage of the sample weight, shall
be at least 2.8%. Within a set of daily performance check samples, the
difference in known milkfat content between the lowest milkfat sample and the
highest milkfat sample, expressed as a percentage of average sample weight,
shall be at least 1.5%.
4. To
determine the milkfat content of a calibration sample or daily performance
check sample, the sample provider shall use either a manual or robotic version
of the Modified Mojonnier method as described in the "Official Methods of
Analysis of AOAC International," 18th edition (2005), section 989.05.
Note: The Official Methods of Analysis of AOAC
International," 18th edition (2005), is on file with the division and the
legislative reference bureau, and may be obtained from AOAC International, 2275
Research Blvd., Rockville, MD 20850, website
(f)
Calibration and daily
performance check samples; protein contents.
1. The provider of a calibration sample under
par. (b) or a daily performance check sample under par. (c) shall determine the
known percentage content of protein in that sample by averaging the results of
3 protein tests using the method specified under subd. 3. The percentage
protein results from those 3 tests shall not vary by more than 0.034 percentage
points.
2. The known protein
content of a calibration or daily performance check sample, expressed as a
percentage of sample weight, shall be at least 2.7%. Within a set of
calibration samples, the difference in known protein content between the lowest
protein sample and the highest protein sample, expressed as a percentage of
average sample weight, shall be at least 0.7%. Within a set of daily
performance check samples, the difference in known protein content between the
lowest protein sample and the highest protein sample, expressed as a percentage
of average sample weight, shall be at least 0.5%.
3. To determine the protein content of a
calibration sample or daily performance check sample, the sample provider shall
use the traditional or block digester/steam distillation Kjeldahl method as
described in the Official Methods of Analysis of AOAC International," 18th
edition (2005), section 991.20.
Note: The Official Methods of Analysis of AOAC
International," 18th edition (2005), is on file with the division and the
legislative reference bureau, and may be obtained from AOAC International, 2275
Research Blvd., Rockville, MD 20850, website
(g)
Calibration and daily
performance check samples; total solids.
1. The provider of a calibration sample under
par. (b) or a daily performance check sample under par. (c) shall determine the
known percentage content of total solids in that sample by averaging the
results of 3 total solids tests using the method specified under subd. 3. The
percentage total solids results from those 3 tests shall not vary by more than
0.054 percentage points.
2. The
known total solids content of a calibration or daily performance check sample,
expressed as a percentage of sample weight, shall be at least 11%. Within a set
of calibration samples, the difference in known total solids content between
the lowest total solids sample and the highest total solids sample, expressed
as a percentage of average sample weight, shall be at least 2.00%. Within a set
of daily performance check samples, the difference in known total solids
content between the lowest total solids sample and the highest total solids
sample, expressed as a percentage of average sample weight, shall be at least
1.5%.
3. To determine the total
solids content of a calibration sample or daily performance check sample, the
sample provider shall use the direct forced air oven drying method as described
in the Official Methods of Analysis of AOAC International," 18th edition
(2005), section 990.20.
Note: The Official Methods of Analysis of AOAC
International," 18th edition (2005), is on file with the division and the
legislative reference bureau, and may be obtained from AOAC International, 2275
Research Blvd., Rockville, MD 20850, website
(h)
Calibration and daily
performance check samples; solids-not-fat. The provider of a
calibration sample under par. b or a daily performance check sample under par.
(c) shall calculate the known percentage content of solids-not-fat in that
sample by subtracting the percent milkfat as determined under par. (e) from the
total solids for that sample as determined under par. (g). The calculation
method shall be that described in the Official Methods of Analysis of AOAC
International," 18th edition (2005), section 990.21.
Note: The Official Methods of Analysis of AOAC International," 18th edition (2005), is on file with the division and the legislative reference bureau, and may be obtained from AOAC International, 2275 Research Blvd., Rockville, MD 20850, website http://www.aoac.org.
(i)
Automated testing
devices; constant voltage. A constant voltage regulator shall be
connected to, or form a part of, every milk component testing device that is in
line with a single phase 115 or 220-volt power supply.
(j)
Records related to calibrations,
daily performance checks, and reference checks.
1. A dairy plant operator shall keep a record
of every calibration, performance check, or reference check conducted on a milk
component testing device under this section.
2. Every record required under subd. 1 shall
be signed by the licensed tester who made the record. Calibration records shall
be kept separate from performance check and reference check records.
(k)
Accuracy of devices;
division audit. The division may audit the accuracy of milk component
testing devices using test samples prepared by the division under pars. (e) to
(h).
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