ASTM F874-98(2008)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:F874 −98(Reapproved 2008)
Standard Test Method for
Temperature Measurement and Profiling for Microwave
Susceptors
ThisstandardisissuedunderthefixeddesignationF874;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope F1500 Test Method for Quantitating Non-UV-Absorbing
Nonvolatile Extractables from Microwave Susceptors Uti-
1.1 Thisisatestmethodformeasuringsurfacetemperatures
lizing Solvents as Food Simulants
attained by microwave interactive packaging and cooking aids
(that is, susceptors). It is useful for measuring susceptor/food
3. Apparatus
interface temperatures during microwave preparation of foods
with susceptor-based packaging, heating pads, and crisping
3.1 Microwave Oven, no turntable, unmodified except for
sleeves, etc. It may also be used to measure the temperature of
small holes to allow for probe lead access to the oven cavity.
a susceptor exposed to extractives testing or in a liquid
The oven should be calibrated in accordance with Test Method
extraction cell to be used for nonvolatile extractives testing.
F1317.
The latter procedures are performed to establish test conditions
3.2 Fluoroptic Thermometry System .
for conducting extraction and migration studies using tempera-
3.3 Vials, headspace, 20 mL.
ture versus time profiles approximating those for actual micro-
wave preparation of the product.
3.4 Septa,polytetrafluorethylene(PTFE)polymerfacedsili-
1.1.1 Several of the steps of this test method are taken
cone rubber.
directly from Test Method F1308 which gives extraction
3.5 Vial Crimp Caps.
testing procedures for susceptors.
3.6 Microwave Nonvolatile Extraction Cell—This cell must
1.2 The values stated in SI units are to be regarded as
be constructed of PTFE-fluorocarbon polymer. Additional
standard. No other units of measurement are included in this
details on this cell may be found in Test Method F1349.
standard.
3.7 Beakers, 600 and 250 mL, or other sizes as appropriate.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.8 Aluminum Foil, household roll.
responsibility of the user of this standard to establish appro-
3.9 Adhesive Tape, such as Kapton high-temperature tape,
priate safety and health practices and determine the applica-
vinyl tape, silicone tape, etc.
bility of regulatory limitations prior to use.
3.10 High-Vacuum Silicone Grease .
2. Referenced Documents
3.11 Syringe Needle, 13 gage diameter.
2.1 ASTM Standards:
3.12 Corn Oil, Miglyol 812 (a fractionated coconut oil), or
F1308 Test Method for Quantitating Volatile Extractables in
synthetic fat simulant HB 307. See Test Method F1349 for
Microwave Susceptors Used for Food Products
details.
F1317 Test Method for Calibration of Microwave Ovens
3.13 Petri Dishes.
F1349 Test Method for Nonvolatile Ultraviolet (UV) Ab-
sorbing Extractables from Microwave Susceptors
3.14 Fan, tabletop.
3.15 Blue Ice.
This test method is under the jurisdiction ofASTM Committee F02 on Flexible
3.16 Vials, for alternative profile method, 40-mLclear vials.
Barrier Packaging and is the direct responsibility of Subcommittee F02.15 on
Chemical/Safety Properties.
3.17 Screw Caps.
Current edition approved Oct. 1, 2008. Published January 2009. Originally
approvedin1990.Lastpreviouseditionapprovedin2003asF874 – 98(2003).DOI:
4. Procedure
10.1520/F0874-98R08.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.1 General:
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4.1.1 Start all tests with a cool microwave oven, that is,
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. ambient temperature. Use a fan and blue ice to cool oven floor
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F874−98 (2008)
FIG. 1 Probe Configuration for Popcorn Bag Temperature Mea-
surement
or any other reliable method to suitably return the oven to
ambient temperature between replicates.
4.1.2 Test three replicates per variable.
FIG. 2 Effect of Foil Sleeve Window Size (cm ) on Temperature
Attained by Frozen Fish Product Susceptor
5. Measurement of Food/Susceptor Interface
Temperature During Microwave Cooking
probe, preferably at 5-s intervals, but at intervals not to exceed
5.1 Place product in center of the microwave oven as a
15 s. It is suggested that readings be taken at 1-s intervals if
consumer would. Mark the position of first replicate on oven
possible, in order to generate a smoother curve. Calculate the
floor, and position subsequent replicates similarly.
average of the replicate runs at each recorded time for each
5.2 Position probes at food susceptor interface in such a
probe position. Do not use data if discontinuities appear in plot
manner that good probe/susceptor contact is maintained during
(indicative of loss of susceptor/probe contact).
cooking, disturbing the food load as little as possible. The
analyst may wish to position multiple probes on different
6. Temperature Profiling of Susceptors in Vials Used for
regions of the susceptor, such as the center and edge, as the
Volatile Extractives Testing
temperature attained at different locations may differ signifi-
6.1 First determine the temperature versus time profile for
cantly.
the product during microwave preparation in accordance with
5.2.1 If the nature of the product permits, the analyst may
Section 5.
wish to determine whether probes positioned parallel to the
2 2
susceptor surface, or abutted to the susceptor surface would 6.2 Cut a 10 by 65-mm (6.5 cm or 1-in. ) portion from the
result in better temperature measurement as evidenced by susceptor sample to be tested. Insert carefully into vial,
better reproducibility between replicate runs and less discon- positioning the sample on the vial side, with the active side
tinuity, due to loss of contact, of temperature readings versus facing into the vial.
time.
6.3 Using a 13-gage syringe needle, pierce a hole into a
5.3 For in-package measurements for products such as septum, place septum on vial and crimp.
microwave popcorn, probe access into the package is achieved
6.4 Insert one temperature–sensing probe through the sep-
by drilling approximately 0.1-in. holes through the package.
tum hole into the vial and manipulate it until it is in contact
(SeeFig.1forprobeplacementinsideapopcornbag.)Itisalso
with the active face of the susceptor material.
advisable to route the probes along the bottom of the package
6.5 Place vial on its side in the center of the microwave
to avoid disruption of probe/susceptor contact as the bag
oven, marking the exact location on the oven floor for
expands during cooking. If it has been demonstrated that the
subsequent replicates. Place the cap of the vial towards the
outer bag surface and inner bag surface temperatures are
probe access port in the oven cavity, with susceptor active face
equivalent,thentapingtheprobestotheoutersurfacewouldbe
up.
satisfactory.
6.6 As an alternative to 6.2 through 6.5, multiple probes can
5.4 For products prepared on a susceptor board, such as
be used for doing temperature profiling, using the following
microwave pizza, the probe should be immobilized to the
procedure. Cut a 10 by 65-mm portion from the susceptor
susceptor board in parallel contact by applying a suitable
sample to be tested. Using a razor blade, carefully cut an “X”
adhesive tape 0.5 in. behind the probe tip.
in the center of the septum. Place the number of temperature-
5.5 For products without free fat or oil at the food susceptor
sensing probes to be used through the open hole in the screw
interface, it is advisable to apply high-vacuum silicone grease
cap and then through the “X” in the septum and attach them to
to the tip of the probe to assure good thermal contact with the
the sample using the adhesive tape to maintain continuous
susceptor.
contact. Place the sample, with probes attached, into the vial
5.6 Microwave at full power for the maximum directed andsecurethescrewcapontothevial.Placethevialonitsside
cooking time of the product, recording the temperature of each in the center of the microwave oven, marking the exact
F874−98 (2008)
TABLE 1 Reproducibility of Single-Probe Readings in One
Representative Laboratory,° F
NOTE 1—Triplicate analyses of popcorn susceptor in vials with 250 mL
of water in a 400-mL beaker.
Mean (coeffi-
Time, s #1 #2 #3 Average cient of vari-
ance)
120 318.1 300.4 321.5 31
...