1、Designation: F874 98 (Reapproved 2014)Standard Test Method forTemperature Measurement and Profiling for MicrowaveSusceptors1This standard is issued under the fixed designation F874; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, t
2、he year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This is a test method for measuring surface temperaturesattained by microwave interactive packaging and coo
3、king aids(that is, susceptors). It is useful for measuring susceptor/foodinterface temperatures during microwave preparation of foodswith susceptor-based packaging, heating pads, and crispingsleeves, etc. It may also be used to measure the temperature ofa susceptor exposed to extractives testing or
4、in a liquidextraction cell to be used for nonvolatile extractives testing.The latter procedures are performed to establish test conditionsfor conducting extraction and migration studies using tempera-ture versus time profiles approximating those for actual micro-wave preparation of the product.1.1.1
5、 Several of the steps of this test method are takendirectly from Test Method F1308 which gives extractiontesting procedures for susceptors.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to
6、 address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2F1308 Tes
7、t Method for Quantitating Volatile Extractables inMicrowave Susceptors Used for Food ProductsF1317 Test Method for Calibration of Microwave OvensF1349 Test Method for Nonvolatile Ultraviolet (UV) Ab-sorbing Extractables from Microwave SusceptorsF1500 Test Method for Quantitating Non-UV-AbsorbingNonv
8、olatile Extractables from Microwave Susceptors Uti-lizing Solvents as Food Simulants3. Apparatus3.1 Microwave Oven, no turntable, unmodified except forsmall holes to allow for probe lead access to the oven cavity.The oven should be calibrated in accordance with Test MethodF1317.3.2 Fluoroptic Thermo
9、metry System .3.3 Vials, headspace, 20 mL.3.4 Septa, polytetrafluorethylene (PTFE) polymer faced sili-cone rubber.3.5 Vial Crimp Caps.3.6 Microwave Nonvolatile Extraction CellThis cell mustbe constructed of PTFE-fluorocarbon polymer. Additionaldetails on this cell may be found in Test Method F1349.3
10、.7 Beakers, 600 and 250 mL, or other sizes as appropriate.3.8 Aluminum Foil, household roll.3.9 Adhesive Tape, such as Kapton high-temperature tape,vinyl tape, silicone tape, etc.3.10 High-Vacuum Silicone Grease .3.11 Syringe Needle, 13 gage diameter.3.12 Corn Oil, Miglyol 812 (a fractionated coconu
11、t oil), orsynthetic fat simulant HB 307. See Test Method F1349 fordetails.3.13 Petri Dishes.3.14 Fan, tabletop.3.15 Blue Ice.3.16 Vials, for alternative profile method, 40-mL clear vials.3.17 Screw Caps.4. Procedure4.1 General:4.1.1 Start all tests with a cool microwave oven, that is,ambient tempera
12、ture. Use a fan and blue ice to cool oven floor1This test method is under the jurisdiction of ASTM Committee F02 on FlexibleBarrier Packaging and is the direct responsibility of Subcommittee F02.15 onChemical/Safety Properties.Current edition approved April 1, 2014. Published April 2014. Originallya
13、pproved in 1990. Last previous edition approved in 2008 as F874 98(2008). DOI:10.1520/F0874-98R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Docu
14、ment Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1or any other reliable method to suitably return the oven toambient temperature between replicates.4.1.2 Test three replicates per variable.5. Measure
15、ment of Food/Susceptor InterfaceTemperature During Microwave Cooking5.1 Place product in center of the microwave oven as aconsumer would. Mark the position of first replicate on ovenfloor, and position subsequent replicates similarly.5.2 Position probes at food susceptor interface in such amanner th
16、at good probe/susceptor contact is maintained duringcooking, disturbing the food load as little as possible. Theanalyst may wish to position multiple probes on differentregions of the susceptor, such as the center and edge, as thetemperature attained at different locations may differ signifi-cantly.
17、5.2.1 If the nature of the product permits, the analyst maywish to determine whether probes positioned parallel to thesusceptor surface, or abutted to the susceptor surface wouldresult in better temperature measurement as evidenced bybetter reproducibility between replicate runs and lessdiscontinuit
18、y, due to loss of contact, of temperature readingsversus time.5.3 For in-package measurements for products such asmicrowave popcorn, probe access into the package is achievedby drilling approximately 0.1-in. holes through the package.(See Fig. 1 for probe placement inside a popcorn bag.) It is alsoa
19、dvisable to route the probes along the bottom of the packageto avoid disruption of probe/susceptor contact as the bagexpands during cooking. If it has been demonstrated that theouter bag surface and inner bag surface temperatures areequivalent, then taping the probes to the outer surface would besat
20、isfactory.5.4 For products prepared on a susceptor board, such asmicrowave pizza, the probe should be immobilized to thesusceptor board in parallel contact by applying a suitableadhesive tape 0.5 in. behind the probe tip.5.5 For products without free fat or oil at the food susceptorinterface, it is
21、advisable to apply high-vacuum silicone greaseto the tip of the probe to assure good thermal contact with thesusceptor.5.6 Microwave at full power for the maximum directedcooking time of the product, recording the temperature of eachprobe, preferably at 5-s intervals, but at intervals not to exceed1
22、5 s. It is suggested that readings be taken at 1-s intervals ifpossible, in order to generate a smoother curve. Calculate theaverage of the replicate runs at each recorded time for eachprobe position. Do not use data if discontinuities appear in plot(indicative of loss of susceptor/probe contact).6.
23、 Temperature Profiling of Susceptors in Vials Used forVolatile Extractives Testing6.1 First determine the temperature versus time profile forthe product during microwave preparation in accordance withSection 5.6.2 Cut a 10 by 65-mm (6.5 cm2or 1-in.2) portion from thesusceptor sample to be tested. In
24、sert carefully into vial,positioning the sample on the vial side, with the active sidefacing into the vial.6.3 Using a 13-gage syringe needle, pierce a hole into aseptum, place septum on vial and crimp.6.4 Insert one temperaturesensing probe through the sep-tum hole into the vial and manipulate it u
25、ntil it is in contactwith the active face of the susceptor material.6.5 Place vial on its side in the center of the microwaveoven, marking the exact location on the oven floor forsubsequent replicates. Place the cap of the vial towards theprobe access port in the oven cavity, with susceptor active f
26、aceup.6.6 As an alternative to 6.2 through 6.5, multiple probes canbe used for doing temperature profiling, using the followingprocedure. Cut a 10 by 65-mm portion from the susceptorsample to be tested. Using a razor blade, carefully cut an “X”in the center of the septum. Place the number of tempera
27、ture-sensing probes to be used through the open hole in the screwcap and then through the “X” in the septum and attach them tothe sample using the adhesive tape to maintain continuouscontact. Place the sample, with probes attached, into the vialand secure the screw cap onto the vial. Place the vial
28、on its sidein the center of the microwave oven, marking the exactFIG. 1 Probe Configuration for Popcorn Bag Temperature Mea-surementFIG. 2 Effect of Foil Sleeve Window Size (cm2) on TemperatureAttained by Frozen Fish Product SusceptorF874 98 (2014)2location on the oven floor for subsequent replicate
29、s. Again,place the cap of the vial toward the probe access port in theoven cavity.6.7 Before proceeding with replicate runs, one must firstperform trial runs to determine the extent of water loading orvial shielding necessary to limit the microwave energy expo-sure of the susceptor to an amount whic
30、h will result in atemperature that closely approximates, or is slightly higherthan, that attained when used with actual product.6.7.1 Adjustment of the water load can be achieved byvarying the mass of water in one or more 600-mLbeakers or byvarying the beaker size to change the water surface area. F
31、orinstance, one 600-mL beaker containing 500 mL of water iscommonly used for microwave popcorn susceptors.6.7.2 Use of a water load is recommended for productswhich do not contain large amounts of frozen water such aspopcorn and pizza. For products containing large amounts offrozen water such as fro
32、zen fish, it will likely be necessary toshield the sample from overexposure to microwave energy bywrapping a foil sleeve with a cut-out window around the vial.F1349 by 3-cm window directed toward the in-feed port (thearea where the microwaves are being fed into the oven) hasbeen used successfully fo
33、r volatile extractives studies forsusceptors used for frozen fish products. Successful applicationof this technique may depend on position of magnetron inoven.6.8 Microwave at full power for the time period used in 5.6,recording the probe temperature, preferably at 5-s intervals, butat intervals not
34、 to exceed 15 s. Again, the more frequentreadings that can be obtained will give a smoother, moretraceable curve. Calculate the average from the replicate runsat each recorded time.6.9 Plot the average temperature as a function of time from5.6 (using the data from the hottest recorded region of thes
35、usceptor) and 6.8.6.10 Compare the plots. If the trace from the vial-enclosedsample closely approximates or is slightly higher than that forthe product during microwave preparation, then the test con-ditions employed for the in-vial runs are acceptable forconducting volatile extractives testing for
36、this susceptor appli-cation. If the trace is substantially higher or lower than that ofthe susceptor with product, then adjust the mass or surfacearea, or both, by changing container size of the water (using afresh sample of room-temperature distilled water), or adjust thedegree of vial shielding by
37、 altering the size of the window inthe aluminum foil. Repeat 6.8 and 6.9.7. Temperature Profiling of Susceptors in PTFE-Fluorocarbon Polymer Cells Used for NonvolatileExtractives Testing7.1 First, determine the temperature versus time profile forthe product during microwave preparation in accordance
38、 withSection 5.7.2 Select a representative piece of susceptor sample to betested. If the susceptor is part of a package, trim excessmaterial from around the susceptor. Cut the susceptor to fit intothe Waldorf cell with the screw seal ring firmly seated againstthe susceptor surface.7.3 For susceptors
39、 intended for use above and not in contactwith the food product, select an acceptably sized petri dish tomatch the size of the susceptor, proceed through 7.4 and 7.5,and then place the susceptor above contents of the cell withactive face down.7.4 Add 1.0 g of corn oil, or equivalent, to the cell for
40、 each1cm2of susceptor material being tested.7.5 Place 50 mL of room temperature distilled water and aboiling chip into a 250-mL beaker. Place beaker in center rearof microwave oven.7.6 Place the cell in the center of the microwave oven.Always position the vessel in the same position for subsequentru
41、ns.7.7 Insert one or more temperature-sensing probes throughpre-formed holes in Waldorf cell. Manipulate the probes untilthey are in contact with the active face of the susceptormaterial.7.8 Before proceeding with replicate runs, one must firstperform trial runs to determine the extent of water load
42、ingnecessary to limit the microwave energy exposure of thesusceptor to an amount which will result in a temperature thatclosely approximates or is slightly higher than that attained bythe actual product. Adjustment of the water load can beachieved by varying the mass of water in one or more 250-mLbe
43、akers or by varying the beaker size to change the watersurface area.7.9 Microwave at full power for the time period used in 5.6,recording the temperature for each probe, preferably at 5-sintervals, but at intervals not to exceed 15 s. Calculate theaverage from the replicate runs at each recorded tim
44、e.7.10 Plot the average temperature as a function of time from5.6 and 7.3, using the data from the hottest recorded region ofthe susceptor in both cases.FIG. 3 Temperature Profiles for Microwave Pizza and Its Suscep-tor In Vial With Different Water LoadsF874 98 (2014)37.11 Compare the plots. If the
45、trace from the cell closelyapproximates or is slightly higher than that for the productduring microwave preparation, then the test conditions em-ployed for the cell runs are acceptable for conducting nonvola-tile extractives testing for this susceptor application. If the traceis substantially higher
46、 or lower than that of the susceptor withproduct, then adjust the mass or surface area, or both, bychanging container size of the water (using a fresh sample ofroom-temperature distilled water), and repeat 7.9 and 7.10.8. Precision and Bias8.1 Table 1, Table 2, and Table 3 are from a group ofcollabo
47、rative studies based on approximately 700-W micro-wave ovens intended for home use, made by several commer-cial manufacturers. Because different microwave ovens havedifferent microwave energy intensity patterns, the interlabora-tory data are not necessarily indicative of identical test condi-tions.9
48、. Keywords9.1 extractives, nonvolatile, temperature profiling for;extractives, volatile, temperature profiling for; fluoroptic tem-perature measurements; fluoroptic thermometry; microwave;microwave cooking temperatures; microwave susceptors; non-volatile extractives, temperature profiling for; susce
49、ptor;susceptors, microwave; temperature measurements, fluoroptic;temperature profile; temperature profiling, microwave suscep-tors; temperatures, microwave cooking; thermometry; volatileextractives, temperature profiling forASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject t
