1、Designation: F 874 98 (Reapproved 2008)Standard Test Method forTemperature Measurement and Profiling for MicrowaveSusceptors1This standard is issued under the fixed designation F 874; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 c
3、ooking 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 o
4、r 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
5、.1 Several of the steps of this test method are takendirectly from Test Method F 1308 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
6、 to 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:2F 1308
7、 Test Method for Quantitating Volatile Extractablesin Microwave Susceptors Used for Food ProductsF 1317 Test Method for Calibration of Microwave OvensF 1349 Test Method for Nonvolatile Ultraviolet (UV) Ab-sorbing Extractables from Microwave SusceptorsF 1500 Test Method for Quantitating Non-UV-Absorb
8、ingNonvolatile 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 MethodF 1317.3.2 Fluoropti
9、c Thermometry 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
10、F 1349.3.7 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
11、 coconut oil), orsynthetic fat simulant HB 307. See Test Method F 1349 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
12、 temperature. Use a fan and blue ice to cool oven flooror any other reliable method to suitably return the oven toambient temperature between replicates.1This test method is under the jurisdiction of ASTM Committee F02 on FlexibleBarrier Packaging and is the direct responsibility of Subcommittee F02
13、.15 onChemical/Safety Properties.Current edition approved Oct. 1, 2008. Published January 2009. Originallyapproved in 1990. Last previous edition approved in 2003 as F 874 98(2003).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.or
14、g. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.1.2 Test three replicates per variable.5. Measurement of Food/S
15、usceptor 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 that good probe/
16、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.5.2.1 If the n
17、ature 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 less discon-tinuity, due to lo
18、ss of contact, of temperature readings versustime.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 alsoadvisable to
19、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 besatisfactory.5.
20、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 advisable to
21、 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 exceed15 s. It is s
22、uggested 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. Temperature
23、 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. Insert careful
24、ly 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 until it is i
25、n 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 faceup.6.6 As
26、 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 temperature-sensing
27、 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 on its sidei
28、n the center of the microwave oven, marking the exactlocation on the oven floor for subsequent replicates. 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 loadi
29、ng orFIG. 1 Probe Configuration for Popcorn Bag TemperatureMeasurementFIG. 2 Effect of Foil Sleeve Window Size (cm2) on TemperatureAttained by Frozen Fish Product SusceptorF 874 98 (2008)2vial shielding necessary to limit the microwave energy expo-sure of the susceptor to an amount which will result
30、 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. Forinstance, o
31、ne 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 frozen fish, it
32、will likely be necessary toshield the sample from overexposure to microwave energy bywrapping a foil sleeve with a cut-out window around the vial.by 3-cm window directed toward the in-feed port (the areawhere the microwaves are being fed into the oven) has beenused successfully for volatile extracti
33、ves studies for susceptorsused for frozen fish products. Successful application of thistechnique may depend on position of magnetron in oven.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 to exceed 15 s. A
34、gain, 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 thesusceptor) and 6.8.
35、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 this susceptor app
36、li-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 altering the size
37、 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 withSection 5.7.2
38、 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 intended for use
39、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 each1cm2of suscep
40、tor 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 subsequentruns.7.7 Insert one
41、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 loadingnecessary to li
42、mit 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-mLbeakers or by varyin
43、g 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-sFIG. 3 Temperature Profiles for Microwave Pizza and ItsSusceptor In Vial With Different Water LoadsTABLE 1 Reproducibility of Singl
44、e-Probe Readings in OneRepresentative Laboratory, FNOTE 1Triplicate analyses of popcorn susceptor in vials with 250 mLof water in a 400-mL beaker.Time, s #1 #2 #3 AverageMean (coeffi-cient of vari-ance)120 318.1 300.4 321.5 313 2.9135 324.4 301.4 319.0 315 3.2150 322.5 294.0 314.8 310 3.9165 320.5 2
45、88.3 308.7 306 4.2180 316.1 287.1 301.7 302 4.0195 318.8 287.1 299.4 302 4.3210 323.5 290.6 300.1 305 4.6225 326.9 297.2 299.2 308 4.5240 332.7 301.2 296.6 310 5.2F 874 98 (2008)3intervals, but at intervals not to exceed 15 s. Calculate theaverage from the replicate runs at each recorded time.7.10 P
46、lot 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.7.11 Compare the plots. If the trace from the cell closelyapproximates or is slightly higher than that for the productduring microwave preparation, then th
47、e 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 or lower than that of the susceptor withproduct, then adjust the mass or surface area, or both, bychanging container size o
48、f 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 ofcollaborative studies based on approximately 700-W micro-wave ovens intended for home use, made by several commer-cial manufacturer
49、s. Because different microwave ovens havedifferent microwave energy intensity patterns, the interlabora-tory data are not necessarily indicative of identical test condi-tions.9. Keywords9.1 extractives, nonvolatile, temperature profiling for; ex-tractives, volatile, temperature profiling for; fluoroptic tem-perature measurements; fluoroptic thermometry; microwave;microwave cooking temperatures; microwave susceptors; non-volatile extractives, temperature profiling for; susceptor; sus-ceptors, microwave; temperature measurements, fluoroptic;temperature profile; temperature profi
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