1、Designation: E 1346 90 (Reapproved 2006)Standard Practice forBulk Sampling, Handling, and Preparing Edible VegetableOils for Sensory Evaluation1This standard is issued under the fixed designation E 1346; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the recommended procedures forbulk sampling, handling, and prep
3、aring edible vegetable oil(liquid at room temperature) prior to sensory evaluation.1.2 This practice is consistent with the background infor-mation presented in ASTM STP 433, ASTM STP 434, andASTM STP 758. These should be consulted for supplementalguidance.1.3 This standard does not purport to addre
4、ss 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 Publications:2ASTM STP 433
5、 Basic Principles of Sensory EvaluationASTM STP 434 Manual on Sensory Testing MethodsASTM STP 758 Guidelines for the Selection and Trainingof Sensory Panel Members2.2 AOCS Standard:3Method C 1-47 Sampling3. Summary of Practice3.1 This practice consists of the following basic steps:removing oil from
6、bulk source, transporting and starting oilprior to evaluation, preparing oils for evaluation, presentingsamples to panel, and cleaning glassware.4. Significance and Use4.1 This practice is designed for use by the oil processor orresearch laboratory for evaluation by a trained sensory panel,or for us
7、e by quality control (QC) and quality assurance (QA)personnel for sampling from a tank truck, car, or any other bulktransportation container, or by both.4.2 The consistent use of this practice will provide repre-sentative samples for all sensory, chemical and physicalanalyses and will protect the oi
8、l from oxidation.4.3 The objective of this practice is to ensure that the sampleis representative of the sample source from the time ofsampling until the time of evaluation and to protect oil qualityduring that time.4.4 This practice addresses neither evaluation and scalingtechniques, nor the sampli
9、ng, handling, and preparing of solidfats.5. Apparatus5.1 Liquid Zone Sampler,3or core sampler, or trier.4,55.2 Wide-Mouth Jars, made of polyethylene terephthalate,0.5 to 1.0 L.5.3 Amber Glass Bottles, 250 mLto 1 L, with narrow-mouthtops that will withstand freezer temperatures.5.4 Plastic Caps with
10、Liners, or tape (PTFE pipe threadtape), to cover top of bottle opening before capping with newnon-metallic screw type caps. Tape should be 2.5 cm in widthor wider to completely cover bottle openings.5.5 Glass Funnels.5.6 Glove Box with inert gas nitrogen atmosphere, includ-ing an oxygen scavenging d
11、evice.5.7 Glass Vial, 50 mL. Use amber glass for flavor evaluationand clear glass for visual examination of oil.5.8 Standard Disposable Glass Pipets, 10 mL, one per eachsample.5.9 Circulating Waterbath, with automatic timer, thermostatand rack.5.10 Waterbath Thermometer, with range from 20 to 100Cin
12、 1C divisions, calibrated for 76 mm immersion, 305 mmlong.6. Precautions6.1 Oil submitted for chemical and physical testing and forsensory evaluation should be from the same bulk sampling.1This practice is under the jurisdiction of ASTM Committee E18 on SensoryEvaluation and is the direct responsibi
13、lity of Subcommittee E18.06 on Food andBeverage Evaluation.Current edition approved April 1, 2006. Published May 2006. Originallyapproved in 1990. Last previous edition approved in 2000 as E 1346 90 (2000).2Available from ASTM International Headquarters, 100 Barr Harbor Drive, POBox C700, West Consh
14、ohocken, PA 19428-2959.3Available from American Oil Chemists Society, P.O. Box 3989, Champaign,IL 61826.4Available from Zone Devices, Inc., San Rafael, CA.5Available from Refinery Supply Co., Tulsa, OK.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-295
15、9, United States.Tank trucks, cars, or any other bulk transportation containersmay be filled with as many as seven layers and each level of oilmay be slightly different in quality. Oil samples should behandled in the same manner and time frame to ensure high datacorrelation.6.2 Do not expose oil to
16、any environmental condition (forexample, light, heat, oxygen, moisture) or any equipment(metals) that will cause oxidation of the oil and alter sensorycharacteristics of the oil.6.3 Use only new, clean, dry, and odor-free polyethyleneterephthalate wide-mouth jars to collect oil samples; dispose ofja
17、rs rather than cleaning them.6.4 Flush bottles with nitrogen in a glove box prior to fillingthe bottle.6.5 Obtain a representative oil sample for all evaluations(sensory, chemical, instrumental); unblended multiple samplesmay produce different results.6.6 Do not allow glass containers in processing
18、or produc-tion areas where oil sampling is done. Use new plasticcontainers such as polyethylene terephthalate bottles for initialsampling. Flush empty bottle with nitrogen as described in 6.4.6.7 Transfer oil from plastic bottle to recommended glassbottles within one hour of collection and flush hea
19、dspace withnitrogen to minimize potential transfer of odors or flavors fromthe plastic container to the oil (conduct procedure in glove boxunder nitrogen atmosphere).6.8 Use PFTE-lined caps or PFTE tape under caps to protectoil from off-odors or flavors imparted from metallic or unlinedplastic caps.
20、6.9 Store oil in amber glass bottles to protect the oil fromlight oxidation.6.10 Choose size of storage bottle based on purpose ofevaluation, amount of oil required for each testing session orfor number of panelists, and amount of oil needed for instru-mental or chemical tests. For example, a 1 L sa
21、mple of oil thatrequires evaluation quarterly should be stored in four 250-mLbottles.6.11 Discard any unused oil.7. Procedures for Handling Samples Obtained from BulkStorage7.1 Refer to the AOCS Official Method C 1-47 on oilsampling for specifications for detailed information on equip-ment and proce
22、dures.7.2 Flush bottle with nitrogen and fill bottle with oil,allowing a small amount of headspace. Flush headspace withnitrogen to remove oxygen, and cap bottle (conduct procedurein glove box under nitrogen atmosphere).7.3 Headspace Considerations:7.3.1 Keep an inert gas such as nitrogen in contact
23、 with theoil at all times to avoid exposure of the oil to oxygen.7.3.2 Leave 0.5 to 1 cm of headspace between the oil andthe cap liner.7.3.3 Fill headspace with inert gas (nitrogen) to remove alloxygen which deteriorates the oil. Flush only the headspacewith nitrogen since bubbling nitrogen through
24、oil for shortperiods of time has little benefit.7.3.4 Analyze headspace for oxygen to ensure that bottlesare being flushed correctly as follows: (1) Flush headspace ofbottle with nitrogen, seal with silicon rubber septum in screwtype cap, (2) withdraw a gas sample with a syringe through theseptum, a
25、nd (3) inject sample into gas chromatograph withthermal-conductivity detector using a two column system.Column conditions are: ethylvinyl benzene-divinylbenzenepolymer 80 to 100 mesh (3 ft by18 in.) and molecular sieve 5A80 to 100 mesh (9 ft by116 in.) with 25C oven temperatureand 20 mL/min helium f
26、low rate.67.4 Store all oils at 5 or 20C, except for the sample forinitial evaluation, which may be held at ambient temperature(25C) in the dark for 1 h after sampling from bulk storagebefore analyses.7.5 Samples should be held a maximum of 2 days at 5 62C in the dark before evaluation. If evaluatio
27、n is not possiblewithin this time frame, filled containers should be held at20C. Always store samples in the dark.7.6 Do not open bottles until ready for sample evaluation.During this holding period, bottles should remain sealed withnitrogen in the headspace.7.7 Winterized Oil:7.7.1 Frozen sample is
28、 removed from cold storage and heldat refrigerated (5 6 2C) temperature until completely homo-geneous, that is, clear, with no visible solids. The timerequirements for thawing the oil will vary depending uponcontainer size.7.7.2 Sample must be mixed just prior to evaluation byinverting bottle severa
29、l times to ensure homogeneity and tominimize potential density differences within the container; forexample, a 500 mL bottle with between 0.5 and 1 cmheadspace is inverted 10 times.7.8 Non-Winterized Oil:7.8.1 The frozen sample is removed from cold storage andheld at refrigerated (5 6 2C) temperatur
30、e until it stabilizes atthat temperature (5C). Next, move container to ambienttemperature (25 6 5C) until completely homogeneous; clear,no visible solids.7.8.2 Sample must be mixed just prior to evaluation byinverting bottle several times to ensure homogeneity and tominimize potential density differ
31、ences within the container; forexample, a 500 mL bottle with between 0.5 and 12 cmheadspace is inverted ten times.7.9 Samples for instrumental, chemical or physical testingshould be taken from the thawed sample just prior to sensorytesting. All evaluations should be conducted within the sametime fra
32、me as the sensory tests to ensure valid test results forcorrelation analyses. Oil that cannot be tested immediatelymust have the headspace thoroughly re-flushed with nitrogenand the bottle recapped with PFTE tape or a PFTE-lined plasticcap and stored at 5C for no longer than 12 h. Any leftoversample
33、 should be discarded. Re-freezing is abusive to the oiland is not recommended.7.10 Do not thaw samples by heating above the ambienttemperature (25C) by microwave or in waterbath. Theseprocedures are abusive and may deteriorate the oil and develop6Saguy, I., Goldman, M., and Karel, M., “Prediction of
34、 Beta-Carotene Decol-orization in Model System Under Static and Dynamic Conditions of ReducedOxygen Environment,” Journal of Food Science, Vol 50, 1985, pg. 526530.E 1346 90 (2006)2off-odors and flavors, causing the sample to be less thanrepresentative of the sample source.7.11 Once the oil has reac
35、hed refrigerated temperature(5C) (winterized oil), it must be evaluated within 12 h if thebottle has been opened, or within 2 days if the bottle has notbeen opened.7.12 All samples must be at ambient temperature at the timeof preparation for sensory evaluation.8. Procedures for Preparation of Oils f
36、or SensoryEvaluation8.1 Fill waterbath with distilled water and heat to 50C.8.2 Pipet 10 mL oil into each glass vial and cap. Do notallow drips on inside of container as it will increase the surfacearea of the oil to oxygen and cause subsequent deterioration.8.3 Immerse sample vials into pre-heated
37、waterbath at alevel sufficient to cover the oil in the vial. Vials should besuspended in the waterbath on racks rather than sitting on thebottom to allow an even flow of water around each vial and toensure that the temperature is constant without hot or coldspots. Do not cover the waterbath. Vials a
38、re spaced equidistantfrom each other and the edges of the waterbath. No vial shouldtouch another vial or the side of the waterbath. The waterbathmust be of sufficient size to hold all sample vials required fora single panel.8.4 Place vials into controlled temperature, pre-heatedwaterbath for suffici
39、ent time for oils to reach serving tempera-ture of 50 6 1C. Determine minimum time required to bringoil to serving temperature, (usually 6 to 10 min). Serve sampleimmediately. Sample should not be held longer than 30 minsince the oil would be exposed to elevated temperature andoxygen that cause dete
40、rioration in oil quality.8.5 If more than one waterbath must be used, attentionshould be given to standardize the number and placement ofvials within each bath. If the number of vials required exceedsthe capacity of a single waterbath, each judges sample setshould be placed in the same waterbath. Du
41、plicate waterbathsmust be equivalent.8.6 Sample Presentation:8.6.1 When ready to serve oils, remove vials from water-bath, wipe residual water from vials and serve oils immedi-ately. Present samples monadically to keep oils at properevaluation temperature (50 6 1C) and to provide a timedminimum inte
42、rval between samples for clearing the palate.8.6.2 If samples are presented in pairs or other multiples, itis recommended that a method such as aluminum blocks beused to maintain uniform sample temperature in the booth.Aluminum blocks heated to a temperature of 5C higher thanthe serving temperature
43、of the oil will keep the sample at theproper serving temperature for 10 min. Blocks should haveopenings for vials that can extend 4 cm above the top of the oilin the vial. The diameter of the opening should be a maximumof 1 cm wider than the vial to allow adequate transfer of heat.8.7 Special Concer
44、n:8.7.1 PFTE-lined caps or PFTE tape applied over the bottleopening under the caps are recommended as least likely toaffect headspace volatiles or the oils sensory characteristicsduring heating.8.7.2 Amber glass is recommended, however, colored light-ing such as red fluorescent bulbs, low sodium lig
45、hting, ortheatrical gels and filters can also be effective.8.7.3 Visual evaluations of oils should be conducted sepa-rately from odor and flavor testing. Place oils in clear glassvials. Do not heat oil samples.9. Cleaning Glassware9.1 Use new, clean glassware for each evaluation. If this isnot econo
46、mically practical, ensure that glassware is clean andodor-free prior to each use.9.2 Clean vials after each use by washing with commercial,unscented, glassware-washing detergent to remove all oilresidue.9.3 Test glassware for cleanliness by rinsing with distilledwater, (water should sheet off surfac
47、e rather than form drop-lets). If droplets form, clean glassware with alcoholic NaOH(sodium hydroxide), rinse with distilled water, and re-evaluatefor sheeting. Discard any glassware that does not sheet cleanafter the NaOH treatment.9.3.1 Prepare alcoholic NaOH as follows: dissolve 120 gNaOH in 120
48、mLH2O and dilute to 1 Lwith isopropyl alcohol.Soak glassware for no more than 30 min to minimize etching.9.4 Discard caps and liners after one use since it is notpossible to sufficiently clean these for reuse.9.5 Store glassware in closed cabinet away from chemicalodors to protect from contamination
49、.9.6 Discard glassware that is etched or that does not meetminimum standards for cleanliness.ASTM 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 to revision at any time by the responsible technical committee and must be reviewed every five years andif not r
