1、Designation: E1346 90 (Reapproved 2010)Standard Practice forBulk Sampling, Handling, and Preparing Edible VegetableOils for Sensory Evaluation1This standard is issued under the fixed designation E1346; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 case of revision, 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 practice covers the recommended procedures forbulk sampling, handling, and prepari
3、ng 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 The values stated in SI units are to be re
4、garded asstandard. The values given in parentheses are for informationonly.1.4 This standard does not purport 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 determin
5、e the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Publications:2ASTM STP 433 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:3
6、Method C1-47 Sampling3. Summary of Practice3.1 This practice consists of the following basic steps:removing oil from bulk source, transporting and starting oilprior to evaluation, preparing oils for evaluation, presentingsamples to panel, and cleaning glassware.4. Significance and Use4.1 This practi
7、ce is designed for use by the oil processor orresearch laboratory for evaluation by a trained sensory panel,or for use 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
8、 practice will provide repre-sentative samples for all sensory, chemical and physicalanalyses and will protect the oil 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 pro
9、tect oil qualityduring that time.4.4 This practice addresses neither evaluation and scalingtechniques, nor the sampling, 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 Amb
10、er Glass Bottles, 250 mLto 1 L, with narrow-mouthtops that will withstand freezer temperatures.5.4 Plastic Caps with 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
11、bottle openings.5.5 Glass Funnels.5.6 Glove Box with inert gas nitrogen atmosphere, includ-ing an oxygen scavenging device.5.7 Glass Vial, 50 mL. Use amber glass for flavor evaluationand clear glass for visual examination of oil.1This practice is under the jurisdiction of ASTM Committee E18 on Senso
12、ryEvaluation and is the direct responsibility of Subcommittee E18.06 on Food andBeverage Evaluation.Current edition approved Aug. 15, 2010. Published December 2010. Originallyapproved in 1990. Last previous edition approved in 2006 as E1346 90 (2006).DOI: 10.1520/E1346-90R10.2Available from ASTM Int
13、ernational Headquarters, 100 Barr Harbor Drive, POBox C700, West Conshohocken, 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 Internationa
14、l, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 1C divisions, calibrated
15、 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.Tank trucks, cars, or any other bulk transportation containersmay be filled with as many as seven layers and each level of oilmay be slig
16、htly 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 any environmental condition (forexample, light, heat, oxygen, moisture) or any equipment(metals) that will cause oxidation of the oil and alter sensorycha
17、racteristics of the oil.6.3 Use only new, clean, dry, and odor-free polyethyleneterephthalate wide-mouth jars to collect oil samples; dispose ofjars 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 eval
18、uations(sensory, chemical, instrumental); unblended multiple samplesmay produce different results.6.6 Do not allow glass containers in processing or produc-tion areas where oil sampling is done. Use new plasticcontainers such as polyethylene terephthalate bottles for initialsampling. Flush empty bot
19、tle with nitrogen as described in 6.4.6.7 Transfer oil from plastic bottle to recommended glassbottles within one hour of collection and flush headspace withnitrogen to minimize potential transfer of odors or flavors fromthe plastic container to the oil (conduct procedure in glove boxunder nitrogen
20、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.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 oi
21、l 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 sample of oil thatrequires evaluation quarterly should be stored in four 250-mLbottles.6.11 Discard any unused oil.7. Procedures for Handling Samples Obtain
22、ed from BulkStorage7.1 Refer to the AOCS Official Method C1-47 on oilsampling for specifications for detailed information on equip-ment and procedures.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
23、bottle (conduct procedurein glove box under nitrogen atmosphere).7.3 Headspace Considerations:7.3.1 Keep an inert gas such as nitrogen in contact 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
24、 with inert gas (nitrogen) to remove alloxygen which deteriorates the oil. Flush only the headspacewith nitrogen since bubbling nitrogen through 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
25、headspace ofbottle with nitrogen, seal with silicon rubber septum in screwtype cap, (2) withdraw a gas sample with a syringe through theseptum, and (3) inject sample into gas chromatograph withthermal-conductivity detector using a two column system.Column conditions are: ethylvinyl benzene-divinylbe
26、nzenepolymer 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 flow 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 af
27、ter 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 evaluation 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 s
28、ample evaluation.During this holding period, bottles should remain sealed withnitrogen in the headspace.7.7 Winterized Oil:7.7.1 Frozen sample is removed from cold storage and heldat refrigerated (5 6 2C) temperature until completely homo-geneous, that is, clear, with no visible solids. The timerequ
29、irements for thawing the oil will vary depending uponcontainer size.7.7.2 Sample must be mixed just prior to evaluation byinverting bottle several times to ensure homogeneity and tominimize potential density differences within the container; forexample, a 500 mL bottle with between 0.5 and 1 cmheads
30、pace 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) temperature until it stabilizes atthat temperature (5C). Next, move container to ambienttemperature (25 6 5C) until completely homogeneous; clear,no visible solids.7
31、.8.2 Sample must be mixed just prior to evaluation byinverting bottle several times to ensure homogeneity and tominimize potential density differences 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
32、 physical testingshould be taken from the thawed sample just prior to sensory6Saguy, I., Goldman, M., and Karel, M., “Prediction of Beta-Carotene Decol-orization in Model System Under Static and Dynamic Conditions of ReducedOxygen Environment,” Journal of Food Science, Vol 50, 1985, pg. 526530.E1346
33、 90 (2010)2testing. All evaluations should be conducted within the sametime frame 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 PFT
34、E-lined plasticcap and stored at 5C for no longer than 12 h. Any leftoversample 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 deteri
35、orate the oil and developoff-odors and flavors, causing the sample to be less thanrepresentative of the sample source.7.11 Once the oil has reached 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
36、 opened.7.12 All samples must be at ambient temperature at the timeof preparation for sensory evaluation.8. Procedures for Preparation of Oils for 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
37、 container as it will increase the surfacearea of the oil to oxygen and cause subsequent deterioration.8.3 Immerse sample vials into pre-heated 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
38、 even flow of water around each vial and toensure that the temperature is constant without hot or coldspots. Do not cover the waterbath. Vials are 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
39、sufficient size to hold all sample vials required fora single panel.8.4 Place vials into controlled temperature, pre-heatedwaterbath for sufficient 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
40、 sampleimmediately. Sample should not be held longer than 30 minsince the oil would be exposed to elevated temperature andoxygen that cause deterioration 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 b
41、ath. If the number of vials required exceedsthe capacity of a single waterbath, each judges sample setshould be placed in the same waterbath. Duplicate 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 an
42、d serve oils immedi-ately. Present samples monadically to keep oils at properevaluation temperature (50 6 1C) and to provide a timedminimum interval 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 blo
43、cks beused to maintain uniform sample temperature in the booth.Aluminum blocks heated to a temperature of 5C higher thanthe serving temperature 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
44、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 Concern: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
45、sensory characteristicsduring heating.8.7.2 Amber glass is recommended, however, colored light-ing such as red fluorescent bulbs, low sodium lighting, 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. Pl
46、ace oils in clear glassvials. Do not heat oil samples.9. Cleaning Glassware9.1 Use new, clean glassware for each evaluation. If this isnot economically practical, ensure that glassware is clean andodor-free prior to each use.9.2 Clean vials after each use by washing with commercial,unscented, glassw
47、are-washing detergent to remove all oilresidue.9.3 Test glassware for cleanliness by rinsing with distilledwater, (water should sheet off surface rather than form drop-lets). If droplets form, clean glassware with alcoholic NaOH(sodium hydroxide), rinse with distilled water, and re-evaluatefor sheet
48、ing. Discard any glassware that does not sheet cleanafter the NaOH treatment.9.3.1 Prepare alcoholic NaOH as follows: dissolve 120 gNaOH in 120 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
49、is notpossible to sufficiently clean these for reuse.9.5 Store glassware in closed cabinet away from chemicalodors to protect from contamination.9.6 Discard glassware that is etched or that does not meetminimum standards for cleanliness.E1346 90 (2010)3ASTM 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
