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Thermal heating fluids-a hot issueThe use of thermal heating fluids (THFs) in edible-oil storage and transportationequipment is expected to be a contentious issue when the Codex Alimentarius Com-mission's Oils and Fats Committee meets during March 1999 in the UnitedKingdom. European members of the committee have urged that the use ofTHFs bediscouraged and discontinued; representatives from u.s. industry have arguedthere is no need for halting the use of THFs. This pair of articles, by C.J.M. Meers-hoek, executive director of VERNOF, the trade association representing Dutchcrushers and oil processors, and by Robert M. Reeves, president of the Institute of

It is time to end use of THFs

C.J.M. Meershoek,Executive Director, VERNOF (Verelliging van Neder-

lands Fabrikanten Vall Eetbare Olien en Yettem),Amperlaan 4 E, 2289 CD Rijswijk. The Netherlands

For quite some lime, there has been discussion about theuse of heating Fluids in the oils and fats industry. The dis-cussion began with a decision of the European oil-process-ing industry federation. FEDIOL. to ban thermal heatingoils in processing. The discussion has been further fueledby the discussion in the Codex Alimentarius Oils and FatsCommittees about proposed Codex rules on storage andtranspon.

It is useful to make a clear distinction between two sep-arate applications of heating oils: (a) during the processingof oils and fats at a relatively high temperature, and (b)during transport and storage of oils and fats at a relativelylow temperature.

Discussions about the safety of thermal heating oilsactually began quite some time ago. The I%8 tragedy inKanemi in Japan was a warning for everybody to be verycareful in using heating fluids during processing. The deathof more than 50 persons was caused by an oil that becamecontaminated by a PCB-based heating fluid. Another dead-ly accident occurred in 1973 in Japan involving an edibleoil contaminated by a heating fluid, which turned out to bea blend of several heating oils.

Just like their counterparts elsewhere in the world at thetime, quite a number of European refiners were using heat-ing oils in the processing of oils and fats. All processorswho were using heating oils in processing required fromtheir suppliers guarantees about the safety of such prod-ucts. And all suppliers of heating oils provided a guaranteethat the "fresh" oil is nontoxic, noncarcinogenic, and canbe used at high temperatures (>350°C).

As high quality and product safety became major con-cerns of European consumers, a discussion developedabout the safety of thermal heating oils. Of course, everyprocessing plant had control mechanisms to check possibleleakages of the heating oils. But it was obvious that evensophisticated control systems could not prevent contami-nated oils from reaching the market before detection, giventhe tight logistical schedules.

The question then became to learn more about the safetyof "used" heating oils. Major suppliers of heating oils wereinvited to answer questions about toxicity and carcino-genicity of their products after long-term use at high tem-peratures. It turned out that no supplier could provide a sat-isfactory answer-the requested information simply was

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INFORM, VOl. 9, no. 6 (June 1998)

Shortening and Edible Oils, the U.S. trade association for oil refiners, presentsthose viewpoints. In processing, thermal heating fluids have been used in suchsteps as deodorization, where they can be used to heat the oil to the desired temper-ature for deodorization. Heating fluids have been used to keep edible oils and fatsliquid in cold-temperature areas-in storage tank farms and in ships-so that theyare readily pumpable; the convection movements that result from heating also pro-mote homogeneity. INFORM readers are invited to submit their thoughts on thetopic as letters to the editor.

THFs do not pose a health threat

Robert M. Reeves.President, Insf;tute of Shortening and

Edible Oils, 1750 New York Ave. NW, Suite 120,Washington, DC 20008

Thermal healing fluids (THFs) continue to be an issue ofdebate within the international edible fats and oils indus-try. They have been used widely throughout the world asheat transfer media; however, the safety of these fluids hasbeen questioned by European edible-oil processing inter-ests in recent years. The arguments to restrict THFs' usein international trade due to perceived safety risks haveoften been long on emotion and short on science, therebygenerating much more artenricn than they rightfullydeserve. This article will attempt to provide a perspectiveon why THFs are acceptable heat transfer media to beused in conjunction with edible fats and oils.

THFs are used to a limited extent in the transportationand storage sectors to facilitate the transfer or loading ofsolid or semisolid fats by transferring heat to the vesselscontaining them. Relatively low temperatures (80-160DF;27-71 DC) are needed to accomplish this function. THFsare used to a greater degree during the processing of edi-ble oils where the efficient transfer of higher temperature(400-700°F; 204-37 J "C) is desirable (e.g., deodoriza-tion). THFs also find significant utilization in the food-processing sector where large-scale, deep-frying opera-

nons are employed to cook many foods, including meat,poultry, seafood, doughnuts, and french-fried potatoes.Here higher-temperature THFs (400-600°F; 204-3 ISoC)are also used.

THF systems used in food applications are "closed" indesign so that THFs do not come in direct contact with thefood being healed. Generally. the healed vessel is sur-rounded by a THF-containing coil, or the cooking or heat-ing vessel contains coils or tubes containing the heat trans-fer fluids. Because of the remote possibility of a pinholeleak in a such a system. THFs used in food applicationsshould be made safe for such uses and these systemsappropriately maintained and monitored.

Historically, certain types of THFs gained negativepublicity during the late 1960s and 1970s as a result ofseveral contamination incidents involving THFs contain-ing polychlorinated biphenyls (PCBs). Perhaps the twolargest and best-known incidents took place in Japan,causing health complications for scores of individuals.The worldwide regulatory community was prompt inappropriately banning any use of PCB-containing THFsthat could potentially contaminate the food supply.

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tcominued from PORe542)

not available. This was sufficient reason for FEDIOL tobegin considering a ban on use of thermal healing oils inprocessing.

To avoid protracted discussions and to be able to guar-antee a high degree of product safety, FEDiOl decided inDecember 1991 to require that by Jan. I, 1997. all Euro-

It should be made clear that thedecision to abandon use of thermal

heating oils was an industrydecision and not a measure taken by

governmental authorities.

pean Union (EU) processing units should replace use ofthermal heating oils by use of high-pressure steam. Duringthe five-year transition period. a code of practice was for-mulated for plants that were still using thermal healing oils.In fact. all EU edible-oil refining facilities (except one)have been converted to high-pressure steam.

For a clear understanding, it must be realized that this isan internal EU situation. Suppliers of processed oils andfats outside the EU can continue to use thermal heatingoils. but they may be confronted by strict conditions onquality control imposed by EU buyers. It should be madeclear that the decision to abandon use of thermal heatingoils was an industry decision and not a measure taken bygovernmental authorities.

The issue also was raised in the Council of the Interna-tional Association of Seed Crushers (IASC), which is theglobal forum for oilseed processors. In the lASC discus-sions, the Japanese industry supported FEDIOL doubtsabout the safety of heating oils. Other major producers ofoils and fats who were using thermal heating oils could nOI.unfortunately. supply any additional information regardingthe safety of the heating oils they were using.

The main arguments from the opponents of the FEDIOLand JOPA (Japanese Oilseed Processors Association) posi-tion were that heating oils had been used for a long timeand no negative risks were known.

The differing opinions reflect sociocultural differences.In Europe (and in Japan), consumer concern and awarenessabout product safety are major issues. Industry has to takeconsumer attitudes into account and to act accordingly.

As mentioned previously, heating oils also are used dur-ing transport and storage of edible oils. Although control ofleakages, as well as measures in case of leakages. of heat-ing fluids will be taken by ship and storage lank owners. it

is quite understandable that their approach to these prob-lems is somewhat different from that of oil processors whoare close to consumer markets.

Against this background. as well as for quality reasons,the IASC prescribed that only hot water or low-pressuresteam should be used for heating during transport of edibleoils.

In the early 198Gs, the Palm Oil Research Institute ofMalaysia (PORIM) drafted a code of practice on storage.Based on the existing transport requirement, PORlM alsoprescribed hot water or steam for heating during storage.PORlM presented its draft code to the IASC for discussionwith all parties in world trade and industry. Finally thecode was agreed upon and, among others. also published inthe February 1985 issue of the Journal of the American OilChemists' Society 162:438-4421.

With this history in mind. it was quite obvious that,when the Codex secretariat presented a Code on Storageand Transport to the Codex Alimentarius Committee onOils and Fats. the proposed code would mention hot wateror steam as the heating medium.

So. it was astonishing to note during the 1996 CodexOils and Fats Committee meeting that the Malaysian dele-gation. supported by the U.S. delegation, pleaded in sup-port of the use of thermal heating oils in case of transportor storage. whereas the respective industries in these coun-tries-full members of all IASC bodies-had never raisedthe question to change the IASC-endorsed heating instruc-tions.

These heating instructions have been part of the IASChandbook for a long lime. the latest edition of which waspublished in August 1993 after a revision that was pro-posed by the IASC Technical and Quality Committee andapproved by the IASC Council. The Malaysian and U.S.industry are represented on both these bodies.

Malaysian. European, and U.S. companies are majorplayers in the oils and fats world. It is quite obvious thatthese companies have not just paid lip service to the codesthat they have helped 10 draft and accept. So, for more than20 years, hOI water and steam have been recommended ashealing media for transport and storage of edible oils andhave been commonly used for heating purposes.

It would seem somewhat strange 10 oppose such a prac-tical application without engaging in a fundamental discus-sion about the safety of heating oils and the advantages ofconversion 10 hot water and steam.

Thus. the discussion in the Codex Committee left Euro-peans with several questions as to the real motives behindthe U.S. and Malaysian opposition 10 the draft CodexCode.

As previously mentioned. product safety is a hot issue inEurope. For that reason. European trade and industry, aswell as legislators, will not change their position withoutconvincing arguments on the part of the defenders of heal-ing oils. But so far we have not seen any argument or evena suggestion for a discussion about the subject in the lAse,which means the global industry is still in support of a banon the use of thermal heating oils for the heating of edibleoils during transport. 0

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(continued [rom page 543)

The United States and many other countries respondedto the banning of PCBs by developing THFs of completelydifferent chemical composition. totally devoid of PCBs.Because these newer compounds were of low toxicitiesand because only very minor leaks of THFs could goundetected in closed systems for any appreciable length oflime, the use of THFs has not been considered a healthrisk 10 consumers. Indeed the safety record of these non-PCB THFs for the past 40 years of widespread usage hasbeen unblemished by any known ingestion injuries associ-ated with their use.

The European edible-oil community's response to thePCB situation has been to phase out THF systems andreplace them with hot water/steam heal transfer systems.The vast majority of edible-oil processing installations inEurope have converted to hot water/steam systems. This islargely the result of the EC Seed Crushers and OilProcessors Federation (FEDJOL) approval of a code ofpractice in December 1991 that basically provided that allof its oil processing facilities were to have convened tohOI water/steam by Jan. I, 1997.

It was also in December 1991 that language banningTHFs as heating media appeared in a draft InternationalCode of Practice for the Storage and Transport of EdibleOils in Bulk being considered by the Code AlimentariusCommittee on Fats and Oils (CCFO). A code of practicehad been submitted previously to the Codex committee in1986 by the Palm Oil Research Institute of Malaysia(PORIM). The CCFO submitted the draft to the Federationof Oils. Seeds, and Fats Associations (now FOSFA Inter-national) in February 1987 for its input. Neither of thesedraft documents contained language prohibiting the use ofTHFs as heating media.

Voluntary actions by trade groups such as FEDIOL toalter processing practices within such a group's member-ship without creating trade barriers are acceptable actionsto take. The inclusions of provisions in international stan-dards that will affect global trade. however, take on newand significantly greater meaning, Codes of practice putinto place by the Codex Alimentarius Commission arenow considered "authoritative" by the World Trade Orga-nization (WTO) and are expected to be complied with byall WTO member countries. Any significant changes insuch international standards, be they advisory or mandato-ry. should be fully justified by scientific evidence that theydo indeed reduce health risks or otherwise benefit interna-tional trade. Thus far there has been no such scientific jus-tification presented to Codex regarding the alleged risks ofTHFs.

The trend in the United States and other edible-oil pro-ducing nations also has been to replace conventional THFsystems with hot water/steam systems as processing facili-ties are renovated. expanded, or built. The main reason,however, has been to achieve significant savings in facilityoperating costs due to reduced energy requirements andnot because of perceived safety concerns.

Although the FEDIOL Code of Practice includes per-

formance and testing criteria for THFs, it appears thatnone has received approval for usage thus far. The FEDJ-OL Code of Practice originally was announced as apply-ing to all oils. regardless of origin. effectively prohibitingoils imported into the EU from facilities using THFs. Thisinterpretation. however. has been altered in recent monthsto apply only to oils produced by FEDIOL member facili-ties.

The main reason expressed by FEDIOL for effectivelybanning the use of THFs was the question of THF safety.THFs generally are grouped into four categories based ontheir composition: diphenyl-diphenyl oxides, terphenyls,mineral oil and its derivatives, and silicone or siliconemixtures. All of these materials have low toxicities andhave been shown not to pose unreasonable risks to users orto consumers.

To date, there have been no known actions by regulato-ry authorities throughout the world to restrict or ban non-PCB-type THFs. In fact. some regulatory agencies specifi-cally have approved many of these materials for use infood processing operations. For example, in the UnitedStates. the U.S. Department of Agriculture (USDA). afterthorough evaluation of these materials, has approveddiphenyl-diphenyl oxide, mineral oil, and silicone-basedTHFs for use in meat and poultry processing facilities.Kosher certification also has been awarded to many plantsusing THFs.

Examination of toxicity and safety data of THFsreveals the health risks to humans to be negligible. Of thefour categories of THFs previously listed, the most com-monly used in the United States is the diphenyl-diphenyloxide type. It also has the lowest LD50. Its oral LD50dose in rats is 2,()()(}....4.000mglkg. An LD50 value repre-sents the level of contaminant relative to the subject ani-mal's body weight lit which 50% of the subject animalswill die. Please note that other substances that have beenapproved as direct food additives by the U.S. Food andDrug Administration have equivalent LD50 ranges (oraladministration to rats): acetic acid (vinegar), 3,530; sodi-um chloride (table salt). 3.000-3.750; vitamin A, 2,000;and sodium benzoate (preservative). 2,700-4.070.

In order to gain some perspective relative to humansafety, a 50· kg {l Lfl-pound) rat would have to ingestapproximately 3.5 ounces or 100 grams of diphenyl-diphenyl oxide THFs. at an LDso of 2,000 mglkg, for thedose to be potentially lethal. Further calculations revealthis dosage to be about one pound of THFs per 500pounds of oil. If one assumes a minimal detectability levelof 2.0 parts per million (ppm), in order for a lID-pound"rat" to ingest an LDso equivalent to 3.5 ounces that is notdetectable at less than 2.0 ppm. the "rat" would have toconsume several thousand pounds of oil. The presence ofdiphenyl-diphenyl oxide THFs at 2.0 ppm is readilydetected because it has a very pungent odor at 1.0 ppmand imparts a distinctly unpleasant taste. However, othermore reliable detection methods are employed to deter-mine the presence of THFs, such as analytical testing ofthe deodorized oil, measurement of THFs reservoir loss.and analysis of deodorizer distillate for the presence of

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THFs. The simple organoleptic determination of otherTHFs used in relatively minor amounts in edible-oil pro-cessing is more difficult; however, the LDso values ofthese THFs are much higher (i.e .• less risk).

This exercise in calculation has been provided simplyto point out that it is not reasonable to expect THFs usedin the edible-oils industry to pose a health risk to con-

Tests performed on one mineral oil-based THF used in a deodorizer for

more than nine years showed nomortality in rats orally

administered relatively high levelsof the THF.

sumers. Edible oils potentially contaminated in a likemanner would be unusable as foods, and from a qualityperspective would be removed from the food chain.

The question of whether these products break downafter extended use over long periods of time into com-pounds of unknown safety also has been raised. The man-ufacturers of THFs have indicated the temperatures atwhich these fluids begin to break down are well above thetemperatures of commercial use. Recent tests performedon one mineral oil-based THF used in a deodorizer formore than nine years at temperatures up to 580°F (304°C)showed no mortality in rats orally administered relativelyhigh levels of the THF. More research is needed to fullyanswer these questions, but preliminary results are veryencouraging.

The appropriate level at which THFs may be identifiedin vegetable oils and animal fats also has been an issue ofdebate. Since there are at least four different types ofTHFs in use, at least as many or more test methods shouldbe available that are accurate, reproducible, and able todetect THFs at low concentrations. The test methods forTHFs generally allow detection at a 1-5 ppm level, withsome methods providing detection at below I ppm levels.Although these concentrations of THFs in oil are substan-tially below the amounts that may be associated with evena slight health risk, industry is making an effort to improvethese test methods to even further reduce the detectabilitylevels of THFs, particularly for those most commonlyused.

The THFs issue reentered the spotlight during thesummer of 1995 when a draft code of practice proposedin the Codex Alimentarius Commission's Committee onFats and Oils came under strong criticism for containing

language that would have effectively banned the use ofany heat-transfer medium other than hot water/steam inconjunction with the transport or storage of fats and oils.This provision of the Draft Recommended Code of Prac-tice for the Storage and Transport of Oils in Bulk washotly debated during deliberation at the CCFO held inLondon, England (November 1996). The expressly pro-hibitive language was removed from the draft code ofpractice and replaced with language negatively character-izing THFs and placing significant restrictions on theiruse (e.g., "Thermal heating fluids should not be usedexcept where agreed between contracting parties andnational authorities on the basis of safety evaluation, riskassessment, and inspection procedures"). This languagehas been confusing to many because several differentinterpretations may be made.

By the time the draft code was discussed during theCodex Alimentarius Commission meeting in Geneva inJune 1997, the debate over THFs had escalated to theextent that it was the main reason the entire draft code waspulled back from Step 8 to Step 6 in the Codex process inorder that it be further studied. It appears that the debatewill continue during the next CCFO meeting scheduled forMarch 1999.

The debate on THFs appears to be fueled by basic dif-ferences in approach to the issue. The United States andother oil-producing countries have looked at the scientificevidence related to all aspects of this issue and have con-cluded that there are no significant health risks associatedwith the use of THFs. It may be that political and businessdecisions outside the realm of science have influencedpositions in the European sector supporting internationalrestrictions on THFs.

The Institute of Shortening and Edible Oils (ISEO), theU.S. trade association representing the refiners of ediblefats and oils, has supported the continued use of THFs asit believes they do not pose a significant risk to con-sumers. ISEO was joined in the Edible Oils Coalition inlate 1996 by three other major oilseed/oil processing tradeassociations [the National Institute of Oilseed Products(NIOP), the National Oilseed Processors Association(NOPA), and the Com Refiners Association {CRA)J whotook the following position relative to THFs:

• THFs may be used where appropriate as alternativeheat sources to prevent solidification of fats in storagetanks.

• THFs should be contained in closed systems specifi-cally designed to avoid potential contamination. Strict pro-cedures of operation and maintenance must be ensured.

• Facilities and vessels using THFs should have system-atic procedures in place to detect leakage of fluids intocargoes. In such event, immediate corrective action shouldbe implemented.

• All materials, including THFs, should meet appropri-ate national legislative requirements.

The acceptance of THFs in the international oilseedcrushing community is reflected by the approval in May1997 by the International Association of Seed Crushers(IASC) of an official position which considers THFs to

INFORM. Vol. 9, no. 6 (June 1998)

..be considered a safe and acceptable heat-transfer mediumthat is satisfactory in the domestic refining process."

Even though there is already an acceptable level ofsafety associated with THFs, further efforts are beingmade to assure an even greater margin of safety associatedwith their usage. Test methods are continually beingimproved to detect THFs at lower concentrations in oil.Additional efforts are being made to identify the compo-nents of THFs used for extended periods of time regardingtheir health effects.

In summary, THFs currently being used in the globaloils processing, storage, and transportation sectors are safeand suitable for their intended use. These non-PCB-con-taining heating media have a proven track record in foodsafety for more than 40 years with no reported incidents ofinjury associated with them. Regulatory authorities havecarefully examined these heating media throughout theworld and have placed no significant restrictions on them

due to their relative safety and the methods employed toutilize them.

Although the trend in heat transfer systems in the edi-ble-oils industry is clearly toward steam/hot water sys-tems, existing closed-loop THF systems continue to pro-vide a safe and effective method of heat transfer. Conver-sions to steam/hot water systems have been made for avariety of reasons, including improved heat transfer effi-ciency, reduced energy costs, reduced maintenance, andreduction in perceived safety risks.

The edible-oils industry has long employed the prin-ciple of sound science in making decisions affecting thesafety and integrity of its products. It should continue toallow scientific evidence, rather than emotion, to deter-mine its actions. Perhaps, then, it is time to move onfrom the THF debate to other challenges with the fatsand oils industry which are more worthy of our atten-tion. •

eodorizer Heating Systems: Steam vs. Organic Vapor !l.!.;:::;,;;-"~"Much has been written. and a great deal of research has been conducted,in an attempt to compare the merits of steam and organic vapor as heattransfer media for deodorization applications. Both have advantages anddrawbacks. Infonned media (and system) selection can be made onlythrough careful comparison.

Organic Vapor as HeatIng MediaOrganic vapor has several important advantages: it is an excellentconductor of heM; it is relatively non-toxic and it is readily availablefrom a wide runge ofsuppliers.1t is not without its problems. though.The cost of thermal oil must be considered. Organic vapor systems. withtheir requisite number of pumps, flanges and valves demand regularmaintenance. Such systems are prone to fluid leaks during operation.Thermal fluid losses can easily cost a lerge application tens of thou sandsof dollars per year. Edible oil contaminated by organic vapor is rendereduseless. and although new organic heat media are normally non-toxic.aging may create breakdown components such as benzene.

Steam-based Heat TreatmentExposure to contamination risks has led many refillCl"Sofedib1c oil toconsider steam as a heatteansfer medium. Benefits of steam includeefficient heat transfer properties and elimination of the risk of productcontamination. Typical open-type steam boilers are very inefficient dueto nash losses. High-pressure systems fo.- deodorizing, with their make-up and boiler feedwater systems are very expensive. Moreover, open-type boilers are susceptible to the same leak and make-up woes affectingtypical organic vapor systems.

Closed-loop Steam SystemsFcnunatcly, an alternative exists to provide process heat fordeodorization facilities. Taking the best benefits of steam boilers andcombining them with the safety and efficiency of organic vapor systems,GTS Energy, Inc.. of Marieua, Georgia USA created a high·pressuresteam generation system called NUKiII. This closed-loop systemeliminates the need for makeup components (fecdwater and controldevices, pumps etc.) which add complexity and cost to a typical steamboiler, Because OTS Energy's hermetically closed system rarely needswater added, operation is quite simple compared with an organic vapor-based system. Closed steam/condensatc systems remove the potential forflash or blowdown losses. Typical open boilers can lose 15-20% of theircapacity in this way. No maintenance of pumps. steam traps or watertreatment is required And because of the pressure and vacuum-tightconstruction and design of the NUKili air cannot enter the system.COlT05ion, possible in an open-type boiler, can be avoided.

ConclusionAlthough sometimes requiring higher initial investment. closed-loopsteam gcneration s)'Stems pay for themselves through savings in media,maintenance and energy. For in-depth information on NUK<II heattransfer media and systems, please telephone, write or visit the thermalheating experts at OTS Energy.

445 Windy Hill ROMIMarien •. GA lOO6O USAI'bone 1701801.8&84 Fax nOllO [·8985www.~.comnuk@~.com

For InbmoIIon ~ .108 on Jorm on lost page

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