Enzymatic Interesterification: Process Advantages and ...

1 7 Husum, T L*; Pedersen, L S*; Nielsen, P M*; Christensen, M W*; Kristensen, D* and Holm, H C* INTRODUCTIONT here are many reasons for changing the melting properties of fats and oils(and mixtures of these) ranging from increasing or decreasing the meltingpoint (or cloud point) of an oil, to altering the melting profile of an oil , five different methods of changing the melting properties pro-files of fats and oils exist - blending, fractionation, chemical interesterifica-tion, Enzymatic interesterification and hydrogenation. In this presentation,we will only discuss the last three methods which have one thing in com-mon; they all change the composition of the fat molecules during Interesterification: Process Advantages andProduct BenefitsInteresterification or ester-esterexchange is a Process during whichthe fatty acids of triglycerides exch-ange positions from one glycerideto another, thereby altering theoverall chemical composition andphysical properties of the interester-ified fats.

2 Interesteri- fication is thusan efficient way for changing andcontrolling the melting characteris-tics of oils and fats. Hydrogenation alters the fatcomposition by addition of hydro-gen atoms to the double y d rogenated fat is made less unsa-turated and thereby more hard dur-ing the will show how enzymaticinteresterification has been deve-loped and made cost-efficient, sothat it now can compete with chem-ical interesterification and hydro-genation, both on Process benefits,product quality and on the overallp rocess costs (capital an operational).DEVELOPMENTS WITHINENZYMATIC INTERESTERIFICA-TIONE nzymatic interesterification hasbeen used by scientists in laborato-ry scale columns, producing up to afew kilos of product per hour, formore than 20 years. But due tonormally high enzyme prices,mar-ket penetration has been limited tospecialty products. A quantum leap in lipaseimmobilization technology wasobtained with the development ofthe granulation technology.

3 Thetechnology led Novozymes todevelop a low cost silica granulatedlipase for bulk fat modification. Thisgranulated lipase product enableslipases to be used for production ofbulk fats such as margarine, short-enings and vanaspati by interester-ification. Although the granulated lipaseproduct can be used in both batchand continuous fixed bed opera-tion, we will only discuss the use of graulated lipases in fixed LABORATORY TO PRODUCTION SCALEIn order to turn Enzymatic inter-esterification into an industrial pro-cess for bulk fat modification, itwas necessary to scale up theprocess from the laboratory scale toproduce industrial amounts ofinteresterified fat. In scaling up, it isnot sufficient to only get enoughproduct out of the column. It is alsonecessary to focus on the reactionkinetics and the physical parametersof the immobilized lipase to designa good establish the basis for agood design, studies of the reactionkinetics, particle stability, pressuredrop and film diffusion resistancewere undertaken to characterizethe immobilized lipase product.

4 Besides being well suited forthe observed kinetics, the reactorshould be simple, inexpensive,mobile, easy to operate, robust andcapable of being plugged in bet-ween existing feed and producttanks in the oil on our studies and con-siderations, we developed a Plug &Play Reactor for production fixed bed reactor was chosenas the reactor type. All the listedcriteria were met. The reactor wasadditionally designed so that itcould be easily filled with the gran-ulated lipase on arrival, and there-after be plugged in (either alone or*Novozymes A/S, Smoermosevej Build, ,Dk-2880 Bagsvaerd, Oil Developments 398 Figure 1. The Plug & Play in series) between two exist-ing tanks at the oil mill (Figure 1).PARTIAL HYDROGENATIONIn hydrogenation, the double bondsare broken resulting in a harder is carried out withh y d rogen at high temperature / p re s -sure, catalyzed by a nickel controlling the degree of hydro-genation, it is possible to controlthe melting profile of the fat.

5 Theprocess requires very pure hydro-gen which can be obtained by dif-ferent methods in a separate hydro-gen plant. Hydrogen is the highestvariable cost in the Process . Theoverall reaction takes approximately2 hr. After the reaction, addition ofcitric acid is required to eliminatenickel soaps, filtration, bleachingand deodorization done (Figure 2).The disadvantages of theprocess are the use of hydrogen,chemical catalyst (nickel) and theformation of transfatty acids. Transfatty acids are believed to have anegative impact on health whenconsumed in large amounts. The content of transfatty acidsoften increases to 15%-25%, andunder certain circumstances ashigh as 50%. Fully hydrogenated fats do notcontain trans fatty acids, becauseall the double bonds in the fat mol-ecules have been , the melting profile, whichmakes, margarine pleasant toeat has to be adjusted for. One wayto achieve a more suitable meltingprofile without producing transfatty acids, is to mix a fully hydro-genated fat with a naturally liquidoil or to interesterify the mix to getthe specific melting profile of theend INTERESTERIFICATIONI nteresterification adjusts the melt-ing profile of a blend of saturatedand unsaturated fats.

6 In contrast tohydrogenation and (as shown later) Enzymatic interesterification, thereis no possibility of a partial reactionin chemical interesterification. Thisis because the chemical interesterifi-cation occurs very rapidly oncestarted, equilibrium is reached with-in minutes. The reaction will there-fore be completed and the proper-ties of the interesterified productcan only be controlled by the com-position of the fat the reaction time is short,washing, bleaching and deodoriza-tion are required after chemicalinteresterification. The most com-mon chemical catalysts are sodiummethylate (methoxide) or sodiumethylate (ethoxylate). The catalystshifts the fatty acids of the triglyc-erides around randomly. No transfatty acids are produced, but thecatalyst requires thorough purifica-tion downstream after the inter-esterification to give the requiredquality (Figure 3).The drawback of chemicalinteresterification is, that the cata-lysts are very reactive and must behandled with extreme care to pre-vent contact with the skin or contact with water, the catalystsmay explode.

7 The Process is carried out atharsh conditions, and the by-prod-ucts formed need to be removed bybleaching and washing. All three positions of the tryg-lycerides a re shifted randomly, w h i c hcreates a less natural fat comparedto the Enzymatic method. The pro-cess produces wastewater, and theoil loss is 5-10 kg t-1due to thepost-treatments needed. And, a sm e n t i o n e d ,the level of interesterifi-cation cannot be controlled. Thereaction goes all the way to com-plete randomization in a INTERESTERIFICATIONThe catalyst in Enzymatic interester-ification is a 1,3-specific 2. Batch 3. Batch of oilDrying oil,104oC 54mmHgBatch to93oCWash 5-10%waterRemovewater,drying,bleachingDe o-dorizationReactionCatalyst:NiCooling citricacid + a 1,3-specific lipase, only thefatty acids in the 1,3-positions areshifted around, while the 2-positionis left untouched. Preservation ofthe 2-position means that a morenatural fat is produced.

8 This is incontrast to chemical interesterifica-tion where all three positions arejuggled randomly Figure 4, an example ofenzymatic interesterification of twotriglycerides using a 1,3-specificlipase is shown. Once the lipase isadded to this mixture, the fattyacids on the outer positions (1- and3-positions) are exchanged, leavingthe fatty acid in the 2-positionuntouched. Interesterification ofthese two triglycerides result in amixture containing six triglycerideswhereas random chemical inter-esterification produces a mixture of40 triglycerides (not shown). It is important to understandthat even though different mixturesof triglycerides are obtained usingeither chemical or Enzymatic inter-esterification (using a 1,3-specificlipase), it is still possible to obtainthe desired modification of themelting curves for the interesteri-fied fat. Examples of the melting profilemodification, obtained with chemi-cal and Enzymatic interesterificationof a mixture of palm stearin andcoconut oil (60/40) is shown inFigure 5, which gives the solid similar melting profiles areobtained with the chemical andenzymatic interesterified products,and both reactions give the desiredlow melting points at 35 C-40 C.

9 A margarine produced from theseinteresterified mixtures will havegood mouth feel because of theimproved melting 0 5101520253035404550 StartingmaterialImmobilizedenzymeSodium methioxideFigure 5. Melting properties of a palm stearin/coconut oil 4. Interesterification using a 1,3-specific ( C) Enzymatic Interesterification: Process Advantages and Product BenefitsLipasePalm Oil Developments 3910 The Enzymatic Process is muchsimpler than the chemical and thereis no requirement for any post-treatment of the interesterified oilafterwards. Due to the harsh condi-tions required for the chemical cat-alyst, unwanted by-products areinevitable and post-treatment chemicals are used in theprocess and notrans fats areformed (Figure 6).The benefits of Enzymatic inter-esterification are low investmentcosts (less expensive equipmentneeded), simple and easy continu-ous Process , notransfatty acidsproduced, more natural fat pro-duced, production of a large vari-ety of end-products, environmen-tally friendly production, and nouse of OF PROCESSESAs shown in Figure 7, enzymaticinteresterification has truly becomecost-efficient to chemical interester-ification and is fairly easy to do a directcomparison between chemical andenzymatic interesterification.

10 Whencomparing partial hydrogenationwith interesterification, it needs tobe taken into consideration whetherthe hard fat fraction is an expen-sive fully hydrogenated fat or aninexpensive tropical fat. CONCLUSIONE nzymatic interesterification of fatsand oils provides a safe, easy andcost-efficient alternative to chemicalinteresterification and hydrogena-tion. The Process gives a more nat-ural product, free of trans Process can easily be imple-mented in existing factories fo con-tinuous operation. As no chemicalsare used and the operating condi-tions mild, the only post-treatmentneeded is deodorization. Figure 6. Continuous or batch processes can be 7. Comparing the operation and investment costs of the three ,121,79,152,84,5 Hydrogenation*Chemical interesterification*Enzymaticinteresteri fication*Operating costInvestment costsNote: *Data from M. Kellens (2000). Edible Oil Processing (Hamm and Hamilton eds.)