PHYSICOCHEMICAL PROPERTIES OF PALM STEARIN AND PALM MID FRACTION OBTAINED BY DRY FRACTIONATION

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1 PHYSICOCHEMICAL PROPERTIES OF PALM STEARIN AND PALM MID FRACTION OBTAINED BY DRY FRACTIONATION Bangun P Nusantr Department f Fd and Agricultural Prduct Technlgy, Faculty f Agricultural Technlgy, Gadjah Mada University, Jl. Flra, Ygyakarta bpnusantr@gadjahmada.edu ABSTRACT Palm stearin was btained frm the 1 st dry fractinatin at a yield f 27.6 % with IV: 37.6 and SMP: 51.8 C while palm mid fractin (PMF) was btained frm the 2 nd dry fractinatin at a yield f 24.1 % with IV: 45.8 and SMP: 42.7 C. Palm stearin cnsisted mainly f POP (31.06 %), PPP (20.61%) and POO (15.81 %) while palm mid fractin had disaturated TAG (such as POP: % and POSt: %) as the majr cnstituents. Frm melting prperties, palm stearin had a higher melting temperature (T M : 46.7 C) than that f PMF (T M : 38.5 C). It was als shwn that, in general, palm stearin had higher slid fat cntent at any temperature cmpared t PMF. Palm stearin will likely be suitable as hard stck fr shrtenings and PMF has ptency in margarine frmulatins. Keywrds: Palm stearin, PMF, dry fractinatin, DSC, SFC INTRODUCTION Palm il is being used increasingly in fds such as fr frying il, margarines, shrtenings r cnfectinery prducts. The versatility t different fd applicatins is the result f a unique chemical cmpsitin f palm il (Edem, 2002). Palm il differs frm many f the cmmn vegetable ils in its high level f palmitic acid reaching up t 44%. In cntrast, sybean il and canla il nly cntain 11 % and 5 % f palmitic acid, respectively. Then, it was revealed that additin f palm il t ther fats destined fr shrtening and margarine prductin has a beneficial effect n their textural quality due t the plymrphic stability (Ghsh and Bhattacharyya, 1997; Yap et al., 1989). Palm stearin is prduced cmmercially frm palm il by fractinal crystallizatin. One f the mst established techniques f fractinal crystallizatins is dry fractinatin. Dry fractinatin f palm il will result in tw fractins, namely palm lein and palm stearin. Palm stearin is the slid fractin btained frm dry fractinatin. As the hard fractin, palm stearin accumulates the high melting triacylglycerls f the initial palm il. The physical characteristics f palm stearin fund t be different frm thse f palm il and palm lein (Hendrix and Kellens, 2007). Gibn (2006) nticed that the liquid fractin btained frm dry fractinatin f palm il, palm lein, recently has becme a relatively cheap primary cmmdity because it is frmed in high prprtins in a single stage fractinatin. Fr this reasn, attentin has been fcused n multistage dry fractinatin t prduce lein with higher idine value. The secnd stage f dry fractinatin prduces super lein (as the liquid fractin) and palm mid fractin/pmf (as the slid fractin). Palm stearin and palm mid fractin are the high melting fractins btained frm dry fractinatin. Due t their high melting pint, they have limited uses in the manufacture f edible fd prducts. Hwever, since bth ils are cnsidered as by prducts and psses cheaper prices, palm stearin and palm mid fractin have a striking ptency t be used as a fat stck (Undurraga et al., 2001; Lai et al., 2000). A fundamental understanding f their chemical cmpsitin with respect t the physical states and the factrs which cntrl the physical state (such as thermal treatment and tempering) is f imprtance fr the cntrl f prduct quality and fr the pssible extensin f the range f prducts (Arima et al., 2007; Busfield and Prschg, 1990). As bth palm stearin and palm mid fractin are btained almst at the same level f dry fractinatin prcess (present as the slid fractins), then the purpse f this research is t reveal the differences n their physicchemical prperties. The resulted data culd serve as measures in cnsidering them fr apprpriate uses in a fd system and cntrls f prduct quality. 154

$Then, the palm il was subjected fr dry fractinatin t btain the stearin (POs) and the lein fractin. At the first stage, the palm il was crystallized using a cycle temperature prgram at 18 C fr 12 hurs.$

2 MATERIALS AND METHODS Materials RBD (Refined, Bleached and Dedrized)-palm il was btained frm lcal refinery. Then, the palm il was subjected fr dry fractinatin t btain the stearin (POs) and the lein fractin. At the first stage, the palm il was crystallized using a cycle temperature prgram at 18 C fr 12 hurs. The lein fractin was further fractinated t btain super lein and palm mid fractin (PMF). A cycle temperature prgram at 12 C fr 20 hurs was applied fr the crystallizatin prcess. All chemicals were either f analytical r high-perfrmance liquid chrmatgraph (HPLC) grades. Determinatin f Triacylglycerl (TAG) Distributin The distributin f the triacylglycerls was determined by HPLC, accrding t AOCS Official Methd Ce 5b 89, with a differential refractmeter as detectr. Minr practical adjustments t the flw rate and mbile phase cmpsitin were made in rder t imprve TAG separatin. All equipments (pump, clumn, aut sampler and detectr) were supplied by Waters. Analysis was dne in duplicate. Idine Value (IV) The IV f the palm il and fractinated prducts was determined using the AOCS fficially recmmended methd Cd 1b 87. (Karlsruhe, Germany) using a direct measurement methd. The equipment was calibrated with three supplied standards (0%, 29.8%, and 70.8%). Samples were melted at 70 C and then chilled at 0 C fr 90 min. Next, the samples were held at each measuring temperature fr 30 min prir t measurements. The average f triplicate analysis was reprted. RESULTS AND DISCUSSION Palm Stearin (PS) and Palm Mid Fractin (PMF) Obtained by Dry Fractinatin Palm stearin and palm mid fractin are btained by dry fractinatin and present as byprduct in which bth are the hard fractins (the slid phase after a filter press separatin). Palm stearin is the slid phase f RBD-palm il fractinatin while palm mid fractin is the slid phase f palm lein fractinatin. Even thugh bth palm stearin and palm mid fractin are the slid phases f the dry fractinatin prcess, it seems that they have different physicchemical prperties. The main reasn is RBD-palm il and palm lein which served as raw materials fr dry fractinatin have different levels f unsaturatin. Idine value (IV), slip melting pint (SMP) and the yield f il fractins frm a multistage dry fractinatin f RBD-palm il are depicted n Figure 1. Slip Melting Pint (SMP) SMP was determined accrding t AOCS (methd Cc. 3.25). Capillary tubes filled with fat (1 cm high) were chilled at 10+1 C fr 16 h befre being immersed in a beaker f cld distilled water. The water bath was stirred and heated. The temperature was recrded when the clumn f fat in the capillary tubes rse in the tube. Determinatin f Melting Behaviur by DSC DSC analyses were carried ut using a Q1000 DSC (TA Instruments, New Castle, USA) with a refrigerated cl ing system (TA Instruments) using aluminum SFI pans. Calibratin was made with indium and n-ddecane standards. Nitrgen was used as purge gas in rder t prevent cndensatin in the cells. An empty aluminum SFI pan was used as reference. The samples were quickly cled t -80 C at cling rate -5 C /min and kept fr 5 min in rder t ensure cmplete slidificatin. Melting prfiles were recrded frm 80 t 70 C at a heating rate f 5 C /min. Slid fat Cntent (SFC) SFC f leins was determined with a Bruker wide-line pulse nuclear magnetic resnance (pnmr) spectrmeter Figure 1. A multistage dry fractinatin f RBD-palm il Frm the 1 st dry fractinatin, stearin was btained at a yield f 27.6 % with IV: 37.6 and SMP: 51.8 C. Stearin had a lwer IV cmpared t RBD palm il with an initial IV: Accrding t Knthe (2002), idine value was used as a general measure f the unsaturatin f the il. IV shws the amunt f duble bnds present in the fatty acids. As the il is mre liquid (less saturated), it will impart a higher idine value. This then shwed that the stearin cmpsed mainly f the mre saturated fractin f triacylglycerls f RBD palm il. The examples f high saturated triacylglycerls ccurred 155

3 in the palm il are trisaturated TAG (such as MPP, PPP and PPSt) and disaturated TAG (such as POP, POSt and MOP). Palm mid fractin, at the ther hand, was the hard fractin btained frm the 2 nd stage f dry fractinatin. The idine value f palm mid fractin (IV: 45.8) was lwer than that f RBD palm il (IV: 51.7) and palm lein (IV: 58.2). It means the saturatin degree f triacylglycerls present in the PMF was higher than that in RBD palm il. Hwever, it was shwn that the saturatin degree f triacylglycerls present in the PMF was still lwer cmpared t palm stearin which had an IV: The crystallizatin temperature fr the 2 nd dry fractinatin was als fund significantly lwer than the 1 st dry frac tinatin. Since the idine value f palm lein (IV: 58.2) was higher than the idine value f RBD palm il (IV: 51.7), palm lein had high-melting triglycerides with lwer saturatin degree cmpared t thse f RBD palm il. The lwer saturatin degree f triacylglycerls will impart the lwer melting and crystallizatin temperature f thse triacylglycerls. As the result, palm lein required a lwer crystallizatin temperature t btain sufficient amunt f the slid fractin during the 2 nd dry fractinatin. Triacylglycerls (TAG) Distributin f Palm Stearin and Palm Mid Fractin Accrding t Neff et al. (2001), triacylglycerl cmpsitin (i.e., kinds and quantities f individual TAG) and triacylglycerl structure (i.e., kinds and quantities f individual fatty acids (FA) lcated at the glycerl miety carbns) affect the fd frmulatin prduct functinal prperties, such as: melting pint range, slid fat index, and crystal structure. These physical prperties then affect fd prperties frm texture t taste. Als, the fat xidative stability is, partially, dependent n the TAG distributin and structure. The TAG cntent f the palm stearin and palm mid fractin was given in Table 1. As shwn at Table 1, palm stearin cnsisted mainly f POP (31.06 %), PPP (20.61 %) and POO (15.81 %) while palm mid fractin had POP (61.05 %) as the main cnstituent. These results were in accrdance with the investigatin dne by Arima (2007). Althugh bth palm stearin and palm mid fractin were hard fractins f dry fractinatin, their TAG distributin were likely different. Palm stearin had trisaturated TAG (such as PPP and PPSt) and mnunsaturated TAG (such as POP and POSt) as the main cnstituents. Meanwhile, palm mid fractin was cmpsed mainly f mnunsaturated TAG (such as POP, and POSt). During the 1 st dry fractinatin, the high-melting glycerides f RBD-palm il accumulated in the stearin fractin (as palm stearin). Palm stearin almst acquired all trisaturated TAG which is present in the RBD palm il. It was shwn that Table 1. Triacylglycerls distributin f Palm Stearin and Palm Mid Fractin TAG distributin (%) TAG-species * Palm Stearin Palm Mid Fractin LLO PLL OOL POL PLP OOO POO POP PPP StOO POSt PPSt StOSt PStSt tr ** tr * Where: P (Palmitic), St (Stearic), O (leic) and L (Linleic). ** tr: trace. trisaturated TAG increased cnsiderably in palm stearin while POP as the majr TAG in RBD palm il decreased. Trisaturated TAG in palm stearin increased up t % and 5.65 % fr PPP and PPSt, respectively. On the 2 nd dry fractinatin, palm lein was used as the raw material. As the high-melting glycerides f RBD-palm il accumulated in palm stearin, palm lein cntained nly small amunt f trisaturated TAG. The high-melting glycerides f palm lein then shifted t the mnunsaturated glycerides, especially POP whse melting temperature was just next t the trisaturated TAG. During the 2 nd dry fractinatin, mnunsaturated TAG as the high-melting glycerides f palm lein accumulated in the slid fractin (as PMF). Palm mid fractin then was cmpsed mainly f mnunsaturated TAG (POP: % and POSt: %) in additin t a small amunt f leftver trisaturated TAG (PPP: 2.85 % and PPSt: 3.13 %). Melting Behavir f Palm Stearin and Palm Mid Fractin Frm the melting thermgram btained by DSC measurements, three parameters can be extracted namely melting temperature (T M ), ffset temperature (T O ) and melting heat (ΔH M ). The melting temperature demnstrated the temperature at which the melting curve reaches their maximum, r s, the temperature at which the phase transitin ccurred the fastest. The ffset temperature was determined by the intersectin f the baseline at higher temperature with the abslute highest tangent f the curve. Meanwhile, the area 156

4 f the peak accunted fr the ttal released melting heat. The nn-isthermal DSC melting prfiles were given in Table 2. Table 2. Melting behavir f palm stearin and palm mid fractin as measured by DSC Sample Nn-isthermal DSC melting prfiles * T M ( C) T O ( C) ΔH M (J/g) Palm Mid Fractin ** Palm Stearin * T M, T O and ΔH M were melting temperature, ffset temperature and melting heat, respectively. ** Mean + SD were reprted. Accrding t Tan and Che Man (2002), accurate cmparisns f the calrimetric experiments in the edible ils can nly be dne when DSC experiments were carried ut at the same scanning rate. The use f slw scan rates was advisable in that it minimized instrumental lag in utput respnse and, at a given temperature, the reactin being examined was clser t chemical equilibrium. In this research, the scanning rate f 5 C was applied. Hwever, several difficulties might be encuntered in melting heat determinatin. Tw f special significances were: (1) the baseline fr the melting curve might nt be hrizntal, and (2) the peak was nt generally symmetrical. The baseline f DSC curves was ften different befre and after a peak, due t changes in the physical prperties f the sample during the reactin which prduced the peak, and thus it was difficult t determine the baseline t be used fr melting heat determinatin. Therefre, interpretatin f melting heat must be dne with cautin. As shwn in Table 2, PMF had a lwer melting temperature (T M : 38.5 C) than that f palm stearin (T M : 46.7 C). The lwer melting temperature f PMF was caused by the higher unsaturatin degree f TAG which was indicated by the higher value f IV cmpared t palm stearin. The higher unsaturatin degree f TAG, the lwer melting temperature will be. PMF will cmpletely slidify at 40.7 C while palm stearin will cmpletely melt at 49.8 C. Accrding t Nr Aini and Miskandar (2007), shrtenings were referred t naturally ccurring fats that were slid at rm temperature and used t shrten mainly baked prducts. Palm stearin will likely be suited as a base stck fr shrtenings. Palm stearin had the higher melting temperature and was cmpsed mainly f trisaturated and mnunsaturated triacylglycerls. Tripalmitin (PPP) is β crystal tending and can prvide strength and structure t the prducts. In the Middle East, Suth, and Sutheast Asian cuntries (particularly India), a shrtening-like prduct called vanaspati was made by the hydrgenatin f blended ils. In the Indian cntext, vanaspati was widely used as an inexpensive substitute fr ghee (dehydrated butter il), which has a grainy structure that was similar t vanaspati. Of the plymrphic frms, β crystals were the mst desirable because f their bigger sizes, higher density and greater stability (Mayaml et al., 2004). PMF was sfter than palm stearin. PMF will be mre apprpriate t be used as the raw material fr margarine. Margarine is a water-in-il emulsin in which water drplets are kept separately by the fat crystals. Due t its sftness, PMF can prvide and enhance the plasticity f the prduct at lw temperature ranges. The quality f margarines is t sme extent dependent n the frmulatin and prcessing. The melting pint f the il frmulatin can be adjusted by incrprating mre liquid il int the blend (Lai et al., 2000). Table 2 indicated that the melting heat f palm stearin (ΔH M : J/g) was higher than that f palm mid fractin (ΔH M : J/g). Accrding t Tan and Che Man (2002), the il sample with a higher degree f saturatin requires mre energy during the melting prcess. When the il becmes mre saturated, it will need higher energy fr prcessing. In the industrial fractinatin f vegetable ils, it is an imprtant prcedure t cntrl the heat by varying the rate f heat remval and agitatin. Slid Fat Cntent f Palm Stearin and Palm Mid Fractin The percentage slid fat cntent (% SFC) f palm stearin and palm mid fractin was measured as a functin f temperature. In general, palm stearin had higher SFC at any temperature. As palm stearin was mre saturated than palm mid fractin, palm stearin cntained mre high-melting glycerides. High melting glycerides melted later and imparted higher SFC at a given temperature. Palm stearin and palm mid fractin were almst cmpletely melted at the temperature 35 C and 60 C. SFC (%) Palm Stearin Palm Mid Fractin Figure 2. Slid fat cntent (%) f palm stearin and palm mid fractin As shwn at Figure 2, the SFC f palm stearin was gradually decreased frm 86 % at 0 C t almst cmpletely 157

5 liquid at 60 C. The trend f decreasing SFC n palm stearin might be affected by its wide-ranging TAG cntent which was mainly POP, PPP and POO. Nevertheless, the trend f decreasing SFC n palm mid fractin was fund t be different. The SFC f palm mid fractin was slightly decreased frm 0 C t 20 C and then suddenly drpped at 30 C. It was recgnized that the TAG cntent f palm mid fractin which had nly diunsaturated (POP and POSt) as the majrity culd give such effects. Accrding t Jirasubkunakrn et al. (2007), the crystallizatin behavir, crystal prperties and melting prfile f vegetable ils were imprtant fr their applicatin in fd prducts. Shrtenings were required t display a plastic behavir acrss a range f temperatures. The slid fat cntent f the fat blend was a majr factr that determined the texture f the fat. Hwever, the fat crystal plymrph and the micrstructure f the netwrk f crystalline particles als determined the mechanical prperties f the fat. As palm stearin had brader SFC, it wuld be mre suitable fr shrtenings. The physical prperties f margarine were als dictated by the SFC, particularly f the high melting glycerides, because these TAG were thught t set the trend in the plymrphic crystal behavir (Lai et al., 2000). The sfter palm mid fractin culd be utilized in the margarine frmulatin t give the best pssible cnsistency requirements fr cmpsitin, packing and handling. CONCLUSION Palm stearin and palm mid fractin had different physicchemical prperties althugh bth f them were the slid phases btained frm dry fractinatin prcess. Palm stearin cnsisted mainly f POP (31.06 %), PPP (20.61 %) and POO (15.81 %) while palm mid fractin had POP (61.05 %) as the main cnstituent. Frm melting prperties, palm stearin had a higher melting temperature (T M : 46.7 C) than that f PMF (T M : 38.5 C). It was als shwn that, in general, palm stearin had higher slid fat cntent at any temperature cmpared t PMF. REFERENCES Ali, A., Selamat, J., Che Man, Y.B. and Suria, A.M. (2001). Effect f strage temperature n texture, plymrphic structure, blm frmatin and sensry attributes f filled dark chclate. Fd Chemistry 72: AOCS (1990). Official and tentative methds f American Oil Chemist s Sciety (15 th ed.). Champaign: American Oil Chemist s Sciety Press. Arima, S., Ueji, T., Uen, S., Ogawa, A. and Sat, K. (2007). Retardatin f crystallizatin-induced destabilizatin f PMF-in-water emulsin with emulsifier additives. Cllids and Surfaces 55: Busfield, W.K. and Prschg, P.N. (1990). Thermal analysis f palm stearine by DSC. JAOCS 67: Edem, D.O. (2002). Palm il: Bichemical, physilgical, nutritinal, hematlgical, and txiclgical aspects: A review. Plant Fds fr Human Nutritin 57: Ghsh, S. and Bhattacharyya, D.K. (1997). Utilizatin f high-melting palm stearin in lipase-catalyzed interesterificatin with liquid ils. JAOCS 74: Gibn, V. (2006). Fractinatin f lipids fr use in fd. In: Gunstne, F.D. (ed.) Mdifying lipids fr use in fd, p Wdhead Publishing Limited, Cam bridge. Hendrix, M. and Kellens, M. (2007). Fractinatin prcesses and devices fr ils and fats. Wrld Intellectual Prperty Organizatin, n. WO 2007/ A1, issued n Jirasubkunakrn, W., Bell, A.E., Grdn, M.H. and Smith, K.W. (2007). Effects f variatin in the palm stearin : palm lein rati n the crystallisatin f a lw-trans shrtening. Fd Chemistry 103: Knthe, G. (2002). Structure indices in FA chemistry. Hw relevant is the idine value? JAOCS 79: Lai, O.M., Ghazali, H.M. and Chng, C.L. (1998). Physical prperties f Pseudmnas and Rhizmucr miehei lipase-catalyzed transesterified blends f palm stearin: palm kernel lein. JAOCS 75: Lai, O.M., Ghazali, H.M., Ch, F. and Chng, C.L. (2000). Enzymatic transesterificatin f palm stearin:anhydrus milk fat mixture using 1,3-specific and nn-specific lipases. Fd Chemistry 70: Mayaml, P.N., Samuel, T., Balachandran, C., Sundaresan, A. and Arumughan, C. (2004). Zer-trans shrtening using palm stearin and rice bran il. JAOCS 81: Nr Aini, I. and Miskandar, M.S. (2007). Utilizatin f palm il and palm prducts in shrtenings and margarines. Eurpean Jurnal f Lipid Science and Technlgy 109: Tan, C.P. and Che Man, Y.B. (2002). Differential scanning calrimetric analysis f palm il, palm il based prducts and ccnut il: effects f scanning rate variatin. Fd Chemistry 76: Undurraga, D., Markvits, A. and Eraz, S. (2001). Cca butter equivalent thrugh enzymatic interesterificatin f palm il midfractin. Prcess Bichemistry 36: Yap, P.H., deman, J.M. and deman, L. (1989). Plymrphism f palm il and palm il prducts. JAOCS 66:

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