Production of Zero-Trans Margarines from Blends of Virgin Coconut Oil

Food Sci. Technol. Res., 19 (3), 425–437, 2013

Production of Zero-trans Margarines from Blends of Virgin Coconut Oil,

Palm Stearin and Palm Oil

* Sopark Sonwai and Vipavee Luangsasipong

Department of Food Technology, Faculty of Engineering and Industrial Technology, Silpakorn University, Nakhonpathom, 73000, Thailand

Received October 30, 2012; Accepted January 24, 2013

This research investigated the possibility of producing zero-trans packet margarines from virgin coconut oil (VCO). VCO was mixed with palm stearin (PS) and/or palm oil (PO) in six weight proportions in order to prepare feedstocks for the production of experimental margarines. The fat blends included two binary blends of PS/VCO (40:60 and 30:70) and four ternary blends of PS/VCO/PO (30:40:30, 20:40:40, 30:50:20 and 20:50:30). The six fat blends and the experimental margarines produced from the blends were characterized and compared with commercial trans- (CTM) and zero-trans (CZTM) margarines in terms of microstructure, polymorphism, solid fat content, melting and crystallization behavior, textural and sensory properties. It was found that the binary fat blend which contained 30% PS and 70% VCO was the most suitable blend to be used as feedstock for the production of zero-trans packet margarine. The blend exhibited a tendency to crystallize into β’ structure with a good cooling effect and a low SFC value at body temperature, indicating that it would not cause waxy mouthfeel when consumed. In addition, the margarine produced from the blend demonstrated good consistency with a hardness characteristic close to that of a commercial trans-packet margarine and also received the highest score for overall acceptability.

Keywords: margarine, virgin coconut oil, palm stearin, palm oil, zero-trans

Introduction stability of margarine is influenced by the actual amount of Margarine is a water-in-oil emulsion food product and solid fat present and by the characteristics of the crystal lat- by U.S. FDA standards of identity must contain at least 80% tice (Chrysan, 1996). The β’ form is the most desirable in fat (Fomuso and Akoh, 2011). Margarine was originally de- margarines because it gives smooth texture to the products veloped in 1869 as an alternative to butter which, during that (D’Souza et al., 1990). period, was in short supply and expensive (Chrysan, 1996). The product range of margarine consists of table mar- The aqueous phase of margarine is composed of water, salt, garines, bakery margarines, and specialized puff pastry and preservatives. The fat phase consists of a blend of liquid margarines. Table margarines can be divided into two main and solid triglycerides, antioxidants and emulsifiers (Fomuso types: packet margarines, which are designed to be spread- and Akoh, 2011). Lecithin, distilled monoglyceride, and able at ambient temperature, and tub margarines, which are distilled diglyceride are common emulsifiers added to the spreadable on removal from the refrigerator at a temperature fat phase together with flavoring agents and coloring agents of 5 − 10℃ (Laia et al., 2000). Packet margarines usually (Miskandar et al., 2002). Characteristics which determine exhibit much higher solid fat content (SFC) than those of tub margarine quality, such as spreadability and consistency, are margarines in the SFC curves. When packet margarines are important. These characteristics are influenced by many pro- intended for use in a tropical climate, with ambient tempera- cess conditions, such as crystallization temperature, emulsion tures around 30℃, higher solid contents are required (Rasid temperature, agitation rate, cooling rate, etc. The structural et al., 1996). Most margarine fats are prepared from partial hydroge- *To whom correspondence should be addressed. nation where trans fatty acid (TFA) formation is inevitable E-mail: [email protected]; [email protected] (Adhikari et al., 2010a). The partial hydrogenation process 426 S. Sonwai & V. Luangsasipong is used to impart desirable physical and textural properties physical and textural properties close to those of commercial to margarines (Kim et al., 2008). Recently, it has become packet margarines. known that potential adverse health effects, such as increased risk for coronary heart disease, have been associated with the Materials and Methods consumption of semi-solid fats containing trans fatty acids Materials VCO 100% cold press with an iodine value from partially hydrogenated oils (Enig, 1996). Therefore, (IV) of 9.4 g I2/100 g was purchased from a local supermar- semi-solid fat with low or no trans fatty acids needs to be ket (Bangkok, Thailand). Refined, bleached and deodorized developed in the food industry (Adhikari et al., 2010b). PO (IV of 47.1 g I2/100 g) was kindly supplied by a local

Coconut oil is edible oil obtained from matured coco- palm oil refiner. PS (IV of 38.5 g I2/100 g) was provided nuts. Commercial coconut oil is produced from the dried by Moragot Industries PCL (Bangkok, Thailand). Distilled kernel meat of coconut or copra, which is exposed to very monoglyceride, supplied by Berli Jucker (Bangkok, Thai- high temperatures until most of the moisture is removed, and land), was used as an emulsifier. Two commercial marga- goes through refining, bleaching and deodorizing processes rines, a trans-packet margarine and an imported zero-trans (Marina et al., 2009). On the contrary, virgin coconut oil margarine, were purchased from a supermarket in Bangkok, (VCO) is obtained from fresh, mature kernel of the coconut Thailand. All other reagents and solvents were of analytical by mechanical or natural means, with or without the use of or chromatographic grade. heat and without undergoing chemical refining, bleaching, or Trans-fatty acid analysis The contents of trans-fatty deodorizing in order to protect the oil’s essential properties acids in three pure fat samples (PS, VCO and PO) were (Villarino et al., 2007). Coconut oil is thought to be benefi- analyzed by using AOAC Official method 985.21 (AOAC, cial to health because it contains high amount of medium- 1995). chain triglycerides, which are made mainly of saturated fatty Fat blending Six fat blends of PS, VCO and PO were acids with chain length from 6 to 12 carbon atoms (Che prepared. The proportions of the blends are given in Table Man and Marina, 2006). Medium-chain triglycerides are 1. Two of the fat blends are binary, containing only PS and hydrolyzed faster and more completely than long-chain tri- VCO whereas the rest are ternary, containing PS, VCO and glycerides (Adhikari et al., 2010b). In addition, it has been PO. Different properties of the fat blends were character- reported that medium-chain triglycerides may reduce the ized as described below. The amount of trans-fatty acids in incorporation and storage of dietary fats and oil in adipose all fat blends was calculated based on the proportion of the tissue (Tsuiji et al., 2001). In 2004, Nevin and Rajamohan pure fats in each blend. Then, the fat blends were used as fat reported that VCO obtained by wet process had a beneficial feedstocks for the production of experimental margarines. effect in lowering lipid components by reducing total cho- Preparation of commercial margarine fats Two mar- lesterol, triglycerides, phospholipids, low-density lipoprotein garine fats were separated from the two commercial marga- cholesterol levels and increasing high-density lipoprotein rines: trans- and zero-trans, following a method described cholesterol in serum and tissues. The polyphenol fraction by Kim et al. (2008). Briefly, the margarines were melted at of VCO was also found to be capable of preventing in vitro 80℃, and the top fat layers were decanted into a separatory LDL oxidation with reduced carbonyl formation. funnel and washed five times with warm water. To remove In this study, zero-trans packet margarines were produced residual moisture, the fats were filtered through an anhydrous from blends of VCO, palm stearin (PS) and palm oil (PO). sodium sulfate layer with a Whatman filter paper (pore size The three oils were blended into different weight proportions = 0.45 μm) under vacuum. The anhydrous margarine fats and their chemical and physical properties as well as crystal- obtained from commercial trans- and zero-trans margarines lization behavior were studied. Then, the fat blends were used as feedstocks for the production of zero-trans experi- Table 1. Composition of PS:VCO:PO blends. mental margarines. Property changes of the experimental Blend Composition (wt%) margarines during storage for eight weeks at three different PSC46 PS/VCO/POa = 40:60:0 temperatures were characterized and compared with those PSC37 PS/VCO/PO = 30:70:0 of commercial margarines in order to select the best formu- PSCP352 PS/VCO/PO = 30:50:20 lation for the margarine produced from VCO. In order to PSCP343 PS/VCO/PO = 30:40:30 PSCP253 PS/VCO/PO = 20:50:30 maximize the use of VCO, which is widely available in Thai- PSCP244 PS/VCO/PO = 20:40:40 land and other Asian countries, this desired margarine should a consist of a maximum weight proportion of VCO, and should Abbreviations: PS, palm stearin; VCO, virgin coconut oil; PO, palm oil. be stable (i.e. can withstand a tropical climate) and exhibit Production of Zero-trans Margarines from Virgin Coconut Oil 427 were named TMF and ZTMF, respectively. highest temperature of each fat sample. TCO and TMC were Fatty acid composition analysis The fat blends and the considered to be the temperatures at which the crystallization commercial margarine fats were converted into fatty acid began and the melting ended, respectively (Kim et al., 2008). methyl esters using AOAC official method 969.33 (AOAC, Polymorphic structure analysis The crystal polymor- 1995). The fatty acid methyl esters analysis was performed phic forms of both the experimental fat blends and the com- in a Shimadzu GC with flame ionization detector (GC-FID). mercial margarine fats were determined by an x-ray diffrac- The system had an ATTM-WAX capillary column (50 m long, tometer (Rigaku TTRAX III, Rigaku Corporation, Tokyo, 0.25 mm internal diameter and 0.20 µm film thickness). Japan). Scans were performed in wide-angle x-ray scattering Compound identification was carried out using external (WAXS) from 15°2θ to 25°2θ with a scan speed and a step standards of fatty acids methyl esters. Helium was used as width of 2.7°2θ/min and 0.02°2θ, respectively. The samples a carrier gas with a flow rate of 0.5 mL/min and with a con- were melted at 80℃ for 30 min and then pored into rectan- trolled initial pressure of 93.2 kPa at 120℃. N2 and air were gular plastic moulds (20 mm × 25 mm × 3 mm). Samples makeup gases. The injection temperature was 210℃, and were later left to crystallize at 4℃for 24 h, after which they the oven temperature program was holding at 120℃ for 3 were analyzed (Kim et al., 2008). Generally, short spacings min before increasing at a rate of 10℃/min to 220℃, hold- for the β’ form of fats are identified with two strong spacings ing at this temperature for 30 min, increasing at a rate of 5℃/ at 3.88 and 4.20 Å or three strong spacings at 3.71, 3.97 and min to 240℃, followed by holding at 240℃ for 30 min. The 4.27 Å (D’Souza et al., 1990). In addition, a strong short split ratio was 100:1, the injection volume was 1 µL, and the spacing at 4.36 Å has also been reported for the β’ poly- detector temperature was 280℃. All margarine fats were morph of palm oil and palm stearin (Yap et al., 1989). In analyzed after which their chromatograms were acquired. contrast, β polymorph always displays a strong d-spacing at All fatty acid contents were given based on percentage area. 4.6 Å (D’Souza et al., 1990). In this work, the content of β’ Characterization of solid fat content SFC of the sam- and β structures in the samples was estimated by the relative ples was measured by pulsed-nuclear magnetic resonance (p- intensity of the short spacings of β’ form at 4.36 Å and that NMR) spectrometer (Minispec-mq20, BRUKER, Karlsruhe, of β form at 4.6 Å following a method described by Kim et Germany). Changes in the SFC as a function of temperature al. (2008). between 15℃ and 50℃ and melting behavior of the fat Crystal morphological study The crystal morphology blends and the commercial margarine fats were studied using of the experimental fat blends and the commercial margarine a method for measuring SFC of fat for margarines developed fats crystallized under static conditions at three different tem- by the “Joint Committee for the Analysis of Fats, Oils, Fatty peratures was observed using a polarized light microscope Products, Related Products and Raw Materials (GA FETT)” (Olympus BX51, Olympus Optical Co., Ltd., Tokyo, Japan) as described by Fiebig and Luttke (2003). equipped with a digital camera (Olympus C-7070, Olympus Analysis of crystallization and melting profiles The Optical Co., Ltd., Tokyo, Japan). All fat samples were melt- crystallization and melting profiles of the fat blends and the ed at 80℃ for 15 min to totally eliminate the memory effect. commercial margarine fats were determined with a Perkin- 20 µL of each molten sample was placed on a pre-heated Elmer differential scanning calorimeter (DSC) (model DSC glass slide and covered by a cover slip. Then, the prepared 8000, PerkinElmer Co., Norwalk, CT) following procedure slides of each samples were divided into three groups and Cj 1-94 recommended by AOCS (AOCS, 1998). The heat stored for 24 h at 4℃ (a refrigeration temperature), 25℃ and flow of the instrument was calibrated with indium (mp 32℃ (a room temperature), respectively, using temperature- 156.6℃) as a reference standard. A fat sample of 6 − 8 mg controlled cabinets. A 10× lens was employed to image the was placed in an aluminum pan (30 µL capacity) and her- gray scale photographs of the fat crystals. metically sealed. An empty pan served as reference. The Margarine processing Six experimental marga- samples were heated from room temperature to 80℃ and rines were produced using the six fat blends of PS/VCO/ held for 10 min to ensure homogeneity and to destroy any PO as feedstocks (Table 1). The margarines were named crystal memory. Then, the samples were cooled to −60℃ PSC46M, PSC37M, PSCP352M, PSCP343M, PSCP253M at the rate of 5℃/min and held at this temperature for 30 and PSCP244M for margarines that were made from the min. This was followed by heating the sample at the rate of fat blends PSC46, PSC37, PSCP352, PSCP343, PSCP253 5℃/min to 80℃. The crystallization and melting profiles and PSCP244, respectively. The margarine formulation (w/ were generated during the cooling and heating, respectively. w) used in this study is as followed: lipid phase, 83% (fat

The crystallization onset (TCO) and melting completion tem- blends, 82.5%; distilled monoglyceride, 0.5%) and aqueous peratures (TMC) were obtained from the peaks located at the phase, 17% (distilled water, 16%; salt, 1%). The addition 428 S. Sonwai & V. Luangsasipong of 0.5 wt% of distilled monoacylglycerol as emulsifier gives for dislike extremely) by thirty panelists chosen from post- good stability for a water-in-oil emulsion system, due to its graduate students and staff of the Department of Food Tech- low HLB and low acid value (Saadi et al., 2011). The fat nology, Silpakorn University. The testing quantity of each blend was melted in a double-jacket stainless steel vessel at sample was approximately 5 mL. The freshly-made marga- 60℃ for 10 min and the emulsifier was mixed in to form an rine samples, which were contained inside plastic cups (40 oil phase. The temperature of the sample inside the vessel mm in diameter and 15 mm in height), were stored at 25℃ was controlled by the temperature of the water that located for 4 weeks before the sensory test was performed at room between the jacket. The temperature of the oil phase was temperature. reduced to 45℃ and the water phase containing salt at room Statistical analysis The obtained data was analyzed temperature (~32℃) was then added slowly to the oil phase by Analysis of Variance with Least Significant Difference with an agitation rate of 1000 rpm for 10 min to form a good (ANOVA/LSD) at 95% confidence interval. emulsion. The emulsion was then poured into a double in- sulated bowl of an ice cream maker equipped with a liquid Results and Discussion coolant located between the walls where it was mixed and Fatty acid composition analysis Table 2 shows fatty crystallized at a temperature range of 10 − 12℃. For com- acid contents of the fat blends and the commercial margarine parison, two newly purchased commercial margarines (a fats. The chain lengths of fatty acids present in coconut oil, trans-packet margarine (CTM) and a zero-trans margarine PS and PO range from C12 − C22 (Kim et al., 2008, Winay- (CZTM)) were also melted down and recrystallized using anuwattikuna et al., 2008). Coconut oil is high in Lauric the same procedure. Then, the partially crystallized emul- acid (C12) while PS and PO contain high amount of palmitic sion was put inside plastic cups (40 mm in diameter and 15 acid (C16). As a result, all fat blends were high in palmitic mm in height) and was later allowed to age in a temperature- acid (22.6 − 35.3%) and lauric acid (17.8 − 33.7%). As the controlled cabinet set at 25℃ for 2 h. After the aging period, amount of VCO in the fat blends increased, the content of each of the six experimental margarines as well as each of lauric acid increased accordingly with a decrease in palmitic the commercial margarines was divided into three groups acid content. The amount of stearic acid (C18) was higher and stored at the three different test temperatures (at 4℃, in the ternary blends (20.3 − 23.6%) compared to the binary 25℃ and 32℃) for 8 weeks and characterized as followed. blends (12.6 − 15.0%). This was because there was higher Changes in the SFC of the margarines during storage amount of PS and PO together in the former than in the lat- The SFC of the margarine samples was followed during ter. The table also shows that the content of saturated fatty storage using the p-NMR. Before being stored for 8 weeks acids was much higher than that of unsaturated fatty acids in at the three different temperatures mentioned above, the all fat blends. freshly-prepared experimental margarines and commercial The commercial trans-margarine fat was composed margarines were carefully placed inside p-NMR tubes using mainly of palmitic, oleic (C18:1) and lauric acids, whereas the a spatula and a stainless steel plunger. The SFC measure- fatty acid content of the commercial trans-free margarine fat ments were performed once every week. Data were reported was dominated by oleic acid, which amounted to more than as averages of three measurements. 57%. Texture profile analysis (TPA) Changes in textural prop- Trans-fatty acid analysis Table 3 shows content of TFA erties (hardness, adhesiveness and cohesiveness) of all mar- (g/100 g lipid basis) in the pure fats and the fat blends. For garine samples were followed during storage for 8 weeks at the pure fats, PS contained the highest content of total TFA 4, 25 and 32℃ adopting the procedure of TPA described by (0.15 g/100 g lipid basis) followed by PO. The major TFA in

Bourne (1978). A double compression test was performed PS and PO were C20:1 and C18:1n-11, respectively. In contrast, using a TA-XT2i Texture Analyzer (Stable Micro Systems, VCO contained only a trace amount of TFA (< 0.001 g/100 g). London, England). The temperature inside the room where Total contents of TFA in all fat blends lie in between 0.045 the test was performed was maintained at 25℃. A 45° coni- − 0.072 g/100g lipid basis. Generally, the amount of trans- cal probe attached to a 5 kg compression load cell was pen- fat present in zero-trans margarines is limited to less than etrated into the sample at 1.0 mm/s to a depth of 10 mm from 0.5 g TFA/serving (Anon, 2003). A serving size is set by the surface and then returned to the initial position at the the FDA at 14 g for margarines. An experimental margarine same speed. containing 82.5% fat that is made using the blend PSCP343, Sensory analysis Overall acceptability of all marga- which exhibited the highest content of TFA, as a fat feed- rine samples were evaluated and compared using a 5-point stock would contain only 0.0083 g TFA/serving. Conse- hedonic scale (5 for like extremely, 3 for moderate and 1 quently, all experimental margarines produced later in this Production of Zero-trans Margarines from Virgin Coconut Oil 429

Table 2. Fatty acid compositions of fat blends (PSC46, PSC37, PSCP352, PSCP343, PSCP253 and PSCP244), commercial trans-margarine fat (CTMF) and commercial zero-trans margarine fat (CZTMF).

Fatty Acid Content (area %) Fatty acid CTMF CZTMF PSC46 PSC37 PSCP352 PSCP343 PSCP253 PSCP244

e f b a c d c d Lauric (C12) 10.2 ± 0.23 4.7 ± 0.14 29.1 ± 0.31 33.7 ± 0.51 22.9 ± 0.82 19.0 ± 0.73 24.4 ± 1.41 17.8 ± 0.46 f g b a c d c e Myristic (C14) 4.7 ± 0.08 1.7 ± 0.02 12.2 ± 0.03 12.8 ± 0.15 9.5 ± 0.06 8.3 ± 0.03 9.5 ± 0.15 7.7± 0.02 c f d e c a d b Palmitic (C16) 31.9 ± 0.01 12.0 ± 0.06 30.0 ± 0.32 22.6 ± 0.12 31.5 ± 0.39 35.3 ± 0.31 29.3 ± 0.74 33.7 ± 0.10 f g d e c a b a Stearic (C18) 7.7 ± 0.17 6.6 ± 0.03 15.0 ± 0.16 12.6 ± 0.03 20.3 ± 0.04 23.6 ± 0.47 22.2 ± 1.28 23.6 ± 0.36 b a e e d c cd c Oleic (C18:1) 27.5 ± 0.47 57.3 ± 0.25 2.6 ± 0.02 2.7 ± 0.01 4.0 ± 0.01 4.7 ± 0.14 4.5 ± 0.21 4.9 ± 0.14 ab b ab ab a ab ab ab Linoleic (C18:2) 0.01 ± 0.005 0.01 ± 0.001 0.03 ± 0.004 0.03 ± 0.002 0.05 ± 0.003 0.03 ± 0.027 0.04 ± 0.003 0.04 ± 0.033 b a d cd bc cd bcd Linolenic (C18:3) 0.09 ± 0.008 2.2 ± 0.03 0.04 ± 0.005 − 0.06 ± 0.001 0.07 ± 0.002 0.06 ± 0.003 0.07 ± 0.006 b a d f c b ef e Arachidic (C20) 0.21 ± 0.014 0.38 ± 0.014 0.16 ± 0.003 0.04 ± 0.005 0.19 ± 0.002 0.23 ± 0.010 0.05 ± 0.002 0.07 ± 0.002

Behenic (C22) 0.01 ± 0.005 − − − − − − − Others 17.7 ± 0.35a 15.1 ± 0.22b 11.0 ± 0.21cd 15.5 ± 0.26b 11.4 ± 0.42cd 8.8 ± 0.15e 10.0 ± 1.89de 12.2 ± 0.13c

For compositions and abbreviations of the fat blends see Table 1. All data are mean values ± standard deviations of duplicate measurements. a − g Values with the same letter in each row are not significantly different P( > 0.05).

Table 3. Trans-fatty acid compositions of pure fats and fat blends (PSC46, PSC37, PSCP352, PSCP343, PSCP253 and PSCP244) (g/100 g lipid basis).

Pure Fats Fat Blends Trans-fatty acid PSa PO VCO PSC46 PSC37 PSCP343 PSCP244 PSCP352 PSCP253

C16:1 tr tr tr tr tr tr tr tr tr

C18:1n-6 0.01 0.01 tr 0.004 0.003 0.006 0.006 0.005 0.005

C18:1n-9 0.01 0.01 tr 0.004 0.003 0.006 0.006 0.005 0.005

C18:1n-11 0.02 0.04 tr 0.008 0.006 0.018 0.020 0.014 0.016

C18:2 0.01 tr tr 0.004 0.003 0.003 0.002 0.003 0.002

C20:1 0.11 0.03 tr 0.044 0.033 0.042 0.034 0.039 0.031

C22:1 tr tr tr tr tr tr tr tr tr Total 0.16 0.09 tr 0.064 0.048 0.075 0.068 0.066 0.059

For compositions and abbreviations of the fat blends see Table 1. tr means the content of trans-fatty acid is less than 0.001 g/100 g lipid basis.

work using the six fat blends could be categorized as zero- 80 trans margarines. CTMF CZTMF 70 Characterization of solid fat content SFC is one of PSC46 the physical parameters related to the quality of margarine PSC37 60 including general appearance, oil exudation, organoleptic PSCP352 properties and spreadability (Chu et al., 2002). The plot 50 PSCP343 PSCP253 (%) showing the relationship between SFC and temperature of PSCP244

C 40 F the fat blends and the margarine fats is given in Figure 1. S At 15℃ and below, the SFC of all fat blends were higher 30 than 40% whereas the SFC of the margarine fats were 35% 20 and lower. The fat from the zero-trans margarine, CZTMF, exhibited the lowest SFC at all temperatures. At 20℃, the 10 SFC of all samples, except CZTMF, were above 10%, an 0 essential indicator that oiling off due to oil exudation would 10 20 30 40 50 Temperature (oC) not occur with those fats (Laia et al., 2000). As the temperature increased from 20 to 25℃, the SFC of CTMF and Fig. 1. Solid fat contents (SFC) of fat blends (PSC46, PSC37, PSCP352, PSCP343, PSCP253 and PSCP244), commercial trans- CZTMF decreased slowly while the SFC of all the fat blends margarine fat (CTMF) and commercial zero-trans margarine fat decreased more rapidly, implying that the fat blends would (CZTMF) measured at different temperatures. For compositions and melt more quickly than the commercial margarine fats. The abbreviations of the fat blends see Table 1. 430 S. Sonwai & V. Luangsasipong changes in SFC in the temperature range of 15 − 25℃ is samples are given in Fig. 2. The crystallization thermograms related to the cooling effect, which is a desirable mouthfeel of the fat blends showed 2 − 3 distinct peaks (Fig. 2a), indi- property for margarines, and the greater the SFC drop the cating that heterogeneous types of triglycerides were crys- greater the cooling effect (Hoffmann, 1989). In this regard, tallized at different temperatures. The crystallization peaks the SFC decreases between 15 and 25℃ in a declining order and TCO were shifted towards low temperatures when the were 42.53% (PSC37), 36.92% (PSC46), 33.03% (PSCP352), proportion of PS in the fat blends decreased with an increase 29.81% (PSCP253), 27.4% (PSCP343), 26.2% (PSCP244), in either VCO or PO. For the binary blends of PS and VCO,

11.27% (CTMF) and 6.8% (CZTMF). Accordingly, PSC37 TCO decreased from 23.5℃ to 19.5℃ as the amount of PS and CZTMF gave the highest and lowest cooling effect, re- in the blends decreased from 40% (wt) in PSC46 to 30% spectively. (wt) in PSC37. A similar trend continued with the ternary Approaching the room temperature of 30 − 32℃ in a blends, e.g. as the quantity of PS in the blends decreased, country with a tropical climate, the SFC of the fat blends, TCO dropped from 22.8℃ (PSCP343) to 21.8℃ (PSCP244). though most still higher, were close to those of the margarine In addition, the number of crystallization peaks appeared to fats. The SFC of PSC37 and PSCP253 were almost the same increase as the amount of PS in the fat blend decreased. Out as that of CTMF. At the body temperature of 37℃, the SFC of all samples, TCO of CTMF was the highest (28.6℃). Par- of all fat samples were lower than 10%. In order to eliminate waxy mouthfeel, a margarine fat should have SFC < 3.5% (a) CTMF T at temperatures above 33℃ (Chrysan, 1996). From Fig. 1, CO only PSC37, PSCP253 and both margarine fats showed SFC CZTMF W) m close to 3.5% at around 33℃. ( PSC46 w w lo F

In order to have good spreadability at refrigeration tem- PSC37 a t e perature, SFC of fats should be lower than 32% at 10 (Lida H ℃ PSCP352 c

and Ali, 1998). The SFC of the fat blends were higher than rm i e PSCP343 h t

32% at 10 . However, the aim of this work was to produce o

℃ x E zero-trans packet margarines, which should be spreadable PSCP253 ze d i l at room temperature. The SFC of all fat blends were well a PSCP244 r m o below 32% at room temperature. This should give good N spreadability to the margarines made from all the blends. According to Liu et al. (2010), the SFC of a commercial- ly available margarine in Shanghai (China) with acceptable -60 -40 -20 0 20 40 Temperature (oC) hardness was as high as 75.11% at 10℃. High SFC is not directly related to high hardness in fats as the SFC is not the (b) sole parameter that influences the ultimate strength of the fat T MC crystal network. Apart from the SFC, the mechanical prop- CTMF mW) erties of fats can be influenced by other factors, e.g., lipid ( CZTMF w o Fl

composition, polymorphism, crystallization behavior and t

e a PSC46 H microstructure (Liu et al., 2010). The high SFC values of c PSC37

the fat blends at low temperature range would give the mar- er mi h t garines produced from these blends stability and consistency, do PSCP352 n E which is extremely useful for margarines available in tropical ze d

i PSCP343 regions. In addition, the big drop in SFC of the fat blends l m a r

o PSCP253 when the temperature increased from 5 to 30℃ would allow N the fats to melt quickly when consumed and the low SFC at PSCP244 the body temperature would leave almost no waxy mouthfeel. The SFC results imply that PSC37 and PSCP253 may -40 -20 0 20 40 60 Temperature (oC) be appropriate for the production of margarines that maintain stability, are spreadable at room temperature, give great cool- Fig. 2. DSC crystallization (a) and melting (b) thermograms of fat blends (PSC46, PSC37, PSCP352, PSCP343, PSCP253 and ing effect and melt almost completely at body temperature. PSCP244), commercial trans-margarine fat (CTMF) and commer- Analysis of crystallization and melting profiles The cial zero-trans margarine fat (CZTMF). For compositions and ab- DSC thermograms for crystallization and melting of all fat breviations of the fat blends see Table 1. Production of Zero-trans Margarines from Virgin Coconut Oil 431 tial hydrogenation was likely the cause for the high TCO of trapped in the crystalline matrix and this could make it more CTMF. The crystallization thermogram of CZTMF exhibited difficult for the solid-state phase transition form β’ to β to oc- 2 peaks, one big located at −39.5℃ and one small located at cur. Consequently, β’ remained the predominant polymorph 19.5℃, that were farthest apart. The abundance in unsatu- in PSC37. For ternary blends, at a fixed amount of PS in the rated fatty acids in triglyceride molecules of ingredient oils blends, as the amount of VCO increased with a correspond- (rapeseed, sunflower, olive, and palm oils) in CZTMF was ing decrease in PO, the level of β increased. This was pos- the key contribution for the crystallization peak at the very sibly the result of more solid-state transition from to β’ to β low temperature. that occurred with those blends with high VCO content. The The melting thermograms of the fat blends showed at polymorph of both commercial margarine fats, however, was least 3 distinct peaks. As the amount of PS in the fat blends in β’ form only. decreased, resulting in smaller portions of higher melting The fat crystals in margarines could exist in two poly- triglycerides in the blends, the multiple melting peaks and morphic structures, β’ and β. However, β’ polymorph is more

TMC were moved slightly towards lower temperatures. In desirable. This type of crystal is small, about 5 − 7 µm in addition, when the amount of PS in the fat blends dropped length, hence contributing to a shiny surface, smooth texture to 20% (wt), the first melting peak on the high temperature and spreadability of the product (Miskandar et al., 2002, Id- end with the peak temperature of ~47.9℃ disappeared. The ris et al., 1996). β crystals are initially small but they grow characteristics of the melting thermograms of CTMF and into large needle-like agglomerates about 20 − 30 µm, lead- CZTMF were different from those of the fat blends. The ing to sandy and hard texture (Miskandar et al., 2002, Liu et thermogram exhibits several broad melting peaks overlap- al., 2010, deMan and deMan, 2002). The results from the ping one another. The lower melting peaks of CZTMF polymorphic structure investigation given in Table 4 imply were located at melting temperatures much lower than other that PSC37, PSCP343 and PSCP 244 would be most suitable samples. The peaks represented the melting of unsaturated for the production of margarines due to their tendency to triglycerides that were the main triacylglycerol components crystallize in β’. of the trans-free margarine fat. In general, it is difficult to produce a β’-stable soft marga- Polymorphic structure analysis The polymorphic rine from non-hydrogenated oils and usually a β’-stabilizing structures of the fat samples crystallized at 4℃ are shown in compound has to be included (Idris et al., 1996). In addition, Table 4. Two types of polymorphic structures, β’ and β, were it has been reported that margarines with acceptable sensory present in all fat blends. β’ was a predominant polymorph in characteristics sold in some countries contained crystals that blends PSC37, PSCP343 and PSCP244. The fat crystals ex- were a mixture of β’ and β structures, with β’ dominating hibited the same level of β’ and β in blends PSC46, PSCP352 over β (Idris et al., 1996). These margarines, produced to be and PSCP253. For binary fat blends, 10% reduction in the sold in a tropical climate, were formulated from PO or palm amount of PS in the blends from 40% in PSC46 to 30% in olein and palm kernel oil with a liquid oil but no hydroge- PSC37, with 10% increase in VCO content, resulted in an nated oil. Compared to β’ polymorphs, crystals in β structure increase in the level of β’. The fat blend PSC37 exhibited tend to be larger and hence giving a harder texture and higher a higher SFC at 4℃ than that of PSC46 blend (Fig. 1). A consistency to the margarine products. higher SFC means that more triglyceride molecules are Crystal morphological study Figure 3 shows crystal

Table 4. Polymorphic form of fat blends (PSC46, PSC37, PSCP352, PSCP343, PSCP253 and PSCP244), commercial trans- margarine fat (CTMF) and commercial zero-trans margarine fat (CZTMF) crystallized at 4℃ under static conditions for 24 h.

Fat samples d-spacing (Å) Polymorphic forms Level of β’ and β forms* PSC46 4.6 s 4.36 s 3.88 s β’ + β β’ = β PSC37 4.6 m 4.36 s 3.88 s β’ + β β’ > β PSCP343 4.6 m 4.36 s 3.88 s β’ + β β’ > β PSCP244 4.6 m 4.36 s 3.88 s β’ + β β’ > β PSCP352 4.6 s 4.36 s 3.88 s β’ + β β’ = β PSCP253 4.6 s 4.36 s 3.88 s β’ + β β’ = β CTMF 4.36 s 4.2 s 3.88 s β’ β’ CZTMF 4.36 w 3.88 s β’ β’

m = medium, s = strong, w = weak. *Estimated from β/β’ = [(intensity of short spacing at 4.6 Å)/(intensity of short spacing at 4.36 Å)], that was classified as β’ = β (1.2 ≥ β/β’ > 0.8), β’ > β (0.80 ≥ β/β’ > 0.4) or β’ >> β (0.4 ≥ β/β’ > 0) (Kim et al., 2008). 432 S. Sonwai & V. Luangsasipong

Fig. 3. Crystal morphology of fat blends (PSC46, PSC37, PSCP352, PSCP343, PSCP253 and PSCP244), commercial trans-margarine fat (CTMF) and commercial zero-trans margarine fat (CZTMF) crystallized at 4℃ under static conditions for 24 h. For compositions and abbreviations of the fat blends see Table 1. Production of Zero-trans Margarines from Virgin Coconut Oil 433 morphology of all fat blends crystallized at 4 under quies- ℃ 80 CTM (a) cent conditions for 24 h. Fat crystals in all fat blends, except CZTM 70 PSCP343, were radially-oriented spherulites. These spheru- PSC46M 60 lites consisted of plate-like polycrystalline crystals radiating PSC37M PSCP352M 50 and branching from central nuclei. Some degree of crystal ) PSCP343M % (

aggregation, presumably by van der Waals forces (Berger et C 40 PSCP253M F

S PSCP244M al., 1979), is evident in the images, except PSC37. The size 30 of the spherulites in PSC46, PSCP244 and PSCP352 were 20 generally larger than the crystals in PSC37 and PSCP253. In 10 contrast, the crystal morphology for PSCP343 was continu- 0 ous needle-like with the highest crystal number compared 0 1 2 3 4 5 6 7 8 Storage time (week) to other fat blends. As the content of PS in the fat blends 12 CTM (b) decreased 10% (wt) from PSC46 to PSC37 and from PSCP CZTM 343 to PSCP253 with an increase in VCO, the size of crystal 10 PSC46M aggregates diminished and the portion of liquid oil increased. PSC37M 8 PSCP352M

On the other hand, a 10% increase in VCO while the content ) PSCP343M % (

C 6 PSCP253M

of PS remained constant (i.e., from PSCP352 to PSCP343 F S and from PSCP253 to PSCP244) resulted in higher crystal PSCP244M 4 number and larger crystal size with decreased liquid portion. The microstructure of crystals in the commercial trans- 2 margarine fat, CTMF, was a mixture of large loosely-packed 0 spherulites and granular texture with some evidence of 0 1 2 3 4 5 6 7 8 Storage time (week) crystal aggregation, whereas the crystal morphology of the 12 CTM (c) zero-trans margarine, CZTMF, were discontinuous plate- CZTM like. Many individual crystals were present in CZTMF with 10 PSC46M PSC37M small degree of crystal aggregation. This is in agreement 8 PSCP352M with what was previously observed in the microstructure of a ) PSCP343M % (

C 6 PSCP253M

trans-free margarine (Kim et al., 2008). F S Solid fat content of margarine products Changes in PSCP244M 4 SFC of the margarine products during storage for 8 weeks at three different temperatures are given in Fig. 4. Apart from a 2 substantial increase and a small drop in SFC during the first 0 0 1 2 3 4 5 6 7 8 week of storage at 4℃ (Fig. 4a) and 32℃ (Fig. 4b), respec- Storage time (week) tively, the SFC values of all margarines remained relatively Fig. 4. Changes in solid fat content (SFC) of experimental marga- constant throughout 8 weeks of storage. This implies that rines (PSC46M, PSC37M, PSCP352M, PSCP343M, PSCP253M the margarines, both produced in the laboratory and commer- and PSCP244M), commercial trans-margarine (CTM) and commer- cially available, were stable with consistent physical charac- cial zero-trans margarine (CZTM) during 8 weeks of storage at 4℃ teristics. At any storage week, zero-trans commercial mar- (a), 25℃ (b) and 32℃ (c). garine, CZTM, exhibited the lowest SFC values in all three storage temperatures. At 4℃, SFC of all margarines, except of CTM at 32℃ was likely due to the fact that it contained CTM and CZTM, were not significantly different from one hydrogenated fats. another (Fig. 4a). As the storage temperature increased to Textural properties Changes in the hardness of all mar- 25℃, SFC measured at any storage week of all margarines garine samples during storage at three different temperatures decreased noticeably from 4℃, with PSC46M exhibiting are shown in Fig. 5 where it was evident that the hardness the highest SFC throughout 8 weeks of storage (Fig. 4b). At of the samples was influenced by the storage temperature. 32℃, SFC of all margarines decreased to below 10% (Fig. At 4℃, PSC46M exhibited the highest hardness at 4 and 8 4c). PSC46M and the commercial trans-margarine, CTM, weeks of storage, possibly due to its highest content in PS, were the formulations with highest SFC at this temperature. followed by PSC37M, PSCP352M and PSCP253M (Fig. 5a). The high SFC of PSC46M at all three storage temperatures The hardness of all samples increased substantially during was likely due to its high PS content whereas the high SFC the first 1 − 2 weeks of storage and this is likely due to the 434 S. Sonwai & V. Luangsasipong

Fig. 5. Hardness of experimental margarines (PSC46M, PSC37M, PSCP352M, PSCP343M, PSCP253M and PSCP244M), commercial trans-margarine (CTM) and commercial zero-trans margarine (CZTM) during 8 weeks of storage at 4℃ (a), 25℃ (b) and 32℃ (c). Lower case letters represent significant differences within one margarine sample between 0, 2, 4 and 8 weeks of storage. Capital letters represent significant differences between different margarine samples at the same storage week. Hardness values with the same letter are not significantly different (P > 0.05). Production of Zero-trans Margarines from Virgin Coconut Oil 435 decrease in the temperature from the incubation tempera- with storage time. At 32℃, the same trend from 25℃ con- ture during the margarine manufacturing (25℃ for 2 h) to tinued where PSCP343M remained the sample with the high- the storage temperature. The increase in the hardness from est hardness at 8 weeks of storage, followed by PSCP352M weeks 0 to 2 of all samples reflects the increase in SFC (Fig. and PSC46M. Similarly, the hardness of all margarines did 4). However, the further hardness increase between weeks not vary significantly with storage time at room temperature 2 and 4 (where the SFC had already reached plateaus) of all The hardness of the trans-free margarine, CZTM, was samples, except CTM and CZTM, indicates again that SFC significantly lower than all other margarine samples at all is not a sole factor to be correlated to the hardness. Further storage temperature. This is in agreement with the changes evidence could be seen from the figure that as the hardness in SFC results (Fig. 4) where CZTM demonstrated the low- at 8 weeks of storage decreased significantly from 37.7 N for est SFC at all three storage temperatures. The lack in crystal PSC46M to 34.0 N for PSC37M and 32.5 N for PSC352M, aggregates in the margarine’s microstructure (Fig. 3) and the SFC of these samples at the sample storage week were hence interaction between them might have led to a weak not significantly different from one another. crystal network, resulting in its low hardness and stability. At 25℃, the hardness of all samples decreased dramati- On the contrary, the hardness of trans-margarine, CTM, was cally from 4℃. PSCP343M exhibited the highest hardness not significantly different from that of PSCP244M at room at 8 weeks possibly due to its high content of PS (30% wt) temperature and was very close to that of PSC37M at both and high combined content of PS and PO (60% wt). At 25℃ and room temperature. this storage week, PSC46M showed the same hardness Changes in adhesiveness and cohesiveness of the samples as PSCP352M. The hardness of all margarines, except during storage at 25℃ are shown in Fig. 6. As the stor- PSCP343M and PSCP253M, did not change significantly age time increased from 0 to 8 weeks, the adhesiveness

Fig. 6. Adhesiveness (a) and cohesiveness (b) of experimental margarines (PSC46M, PSC37M, PSCP352M, PSCP343M, PSCP253M and PSCP244M), commercial trans-margarine (CTM) and commercial zero-trans margarine (CZTM) during 8 weeks of storage at 25℃. Lower case letters represent significant differences within one margarine sample between 0, 2, 4 and 8 weeks of storage. Values with the same letter are not significantly different P( > 0.05). 436 S. Sonwai & V. Luangsasipong

the blend showed good consistency and demonstrated hard- PSC46M c ness characteristic close to that of a commercial trans-packet

PSC37M a margarine. In addition the margarine received highest score for overall acceptibility. PSCP352M c

PSCP343M b Acknowledgements Funding from Silpakorn University Research

PSCP253M d and Development Institute (SURDI) is truly appreciated. The au- thors would like to thank Punnee Ponprachanuwat for her help in PSCP244M b GC analyses, and Bruker Biospin AG (Thailand) for the use of p- CTM b NMR. CZTM d

0 1 2 3 4 5 References Hedonic scale Adhikari, P., Zhu, X.M., Gautam, A., Shin, J.A. and Hu, J.N. Fig. 7. Sensory evaluation of experimental margarines (PSC46M, (2010a). Scale-up production of zero-trans margarine fat using PSC37M, PSCP352M, PSCP343M, PSCP253M and PSCP244M), pine nut oil and palm stearin. Food Chem., 119, 1332-1338. commercial trans-margarine (CTM) and commercial zero-trans margarine (CZTM) stored for 4 weeks at 25℃. Adhikari, P., Shin, J.A., Lee, J.H., Hu, J.N., Zhu, X.M., Akoh, C.C. a − d Values with the same letter are not significantly different P( > and Lee, K.T. (2010b). Production of trans-free margarine stock 0.05). by enzymatic interesterification of rice bran oil, palm stearin and coconut oil. J. Sci. Food Agri., 90, 703-711. decreased significantly for PSCP343M, PSCP253M and Anon. (2003). Food labeling: trans fatty acids in nutrition labeling, PSCP244M, and slightly increased for CTM (Fig. 6a). Inter- final rule. Federal Register., 68, 41433-41506. estingly, there was no obvious trend for the adhesiveness of AOAC. (1995). “Official Methods of Analysis of AOAC Interna- PSC46M, PSC37M and CZTM as the storage time increased tional.” AOAC International, Arlington, VA. while the adhesiveness of PSCP352M remained relatively AOCS. (1998). “Official Methods and Recommended Practices of unchanged. There appeared to be no direct relationship be- the American Oil Chemists’ Society.” AOCS Press, Champaign, tween the adhesiveness and the cohesiveness of the marga- IL. rine samples. The cohesiveness increased with storage time Berger, K.G., Jewell, G.G. and Pollitt, R.J.M. (1979). Oils and fats. for of PSC46M, PSC37M, PSCP352M and CTM but there In “Food Microscopy,” ed. by J.G.Vaughan. Academic Press, was no noticeable trend for the adhesiveness of PSCP343M, New York, pp. 445-497. PSCP253M, PSCP244M and CZTM as the storage time in- Bourne, M.C. (1978). Texture profile analysis. Food Technol., 32, creased (Fig. 6b). 62-72. Sensory analysis The results from the sensory evalua- Che Man, Y.B. and Marina, A.M. (2006). Medium chain triacl- tion of the margarine samples are given in Fig. 7. PSC37M glycerol. In “Nutraceutical and Specialty Lipids and their Co- exhibited the highest score for overall acceptability on the Products,” ed. by F. Shahidi. Taylor & Francis Group, New York, hedonic scale. The scores for PSCP343M, PSCP244M and pp. 27-56. CTM were approximately the same. They were signifi- Chrysan, M.M. (1996). Margarines and spreads. In “Bailey’s In- cantly lower than that of PSC37M but significantly higher dustrial Oil and Fat Products (vol. 4),” ed. By Y.H. Hui. John than the scores for PSC46M and PSCP352M. In addition, Wiley and Sons Inc, New York, pp. 33-82. PSCP253M and CZTM showed the lowest scores. Chu, B.S., Ghazali, H.M., Lai, O.M., Che Man, Y.B. and Yusof, S. (2002). Physical and chemical properties of a lipase-transester- Conclusion ified palm stearin/palm kernel olein blend and its isopropanol- In this work, zero-trans packet margarines were manu- solid and high melting triacylglycerol fractions. Food Chem., 76, factured using many blends of VCO, PS and PO with dif- 155-164. ferent weight fractions as feedstocks. It was found that deMan, J.M. and deMan, L. (2002). Texture of fats. In “Physical blend PSC37 which contained 30% PS and 70% VCO was properties of lipids,” ed. by A.G. Marangoni and S.S. Narine. the most suitable feedstock for the production of zero-trans Marcel Dekker, New York, pp. 191-217. packet margarine. The blend exhibited a tendency to crystal- D’Souza, V., deMan, J.M. and deMan, L. (1990). Short spacings lize into β’ structure with a good cooling effect and low SFC and polymorphic forms of natural and commercial solid fats: a at body temperature, indicating that it would not cause waxy review. J. Am. Oil Chem. Soc., 67, 835-843. mouthfeel when consumed. The margarine produced from Enig, M.G. (1996). Trans fatty acids in diets and databases. Cereal Production of Zero-trans Margarines from Virgin Coconut Oil 437

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