Structured lipids obtained by chemical interesterification of olive oil and palm stearin

Interesterification of palm stearin (PS) with liquid vegetable oils could yield a good solid fat stock that may impart desirable physical properties, because PS is a useful source of vegetable hard fat, providing β′ stable solid fats. Dietary ingestion of olive oil (OO) has been reported to have physiological benefits such as lowering serum cholesterol levels. Fat blends, formulated by binary blends of palm stearin and olive oil in different ratios, were subjected to chemical interesterification with sodium methoxide. The original and interesterified blends were examined for fatty acid and triacylglycerol composition, melting point, solid fat content (SFC) and consistency. Interesterification caused rearrangement of triacylglycerol species, reduction of trisaturated and triunsaturated triacylglycerols content and increase in diunsaturated-monosaturated triacylglycerols of all blends, resulting in lowering of melting point and solid fat content. The incorporation of OO to PS reduced consistency, producing more plastic blends. The mixture and chemical interesterification allowed obtaining fats with various degrees of plasticity, increasing the possibilities for the commercial use of palm stearin and olive oil.     

Effects of variation in the palm stearin: Palm olein ratio on the crystallisation of a low-trans shortening

Changes in the rheological properties during crystallisation and in the crystal size and morphology of blends containing rapeseed oil with varying percentages of palm stearin (POs) and palm olein (POf) have been studied. The crystals formed from all three blends were studied by confocal laser scanning microscopy, light microscopy and environmental scanning electron microscopy, which revealed the development of clusters of 3–5 individual elementary “spherulites” in the early stages of crystallisation. The saturated triacylglycerol content of the solid crystals separated at the onset of crystallisation was much greater than that in the total fat. Fat blends with a higher content of palm stearin had a more rapid nucleation rate when observed by light microscopy, and this caused an earlier change in the rheological properties of the fat during crystallisation. Using a low torque amplitude (0.005 Pa, which was within the linear viscoelastic region of all samples studied) and a frequency of 1 Hz, the viscoelastic properties of melted fat during cooling were studied. All samples, prior to crystallisation, showed weak viscoelastic liquid behaviour (G″, loss modulus >G′, storage modulus). After crystallisation, a more “solid like” behaviour was observed (G′ similar to or greater than G″). The blend having the highest concentration of POs was found to have the earliest onset of crystallisation (27% w/w POs; 12 mins, 22% w/w POs; 13.5 mins, 17% w/w POs, 15 mins, respectively). However, there were no significant differences in the time to the point when G′ became greater than G′ among the three blends.     

利用酯交换法改进棕榈油硬脂的加工性能

将棕榈油硬脂(ST)与大豆油(SBO)按不同比例混合再进行酯交换反应可以得到不同固脂特征的油脂。实验发现,其中的酯交换油脂IE(70%ST 30%SBO)最适合于加工成通用型起酥油。对这种酯交换油脂的打发性、软硬度及氧化稳定性进行了分析,并与目前市场上常见的全棕榈油基起酥油进行了比较,发现酯交换油脂的柔软度和打发性能均优于后者,但其氧化稳定性不及全棕榈油基起酥油。     

棕榈油硬脂和大豆油酶法酯交换的研究

进行了固定化脂肪酶Lipozyme TL IM催化棕榈油硬脂和大豆油酶法酯交换的研究,考察了酶法酯交换分批操作的反应动力学曲线,发现5%的加酶量、70℃下反应,反应3 h内达到平衡,反应温度在70~90℃对反应速度无明显影响。采用填充床式反应器进行连续反应,结果表明通过装有10 g脂肪酶柱子的最佳流速为30 g/h。对化学酯交换和酶法酯交换产品性质的比较发现,二者SFC无明显差异。采用填充床式反应器对40∶60和30∶70的棕榈油硬脂和大豆油的混合物进行酶法酯交换反应,测定了反应产物的SFC曲线,为将来的应用开发提供参考数据。     

Effects of chemical interesterification on solid fat content and slip melting point of fat/oil blends

Fat/oil blends, formulated by mixing fully hydrogenated palm oil stearin or palm oil stearin with vegetable oils (canola oil and cottonseed oil) in different ratios from 30:70 to 70:30 (w/w %), were subjected to chemical interesterification reactions on a laboratory scale. Fatty acid (FA) composition, iodine value, slip melting point (SMP) and solid fat content (SFC) of the starting blends were analysed and compared with those of the interesterified blends. SMPs of interesterified blends were decreased compared to starting blends because of extensive rearrangement of FAs among triacylglycerols. These changes in SMP were reflected in the SFCs of the blends after the interesterification. SFCs of the interesterified blends also decreased with respect to the starting blends, and the interesterified products were softer than starting blends. These interesterified blends can be used as an alternative to partial hydrogenation to produce a plastic fat phase that is suitable for the manufacture of margarines, shortenings and confectionary fats.     

Enzymatic interesterification of palm and coconut stearin blends

Hard fractions of palm oil and coconut oil, blended in the ratios of 90:10, 85:15, 80:20 and 75:25, were interesterified for 8 h using Lipozyme TL IM. Major fatty acids in the blends were palmitic acid (41.7–48.4%) and oleic acid (26.2–30.8%). Medium‐chain fatty acids accounted for 4.5–13.1% of the blends. After interesterification (IE), slip melting point was found to decrease from 44.8–46.8 °C to 28.5–34.0 °C owing to reduction in solids content at all temperatures. At 37.5 °C, the blends containing 25% coconut stearins had 17.4–19% solids, which reduced to 0.4–1.5% on IE, and the slip melting point (28.6 and 28.8 °C) indicated their suitability as margarine base. The reduction in solid fat index of the interesterified fats is attributed to the decrease in high‐melting triacylglycerols in palm oil (GS₃ and GS₂U type) and increase in triolein (GU₃) content from 1 to 9.2%. Retention of tocopherols and β‐carotene during IE was 76 and 60.1%, respectively, in 75:25 palm stearin and coconut stearin blend.     

Zero trans shortening using rice bran oil, palm oil and palm stearin through interesterification at pilot scale

Fat blends, formulated by mixing refined, bleached and deodorised (RBD) palm oil (PO) or RBD palm stearin (PS) with RBD rice bran oil (RBO) in various ratios were subjected to chemical interesterification (CIE) at pilot scale using sodium methoxide (NaOMe) as catalyst. The resultant interesterified fat was processed through a margarine crystalliser under optimised conditions. The blends before and after CIE were investigated for triacylglycerol (TAG) composition, solid fat content (SFC) and melting characteristics, polymorphic form, fatty acid composition (FAC), bioactive (tocols, sterols, oryzanol) constituents and trans fatty acids (TFA). CIE was found to be very effective in terms of rearrangement of fatty acids (FAs) among TAGs and consequent changes in the physical characteristics. The SFC of the interesterified PS/RBO blends decreased significantly ( P  ≤ 0.05) when compared with those of PO/RBO blends. The interesterified binary blends with 50–60% PS and 40–50% RBO, and 70–80% PO and 20–30% RBO had SFC curves in the range of all-purpose type shortenings. CIE facilitated the formation of β' polymorphic forms. FAC of shortenings prepared using the optimised blends contained 15–20% C_18:2 polyunsaturated fatty acid (PUFA) and no TFA. Total tocol, sterol and oryzanol content of zero trans shortenings were 650–1145, 408–17 583 and 1309–14 430 ppm. CIE using NaOMe did not affect the bioactive constituents significantly ( P  ≤ 0.05).     

Optimizing palm oil and palm stearin utilization for sensory and textural properties of chicken frankfurters

This study was designed to explore the potential of refined, bleached and deodorized (RBD) palm oil (PO) and palm stearin (POs) utilization in chicken frankfurters. A 10 points augmented simplex-centroid design was used to study the effect of chicken fat (CF), PO and POs as well as the interaction of these fats on the emulsion, textural and sensory properties of chicken frankfurters. All frankfurters were formulated to contain approx 25% fat, 52% moisture and 10% protein. No significant difference was found in end chopping temperatures of all meat batters even though the temperature of PO and POs upon incorporation into meat batters was 50°C higher than CF. Strong emulsions were formed as no fluid losses were observed in all the meat batters tested after heating. Texture profiles of the frankfurters containing PO and/or CF were quite similar, but increment of POs raised hardness, chewiness, and shear hardness of the frankfurters. Acceptability of the frankfurters was evaluated using hedonic test. Panelists found no difference in hardness preference between frankfurters made from totally CF and PO, while frankfurters made from POs were rated as hard and brittle. CF was important in determining acceptability of the frankfurters, as reduction of CF in formulation resulted in lower scores in chicken flavor, juiciness, oiliness and overall acceptance of the frankfurters. Frankfurters with sensory acceptability comparable to a commercial one were found to comprise of more than 17% CF, and less than 67% PO and 17% POs of the fat blend.     

Composition and crystallization behavior of solvent-fractionated palm stearin

Palm stearin (PS) is an extensively used trans-free hardstock. Depending on process parameters, fractions with unique compositions, hardness, and solid fat content can be tailored toward specific applications. In this work, the composition and crystallization of PS fractionated with acetone at 30°C, 35°C, or 40°C into various liquid (LF) and solid (SF) fractions were investigated. After fractionation, iodine value (IV) of PS changed from 37 to values ranging from 24 to 51. The IV of the LF increased with a decrease in fractionation temperature whereas that of the SF (~24) was unaffected. The main fatty acids of all PS fractions were palmitic and oleic acids, with the LF having a lower palmitic acid but higher oleic acid content than the SF. LF and SF obtained at higher fractionation temperatures showed more rapid crystallization rates. Under the microscope, the LF fractionated at 30°C and 35°C consisted of spherulites whereas those fractionated at 40°C exhibited dendritic crystals. All SF consisted of spherulites comprised of large rod-like crystals. All samples existed as mixtures of β’ and β crystals. This study serves as the basis for the development of baking margarines and pastry shortenings using fractionated PS.     

棕榈油硬脂和棕榈油中间分提物性能及相容性研究

为改善油脂可塑性和口溶性,及为开发以棕榈油产品为主要原料专用油脂产品提供理论依据,研究棕榈油硬脂(PSt)、棕榈油中间分提物(PMF)两者间相容性。测定二元混合体系固体脂肪含量(SFC)值,并通过计算其理论值与实测值之间差值△SFC,结合T–△SFC曲线、二元等温曲线等直观分析,结果表明:PSt与PMF混合物在25℃、PSt含量为30%～50%时,二者间偏晶现象严重;而在35℃～50℃时,二者间共晶现象较为严重;在0℃～10℃和30℃～35℃范围内,二者间具有较好相容性。     

Production of trans‐free margarine stock by enzymatic interesterification of rice bran oil,palm stearin and coconut oil

BACKGROUND: Trans‐free interesterified fat was produced for possible usage as a spreadable margarine stock. Rice bran oil, palm stearin and coconut oil were used as substrates for lipase‐catalyzed reaction. RESULTS: After interesterification, 137–150 g kg^?1 medium‐chain fatty acid was incorporated into the triacylglycerol (TAG) of the interesterified fats. Solid fat contents at 25 °C were 15.5–34.2%, and slip melting point ranged from 27.5 to 34.3 °C. POP and PPP (β‐tending TAG) in palm stearin decreased after interesterification. X‐ray diffraction analysis demonstrated that the interesterified fats contained mostly β′ polymorphic forms, which is a desirable property for margarines. CONCLUSIONS: The interesterified fats showed desirable physical properties and suitable crystal form (β′ polymorph) for possible use as a spreadable margarine stock. Therefore, our result suggested that the interesterified fat without trans fatty acid could be used as an alternative to partially hydrogenated fat. Copyright © 2010 Society of Chemical Industry     

Crystallisation kinetics of palm stearin,palm kernel olein and their blends

The kinetics of isothermal crystallisation of palm stearin, palm kernel olein and their blends (20–80 g/100 g palm stearin with 20 g/100 g increment) were determined using differential scanning calorimetry (DSC). The mechanism of crystallisation (n) was calculated by applying the Avrami equation using the crystallisation curves obtained at 10, 15 and 20 °C. The DSC isothermal crystallisation data at 10, 15 and 20 °C fitted well into the Avrami equation over the entire fractional crystallisation with correlation coefficient always greater than 0.98. Based on the Avrami exponent obtained, the palm stearin and palm kernel olein have different nucleation and growth mechanisms. The suggested mechanism for palm kernel olein was high nucleation rate at the beginning of crystallisation, which decreased with time, and plate-like growth (n = 2). On the other hand, the mechanism for palm stearin was instantaneous heterogeneous nucleation followed by spherulitic growth (n = 3). For blends of palm stearin and palm kernel olein, the mechanisms of crystallisation were 2 and 3 depending on the composition of the blends and crystallisation temperatures.     

Application of hydrogenated palm kernel oil and palm stearin in whipping cream

Non-dairy creams made from hydrogenated palm kernel oil (HPKO) are generally more stable than dairy creams. However, in summer the emulsion tends to separate. This paper outlines some steps that were taken to modify the HPKO with the intention of increasing the stability without affecting whipping performance. This was achieved by blending HPKO with palm stearin (POs). Interesterification was employed to eliminate the increase in solid fat content at 37°C and 40°C. Results of the experiment showed that an interesterified HPKO: POs 66:34 blend proved to have satisfactory whipping performance when compared to creams made with HPKO alone.     

酶促酯交换对棕榈硬脂基塑性脂肪甘三酯组成及物理性能的影响

利用脂肪酶Lipozyme TLIM催化棕榈硬脂(PS)与大豆油(SO)(PS∶SO分别为9∶1,8∶2,7∶3,6∶4,5∶5,wt%)酯交换反应,研究酯交换反应前后混合油脂体系中甘三酯组成的变化及其与油脂物理性能的关系。结果发现,酯交换后油脂中PPP、LLL、POP、PPL、PLL、PLO六种甘三酯含量发生明显变化,其中PPP、LLL含量下降,PPL、PLL、PLO含量增加,而POP除9∶1外,其含量均下降;SSS(S代表饱和脂肪酸)和UUU(U代表饱和脂肪酸)型甘三酯含量下降,而SUU和SUS含量增大,导致油脂熔点和固体脂肪含量(SFC)均不同程度下降,从而可制备不同SFC要求的塑性脂肪。PS∶SO为7∶3、6∶4、5∶5时,酯交换后油脂β’晶型增多,可为人造奶油、速冻专用油脂等塑性脂肪提供理想晶型。      

Trans-free plastic shortenings from coconut stearin and palm stearin blends

Coconut oil was fractionated to get 40% and 60% stearins (CSt1 and CSt2), blended with a hard fraction (PSt) from palm oil (10–90%) and its suitability as a plastic fat was studied. Slip melting point increased with increase in the level of PSt and ranged from 25.9 to 49.6 °C. CSt2 did not contain any solids above 20 °C but increased on incorporating PSt and showed the wider melting range required for plastic fats. Melting profiles of the blends containing 30% and 40% PSt were comparable with that of a commercial bakery shortening. Triglyceride composition showed that the blends contained lower and higher molecular weight triglycerides desirable for plastic fats. FTIR spectra showed a distinct peak at 966 cm⁻¹ characteristic of trans fatty acids in commercial shortening while the peak was absent in blends. This study showed that the blends containing 60–70% CSt with PSt are suitable as trans-free plastic fats.     

Effects of silicone and ascorbyl palmitate on the quality of palm olein used for frying of prawn crackers

The effects of ascorbyl palmitate (AP) and silicone on the quality changes of refined, bleached and deodorised palm olein (RBD olein) during intermittent frying of prawn crackers for 4.5 h per day were evaluated. The percentage polar components, the C18:2/C16:0 fatty acid ratio, and the acid value of used frying oil without additives were comparable to those for oil containing 200 mg kg^?1 AP. Oil with 2 mg kg^?1 silicone as well as oil containing 200 mg kg^?1 AP plus 2 mg kg^?1 silicone that had been used for frying had lower percentage polar components, higher C18:2/C16:0 ratios and lower acid values than RBD olein without additive. The results showed that silicone had a protective effect on the oil but that the rate of deterioration of the oil in the presence of AP was comparable to that of oil without additive during frying of prawn crackers. The results also showed that the extent of oil oxidation in RBD olein subject to static heating at 180°C for 4.5 h per day for four consecutive days was comparable to that of RBD olein without additive that had been used for frying of prawn crackers.     

Interactions between tocopherols,tocotrienols and carotenoids during autoxidation of mixed palm olein and fish oil

Electron spin resonance (ESR) and spin trapping detection of radical formation showed that the oxidative stability of palm olein/fish oil mixtures increased with the amount of palm olein. Mixtures with red palm olein were less stable than were mixtures with yellow palm olein. Addition of ascorbyl palmitate and citric acid gave further reduction of radical formation, whereas no effect was observed by adding lecithins. Storage of palm olein/fish oil mixtures (4:1) at 30 °C confirmed that red palm olein mixtures were less stable than were yellow palm olein mixtures. Ascorbyl palmitate together with citric acid improved the stability in both cases. The concentrations of α-tocopherol and α-tocotrienol decreased during storage, whereas β-, γ-, and δ-tocotrienols were unaffected. Ascorbyl palmitate reduced the losses of α-tocopherol and α-tocotrienol. The rate of loss of carotenoids was independent of the presence of fish oil and, except for an initial fast drop, also of the presence of ascorbyl palmitate.     

Scaled-up production of zero-trans margarine fat using pine nut oil and palm stearin

An interesterified structured lipid was produced with a lipid mixture (600 g) of pine nut oil (PN) and palm stearin (PS) at two weight ratios (PN:PS 40:60 and 30:70) using lipase (Lipozyme TL IM, 30 wt.%) as a catalyst at 65 ^°C for 24 h. Major fatty acids in the interesterified products were palmitic (35.1–40.4%), oleic (29.5%), and pinolenic acid (cis-5, cis-9, cis-12 18:3; 4.2–5.9%). α-Tocopherol (1.1–1.3 mg/100 g) and γ-tocopherol (0.3–0.4 mg/100 g) were detected in the interesterified products. Total phytosterols (campesterol, stigmasterol, and β-sitosterol) in the interesterified products (PN:PS 40:60 and 30:70) were 63.2 and 49.6 mg/100 g, respectively. Solid fat contents at 25 ^°C were 23.6% (PN:PS 40:60) and 36.2% (PN:PS 30:70). Mostly β′ crystal form was found in the interesterified products. Zero-trans margarine fat stock with desirable properties could be successfully produced from pine nut oil and palm stearin.     

Enzymatic interesterification of palm stearin with Cinnamomum camphora seed oil to produce zero-trans medium-chain triacylglycerols-enriched plastic fat

It is known that Cinnamomum camphora seed oil (CCSO) is rich in medium-chain fatty acids (MCFAs) or medium-chain triacylglycerols (MCTs). The purpose of the present study was to produce zero-trans MCTs-enriched plastic fat from a lipid mixture (500 g) of palm stearin (PS) and CCSO at 3 weight ratios (PS:CCSO 60:40, 70:30, 80:20, wt/wt) by using lipase (Lipozyme TL IM, 10% of total substrate) as a catalyst at 65 °C for 8 h. The major fatty acids of the products were palmitic acid (C16:0, 42.68% to 53.42%), oleic acid (C18:1, 22.41% to 23.46%), and MCFAs (8.67% to 18.73%). Alpha-tocopherol (0.48 to 2.51 mg/100 g), γ-tocopherol (1.70 to 3.88 mg/100 g), and δ-tocopherol (2.08 to 3.95 mg/100 g) were detected in the interesterified products. The physical properties including solid fat content (SFC), slip melting point (SMP), and crystal polymorphism of the products were evaluated for possible application in shortening or margarine. Results showed that the SFCs of interesterified products at 25 °C were 9% (60:40, PS:CCSO), 18.50% (70:30, PS:CCSO), and 29.2% (80:20, PS:CCSO), respectively. The β' crystal form was found in most of the interesterified products. Furthermore, no trans fatty acids were detected in the products. Such zero-trans MCT-enriched fats may have a potential functionality for shortenings and margarines which may become a new type of nutritional plastic fat for daily diet.     

Enzymatic interesterification of anhydrous butterfat with flaxseed oil and palm stearin to produce low-trans spreadable fat

Lipase-catalysed interesterification was performed to produce low-trans spreadable fat (LTSF) with anhydrous butterfat (ABF), flaxseed oil (FSO), and palm stearin (PS) using biocatalysts (Lipozyme RM IM and Novozym SP435). The reaction was carried out for 24 h at 60 °C in a shaking water bath (180 rpm). Seven substrate blends for the production of LTSF were prepared: 12:6:2, 10:6:4, 9:6:6, 8:6:6, 6:6:8, 6:6:9, and 4:6:10 (ABF/PS/FSO, by weight). After 24-h interesterification, decreased saturated fatty acid (SFA) contents in LTSFs were observed with ranges from 67% to 41%. LTSFs exhibited low atherogenic index (AI) with ranges from 2.8 to 0.8, compared with 3.3–4.7 AI of butter fat. Equivalent carbon number (ECN) 42–46 in the newly produced triacylglycerol (TAG) increased according to rearrangement of FAs on TAG backbone. The α-linolenic acid contents (mol%) of each LTSF were 5.6% (12:6:2), 10.7% (10:6:4), 15.1% (9:6:6), 15.8% (8:6:6), 20.8% (6:6:8), 22.4% (6:6:9) and 26% (4:6:10). The trans fatty acids in the LTSFs was not more than 2%. Melting point ranges of LTSF were from 37 (9:6:6) to 32 °C (4:6:10).