Zero trans fats from soybean oil and fully hydrogenated soybean oil: Physico-chemical properties and food applications

Blends of soybean oil (SO) and fully hydrogenated soybean oil (FHSBO), with 10%, 20%, 30%, 40% and 50% FHSBO (w/w) content were interesterified under the following conditions: 0.4% sodium methoxide, 500 rpm stirring, 100 °C, 20 min. The original and interesterified blends were examined for triacylglycerol composition, melting point, solid fat content (SFC) and consistency. Interesterification caused considerable rearrangement of triacylglycerol species, reduction of trisaturated triacylglycerol content and increase in monounsaturated and diunsaturated triacylglycerols, resulting in lowering of respective melting points. The interesterified blends displayed reduced SFC at all temperatures and more linear melting profiles as compared with the original blends. Yield values showed increased plasticity in the blends after the reaction. Isosolid diagrams before and after the reaction showed no eutectic interactions. The 90:10, 80:20, 70:30 and 60:40 interesterified SO:FHSBO blends displayed characteristics suited to application, respectively, as liquid shortening, table margarine, baking/confectionery fat and all-purpose shortenings/biscuit-filling base.     

EFFECT OF CHEMICAL INTERESTERIFICATION ON PHYSICOCHEMICAL PROPERTIES AND INDUSTRIAL APPLICATIONS OF CANOLA OIL AND FULLY HYDROGENATED COTTONSEED OIL BLENDS

Blends of canola oil (CO) and fully hydrogenated cottonseed oil (FHCSO), with 20, 25, 30, 35 and 40% FHCSO (w/w) were interesterified under the following conditions: 0.4% sodium methoxide, 500 rpm stirring, 100C, 20 min. The original and interesterified blends were examined for triacylglycerol composition, melting point, solid fat content (SFC) and consistency. Interesterification caused considerable rearrangement of triacylglycerol species, reduction of trisaturated triacylglycerol content and increase in disaturated-monounsaturated and monosaturated-diunsaturated triacylglycerols in all blends, resulting in lowering of respective melting points. The interesterified blends showed reduced SFC at all temperatures and more linear melting profiles if compared with the original blends. Consistency, expressed as yield value, significantly decreased after the reaction. Iso-solid curves indicated eutectic interactions for the original blends, which were eliminated after randomization. The 80:20, 75:25, 70:30 and 65:35 (w/w) CO: FHCSO interesterified blends showed characteristics which are appropriate for their application as soft margarines, spreads, fat for bakery/all-purpose shortenings, and icing shortenings, respectively.

PRACTICAL APPLICATIONS

Recently, a number of studies have suggested a direct relationship between trans isomers and increased risk of vascular disease. In response, many health organizations have recommended reducing consumption of foods containing trans fatty acids. In this connection, chemical interesterification has proven the main alternative for obtaining plastic fats that have low trans isomer content or are even trans isomer free. This work proposes to evaluate the chemical interesterification of binary blends of canola oil and fully hydrogenated cottonseed oil and the specific potential application of these interesterified blends in food products.     

Compositional and thermal characteristics of palm olein-based diacylglycerol in blends with palm super olein

Palm olein-based diacylglycerol (POL-DAG) was blended with palm super olein (POoo) in various concentrations (10–90%), with increments of 10% (wt/wt) POL-DAG. The physical and chemical characteristics, i.e., iodine value, acylglycerol content, fatty acid composition, melting and crystallization profiles and solid fat content, for POL-DAG, POoo and their binary blends were evaluated. The mid-infrared FTIR was used to determine the absorption bands of the different concentrations of the oil blends. Only slight differences of FAC and IV were observed. POL-DAG:POoo blends showed significant changes (p < 0.05) in DAG content and decreases in TAG content with increasing POL-DAG content. The DSC thermograms showed that the addition of different concentrations of POL-DAG changed the melting and crystallization behavior of the oil blends (POL-DAG:POoo). The crystallization onset point increased (p < 0.05) with an increasing POL-DAG concentration (10–90%). POL-DAG has the same absorption bands as POoo, with the exception of several minor peaks that appeared at (I) 2954 cm^− 1, (II) 1267 cm^− 1, (III) 1199 cm^− 1, (IV) 1222 cm^− 1 and (V) 966 cm^− 1. This study will provide essential information for the palm oil industry to identify the most suitable POL-DAG blends with desirable physicochemical properties for food application purposes.     

Preparation of specialty fats from beef tallow and canola oil by chemical interesterification: physico-chemical properties and bread applications of the products

Blends of beef tallow (BT)/canola oil (CO) (85:15, 65:35, w/w) were interesterified under the following conditions: 0.4% CH₃ONa, 60 °C, 30 min. Triacylglycerol (TAG) composition, polymorphic forms, crystal morphology, thermal properties, rheological properties and oxidative stability of the original and interesterified blends were evaluated. Chemical interesterification (CIE) caused a more balanced rearrangement of TAG species, reduction of trisaturated (S₃), triunsaturated (U₃) TAG content and increase in monosaturate-diunsaturated (SU₂) TAG content. X-ray diffraction (XRD) revealed that all the interesterified blends were exclusively double chain (2L) stacking β′ crystal. Thermal curves confirmed slight narrow melting and crystallization temperature ranges appearing in interesterified blends, mainly due to decreased S₃ and U₃ type TAGs and increased SU₂ after CIE. Rheological analysis showed that CIE led to dropping in both hardness, storage modulus (G′) and loss modulus (G″) of BT/CO blends. The oxidative stability of the interesterified fats, which was reduced compared with the substrate blends, was significantly improved using 0.02% TBHQ. A shortening and a margarine, both containing low trans were prepared by interesterified BT/CO 85:15, 65:35 blends, respectively, which were crystallized in a votator and tested in bread baking. The results of instrumental and sensory analyses showed similar acceptability of the two types of breads. The present study suggests that the interesterified fats fulfill the requirements of marketable bakery shortenings and margarines, respectively.     

Thermal behavior of concentrated oil-in-water emulsions based on soybean oil and palm kernel olein blends

Droplet size distribution and thermal behavior of concentrated oil-in-water emulsions based on soybean oil (SBO)/palm kernel olein (PKO) blends were investigated. The emulsions were prepared using 70% (wt./wt.) oil blends of SBO/PKO as dispersed phases and stabilized by egg yolk. An increase in PKO level (0–40% wt./wt.) in the oil dispersed phase volume fraction caused significant increases (p < 0.05) in volume-weighted mean diameter (d_4,3). The DSC data suggested that crystallization of the emulsions was induced by a ‘template effect’ of yolk constituents via a surface heterogeneous nucleation. Emulsions with 0–20% (wt./wt.) PKO levels in the dispersed phase demonstrated a good cool–heat stability even after three successive thermal cycles (from 50 °C to ?70 °C at 10 min/°C). After the first thermal cycle, emulsions with 30% and 40% PKO levels in the oil dispersed phase were destabilized due to strong coalescence and crystallized via volume-surface heterogeneous nucleation. The unstable emulsions were attributable to high level of saturated triacylglycerols from PKO, with high droplet size characteristic, causing them to be more prone to partial coalescence.     

In search of confectionary fat blends stable to heat: Hydrogenated palm kernel oil stearin with sorbitan monostearate

The potential of sorbitan monostearate (SMS) addition to change the basic-crystal-structure of a confectionary fat blend (CFB) with the aim to enhance its heat resistance was investigated. The CFB used in this study was a blend of hydrogenated palm kernel oil stearin, lecithin, polyglycerol polyricinoleate (PGPR) and cocoa butter. Samples made with different proportions of SMS to CFB were prepared and the crystal structure, the melting behaviour, the crystal morphology and crystallization kinetics were studied. Heat resistance was evaluated using a temperature-variable rheological method. Powder X-ray diffraction (XRD) studies in the wide angle region (WAXS) revealed the presence of two crystalline polymorphs (α and β′) in all blends. While XRD studies in the small angle region (SAXS) revealed a shift in the CFB peak position upon addition of SMS. The presence of two polymorphic forms was confirmed by differential scanning calorimetry (DSC), while a third endotherm was evident when the amount of SMS present in the system was greater than 40%. Studies on the nucleation and crystallization kinetics showed that crystal nucleation and growth occurred in two stages: SMS appeared first followed by CFB. Iso-solid diagrams constructed from the melting profiles obtained from SFC-temperature measurements indicated monotectic solution behaviour between SMS and the CFB.The microstructure, as observed under polarized light, changed from small crystals for the CFB to needles for mixtures with 10% SMS, to spherulites for mixtures with 50% SMS, to clusters for mixtures containing between 80 and 100% SMS. Cryo-TEM showed nanoplatelet formation for the CFB and nano-blobs for SMS. The storage modulus (G′) for mixtures containing 25% SMS decreased from G′ = 1.72 10⁷ ± 4.60 10⁶ Pa at 20 °C to G′ = 3.24 10⁵ ± 2.15 10⁴ Pa at 40 °C. Thus, SMS addition to confectionery fats can provide heat resistance to the CFB.     

The cooling rate effect on the microstructure and rheological properties of blends of cocoa butter with vegetable oils

The elasticity (G′) and yield stress (σ¹) of blends of cocoa butter (CB) in vegetable oils (i.e., 30% CB/canola and 30% CB/soybean oil) crystallized at temperatures (T_Cr) between 9.5 °C and 13.5 °C and two cooling rates (1 °C/min and 5 °C/min) were determined, evaluating their relationship with parameters associated with the formation and structural organization of the crystal network [i.e., solid fat content (SFC), Avrami index, crystallization rate, fractal dimension (D)]. The results showed that T_Cr and cooling rate had a different effect for each blend on the three-dimensional organization of the crystal network, and on the proportion and size of β′ and β crystals. Thus, under low supercooling conditions at both cooling rates, the crystallized CB/canola oil blend was formed by a mixture of small β′ and large β crystals that provided high G′ and σ¹ at low SFC (i.e., 20.5–20.9%) and D (i.e., 1.66–1.72) values. The CB/soybean oil blend achieved similar G′ and σ¹ independent of cooling rate only at high supercooling. In this case, the crystal network was formed mainly by small β′ crystals with SFC (i.e., 25.4–26.3%) and D (i.e., 2.86–2.79) values higher (P < 0.05) than in the CB/canola oil blend at low supercooling.     

Effect of cooling rate on lipid crystallization in oil-in-water emulsions

The effect of cooling rate on the destabilization of oil-in-water (o/w) emulsions was studied as a function of oil content (20% and 40% o/w), homogenization conditions, and crystallization temperatures (10, 5, 0, ?5 and ?10 °C). The lipid phase was a mixture of anhydrous milk fat and soybean oil, and whey protein was used as the emulsifier. Differential scanning calorimetry was used to analyze the crystallization and melting behaviors; while a vertical scan macroscopic analyzer measured the physicochemical stability. Slow cooling rate increased the stability of emulsions with 20% oil. In addition, slow cooling promoted the onset of crystallization and delayed crystal growth. These effects were more significant in emulsions formulated with 20% oil and formulated under processing conditions that resulted in bigger droplet sizes (～0.9 μm).     

Effects of flaxseed oil concentration on the performance of a soy protein isolate-based emulsion-type film

Biodegradable edible films have the potential to either replace or reduce the amount of synthetic packaging utilized by the food industry. The overall goal of this research was to investigate the effect of flax seed oil concentration (1–10%) on the mechanical, moisture barrier and swelling properties of soy protein isolate (SPI) (5.0% w/w SPI, 40% w/w glycerol) emulsion-based films. Film forming solutions showed a bimodal oil droplet distribution with peak sizes occurring at < 10 and ~ 100 μm. As the oil content increased, the size distribution shifted towards smaller droplet sizes. An equal size ratio was noted at the 5.0% oil content level. All film forming solutions were pseudoplastic in nature, where viscosity increased from 18 to 58 mPa (at 1 s^− 1) as a function of oil content (3% to 10%). Tensile strength of formed films reached a maximum at 5.35 MPa at the 5% w/w oil level, whereas tensile elongation increased from 11.3% to 22.2% with increasing oil content. Puncture strength and deformation, as well as water vapour permeability was relatively independent of the oil content. Moisture content and swelling properties of formed films were found to both decrease from 22.8% to 18.7%, and from 3114% to 1209%, respectively as the oil content was raised from 1 to 10%, and films became darker, redder and more yellow in colour as the percentage of flax seed oil increased.     

Crystallization of NaCl by fast evaporation of water in droplets of NaCl solutions

Excessive salt (NaCl) intake has been related to several diseases. Small salt crystals that rapidly dissolve in the oral cavity may decrease swallowing of untasted salt. The aim of this research was to evaluate the crystallization of salt as microcrystals by fast water evaporation from droplets of saline solutions within a hot oil phase. The effects of the oil temperature (150; 165 and 180 °C), droplet volume (17 and 42 μL) and brine concentration (15 and 26% w/v) were studied. Crystalline particles with mean sizes between 9 and 23 μm, and containing about 2% of remaining oil were obtained. The crystal size decreased by increasing the oil temperature, solution concentration and volume of the droplets. The dissolution rate of these microcrystals was more than 2 times faster than that of the original crystals. The microcrystals obtained could be added in surface-salted foods (snacks, salads) to optimize or reduce the sodium intake while maintaining saltiness perception.     

Oxidation kinetics of soybean oil/anhydrous milk fat blends: A differential scanning calorimetry study

The oxidation kinetics of soybean oil (SBO)/anhydrous milk fat (AMF) blends was studied by differential scanning calorimetry (DSC). Lipid blends containing 0–100% of SBO in AMF at 10% intervals were analyzed. Samples were heated in the DSC at different heating rates (2.5, 5.0, 7.5, 10.0 and 12.5 °C/min) and oxidation kinetics parameters from the Arrhenius equation (activation energy, pre-exponential factor and oxidation rate constant) were calculated using the Ozawa–Flynn–Wall method. Results show a significant increase in the oxidation rate (k) with temperatures for 60–90% SBO blends. The increase in k with SBO addition was only significant for 240 and 250 °C. A significant correlation between the rate constant and the chemical composition of the samples was not observed. This behavior suggests possible interactions among fatty acids present in the blends.     

Carotenoid transfer to oil during thermal processing of low fat carrot and tomato particle based suspensions

Carotenoid solubilization in the oil phase is a prerequisite for carotenoid bioaccessibility during digestion. However, the level of bioencapsulation and the hydrophobicity of carotenoids were proven to strongly affect their transfer to oil during in vitro digestion. Therefore, thermal processing (95–110 °C) was exploited to favor carotenoid transfer from tomato- and carrot-based fractions to the oil before digestion. Initially, the total (all-trans + cis) carotenoid content in the oil increased quickly, thereafter, depending on the temperature applied, either a drop or a plateau was reached at longer treatment times. Treatment conditions of > 100 °C for 10 min significantly favoured carotenoid transfer to oil (≥ 75%). The rates of transfer to oil were as follows: β-carotene ≈ α-carotene > lycopene. The results revealed that the cell wall hinders carotenoid transfer to oil during thermal processing. Overall, the results indicate that typical high temperature short time thermal processing can be sufficient to achieve maximal carotenoid transfer to oil with minimal degradation in real food systems/food emulsions and this can be crucial to improve the nutritional quality of carrot and tomato based products.     

Proximate composition,cholesterol and fatty acids profile of canned sardines (Sardinella brasiliensis) in soybean oil and tomato sauce

Different brands of sardines canned in soybean oil and tomato sauce, that are commercialized in Brazil, had their proximate composition, cholesterol content and fatty acids composition analyzed. Protein contents were equivalent to the values found for sardines in natura, ranging from 19.8 to 24.4%. High variations of the total lipids content (5.30–16.8%) were verified; the highest levels were found for sardines canned in soybean oil. The cholesterol content ranged from 50.4 to 65.1 mg/100 g. The highest levels of essential C18:2n − 6 and C18:3n − 3 fatty acids were found in sardines canned in soybean oil. The EPA (C20:5n − 3) and DHA (C22:6n − 3) concentrations ranged from 5.39 to 15.1% and from 3.89% to 9.51%, respectively, and the highest levels were observed in sardines canned in tomato sauce.     

Effect of high hydrostatic pressure (HHP) on crystal structure of palm stearin emulsions

High hydrostatic pressure (HHP) treatment was used to control the crystallization behavior of solid lipid nanoparticles stabilized with sodium caseinate (SC) and soy lecithin Phospholipon 80H (80H). Samples were pressurized at 100 and 500 MPa, at 10, 20 and 40 °C for 15 min. The stability of emulsions was analyzed by visual observation for gelation, and the change in the droplet size distribution using light scattering measurements after HHP treatment and storage for 28 days at 4 °C. The crystal micro-structure (i.e., solid lipid content and crystal morphology) were evaluated from differential scanning calorimetry (DSC) thermograms for melting enthalpies and temperatures. Initial droplet size (0.199 μm for 80H and 0.182 μm for SC) was not affected significantly (p > 0.05) either by HHP processing or storage. DSC results showed that pressure has a significant effect (p < 0.05) on the crystal polymorphs contents. Change in polymorphic content due to HHP treatment was approximately 50% at the first day of storage for all samples. Storage time was also found to be significantly effective (p < 0.05) on polymorphic structure and the change in polymorphic content was approximately 46% throughout the storage period. It was shown that HHP treatment can be used to control the crystal morphology of crystalline lipid droplets, which can serve as potential encapsulation systems for bioactive molecules.     

Effects of high intensity ultrasound and emulsifiers on crystallization behavior of coconut oil and palm olein

The objective of this research is to evaluate the crystallization behavior of coconut oil (CO) and palm olein (PO) as affected by the addition of two monoacylglycerols (MAG) emulsifiers and by the use of high intensity ultrasound (HIU). MAG with high content of palmitic, oleic, and linoleic acid (EM1) and MAG with high content of stearic acid and no unsaturated fatty acids (EM2) were used. Results show that the addition of emulsifiers did not affect crystallization kinetics of CO and similar solid fat contents (1.32 ± 0.94) (SFC) and melting enthalpies (5.90 ± 4.56) were obtained. The addition of EM1, however, significantly delayed the crystallization of PO as evidenced by a significantly lower SFC and melting enthalpy. SFC for PO was 8.56 ± 0.913 while SFC for PO + EM1 was 3.63 ± 1.38. Sonication induced the crystallization of CO samples crystallized with and without EM1 and EM2 while only induced the crystallization of PO + EM1 as measured with SFC. The induction in crystallization by HIU was also evidenced by higher enthalpy with values up to a range of 8 J/g to 11 J/g. A decrease in elasticity from 3.17 × 10⁶ to 2.52 × 10⁵ was observed in CO crystallized with emulsifiers which could be reverted by the application of HIU. Contrarily, the addition of emulsifiers increased elasticity of PO from 3.35 × 10² to 4.83 × 10⁴ and sonication did not affect these values significantly. Differences observed in elasticity values are attributed not only to the amount of solid material obtained but also to the type of microstructure of the crystalline network formed during crystallization.     

Lipase-catalyzed synthesis and characterization of flaxseed oil-based structured lipids

The biosynthesis of structured lipids (SLs) was carried out by the interesterification of flaxseed oil (FO) and tricaprylin (TC) in an organic solvent medium (OSM), using selected commercial lipases, including Amano DF, Novozym 435, Lipozyme TL-IM and Lipozyme RM-IM. The fatty acyl chains of the synthesized triacylglycerols (TAGs) were identified by atmospheric pressure chemical ionization/mass spectrometric (APCI/MS) analysis, while the fatty acid positional distribution of the MLM- and MML-SLs (M-medium and L-long chain fatty acids) was determined by silver-ion high-performance liquid chromatographic (Ag⁺/HPLC) analysis. The effects of reaction temperature (T_r, 30–50 °C), enzyme concentration (E_c, 0.5–4%, w/v), initial water activity (a_w, 0.05–0.43) and reaction time (R_t, 0–72 h) on the efficiency of the enzymes, were studied. The bioconversion yield (%) of the synthesized MLM- and MML-SLs was monitored under the established reaction parameters for each lipase. The maximum yield of MLM-SLs was obtained in the order, of Novozym 435 > Lipozyme TL-IM > Lipozyme RM-IM > Amano DF. Moreover, considering the ratio of the MLM- to MML-SLs produced by each enzyme, Novozym 435 and Lipozyme TL-IM were selected as the most effective enzymes for interesterification of FO and TC.     

On the fractional crystallization of palm olein: Solid solutions and eutectic solidification

In this contribution, the nature of particular crystal growth behavior observed in industrial dry fractionation of palm olein is further elucidated. Refined palm olein was prepared with three different concentrations of tripalmitoyl-glycerol (0.6%, 0.8% and 1%) and crystallized under stirring at 13, 15 and 17 °C to study the effect of internal seeding with tripalmitoyl-glycerol (PPP) on bulk crystallization properties. Notably at 15 °C, the increase in the solid fat content of the crystal suspension as function of time was heavily promoted by higher PPP-contents. The resulting crystals displayed a broad melting peak between 28 and 40 °C in DSC-measurements, which suggested the presence of a solid solution in a metastable form, mainly consisting of PPP and dipalmitoyl-oleoylglycerol (POP). SAXS-measurements supported this thesis by revealing long spacings with varying length, while short spacings obtained in WAXD consistently indicated the orthorhombic subcell of a β′-polymorph. The data suggest that the internal seeding effect of PPP in palm olein, as applied in industrial crystallization, in fact relies on substantial miscibility with POP, rather than on a heterogeneous nucleation effect resulting in two separate crystalline phases. The miscibility of PPP and POP then would result in a facilitated alignment of POP-molecules in the direction of the methyl end (or lamellar) plane and higher growth rates. Secondly, a peculiar change in crystal morphology could be consistently linked with the occurrence of a sharp melting peak at 24 °C in DSC, as well as with a substantial increase of the viscosity of the crystal suspension. This morphological shift concurred with an increased incorporation of palmitoyl-oleoyl-stearoylglycerol in the lattice, possibly giving rise to eutectic crystallization in lamellar crystal structures instead of the commonly observed dendritic crystals. The clarification of both phenomena provides a valuable, profound insight in the crystal growth step in the processing of edible oils.     

Sensory stability and oxidation of fish oil enriched milk is affected by milk storage temperature and oil quality

The experiments evaluated the influence of fish oil quality and cold storage temperature on the oxidative stability of milk emulsions containing 1.0% w/w milk fat and 0.5% w/w of either a pure fish oil or a fish oil:rapeseed oil mixture. The results showed that it was possible to produce a pasteurised milk product enriched with the important n-3 PUFA from fish oil with acceptable sensory characteristics if (1) the emulsions were based on a mixture of fish oil and rapeseed oil and (2) the initial peroxide value (PV) of the added oil blend was below 0.5 meq kg⁻¹. The sensory analysis showed a clear distinction between emulsions based on oil with PV 0.1 and 0.5 meq kg⁻¹, whereas the PV and the gas chromatographic (GC) analysis of volatile oxidation products were not sensitive enough to reveal these differences clearly. The GC analyses showed that the onset of formation of the volatiles was earlier with increased storage temperature in the range of 2–9 °C.     

Factors affecting the rheological properties of a structured cellular solid used as a fat mimetic

The effects of water content, monoglyceride chain length and concentration, oil type, and the addition of oil-phase and water-phase additives on the elastic modulus and yield stress of a structured oil in water were evaluated. The goal was to increase the elastic modulus of the original emulsion from 8.42 × 10³ ± 11.3 Pa to 1.55 × 10⁶ ± 2.1 × 10⁵ Pa, and the yield stress from 112 ± 2.31 Pa to 835 ± 227 Pa. The addition of wax at greater than 10% (w/w), the use of palm oil or the gelation of the liquid oil phase with 5–7.5% rice bran wax, the use of C-18 saturated monoglyceride at 6%(w/w), and 4% (w/w) for C-22 saturated monoglyceride molecules were effective modifications capable of improving the mechanical behavior of the emulsion so that it can be used as a zero trans and reduced saturated fat laminating shortening substitute for puff pastry products.     

Phospholipids determination in vegetable oil by thin-layer chromatography and imaging densitometry

A rapid reliable method was developed to measure vegetable oil phospholipid content by thin-layer chromatography–imaging densitometry. Phospholipid samples were obtained from crude soybean oil by water degumming and then analyzed and quantified by thin-layer chromatography and imaging densitometry. Phosphatidyl choline (PC), phosphatidyl ethanolamine (PE) and phosphatidyl inositol (PI) standard curves were generated. The total phospholipid content of the oil was 1.12–1.26%, of which 27.1 ± 1.86% was PC, 22.7 ± 0.45% was PE, while PI accounted for 17.2 ± 0.85% of the total. A high correlation coefficient of 0.985 was found for reproducibility of pixel area (OD*mm) at a constant concentration of standard phospholipid. Regression analysis of the pixel area vs the phospholipid (PC, PE, and PI) weights (μg) generated R² greater than 0.983. Thin-layer chromatography–imaging densitometry proved a useful tool for rapid determination and quantification of the major phospholipids in soybean oil.