Showing papers in "Journal of the American Oil Chemists' Society in 2009"
TL;DR: The melting point of a pure fatty acid or ester as determined by differential scanning calorimetry can vary up to approximately 1 °C compared to data in prior literature as mentioned in this paper, which plays a significant role in determining possible applications.
Abstract: The melting point is one of the most important physical properties of a chemical compound and it plays a significant role in determining possible applications. For fatty acid esters the melting point is essential for a variety of food and non-food applications, the latter including biodiesel and its cold-flow properties. In this work, the melting points of fatty acids and esters (methyl, ethyl, propyl, butyl) in the C8–C24 range were determined by differential scanning calorimetry (DSC), many of which for the first time. Data for triacylglycerols as well as ricinoleic acid and its methyl and ethyl esters were also acquired. For some compounds whose melting points have been previously reported, data discrepancies exist and a comprehensive determination by DSC has not been available. Variations in the present data up to several °C compared to data in prior literature were observed. The melting points of some methyl-branched iso- and anteiso-acids and esters were also determined. Previously unreported systematic effects of compound structure on melting point are presented, including those for ω-9 monounsaturated fatty acids and esters as well as for methyl-branched iso and anteiso fatty acids and esters. The melting point of a pure fatty acid or ester as determined by DSC can vary up to approximately 1 °C. Other thermal data, including heat flow and melting onset temperatures are briefly discussed.
338 citations
TL;DR: A study on the commercial virgin coconut oil (VCO) available in the Malaysian and Indonesian market was conducted in this paper, which reported the chemical characteristics and fatty acid composition of VCO.
Abstract: A study on the commercial virgin coconut oil (VCO) available in the Malaysian and Indonesian market was conducted. The paper reported the chemical characteristics and fatty acid composition of VCO. There was no significant difference in lauric acid content (46.64–48.03%) among VCO samples. The major triacylglycerols obtained for the oils were LaLaLa, LaLaM, CLaLa, LaMM and CCLa (La, lauric; C, capric; M, myristic). Iodine value ranged from 4.47 to 8.55, indicative of only few unsaturated bond presence. Saponification value ranged from 250.07 to 260.67 mg KOH/g oil. The low peroxide value (0.21–0.57 mequiv oxygen/kg) signified its high oxidative stability, while anisidine value ranged from 0.16 to 0.19. Free fatty acid content of 0.15–0.25 was fairly low, showing that VCO samples were of good quality. All chemical compositions were within the limit of Codex standard for edible coconut oil. Total phenolic contents of VCO samples (7.78–29.18 mg GAE/100 g oil) were significantly higher than refined, bleached and deodorized (RBD) coconut oil (6.14 mg GAE/100 g oil). These results suggest that VCO is as good as RBD coconut oil in chemical properties with the added benefit of being higher in phenolic content.
292 citations
TL;DR: In this article, the thermal behavior, crystal structure, and crystal morphology of rice bran wax (RBX) in bulk and oil-wax mixtures, and to compare them with those of carnauba wax (CRX) and candellila wax (CLX), were examined.
Abstract: Differential scanning calorimetry (DSC), optical microscopy, and X-ray diffraction (XRD) were used to examine the thermal behavior, crystal structure, and crystal morphology of rice bran wax (RBX) in bulk and oil–wax mixtures, and to compare them with those of carnauba wax (CRX) and candellila wax (CLX). The RBX employed in the present study was separated from rice bran oil by winterization, filtration, refinement, bleaching, and deodorization. The RBX crystals melted in the bulk state at 77–79 °C with ΔH
melting = 190.5 J/g, which is quite large compared with CLX (129 J/g) and CRX (137.6 J/g). XRD data of the RBX crystals revealed O⊥ subcell packing and a long spacing value of 6.9 nm. Thin long needle-shaped crystals were observed in the mixtures of RBX and liquid oils [olive oil and salad oil (canola:soy bean oil = 50:50)]; therefore, the dispersion of RBX crystals in these liquid oils was much finer than that of CRX and CLX crystals. Organogels formed when the mixture of every plant wax and liquid oil was melted at elevated temperature and cooled to ambient temperature. However, the mixture of RBX and olive oil at a concentration ratio of 1:99 wt.% formed an organogel at 20 °C, whereas the lowest concentration necessary for CRX to form an organogel in olive oil was 4 wt.% and that for CLX was 2 wt.%. Observation of the rate of gel formation using DSC and viscosity measurements indicated that the gel structure formed soon after RBX crystallized, whereas a time delay was observed between the organogel formation and wax crystallization of CRX and CLX. These results demonstrate RBX’s good organogel-forming properties, mostly because of its fine dispersion of long needle like crystals in liquid oil phases.
241 citations
TL;DR: In this paper, French fries were fried intermittently in canola oil that was heated for 7 h daily over seven consecutive days, and the changes in regular canola oils as affected by frying temperature were studied.
Abstract: The changes in regular canola oil as affected by frying temperature were studied. French fries were fried intermittently in canola oil that was heated for 7 h daily over seven consecutive days. Thermo-oxidative alterations of the oil heated at 185 ± 5 or 215 ± 5 °C were measured by total polar components (TPC), anisidine value (AV), color components formation, and changes in fatty acid composition and tocopherols. Results showed that TPC, AV, color and trans fatty acid content increased significantly (P < 0.05) as a function of frying temperature and time. The oil polyunsaturated fatty acids (PUFA) decreased in direct proportion to frying temperature and time. After 7 days of frying, the amount of PUFA was reduced by half and the trans isomers contribution increased 2.5 times during frying at 215 °C. Of the parameters assessed, total polar component and color had the highest correlation, with correlation coefficients of 0.9650 and 0.9302 for frying at 215 and 185 °C, respectively. TPC formation correlated inversely with the reduction of tocopherols.
204 citations
TL;DR: In this paper, two or more antioxidants which increase the oxidative stability of the biodiesel fuel are discussed. But the authors do not specify which are the ones with improved oxidative stability.
Abstract: Disclosed are biodiesel fuels with improved oxidative stability. Disclosed are biodiesel fuels which comprise two or more antioxidants which increase the oxidative stability of the biodiesel fuel.
155 citations
TL;DR: In this paper, the authors show that combining coconut oil with other vegetable oils provides medium chain fatty acids and oxidative stability to the blends, while coconut oil will be enriched with polyunsaturates, monounsaturates and natural antioxidants.
Abstract: Coconut (Cocos nucifera) contains 55–65% oil, having C12:0 as the major fatty acid. Coconut oil has >90% saturates and is deficient in monounsaturates (6%), polyunsaturates (1%), and total tocopherols (29 mg/kg). However, coconut oil contains medium chain fatty acids (58%), which are easily absorbed into the body. Therefore, blends of coconut oil (20–80% incorporation of coconut oil) with other vegetable oils (i.e. palm, rice bran, sesame, mustard, sunflower, groundnut, safflower, and soybean) were prepared. Consequently, seven blends prepared for coconut oil consumers contained improved amounts of monounsaturates (8–36%, p < 0.03), polyunsaturates (4–35%, p < 0.03), total tocopherols (111–582 mg/kg, p < 0.02), and 5–33% (p < 0.02) of DPPH (2,2-diphenyl-1-picrylhydrazyl free radicals) scavenging activity. In addition, seven blends prepared for non-coconut oil consumers contained 11–13% of medium chain fatty acids. Coconut oil + sunflower oil and coconut oil + rice bran oil blends also exhibited 36.7–89.7% (p < 0.0005) and 66.4–80.5% (p < 0.0313) reductions in peroxide formation in comparison to the individual sunflower oil and rice bran oil, respectively. It was concluded that blending coconut oil with other vegetable oils provides medium chain fatty acids and oxidative stability to the blends, while coconut oil will be enriched with polyunsaturates, monounsaturates, natural antioxidants, and a greater radical scavenging activity.
127 citations
TL;DR: In this paper, several fatty acid alkyl esters were subjected to accelerated methods of oxidation, including Rancimat method and pressurized differential scanning calorimetry (PDSC), and structural trends elucidated from both methods that improved oxidative stability included decreasing the number of double bonds, introduction of trans as opposed to cis unsaturation, location of unsaturation closer to the ester head group and elimination of hydroxyl groups.
Abstract: Several fatty acid alkyl esters were subjected to accelerated methods of oxidation, including EN 14112 (Rancimat method) and pressurized differential scanning calorimetry (PDSC). Structural trends elucidated from both methods that improved oxidative stability included decreasing the number of double bonds, introduction of trans as opposed to cis unsaturation, location of unsaturation closer to the ester head group, and elimination of hydroxyl groups. Also noticed with EN 14112 was an improvement in oxidative stability when a larger ester head group was utilized. Methyl esters that contained ten or less carbons in the fatty acid backbone were unacceptable for analysis at 110 °C (EN 14112) due to excessive sample evaporation. With respect to PDSC, a correlation was noticed in which the oxidation onset temperature (OT) of saturated fatty esters increased with decreasing molecular weight (R2 0.7328). In the case of the monounsaturates, a very strong inverse correlation was detected between molecular weight and OT (R2 0.9988), which was in agreement with EN 14112. Lastly, a strong direct correlation (R2 0.8759) was elucidated between OT and oil stability index (OSI, EN 14112, 80 °C). The correlation was not as strong (R2 0.5852) between OSI obtained at 110 °C and OT.
121 citations
TL;DR: In this paper, the authors examined the effectiveness of primary antioxidants from combinations of butylated hydroxyanisole (BHA), propyl gallate (PG), pyrogallol (PY) and tert-butyl hydroquinone (TBHQ) to increase oxidative stability.
Abstract: Biodiesel is an alternative fuel composed of saturated and unsaturated methyl ester fatty acids that is very prone to oxidation attack. Exposure to air, heat, light, and metallic contaminants can lead to autoxidation, and the degradation of fuel properties such as kinematic viscosity and total acid number. This study examines the effectiveness of blends of primary antioxidants from combinations of butylated hydroxyanisole (BHA), propyl gallate (PG), pyrogallol (PY) and tert-butyl hydroquinone (TBHQ) to increase oxidative stability. Results indicate that binary antioxidant formulations: TBHQ:BHA, TBHQ:PG and TBHQ:PY were most effective at 2:1, 1:1, 2:1 weight ratio, respectively in both distilled soybean oil- (DSBO) and distilled poultry fat- (DPF) based biodiesel. Antioxidant activity increased as the loadings were increased. The synergisms of the antioxidant pairs were different with different biodiesel types, suggesting a dependence on the fatty acid methyl ester (FAME) composition. The best synergistic effect was observed with the TBHQ:BHA blends while the best stabilization factors (SF) were achieved by using the TBHQ:PY blends. Quantification of antioxidant content in stored biodiesel with TBHQ:PY blend demonstrates that the main factor of synergy is the regeneration of PY by TBHQ.
119 citations
TL;DR: In this article, three soy-based polyols intended for application in polyurethanes were prepared by ring opening the epoxy groups in epoxidized soybean oil (ESO, 0.385 mol/100 g epoxy rings) with methanol, 1, 2-ethanediol and 1,2-propanediol in the presence of tetrafluoroboric acid catalyst.
Abstract: Three soy-based polyols intended for application in polyurethanes were prepared by ring opening the epoxy groups in epoxidized soybean oil (ESO, 0.385 mol/100 g epoxy rings) with methanol, 1,2-ethanediol and 1,2-propanediol in the presence of tetrafluoroboric acid catalyst. The effect of the different opening reaction reagents, different low molecular weight alcohols, on the polyols was investigated by spectroscopic, chemical and physical methods. The viscosities, viscous-flow activation energies, molecular weight and melting point of the samples increased in the following order: polyol (3) > polyol (2) > polyol (1) > ESO [polyol (1); polyol (2) and polyol (3) represented the samples synthesized from the same epoxidized soybean oil generated by opening reactions with methanol, 1,2-ethanediol and 1,2-propanediol, respectively]. All the samples were crystalline solids below their melting temperature, displaying multiple melting point peaks. Compared with polyol (1), polyol (2) had a primary hydroxyl group, promoting the reactive activity of the polyol with isocyanates; polyol (3) contained large numbers of hydroxy groups, improving the properties of polyurethanes.
118 citations
TL;DR: In this paper, the phorbol esters present in Jatropha curcas oil were quantified in the fractions obtained at different stages of oil pre-treatment and biodiesel production.
Abstract: Phorbol esters present in Jatropha curcas oil are toxic when consumed and are co-carcinogens. These could be a potential constraint in the widespread acceptance of Jatropha oil as a source of biodiesel. Phorbol esters were quantified in the fractions obtained at different stages of oil pre-treatment and biodiesel production. During degumming some phorbol esters were removed in the acid gums and wash water. This implies that the use of these acid gums in animal feed is not possible and care should be taken when disposing the wash water into the environment. Silica treatment did not decrease the phorbol esters, while stripping/deodorization at 260 °C at 3 mbar pressure with 1% steam injection completely degraded phorbol esters. Phorbol esters were not detected in stripped oil, fatty acid distillate, transesterified oil (biodiesel) and glycerine. The presence of possibly toxic phorbol ester degradation products in these fractions could not be ruled out.
116 citations
TL;DR: In this article, the effects of heat and UV exposure on the degradation of free α-tocopherol (oil form) and dissolved in methanol and hexane were measured.
Abstract: The effects of heat and UV exposure on the degradation of free α-tocopherol (oil form), α-tocopherol dissolved in methanol, and α-tocopherol dissolved in hexane were measured. Results showed that degradation of free α-tocopherol due to heat followed first order kinetics, with the samples held at 180 °C showing the greatest degradation rate. Free α-tocopherol degraded faster at high temperatures than dissolved α-tocopherol. In contrast, free α-tocopherol did not degrade when exposed to UV light for as long as 6 h, but the hexane and methanol samples degraded significantly as a matter of time. The α-tocopherol dissolved in hexane and methanol degraded by 20 and 70%, respectively over this time span. A mechanism for degradation of α-tocopherol was proposed to explain the higher degradation rate of α-tocopherol in methanol, as compared to hexane for times longer than 180 min. Knowledge of degradation kinetics of pure α-tocopherol as a result of temperature or exposure to UVA light whether in free or dissolved form is critically needed to understand how different processing parameters affect the amount of α-tocopherol during extraction, stabilization, storage or encapsulation processes.
TL;DR: In this article, the effect of pretreating defatted soy flakes with ultrasound on soy protein isolate (SPI) yield and functionality was investigated, and the results showed that the loss of the protein native state could be explained by the increased sonication time and power.
Abstract: This study aimed to determine the effect of pretreating defatted soy flakes with ultrasound on soy protein isolate (SPI) yield and functionality. Defatted soy flakes dispersed into water (16%, w/w) were sonicated for 30, 60 and 120 s at ultrasonic amplitudes of 21 and 84 µmpp (peak to peak amplitude in µm), representing low and high power, respectively. The power densities were 0.30 and 2.56 W mL−1, respectively. The SPI yield increased by 13 and 34%, after sonication for 120 s at low and high power, respectively. The sonication of defatted soy flakes for 120 s at the higher power level improved the SPI solubility by 34% at pH 7.0, while decreasing emulsification and foaming capacities by 12 and 26%, respectively, when compared to control SPI. Rheological behavior of the SPI was also modified with significant loss in consistency coefficient due to sonication. Some of these results could be explained by the loss of the protein native state with increased sonication time and power.
TL;DR: In this paper, the authors compared a high temperature/pressure extraction method (accelerated solvent extraction) (ASE) and a modified Folch extraction (MFF) with regard to their ability to extract total oil from three algae samples from the treatment of dairy manure effluent.
Abstract: Increasing interest in the coupling of biological wastewater treatment processes with the generation of value-added products (such as oil containing ω-3 fatty acids (FA)) has stimulated efforts in adapting extraction methods for treatment byproducts. This study's objective was to compare a high temperature/pressure extraction method (accelerated solvent extraction) (ASE) and a manual extraction method (modified Folch extraction) with regard to their ability to extract total oil from three algae samples from the treatment of dairy manure effluent. The efficiency of total oil and FA extraction with three solvents (chloroform/methanol, isopropanol/hexane, and hexane) was also evaluated using the ASE method. Results showed that the ASE method yielded higher values for total oil content compared to the Folch method but similar values for FA content and composition after four extraction cycles with chloroform/methanol. However, the ASE method yielded much higher amounts of FA in the first cycle (85-95% of total extracted) compared to the Folch method (44-55% of total extracted in the first cycle). As expected, the extraction efficiency of the ASE method for FA was dependent on the extraction solvent. FA content values using ASE with chloroform/methanol > isopropanol/hexane > hexane. FA content values using the Folch method or ASE with chloroform/methanol were not significantly influenced by sample particle size within the size range of 0.1-1 mm.
TL;DR: In this article, wild mustard (Brassica juncea L.) oil is evaluated as a feedstock for biodiesel production and a standard transesterification procedure with methanol and sodium methoxide catalyst is used.
Abstract: Wild mustard (Brassica juncea L.) oil is evaluated as a feedstock for biodiesel production. Biodiesel was obtained in 94 wt.% yield by a standard transesterification procedure with methanol and sodium methoxide catalyst. Wild mustard oil had a high content of erucic (13(Z)-docosenoic; 45.7 wt.%) acid, with linoleic (9(Z),12(Z)-octadecadienoic; 14.2 wt.%) and linolenic (9(Z),12(Z),15(Z)-octadecatrienoic; 13.0 wt.%) acids comprising most of the remaining fatty acid profile. The cetane number, kinematic viscosity, and oxidative stability (Rancimat method) of the methyl esters was 61.1, 5.33 mm2 s−1 (40 °C) and 4.8 h (110 °C), respectively. The cloud, pour and cold filter plugging points were 4, −21 and −3 °C, respectively. Other properties such as acid value, lubricity, free and total glycerol content, iodine value, Gardner color, specific gravity, as well as sulfur and phosphorous contents were also determined and are discussed in light of biodiesel standards ASTM D6751 and EN 14214. Also reported are the properties and composition of wild mustard oil, along with identification of wild mustard collected in Brazil as Brassica juncea L. (2n = 36) as opposed to the currently accepted Sinapis arvensis L. (2n = 18) classification. In summary, wild mustard oil appears to be an acceptable feedstock for biodiesel production.
TL;DR: The use of enzymes in aqueous vegetable oilseed extraction for simultaneous recovery of high quality oil and protein is gaining recognition as discussed by the authors, where five enzyme preparations [Protex 7L by Genencor (Rochester, NY USA), Alcalase 2.4L, and Viscozyme L by Novozymes (Bagsvaerd, Denmark), Natuzyme by Bioproton Pty Ltd (Australia), and Kemzyme by Kemin Europa N·V. (Belgium)] were studied to evaluate their effects on the extraction of oil
Abstract: The use of enzymes in aqueous vegetable oilseed extraction for simultaneous recovery of high quality oil and protein is gaining recognition. In the present work, five enzyme preparations [Protex 7L by Genencor (Rochester, NY USA), Alcalase 2.4L, and Viscozyme L by Novozymes (Bagsvaerd, Denmark), Natuzyme by Bioproton Pty Ltd (Australia) and Kemzyme by Kemin Europa N·V. (Belgium)] were studied to evaluate their effects on the extraction of oil and protein from sunflower seeds. Preliminary experiments were conducted for the selection of enzymes, optimum enzyme concentration, incubation time and pH. Maximum oil yield (87.25% of the total oil in the seed) was obtained with Viscozyme L, whereas, Protex 7L offered the highest level of protein in the aqueous phase. The comparison of the quality attributes of enzyme-assisted aqueous extracted (EAAE) oil with those of solvent-extracted and control (oils extracted without enzyme treatment) oils revealed no significant (P > 0.05) variations for iodine value, density, refractive index, unsaponifiable matter, and fatty acid composition among the extraction methods. The control and EAAE oils also exhibited a better oxidation state. The tocopherol concentration for the oils, produced with the enzymes, was noted to be quite improved relative to the control and solvent-extracted oils. A higher antioxidant activity in terms of total phenolic contents, 2,2′-diphenyl-1-picrylhydrazyl scavenging capacity and inhibition of linoleic acid peroxidation was also observed for the EAAE oils as against control and the solvent-extracted oils.
TL;DR: In this article, Fourier transform infrared (FTIR) spectroscopy was used for the determination of adulterants in cod-liver oil and a chemometrics partial least squares (PLS) calibration model was developed for quantitative measurement of the adulterant.
Abstract: Analysis of the adulteration of cod-liver oil with much cheaper oil-like animal fats has become attractive in recent years. This study highlights an application of Fourier transform infrared (FTIR) spectroscopy as a nondestructive and fast technique for the determination of adulterants in cod-liver oil. Attenuated total reflectance measurements were made on pure cod-liver oil and cod-liver oil adulterated with different concentrations of lard (0.5–50% v/v in cod-liver oil). A chemometrics partial least squares (PLS) calibration model was developed for quantitative measurement of the adulterant. Discriminant analysis method was used to classify cod-liver oil samples from common animal fats (beef, chicken, mutton, and lard) based on their infrared spectra. Discriminant analysis carried out using seven principal components was able to classify the samples as pure or adulterated cod-liver oil based on their FTIR spectra at the selected fingerprint regions (1,500–1,030 cm−1).
TL;DR: In this article, the binary and ternary blends of canola oil with the POO, OLO, and COO were used to fry potato pieces at 180 °C.
Abstract: The fatty acid composition, peroxide value (PV), acid value (AV), iodine value (IV), total tocopherols (TT) content, and total phenolics (TP) content of canola oil (CAO), palm olein oil (POO), olive oil (OLO), corn oil (COO), and the binary and ternary blends of the CAO with the POO, OLO, and COO were determined. The blends were prepared in the volume ratios of 75:25 (CAO/POO, CAO/OLO, CAO/COO) and 75:15:10 (CAO/POO/OLO, CAO/POO/COO). The CAO and its blends were used to fry potato pieces (7.0 × 0.5 × 0.3 cm) at 180 °C. During the frying process, the total polar compounds (TPC) content, AV, oil/oxidative stability index (OSI), and color index (CI) of the CAO/blends were measured. In general, frying stability of the CAO was significantly (P < 0.05) improved by the blending, and the frying performance of the ternary blends was found to be better than that of the binary blends.
TL;DR: In this article, 31P NMR analysis of samples prepared in a sodium cholate detergent system was assessed as a method for the quantitative measurement of dairy phospholipids.
Abstract: 31P NMR analysis of samples prepared in a sodium cholate detergent system was assessed as a method for the quantitative measurement of dairy phospholipids. Major phospholipid (PL) classes measured included: phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI), sphingomyelin (SM) and dihydrosphingomyelin (DHSM). The 31P NMR method was validated by comparison with a quantitative two-dimensional thin-layer chromatography (2D-TLC) technique. The 2D-TLC system was more sensitive, able to detect some minor compounds not observed by 31P NMR. However, 31P NMR is more suited to routine analysis, with sample analysis taking 36 min. The method was also more versatile and sample analysis was possible on high phospholipid containing materials without prior lipid extraction (e.g. buttermilk protein concentrate, beta serum liquid).
TL;DR: In this article, five samples of buriti oil from industrial and artisanal suppliers were characterized in terms of nutritional quality parameters (nutraceutical levels) and acidity, and the results showed that the artisanal samples showed lower acidity and higher levels of carotenes and tocols (tocopherols and tocotrienols).
Abstract: Five samples of buriti oil from industrial and artisanal suppliers were characterized in terms of nutritional quality parameters (nutraceutical levels) and acidity. As a first screening, each sample was analyzed by titration, spectrophotometry and an HPLC method, and the results were compared. As expected, artisanal samples showed lower acidity and higher levels of carotenes and tocols (tocopherols and tocotrienols). A blend of industrial and artisanal samples in suitable proportions was completely characterized in terms of analytical and physico-chemical properties, i.e., fatty acid composition, iodine value, partial and total acylglycerol contents, refractive index (40 °C), saponification value, unsaponifiable matter, acidity (expressed as % of oleic acid), peroxide value, phosphorus content, oil stability index, tocol and carotene concentrations. The results of the present study showed that buriti oil is a valuable source of monounsaturated fatty acids, and vitamins A and E. No previous work in the literature has analyzed buriti oil to this extent. The chromatographic method using HPLC was effective in qualifying and quantifying tocopherols, tocotrienols and carotenes.
TL;DR: In this article, a visible Raman spectroscopic method for determining the free fatty acid (FFA) content of extra virgin olive oil with the aid of multivariate analysis was introduced.
Abstract: We introduce a visible Raman spectroscopic method for determining the free fatty acid (FFA) content of extra virgin olive oil with the aid of multivariate analysis. Oleic acid was used to increase the FFA content in extra virgin olive oil up to 0.80% in order to extend the calibration span. For calibration purposes, titration was carried out to determine the concentration of FFA for the investigated oil samples. As calibration model for the FFA content (FFA%), a partial least squares (PLS) regression was applied. The accuracy of the Raman calibration model was estimated using the root mean square error (RMSE) of calibration and validation and the correlation coefficient (R
2) between actual and predicted values. The calibration curve of actual FFA% obtained by titration versus predicted values based on Raman spectra was established for different spectral regions. The spectral window (945–1600 cm−1), which includes carotenoid bands, was found to be a useful fingerprint region being statistically significant for the prediction of the FFA%. High R
2 and small RMSE values for calibration and validation could be obtained, respectively.
TL;DR: In this paper, it was shown that the amount and type of products formed during thermo-oxidative degradation is affected by temperature and time, and the amount of intact phytosterols decreased when temperature and temperature increase.
Abstract: Oxidative degradation of cholesterol has been extensively researched, however, not all products formed have been established. When a phytosterols standard was heated at 60, 120 and 180 °C for different period of time the following groups of components were detected: oxidized phytosterols, fragmented phytosterol molecules, volatile compounds and oligomers. Taking into account all the components formed, we were able to balance the amounts of disappearing sterols with components formed. We established that the amount and type of products formed during thermo-oxidative degradation is affected by temperature and time. The amount of intact phytosterols decreased when temperature and time increase. The amount of oxidized phytosterols was at the highest level when a temperature of 120 °C was applied, whereas the lowest amounts were observed when a temperature of 60 °C was used. At a temperature of 180 °C the amount of oxidized sterols was lower than at 120 °C and it decreased when the heating time was increased. This indicates that oxidized sterols were the main precursors involved in the formation of other components during thermo-oxidative degradation. The amount and type of volatile compounds formed increased when time and temperature increased. We observed diversified groups of volatile compounds formed and most of them are defined as off-flavor compounds for rancid oils.
TL;DR: The extracted oil from milk thistle seeds are rich in essential fatty acids, sterols and vitamin E and can be an attractive candidate for use in food preparation mixed with other vegetable oils or alone.
Abstract: In this study, fatty acids, phytosterol classes and tocopherols composition of Milk thistle seeds oil were determined at four varieties grown in Ardebil-Iran. The four varieties consisted of two modified foreign varieties—Budakalaszi (originally from Hungary) and the CN-seed variety (originally from England) and two native varieties, namely Khoreslo and Babak Castle. The oil content of the seeds ranged from 26 to 31%. Among the fatty acids, linoleic acid had the highest percentage (50–54%) followed by oleic acid (23–29%) and palmitic acid (7–8%). This is the first detailed report on the phytosterol classes of milk thistle seeds oil. The 4-Desmethylsterol class was predominant (1,800–2,200 μg/g) followed by 4,4′-dimethylsterols (50–85 μg/g) and 4-monomethylsterols (26–35 μg/g). The α-, β-, γ-, and δ-tocopherols ranged from 187 to 465, 10 to 51, 9 to 12, and 18 to 80 μg/g oil, respectively. Based on the results obtained, the extracted oil from milk thistle seeds are rich in essential fatty acids, sterols and vitamin E and can be an attractive candidate for use in food preparation mixed with other vegetable oils or alone.
TL;DR: In this article, the authors studied o/w organogels on different length scales to describe and understand their micro-structural features, and found that needle-like structures are formed out of the oil phase into the continuous water phase.
Abstract: Organogels based on edible oils and specific mixtures of phytosterols can serve as structured systems with a low saturated fat content. These low-SAFA organogels can be used also to create o/w emulsions. Little is known about the structures formed in these specific organogels and at the emulsion interface. We studied o/w organogels on different length scales to describe and understand their micro-structural features. Very basic processing conditions such as composition, temperature and storage time were taken into account. Two different types of structure were observed; at the smallest scale, long thin crystals are formed out of the oil phase into the continuous water phase. We propose that these are needle-like crystals. Next, tube-like structures are identified and can be visualized as tubular micelles. A model is proposed which fits the dimension (~7 nm) with the length scale of the molecular building blocks (TAGs and sterols). As edible fats from food products are enzymatically hydrolyzed in the gut prior to absorption, we also looked into the impact on the lipase reaction speed. Simple in vitro enzymatic hydrolysis experiments showed a slower enzymatic digestion. Organogel systems and emulsion made thereof have interesting food structuring properties with possible advantages in composition (low SAFA) and digestion speed.
TL;DR: Principal component analysis of data points in the carbonyl-region showed that there were also differences in the level and regiospecific distribution of monounsaturated/saturated fatty acids, which made it possible to distinguish oils of these three species solely from thecarbonyl region of 13C-NMR spectra.
Abstract: The aim of this study was to use 13C-nuclear magnetic resonance (NMR) regiospecific analyses of triacylglycerols to distinguish fish oils from different fish species for authentication purposes. 13C-NMR data of muscle lipids from Atlantic salmon (Salmo salar L.), mackerel (Scomber scombrus) and herring (Clupea harengus) were obtained, and the distribution of omega-3 polyunsaturated fatty acids between the sn-1,3 and sn-2 glycerol chains calculated from the carbonyl region. The results show that there were significant differences in the sn-2 position specificity of the fatty acids 22:6n-3, 20:5n-3 and 18:4n-3 among the species investigated. The most pronounced difference was that herring had a higher proportion of its 22:6n-3 in the sn-2 position compared to the two other species. Principal component analysis of data points in the carbonyl-region showed that there were also differences in the level and regiospecific distribution of monounsaturated/saturated fatty acids, which made it possible to distinguish oils of these three species solely from the carbonyl region of 13C-NMR spectra.
TL;DR: In this article, an efficient binary solvent mixture for monoacylglycerol (MAG) synthesis by enzymatic glycerolysis of soybean oil was selected, which can avoid the risk of crystallization in practical operations.
Abstract: The present study was aimed at selecting an efficient binary solvent mixture for monoacylglycerol (MAG) synthesis by enzymatic glycerolysis of soybean oil. Solvent combinations of tert-butanol/isopropanol (v/v) at different ratios were studied. Of the investigated cases, tert-butanol:isopropanol at ratio 80:20 was the most suitable organic medium. The optimum conditions for MAG synthesis under the selected mixture were: water 10 wt% based on glycerol, Lipozyme TL IM 15 wt% based on oil and glycerol, weight ratio of solvent to oil 4:1, and molar ratio of glycerol to oil 3.5:1. Under these conditions with a 4-h reaction, the yield of MAG was 72.0% where the triacylglycerol (TAG) content was reduced to only 1.0% (based on acylglycerols). Fatty acid ester (FAE) formation from the solvents was very low in the final product (1.3% based on reaction mixture). The selected binary solvent mixture has good physical properties with low melting point (−26.5 °C), which can avoid the risk of crystallization in practical operations.
TL;DR: Two-stage countercurrent EAEP was evaluated for extracting oil, protein and solids from soybeans using a solids-to-liquid ratio of 1:5-1:6 (extruded flakes/water).
Abstract: Enzyme-assisted aqueous extraction processing (EAEP) is an increasingly viable alternative to hexane extraction of soybean oil. Although considered an environmentally friendly technology where edible oil and protein can be simultaneously recovered, this process employs much water and produces a significant amount of protein-rich aqueous effluent (skim). In standard EAEP, highest oil, protein and solids yields are achieved with a single extraction stage using 1:10 solids-to-liquid ratio (extruded flakes/water), 0.5% protease (wt/g extruded flakes), pH 9.0, and 50 °C for 1 h. To reduce the amount of water used, two-stage countercurrent EAEP was evaluated for extracting oil, protein and solids from soybeans using a solids-to-liquid ratio of 1:5–1:6 (extruded flakes/water). Two-stage countercurrent EAEP achieved higher oil, protein and solids extraction yields than using standard EAEP with only one-half the usual amount of water. Oil, protein and solids yields up to 98 and 96%, 92 and 87%, and 80 and 77% were obtained when using two-stage countercurrent EAEP (1:5–1:6) and standard single-stage EAEP (1:10), respectively. Recycling the second skim obtained in two-stage countercurrent EAEP enabled reuse of the enzyme, with or without inactivation, in the first extraction stage producing protein with different degrees of hydrolysis and the same extraction efficiency. Slightly higher oil, protein and solids extraction yields were obtained using unheated skim compared to heated skim. These advances make the two-stage countercurrent EAEP attractive as the front-end of a soybean biorefinery.
TL;DR: In this article, a blend of palm stearin and soybean oil (70/30, wt%) was modified by chemical interesterification (CIE) and enzymatic interesterization (EIE), the latter batch-wise (B-EIE).
Abstract: A blend of palm stearin and soybean oil (70/30, wt%) was modified by chemical interesterification (CIE) and enzymatic interesterification (EIE), the latter batch-wise (B-EIE) and in continuous (C-EIE). Better oil quality, mainly in terms of acidity, free tocopherol and partial acylglycerol content, was obtained after EIE. The clear melting point after any interesterification process was similar and about 9 °C lower as result of the modification in the TAG profile, which approaches the calculated random distribution. Interesterification changed the SFC profile significantly. For the fully refined interesterified blends, the SFC profile was similar and clearly different from the starting blend. Interesterification decreased the content of solids at temperatures >15 °C and increased the content of solids at temperatures <15 °C. This increase was less remarkable after C-EIE, suggesting that full randomization was not achieved in the used conditions, probably caused by a too short residence time of the oil in the enzymatic bed. During B-EIE, variations in SFC with time, principally at low temperatures, were still observed although the TAG composition was stable. At low temperatures, the reaction rate calculated from SFC was very low, confirming an important effect of the acyl migration on this parameter.
TL;DR: In this paper, a proximate analysis of seeds and physicochemical properties of oils extracted from six Sudanese cucurbit seeds Cucumis mello var. agrestis, CucUMIS melo var. flexuosus, CUCUMIS sativus, Citrullus lanatus var. colocynthoides and Luffa echinata were examined by established methods.
Abstract: The proximate analysis of seeds and physicochemical properties of oils extracted from six Sudanese cucurbit seeds Cucumis mello var. agrestis, Cucumis melo var. flexuosus, Cucumis sativus, Citrullus lanatus var. colocynthoides, Cucumis prophetarum, and Luffa echinata were examined by established methods. For each variety, the proximate analysis showed ranges for moisture, protein, and carbohydrates as 3.70–6.87, 14.50–17.50, and 15.62–28.89% on a dry matter basis, respectively. The oils were extracted by Soxhlet using petroleum ether, with yields that ranged from 10.9 to 27.10% (wt/wt). The obtained extracted oils were subjected to phyiscochemical, fatty acid, and tocopherol analysis. The physicochemical characterization of the oil revealed that the refractive indices and relative densities of the oils fell within the narrow ranges of 1.334–1.442 and 0.874–0.920 g/cm3, respectively. Unsaponifiable matters ranged between 0.8 and 1.2 mg KOH/g, whilst peroxide values (PV) ranged from 2.3 to 4.1 meq/kg. The ranges of the values for free fatty acid (FFA %) were 1.2–4.0%. The predominant fatty acids were 16:0, 18:0, 18:1, and 18:2 with ranges of 8.9–14.2, 6.0–9.4, 14.6–32.1, and 43.6–65.5%, respectively. γ-Tocopherol was the predominant tocopherol in all samples ranging from 0.8 to 43.2% of the total tocopherols, followed by δ-tocopherol and α-tocopherol.
TL;DR: The aim of this study was to characterize the chemical profiles of the oils derived from single variety Turkish olives including Ayvalik, Memecik, Gemlik, Erkence, Nizip Yaglik and Uslu to provide evidence of the variation in virgin olive oil quality.
Abstract: Olives were collected from various districts of Turkey (North and South Aegean sub-region, Bursa-Akhisar, South East Anatolia region) harvested over seven (2001–2007) seasons. The aim of this study was to characterize the chemical profiles of the oils derived from single variety Turkish olives including Ayvalik, Memecik, Gemlik, Erkence, Nizip Yaglik and Uslu. The olive oils were extracted by super press and three phase centrifugation from early harvest olives. Chosen quality indices included free fatty acid content (FFA), peroxide value (PV) and spectrophotometric characteristics in the ultraviolet (UV) region. According to the FFA results, 46% (11 out of 24 samples) were classified as extra virgin olive oils; whereas using the results of PV and UV, over 83% (over 19 of the 24 samples) had the extra virgin olive oil classification. Other measured parameters included oil stability (oxidative stability, chlorophyll pigment, pheophytin-α), cis–trans fatty acid composition and color index. Oxidative stability among oils differed whereas the cis–trans fatty acid values were within the national and international averages. Through the application of two multivariate statistical methods, Principal component and hierarchical analyses, early harvest virgin olive oil samples were classified according to the geographical locations categorized in terms of fatty acid profiles. Such statistical clustering gave rise to defined groups. These data provide evidence of the variation in virgin olive oil quality, especially early harvest and cis–trans isomers of fatty acid profiles from the diverse agronomic conditions in the olive growing regions of Turkey.
TL;DR: In this article, the seed oil content and fatty acid composition of 15 commercially important pomegranate cultivars were determined, and the predominant unsaturated fatty acid was punicic acid (70.42-76.17%).
Abstract: In the present study, seed oil content and fatty acid composition of 15 commercially important pomegranate cultivars were determined. The oil content of pomegranate seeds ranged between 13.95 and 24.13% (d.b). Palmitic, stearic, arachidic, and behenic acid contents of the oils ranged between 2.10–2.77, 1.35–2.01, 0.33–0.48, and 0.16–0.22%, respectively. The predominant unsaturated fatty acid was punicic acid (70.42–76.17%) and a minor unsaturated fatty acid was gadoleic acid (0.42–0.75%). The analysis on unsaturated fatty acids particularly showed significant amounts of punicic acid, which is considered to enhance the oil quality and is of importance to health.