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1.
A combination of (1)H NMR and (31)P NMR spectroscopy and multivariate statistical analysis was used to classify 192 samples from 13 types of vegetable oils, namely, hazelnut, sunflower, corn, soybean, sesame, walnut, rapeseed, almond, palm, groundnut, safflower, coconut, and virgin olive oils from various regions of Greece. 1,2-Diglycerides, 1,3-diglycerides, the ratio of 1,2-diglycerides to total diglycerides, acidity, iodine value, and fatty acid composition determined upon analysis of the respective (1)H NMR and (31)P NMR spectra were selected as variables to establish a classification/prediction model by employing discriminant analysis. This model, obtained from the training set of 128 samples, resulted in a significant discrimination among the different classes of oils, whereas 100% of correct validated assignments for 64 samples were obtained. Different artificial mixtures of olive-hazelnut, olive-corn, olive-sunflower, and olive-soybean oils were prepared and analyzed by (1)H NMR and (31)P NMR spectroscopy. Subsequent discriminant analysis of the data allowed detection of adulteration as low as 5% w/w, provided that fresh virgin olive oil samples were used, as reflected by their high 1,2-diglycerides to total diglycerides ratio (D > or = 0.90).  相似文献   

2.
为了测量从橄榄油中分提的高、低熔点油脂的脂肪酸成分,在4 000～600 cm-1 的范围测量了31个含有不同脂肪酸成分植物油的傅里叶变换红外光谱,用于建立偏最小二乘（PLS）回归分析校正模型。在油脂的傅里叶变换红外光谱变量和脂肪酸组成变量之间建立了交叉验证的PLS校正模型。为了校正油酸和亚油酸含量,在4?000～600 cm-1 的频率范围,经平滑,二阶导数,规范化处理的红外光谱获得了最好的交叉验证校正模型和最佳的预测结果。PLS校正模型预测结果表明,与高熔点橄榄油（油酸,72.29%,亚油酸,9.98%）相比,低熔点橄榄油含有较高的油酸含量和亚油酸含量（油酸,77.46%,亚油酸,12.51%）,预测的结果与气相色谱测量的结果有很好的一致性。建立的PLS校正模型预测橄榄油的不饱和脂肪酸含量具有较好的相关性。该研究为分提油脂质量的判别评价提供了便捷的方法。  相似文献   

3.
High-field 31P NMR (202.2 MHz) spectroscopy was applied to the analysis of 59 samples from three grades of olive oils, 34 extra virgin olive oils from various regions of Greece, and from different olive varieties, namely, 13 samples of refined olive oils and 12 samples of lampante olive oils. Classification of the three grades of olive oils was achieved by two multivariate statistical methods applied to five variables, the latter being determined upon analysis of the respective 31P NMR spectra and selected on the basis of one-way ANOVA. The hierarchical clustering statistical procedure was able to classify in a satisfactory manner the three olive oil groups. Subsequent application of discriminant analysis to the five selected variables of oils allowed the grouping of 59 samples according to their quality with no error. Different artificial mixtures of extra virgin olive oil-refined olive oil and extra virgin olive oil-lampante olive oil were prepared and analyzed by 31P NMR spectroscopy. Subsequent discriminant analysis of the data allowed detection of extra virgin olive oil adulteration as low as 5% w/w for refined and lampante olive oils. Further application of the classification/prediction model allowed the estimation of the percent concentration of refined olive oil in six commercial blended olive oils composed of refined and virgin olive oils purchased from supermarkets.  相似文献   

4.
The present study was designed to assess the agreement between analytical methodologies based on 1H and 31P NMR spectroscopy and conventional analytical methods (titration, gas chromatography, and high performance liquid chromatography) for measuring certain minor and major constituents (free acidity, fatty acids, iodine value, and phenolic compounds) of olive oil. The standard deviations of the NMR method were comparable to those of the conventional methods, except perhaps those of the total hydroxytyrosol and total tyrosol. Linear regression analyses showed strong correlations between NMR and conventional methods for free acidity, total hydroxytyrosol, total tyrosol, total diacylglycerols, (+)-pinoresinol, (+)-1-acetoxypinoresinol, and apigenin; good correlations for linoleic acid, free hydroxytyrosol, and free tyrosol; and weak correlations for oleic acid, linolenic acid, saturated fatty acids, and luteolin. Furthermore, a method comparison study was conducted and the agreement between NMR and conventional methods was evaluated by using the Bland and Altman statistical analysis. The distribution of the data points in the bias plot showed that 96.4% and 100% of the measurements of free acidity and iodine value, respectively, were within the limits of agreement of the two methods. For the remaining constituents of olive oil, the percentage of measurements, located within the limits of agreement, ranged from 94% to 98.5%.  相似文献   

5.
The aim of this research is to find if there is direct evidence relating the fatty acid composition of olive oils to specific cultivars grown within a well-limited geographical region. To group olive oils according to their own cultivars,(13)C high-field nuclear magnetic resonance (NMR) and gas chromatography (GC) were used to analyze 60 extra virgin olive oils from the same Italian region (southwestern Sicily) obtained from four monovarietal cultivars. The (13)C NMR spectrum provides information about glycerol triesters of olive oils, i.e., about the acyl composition of major components and about the fatty acids' positional distribution on the glycerol moiety. GC gives the complete fatty acid profile of olive oil samples. Selection of NMR and GC peaks on the basis of their sensitivity to the different cultivars was performed by using multivariate analysis of variance (MANOVA). Principal component analysis, tree clustering analysis, multidimensional scaling (MDS), and linear discriminant analysis (LDA) were then performed on the MANOVA-selected peaks. Results obtained from (13)C NMR and GC techniques combined with the multivariate statistical procedure are in good agreement and prove the usefulness of fatty acids analysis to group the monovarietal olive oils belonging to the same cultivars. Grouping of olive oils according to their cultivars occurs for particular (13)C resonances all belonging to fatty chains in the sn 1,3 position of the glycerol moiety.  相似文献   

6.
31P NMR spectroscopy has been employed to detect and quantify phenolic compounds in the polar fraction of virgin olive oil. This novel analytical method is based on the derivatization of the hydroxyl and carboxyl groups of phenolic compounds with 2-chloro-4,4,5,5-tetramethyldioxaphospholane and the identification of the phosphitylated compounds on the basis of the 31P chemical shifts. Quantification of a large number of phenolic compounds in virgin olive oil can be accomplished by integration of the appropriate signals in the 31P NMR spectrum and the use of the phosphitylated cyclohexanol as internal standard. Finally, the validity of this technique for quantitative measurements was thoroughly examined.  相似文献   

7.
The contents of triacylglycerols and diacylglycerols in three kinds of olive fruit oils (pulp, seed, and whole fruit) were determined. The fatty acid composition and the quality ratios 1,2-diacylglycerols/1,3-diacylglycerols and 1,2-diacylglycerols/total diacylglycerols were also assessed. Seven major Italian olive varieties were considered. Results of univariate statistical analyses indicated that the above analytical parameters (glyceridic ratios excepted) were effective in discriminating between pulp and seed oils. The seed oil fraction did not determine any change in the glyceridic indices and the acylglycerol or fatty acid composition concerning the whole fruit oil (mixture of pulp and seed oil fractions), the weight (%) of seed ( approximately 2%) being by far lower than the weight (%) of pulp ( approximately 85%) (fruit weight basis). Based on the data of triacylglycerol or fatty acid composition, and using appropriate parametric or nonparametric multivariate statistics, the genetic origins (olive variety) of the three fruit oil kinds were characterized.  相似文献   

8.
(13)C NMR spectra of oil fractions obtained chromatographically from 66 vegetable oils were obtained and analyzed to evaluate the potential use of those fractions in predicting oil stabilities and to compare those results with oil stability prediction by using chemical determinations. The oils included the following: virgin olive oils from different cultivars and regions of Europe and north Africa; "lampante" olive, refined olive, refined olive pomace, low-erucic rapeseed, high-oleic sunflower, corn, grapeseed, soybean, and sunflower oils. Oils were analyzed for fatty acid and triacylglycerol composition, as well as for phenol and tocopherol contents. By using stepwise linear regression analysis (SLRA), the chemical determinations and the (13)C NMR data that better explained the oil stability determined by the Rancimat were selected. These selected variables were related to both the susceptibility of the oil to be oxidized and the content of minor components that most contributed to oil stability. Because (13)C NMR considered many more variables than those determined by chemical analysis, the predicted stabilities calculated by using NMR data were always better than those obtained by using chemical determinations. All these results suggest that (13)C NMR may be a powerful tool to predict oil stabilities when applied to chromatographically enriched oil fractions.  相似文献   

9.
Phospholipid classes were determined qualitatively and quantitatively in eight commercial lecithins and three flour improvers by thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and (31)P nuclear magnetic resonance spectroscopy ((31)P NMR). The total amounts of phospholipids as well as the amounts of phospholipid classes in the samples were comparable but depended on the method used for quantification. Highest selectivity was provided by (31)P NMR as all phospholipids and lysophospholipids could easily be quantified. By TLC only lysophosphatidylcholine could not be quantified, whereas HPLC was the method with the lowest selectivity, because lysophospholipids, except lysophosphatidylethanolamine, could not be determined. Sensitivity was best for HPLC and TLC with detection limits of 20-170 mug/mL. By means of (31)P NMR these figures increased by a factor of 10-70. The coefficients of variation were 5.5, 6.8, and 12.8% for quantification by TLC, HPLC, and (31)P NMR, respectively, showing that TLC was the method with the best reproducibility. Altogether, (31)P NMR can be recommended for the quantification of phospholipids, because it is easy to perform and results can be obtained quickly. As it requires minimum instrumental equipment, TLC is a good alternative to (31)P NMR. If high sensitivity is required, HPLC is the best method.  相似文献   

10.
Conjugated linoleic acids (CLA) were enzymatically acidolyzed with olive oil to produce structured lipids (SL), and their antiatherosclerotic properties were investigated in C57BL/6J mice. Twenty-eight mice were divided into four groups and fed control diet or atherogenic diets supplemented with high cholesterol and high fat (HCHF) containing 5% of lard, olive oil, or SL based on control diet for 4 weeks. The supplementation of SL diet (0.6% CLA) significantly reduced the levels of serum total cholesterol and total triglyceride and increased high-density lipoprotein cholesterol level as compared to lard and olive oil diet groups (p < 0.05). The activity of liver acyl CoA:cholesterol acyltransferase (ACAT) of mice fed the SL diet was significantly lower than that of mice fed the lard or olive oil diet. A reduced formation of aortic fatty streak was observed in SL group. The extent of CLA incorporation depended on tissues or types of phospholipids. More CLA was incorporated in adipose tissue (1.85 mol %) than in the liver (0.33 mol %). Besides, more CLA was found in phosphatidylethanolamine (PE) (0.47 mol %) than in phosphatidylcholine (PC) (0.05 mol %) of hepatic phospholipids. Hepatic phospholipids (PC and PE) of mice fed the SL diet contained reduced contents of arachidonic and linoleic acid compared with mice fed the olive oil or lard diet. The present study suggests that SL could be considered as a functional oil for preventing risks of atheroscelerosis.  相似文献   

11.
A method for moisture determination in olive oil using 31P NMR spectroscopy is developed. This method is based on the replacement of the hydrogen atoms of water molecules with the tagging agents 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane and diphenylphosphinic chloride. Both reagents were successful in determining moisture in olive oil. However, only the second reagent provided a clean and instantaneous reaction under mild condition with no side reactions as observed with the first reagent. A study comparison was made to assess the agreement between the present analytical NMR method and the well-established methods of Karl Fischer titration.  相似文献   

12.
Methods devised for oil extraction from avocado (Persea americana Mill.) mesocarp (e.g., Soxhlet) are usually lengthy and require operation at high temperature. Moreover, methods for extracting sugars from avocado tissue (e.g., 80% ethanol, v/v) do not allow for lipids to be easily measured from the same sample. This study describes a new simple method that enabled sequential extraction and subsequent quantification of both fatty acids and sugars from the same avocado mesocarp tissue sample. Freeze-dried mesocarp samples of avocado cv. Hass fruit of different ripening stages were extracted by homogenization with hexane and the oil extracts quantified for fatty acid composition by GC. The resulting filter residues were readily usable for sugar extraction with methanol (62.5%, v/v). For comparison, oil was also extracted using the standard Soxhlet technique and the resulting thimble residue extracted for sugars as before. An additional experiment was carried out whereby filter residues were also extracted using ethanol. Average oil yield using the Soxhlet technique was significantly (P < 0.05) higher than that obtained by homogenization with hexane, although the difference remained very slight, and fatty acid profiles of the oil extracts following both methods were very similar. Oil recovery improved with increasing ripeness of the fruit with minor differences observed in the fatty acid composition during postharvest ripening. After lipid removal, methanolic extraction was superior in recovering sucrose and perseitol as compared to 80% ethanol (v/v), whereas mannoheptulose recovery was not affected by solvent used. The method presented has the benefits of shorter extraction time, lower extraction temperature, and reduced amount of solvent and can be used for sequential extraction of fatty acids and sugars from the same sample.  相似文献   

13.
Phosphorus-31 nuclear magnetic resonance spectroscopy ( (31)P NMR) was used to differentiate virgin coconut oil (VCO) from refined, bleached, deodorized coconut oil (RCO). Monoglycerides (MGs), diglycerides (DGs), sterols, and free fatty acids (FFAs) in VCO and RCO were converted into dioxaphospholane derivatives and analyzed by (31)P NMR. On the average, 1-MG was found to be higher in VCO (0.027%) than RCO (0.019%). 2-MG was not detected in any of the samples down to a detection limit of 0.014%. On the average, total DGs were lower in VCO (1.55%) than RCO (4.10%). When plotted in terms of the ratio [1,2-DG/total DGs] versus total DGs, VCO and RCO samples grouped separately. Total sterols were higher in VCO (0.096%) compared with RCO (0.032%), and the FFA content was 8 times higher in VCO than RCO (0.127% vs 0.015%). FFA determination by (31)P NMR and titration gave comparable results. Principal components analysis shows that the 1,2-DG, 1,3-DG, and FFAs are the most important parameters for differentiating VCO from RCO.  相似文献   

14.
Composition of the sterol fraction, fatty acid, acidity, and the sensorial evaluation of virgin olive oils were studied in two eastern Spanish varieties grown and processed under the same conditions. Fruits were stored at 5 degrees C and ambient temperature for different times. During fruit storage, there was no significant variation (P = 0.05) in fatty acid composition. However, the sterol composition of the oil varied markedly (in particular, there was an increase in stigmasterol), acidity increased, and there was a very significant decrease in sensorial quality. The stigmasterol content presented a high correlation with the acidity and sensory evaluation (P < 10(-)(6)). The total sterol content increased gradually with olive storage time. Oils with stigmasterol greater than campesterol are graded to a low level (lampant). It is of interest that sensorial quality is revealed by stigmasterol content, a fact unknown until now.  相似文献   

15.
This work deals with the prediction of the geographical origin of monovarietal virgin olive oil (cv. Koroneiki) samples from three regions of southern Greece, namely, Peloponnesus, Crete, and Zakynthos, and collected in five harvesting years (2001-2006). All samples were chemically analyzed by means of 1H and 31P NMR spectroscopy and characterized according to their content in fatty acids, phenolics, diacylglycerols, total free sterols, free acidity, and iodine number. Biostatistical analysis showed that the fruiting pattern of the olive tree complicates the geographical separation of oil samples and the selection of significant chemical compounds. In this way the inclusion of the harvesting year improved the classification of samples, but increased the dimensionality of the data. Discriminant analysis showed that the geographical prediction at the level of three regions is very high (87%) and becomes (74%) when we pass to the thinner level of six sites (Chania, Sitia, and Heraklion in Crete; Lakonia and Messinia in Peloponnesus; Zakynthos). The use of classification and binary trees made possible the construction of a geographical prediction algorithm for unknown samples in a self-improvement fashion, which can be readily extended to other varieties and areas.  相似文献   

16.
The fatty acid (FA) and dimethylacetal profiles of the sn-1 and sn-2 positions of different phospholipid (PL) classes from skeletal muscle of rats as affected by dietary FA profiles were studied. Rats were fed either a control diet, an olive oil-enriched diet, or a sunflower oil-enriched diet. The FA composition of both positions of the studied PL classes was affected by diet to different extents. The FA composition of the sn-2 position of phosphatidylserine was the most influenced by diet, while phosphatidylinositol was less affected by dietary modification. The FA profile of phosphatidylcholine reflected consumed FA better than any other studied PL. Thus, olive oil rats showed higher oleic acid (C18:1 n-9) contents in both positions of phosphatidylcholine, and sunflower oil rats had higher proportions of arachidonic acid (C20:4 n-6) in the sn-1 position of this PL class. Dimethylacetals were scarcely affected by diet, and only the dimethylacetal composition of phosphatidylethanolamine showed significant modifications.  相似文献   

17.
The Hibiscus genus encompasses more than 300 species, but kenaf (Hibiscus cannabinus L.) and roselle (Hibiscus sabdariffa L.) are the two most economically important species within the genus. Seeds from these two Hibiscus species contain a relatively high amount of oil with two unusual fatty acids: dihydrosterculic and vernolic acids. The fatty acid composition in the oil can directly affect oil quality and its utilization. However, the variability in oil content and fatty acid composition for these two species is unclear. For these two species, 329 available accessions were acquired from the USDA germplasm collection. Their oil content and fatty acid composition were determined by nuclear magnetic resonance (NMR) and gas chromatography (GC), respectively. Using NMR and GC analyses, we found that Hibiscus seeds on average contained 18% oil and seed oil was composed of six major fatty acids (each >1%) and seven minor fatty acids (each <1%). Hibiscus cannabinus seeds contained significantly higher amounts of oil (18.14%), palmitic (20.75%), oleic (28.91%), vernolic acids (VA, 4.16%), and significantly lower amounts of stearic (3.96%), linoleic (39.49%), and dihydrosterculic acids (DHSA, 1.08%) than H. sabdariffa seeds (17.35%, 18.52%, 25.16%, 3.52%, 4.31%, 44.72%, and 1.57%, respectively). For edible oils, a higher oleic/linoleic (O/L) ratio and lower level of DHSA are preferred, and for industrial oils a high level of VA is preferred. Our results indicate that seeds from H. cannabinus may be of higher quality than H. sabdariffa seeds for these reasons. Significant variability in oil content and major fatty acids was also detected within both species. The variability in oil content and fatty acid composition revealed from this study will be useful for exploring seed utilization and developing new cultivars in these Hibiscus species.  相似文献   

18.
This paper deals with the characterization of 475 Sicilian virgin olive oils (VOO) produced in 10 different crop years (from 1993 to 2004), according to the cultivar and the geographical origin by means of multivariate statistical analysis applied to fatty acids. In particular, the studied VOOs came from the Peloritana and Maghrebian geological zones. The fatty acid composition was determined by using the official gas chromatographic method. The results suggest that although the effect of the cultivar is significant in the olive oil classification based on the fatty acid composition, a predominant and well-defined geographic effect is also present. This study demonstrated that it is possible to employ an official and inexpensive analytical method coupled with the statistical analysis to ascertain the geographical origin and the cultivar of an extra virgin olive oil.  相似文献   

19.
In this study were successfully observed the one- (1H, 13C) and two-dimensional (1H-13C, 1H-15N, 1H-31P) NMR spectra of milk directly without any pretreatment. The signals of each NMR spectrum were assigned, and their existing states were also analyzed. Lactose existed in a free state in milk. The signals due to the butyric acid chain can be assigned among the other fatty acid chains. Monounsaturated fatty acid (oleic acid chains) and polyunsaturated fatty acid chains (linoleic and linolenic acid) were assigned by their characteristic signals. The signals from citrate, N-acetylcarbohydrates, and lecithin could be observed directly in the 1H-13C HSQC NMR spectra; the assignment of their signals was made through the 1H-13C, 1H-15N, and 1H-31P HMBC spectra of extracted milk. Signals from creatine and N-acetylcarbohydrates were detected for the first time.  相似文献   

20.
This paper introduces a facile method to determine the amount of mono- and diglycerides in virgin olive oils. This method is based on the phosphorylation of the free hydroxyls of the mono- and diglycerides with 2-chloro-4,4,5,5-tetramethyldioxaphospholane and the integration of the appropriate peaks in the (31)P NMR spectrum. Quantitative (31)P NMR spectroscopy can be extended to the quantification of other constituents of olive oils bearing functional groups with labile protons.  相似文献   

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