Authentication of extra virgin olive oils by Fourier-transform infrared spectroscopy

Fourier-transform infrared spectroscopy (FTIR), followed by multivariate treatment of the spectral data, was used to classify vegetable oils according to their botanical origin, and also to establish the composition of binary mixtures of extra virgin olive oil (EVOO) with other low cost edible oils. Oil samples corresponding to five different botanical origins (EVOO, sunflower, corn, soybean and hazelnut) were used. The wavelength scale of the FTIR spectra of the oils was divided in 26 regions. The normalized absorbance peak areas within these regions were used as predictors. Classification of the oil samples according to their botanical origin was achieved by linear discriminant analysis (LDA). An excellent resolution among all categories was achieved using an LDA model constructed with eight predictors. In addition, multiple linear regression models were used to predict the composition of binary mixtures of EVOO with sunflower, corn, soybean and hazelnut oils. For all the binary mixtures, models capable of detecting a low cost oil content in EVOO as low as 5% were obtained.     

市售橄榄油豆甾二烯与脂肪酸烷基酯含量分析

建立了一种前处理简便快速的橄榄油中豆甾二烯含量测定方法,结合橄榄油中脂肪酸烷基酯的检测,对市售不同标称等级的橄榄油样品进行分析。结果表明,橄榄油样品加入内标后用正己烷溶解,商品化硅胶柱净化,正己烷洗脱,DB-5MS色谱柱进行分离,选择离子监测模式采集,内标法定量对豆甾二烯含量进行GC-MS测定。豆甾二烯的检出限为0.05 mg/kg,定量限为0.10 mg/kg,在0.05～2.0 μg/mL质量浓度范围内具有良好的线性关系,回收率为98.05%～100.19%,RSD为0.54%～3.04%。不同标称等级橄榄油中豆甾二烯与脂肪酸烷基酯含量差异较大,两者联用可以更好地用于特级初榨橄榄油品质与掺伪鉴别。     

橄榄油中脂肪酸烷基酯含量测定

采用商品化固相萃取柱净化,气相色谱-质谱联用法检测,建立了一种前处理简单快捷的橄榄油中脂肪酸烷基酯含量测定方法。该方法测定橄榄油中8种脂肪酸烷基酯的检出限均为1.0 mg/kg,加标回收率为99.05%~111.13%,相对标准偏差为0.50%~6.70%。方法重复性好,准确度高。通过测定橄榄油中脂肪酸烷基酯的含量,可以帮助区分橄榄油品质,为特级初榨橄榄油掺伪的鉴别提供技术支持。     

High performance size-exclusion chromatography analysis of polar compounds applied to refined, mild deodorized, extra virgin olive oils and their blends: An approach to their differentiation

An investigation was carried out to evaluate the use of High Performance Size-Exclusion Chromatography (HPSEC) of polar compounds of refined, mild deodorized, extra virgin olive oils as well as of their blends, in attempting to reveal significant differences in the amounts of the substance classes constituting polar compounds among these oils. Two sets of blends were prepared by mixing an extra virgin olive oil with both refined and mild deodorized olive oils in increasing amounts. The obtained data highlighted that the triacylglycerol oligopolymers were absent or present in traces in the extra virgin olive oil, while their mean amount was equal to 0.04 g/100 g and 0.72 g/100 g in mild deodorized and refined olive oils, respectively. Oxidized triacylglycerols and diacylglycerols were more abundant in mild deodorized oil and refined oil than in extra virgin olive oil. The Factorial Discriminant Analysis of the data showed that the HPSEC analysis could reveal the presence of refined/mild deodorized oils in extra virgin olive oils. In particular, the classification functions obtained allowed designation of mixtures containing at least 30 g/100 g of mild deodorized oil and all those containing refined olive oil as deodorized oil, therefore as oils subjected to at least a mild refining treatment.     

Effect of extra virgin olive oil substitution for fat on quality of pork patty

BACKGROUND: Extra virgin olive oil (EVOO) is well known for its beneficial effects on human health. Thus, the purpose of this study was to investigate the effect of EVOO substitution for backfat on qualities of pork patty to avoid high consumption of animal‐originated fat, because it is closely related to development of cardiovascular disease and obesity. RESULT: Water‐holding capacity was higher in control (lean pork + 10% backfat) and T3 (lean pork + 5% backfat + 5% EVOO + 0.5% isolated soy protein + 0.5% carrageenan + 0.5% maltodextrin) than T1 (lean pork + 5% backfat + 5% EVOO + 0.5% isolated soy protein) and T2 (lean pork + 5% backfat + 5% EVOO + 0.5% isolated soy protein + 0.5% carrageenan). Hardness was higher in EVOO substitution for backfat patty samples than control. In sensory evaluation, the control was significantly higher in overall acceptability compared with EVOO substitution for backfat pork patty samples. CONCLUSION: The physical properties of pork patty made by EVOO substitution for backfat were stable as a commercial pork patty (control). However, sensory evaluation scores were higher in control compared to EVOO‐substituted pork patty samples. Copyright © 2008 Society of Chemical Industry     

Monitoring of fatty acid composition in virgin olive oil by Fourier transformed infrared spectroscopy coupled with partial least squares

A rapid Fourier transformed infrared (FTIR) attenuated total reflectance (ATR) spectroscopic method was applied to the determination of fatty acid (FA) profile and peroxide value (PV) of virgin olive oil. Calibration models were constructed using partial least squares (PLS) regression. A FA calibration model was constructed in the spectral range from 3033 to 700 cm⁻¹. Oleic acid (62.0–80.0%), linoleic acid (5.3–15.0%), saturated fatty acids (SFA, 12.6–19.7%), mono-unsaturated fatty acids (MUFA, 64.4–81.0%) and poly-unsaturated fatty acids (PUFA, 6.0–15.9%) were considered for chemometric analysis. PV (5.7–15.7 meq O₂ kg⁻¹) was calibrated using the signal of the full spectral range 4000–700 cm⁻¹ with first derivative pre-treatment. The LODs of the FTIR-chemometric methods were: 3.0% for oleic acid, 0.5% for linoleic acid, 1.3% for SFA, 3.0% for MUFA, 0.3% for PUFA and 1.0 meq O₂ kg⁻¹ for PV. Analytical methods were evaluated by use of validation samples (n = 25 for all the FA related parameters and n = 10 for PV) with nearly quantitative recovery rates (98–103%). The proposed method provided results comparable to official procedures, with the advantages of being less expensive and more rapid.