Olive oil adulterated with hazelnut oils: simulation to identify possible risks to allergic consumers

According to European Union Regulation EC 1531/2001, olive oil labelled as “extra-virgin” should be cold-pressed and contain no refined oil or oil from other oleaginous seeds or nuts. Adulteration of extra virgin olive oil (EVOO) with hazelnut oil (HAO) is a serious concern both for oil suppliers and consumers. The high degree of similarity between the two fats complicates the detection of low percentages of HAO in EVOO. Many analytical approaches have been developed in recent years to trace HAO in EVOO, principally based on chromatographic analyses, differential scanning calorimetry or nuclear magnetic resonance. In addition adulteration of EVOO with HAO may introduce hazelnut-derived allergens. The aim of this work was to analyse the protein and allergen content of EVOO intentionally spiked with raw cold-pressed HAO or solvent-extracted HAO. SDS–PAGE analysis confirmed the presence of hazelnut proteins in solvent-extracted HAO with molecular masses ranging 10–60 kDa. In contrast, cold-pressed HAO showed no traces of protein. In spiked EVOO, solvent-extracted HAO was still detectable at a 1% contamination level. Several bands on SDS–PAGE migrated at apparent molecular masses coinciding with known allergens, such as Cor a 1 (～17 kDa), Cor a 2 (～14 kDa), Cor a 8 (～12 kDa), oleosin (～17 kDa) and Cor a 9 (～60 kDa). MALDI–TOF MS analysis confirmed the presence of two oleosin isoforms and of Cor a 9. Immunoblotting demonstrated that an allergic patient with known reactivity to Cor a 1 and Cor a 2 recognized a 17-kDa band in solvent-extracted HAO. In conclusion, we have shown that adulteration of extra virgin olive oil with solvent-extracted hazelnut oil can be traced by simple SDS–PAGE analysis, and that adulteration introduces a potential risk for hazelnut allergic patients.     

Nontargeted,Rapid Screening of Extra Virgin Olive Oil Products for Authenticity Using Near‐Infrared Spectroscopy in Combination with Conformity Index and Multivariate Statistical Analyses

A rapid tool for evaluating authenticity was developed and applied to the screening of extra virgin olive oil (EVOO) retail products by using Fourier‐transform near infrared (FT‐NIR) spectroscopy in combination with univariate and multivariate data analysis methods. Using disposable glass tubes, spectra for 62 reference EVOO, 10 edible oil adulterants, 20 blends consisting of EVOO spiked with adulterants, 88 retail EVOO products and other test samples were rapidly measured in the transmission mode without any sample preparation. The univariate conformity index (CI) and the multivariate supervised soft independent modeling of class analogy (SIMCA) classification tool were used to analyze the various olive oil products which were tested for authenticity against a library of reference EVOO. Better discrimination between the authentic EVOO and some commercial EVOO products was observed with SIMCA than with CI analysis. Approximately 61% of all EVOO commercial products were flagged by SIMCA analysis, suggesting that further analysis be performed to identify quality issues and/or potential adulterants. Due to its simplicity and speed, FT‐NIR spectroscopy in combination with multivariate data analysis can be used as a complementary tool to conventional official methods of analysis to rapidly flag EVOO products that may not belong to the class of authentic EVOO.     

A capacitive technique to assess water content in extra virgin olive oils

The present research investigated the correlations between capacitance and water content of extra virgin olive oils (EVOO). A commercial capacitor probe for radio applications and an LCR meter were used for electric tests in the frequency range from 500 Hz to 512 kHz. Seventeen samples of different EVOO with a moisture content ranging from 178 to 1321 mg/kg oil were selected for study. To assess the influence of moisture only, the oil with the maximum water content was filtered down to 288 mg/kg oil and five samples with intermediate water contents were prepared and submitted to electrical measurements. Subsequently, the capacitance of all 17 EVOO samples was measured at selected frequencies.     

Radical scavenging-linked antioxidant activity of ethanolic extracts of diverse types of extra virgin olive oils

The present study evaluated the radical scavenging-linked antioxidant activity of hexane/80% ethanol extracts from several types of extra virgin olive oils (EVOOs) derived from varieties arbequina, hojiblanca, picual, their blends, and pure olive oil (POO). The antioxidant potential of the olive oil extracts was assessed by radical scavenging assays using DPPH (2, 2-diphenyl-1-picrylhydrazyl), ABTS (2, 2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid), and hydroxyl radical, as well as hydrogen peroxide and superoxide anion inhibitory activities. Electron donating ability (EDA) using DPPH assay of 80% ethanol extracts from EVOOs, except arbequina oil, was significantly higher than POO. EDA was markedly higher in blended and picual EVOOs than the extracts from arbequina and hojiblanca EVOOs (P < 0.05). Similarly, ABTS radical scavenging activity of the extracts from the EVOOs was in order of picual EVOO > blended EVOO > hojiblanca EVOO >or= POO >or= arbequina EVOO. Further, the superoxide anion scavenging activity of blended, picual, and arbequina EVOOs was significantly higher than that of hojiblanca EVOO and POO, which were barely detectable. Hydroxyl radical scavenging activity of arbequina and hojiblanca was higher than that of blended, picual EVOOs, and POO. In addition, hydrogen peroxide scavenging activity of the extracts from blended, arbequina, hojiblanca, picual EVOOs, and POO was 63.1 +/- 3.1%, 44.4 +/- 10.2%, 52.0 +/- 2.7%, 71.8 +/- 2.5%, and 35.7 +/- 10.0%, respectively. Our results indicate that ethanol extracts of several EVOOs contained higher radical scavenging and antioxidant activity than the POO. This antioxidant potential is partly due to the phenolic compounds present in different olive oil grade and is influenced by cultivar type.     

MALDI-TOF mass spectrometry detection of extra-virgin olive oil adulteration with hazelnut oil by analysis of phospholipids using an ionic liquid as matrix and extraction solvent

The adulteration of extra virgin olive oil (EVOO) with hazelnut oil (HO) is frequent and constitutes a serious concern both for oil suppliers and consumers. The high degree of similarity between the two oils as regards triacylglycerol, total sterol and fatty acid profile, complicates the detection of low percentages of HO in EVOO. However, phospholipids (PLs) are usually present in seed oils at a concentration range of 10–20 g/kg, while the amounts of PLs in VOOs are 300–400 times lower. Thus, in this work a sample pretreatment procedure focused towards the selective PLs extraction was developed; the Bligh–Dyer extraction procedure was modified introducing the ionic liquid resulting from the combination of TBA (tributylamine) and CHCA (α-Cyano-4-hydroxycinnamic acid) as extraction solvent. The selective extraction and enrichment of phospholipids from EVOO and HO samples was then achieved. The relevant extracts were analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) using the same ionic liquid TBA-CHCA as MALDI matrix, that was found to be very suitable for PLs analysis. In fact, a remarkable increase of the phospholipids signals, with a simultaneous decrease of those relevant to triacylglycerols and diacylglycerols, was observed in the relevant mass spectra. The applicability of the whole method to the individuation of the presence of HO in EVOO was demonstrated by the analysis of EVOO samples progressively adulterated with variable quantities of HO, that was still detectable at a 1% contamination level.     

基于多元素含量分析结合化学计量学技术的橄榄油等级鉴别方法

基于多元素含量分析结合化学计量学技术对特级初榨橄榄油和精炼橄榄油进行等级鉴别。结果表明,采用主成分分析可成功区分特级初榨橄榄油和精炼橄榄油,建立可靠的橄榄油等级鉴别的正交偏最小二乘法判别分析模型,结果与主成分分析一致,且各等级橄榄油组内聚类效果明显;聚类分析也有效鉴别了两种等级橄榄油。筛选出区分两个等级橄榄油的8 种特征性元素,分别为Al、Fe、Cu、Ba、V、Sc、La、Zn。因此,采用多元素含量分析结合化学计量学技术可用于特级初榨橄榄油和精炼橄榄油的鉴别。     

Oxidation Processes in Sicilian Olive Oils Investigated by a Combination of Optical and EPR Spectroscopy

Abstract: Extra virgin olive oil (EVOO) is recognized as one of the healthiest foods for its high content of antioxidants, which forestall and slow down radical formation. Free radical‐initiated oxidation is considered one of the main causes of rancidity in fats and oils. As a consequence, reliable protocols for the investigation of oil oxidation based on selective, noninvasive, and fast methods are highly desirable. Here we report an experimental approach based on UV‐Vis absorbance, steady‐state fluorescence, and electron paramagnetic resonance (EPR) spectroscopy for studying oxidation processes induced by temperature for a period up to 35 d on Sicilian EVOO samples. We followed the decrease in β‐carotene content during incubation time and observed changes in polyphenols and tocopherols during the oxidation processes, focusing on the time scale of those changes. Using EPR spectroscopy, the free radical formation in different oil samples is reported, providing a fingerprint for both the antioxidant content and temporal features of the oxidation process at its early stage. Practical Application: We monitor β‐carotene and chlorophyll in an auto‐oxidation process. A protocol based on spectroscopic measurements is presented and can be used for the quality control process of commercial olive oil.     

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.     

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.     

Effects of olive paste fast preheating on the quality of extra virgin olive oil during storage

The olive paste obtained after crushing was fast preheated under different time/temperature conditions and then malaxed in an industrial oil mill (600 kg Frantoio/Leccino olive blend). Legal parameters (peroxides, free acidity and sensory panel), oil yield, total phenolic content, oxidative stability and phenolic profile were monitored during 12 months of storage of the virgin olive oil (VOO) kept in closed bottles in the dark. A fast preheating not longer than 72 s at 38 °C without malaxation lead to an extra VOO with a shelf-life of at least 12-months, similarly to the traditional EVOO obtained with malaxation. A fast preheating not longer than 72 s at 38 °C followed by 10 min malaxation lead to an EVOO with a ‘mild’ sensory profile and a shelf life of at least 12-months. Thus, the use of a specific designed fast preheater instead or before (a shortened) malaxation allows to obtain an EVOO with a low bitter/pungent attribute from olives which are rich of (sometimes unpleasant) phenolic compounds with the aim to meet the preference of targeted groups of consumers. Time and temperature of fast preheating are the critical parameters of the process.     

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     

Oxidative stability of olive oil and its polyphenolic compounds after boiling vegetable process

The changes in the stability and phenolic content of an extra-virgin olive oil and an olive oil following boiling operation in the presence of vegetables have been studied. After the boiling process, none of the olive oil samples was oxidized, independently of the olive oil quality used. However, in contrast with tocopherols, all polyphenolic components decreased in concentration with the thermal treatment and this decrease was dramatic in the presence of vegetables, probably because of their high content in metals such as iron and copper. The addition of olive oil only 15 min before the end of the boiling process was shown to bring benefits in general for the content of both elenolic acid derivatives, 3,4-DHPEA-EA and 4-HPEA-EA, and hydroxytyrosol acetate in the processed oils. Moreover, less destruction of the vegetables polyphenols was also observed when processing olive oils only 15 min before the end of the boiling process. Interestingly, and besides the use of EVOO instead of OO did not bring benefits to the stability of samples or a higher polyphenolic content in the samples after processing, an higher radical scavenging capacity of phenolic extracts obtained from EVOO samples could be observed.     

基于PCA-SVM结合共聚焦拉曼光谱的特级 初榨橄榄油掺伪压榨菜籽油定量分析

为了促进国内橄榄油市场的健康发展，对掺伪同样存在天然类胡萝卜素的低温压榨菜籽油的特级初榨橄榄油进行了定量鉴别研究。采用共聚焦拉曼光谱技术对不同掺伪浓度油样进行测试，基于密度泛函理论对油样的拉曼光谱峰的归属进行了理论分析，并对拉曼光谱数据进行主成分分析（PCA），然后利用支持向量机（SVM）构建PCA-SVM模型。另外，对PCA-SVM模型的检出限进行了研究。结果表明：特级初榨橄榄油与低温压榨菜籽油的拉曼光谱存在一定差异，最明显的光谱差异主要集中在谱峰1 008、1 161、1 528 cm-1和谱段2 800～3 000 cm-1内，与密度泛函理论对不同油样拉曼光谱峰的分析一致；不考虑类胡萝卜素特征信号建立的PCA-SVM模型决定系数大于0.989，均方根误差小于2.990%，检出限为2%（低温压榨菜籽油体积分数）;在特级初榨橄榄油掺伪定量分析中，考虑类胡萝卜素的特征信号有助于提高模型预测精度，但仅限于掺伪低价植物油中无类胡萝卜素存在的情况;PCA-SVM模型在不考虑类胡萝卜素特征信号的情况下依然具有良好的定量预测效果。综上，所建立的PCA-SVM模型可以用于掺伪2%以上低温压榨菜籽油的特级初榨橄榄油的定量鉴别。     

Extra‐virgin and refined olive oils decrease plasma triglyceride,moderately affect lipoprotein oxidation susceptibility and increase bone density in growing pigs

The objective of this study was to determine the health benefits of extra‐virgin and refined olive oils, which are high in mono‐unsaturated fatty acids (MUFAs) and polyphenolic compounds using the pig as a model. Thirty‐two cross‐bred pigs were individually penned, allocated to one of four dietary treatments and fed ad libitum for 28 days. Two of the experimental diets consisted of a basal diet containing 12% tallow and either 7% sunflower oil (TSO) or 7% extra‐virgin olive oil (TEVO) on a w/w basis. The remaining diets contained 19% extra‐virgin olive oil (EVO) or 19% of refined olive oil (RO). On days 7, 14 and 28 fasted and 3‐h post‐prandial blood samples were taken. Body composition was measured at the beginning and end of the study using dual energy X‐ray absorptiometry. Daily gain, feed intake and lean and fat deposition were not significantly different between the treatments. However, the daily increase in bone mineral density was higher in pigs fed diets containing olive oil (1.23 vs 2.54, 6.28, 5.20 mg cm^?2 per day for TSO, TEVO, EVO and RO, respectively, P = 0.050). Both fasting and non‐fasting plasma triglycerides were lower (P = 0.003) in pigs fed MUFA‐rich diets, while the cholesterol profile was not significantly different between the treatments. The results from in vitro copper‐induced lipid peroxidation, expressed in terms of conjugated dienes, showed that low density lipoprotein (LDL) particles in postprandial serum from pigs fed olive oil were moderately more resistant to oxidative modification. In conclusion, these data demonstrate that both extra‐virgin and refined olive oils attenuate postprandial hypertriglyceridaemia, moderately affect oxidation susceptibility and increase bone mineral density in growing pigs. Copyright © 2006 Society of Chemical Industry     

Changes in the oxidative state of extra virgin olive oil used in baked Italian focaccia topped with different ingredients

Four different types of “focaccia” (Italian flat bread) prepared with the same dough and the same extra virgin olive oil but with different seasonings, were analyzed. Lipids were extracted from each sample using the Folch method. The indices commonly used to assess oil quality, the amounts of trans fatty acids and compounds of triglyceride polymerization, oxidation and hydrolysis, were determined in all the samples to better assess the degree of oxidation and hydrolysis of the oils. The findings showed that, once baked, the oil sampled from the different types of focaccias could not be included in the virgin category. The level of oxidation of the baked samples was greater than that in the uncooked oil. However the results obtained showed that the level of degradation of the extracted oils was lower than that found in edible refined oils and it seemed to be influenced by the topping used to flavour the focaccias.     

Rheological behaviour and functionality of inulin‐extra virgin olive oil‐based mashed potatoes

Developing products having a high nutritional value and good storage stability during freezing is a challenge. Inulin (I) and extra virgin olive oil (EVOO) have interesting functional properties. The effect of the addition of I and EVOO blends at different I:EVOO ratios (0:0, 0:60, 15:45, 30:30, 45:15, 60:0, 30:45 and 45:30) on the rheological, physical, sensory and structural properties of fresh and frozen/thawed mashed potatoes formulated without and with added cryoprotectants was analysed and compared. Addition of I and EVOO (either alone or blended) reduced apparent viscosity and pseudoplasticity producing softer systems, indicating that both ingredients behave as soft fillers. Samples with added I at the higher concentrations (≥45 g kg^?1) showed lower flow index and consistency, which is related to formation of smaller I particles; microphotographs indicated that gelling properties of I depended mostly upon processing. Frozen/thawed samples were judged more acceptable and creamier than their fresh counterparts.     

橄榄油总迁移量测试行业标准中问题探讨

目的 针对橄榄油总迁移量测试参考的行业标准中的几个问题, 讨论并提出相关改进建议, 以提高测试的可操作性和结果的准确性。方法 采用控制变量法, 考察适宜性判定时不同橄榄油质量对试样中橄榄油干扰物定量结果的影响, 考察不同温度和时间对橄榄油中水分干燥程度的影响。结果 以45~55 mg橄榄油做单点标准曲线定量适宜性判定限量附近的试样时, 检测结果准确性欠佳, 由10.3、7.0、2.8 mg橄榄油做单点标准曲线定量试样中橄榄油干扰物的质量基本一致; 行业标准中橄榄油中水分的干燥条件要求高、操作困难, 较难实现。结论 适宜性判定时宜采用小于10 mg的橄榄油做单点标准曲线, 以此来定量试样中橄榄油干扰物的质量, 对于水分敏感性试样尽量避免采用干燥橄榄油的方法, 建议采用调理法确定试样的准确质量, 以提高橄榄油总迁移量测试结果的准确性。     

Quantification of adulterant agents in extra virgin olive oil by models based on its thermophysical properties

Two methods to quantify the adulteration of extra virgin olive oil (EVOO) based on the physical characteristic of adulterated samples have been here described. Firstly, the adulterant agent concentration is determined using the density and/or refractive indices (RIs) of adulterated samples of EVOO with sunflower (SO) or corn (CO) oils by suitable linear correlations between density and/or RI. Finally, models based on the combination of differential scanning calorimetry (DSC) equipment and a chaotic parameter (lag-k autocorrelation coefficients, LCCs) is defined here to quantify adulterations of EVOO with refined olive (ROO), refined olive pomace (ROPO), SO or CO oils. This quantification was carried out using successful linear correlation of LCCs and ROO, ROPO, SO or CO concentrations in 462 adulterated samples of EVOO. The LCCs are calculated from DSC scans of adulterated EVOO samples. In both models studied, the adulterant agent concentrations are less than 14% w/w. The former is adequate to calculate the concentration of the adulterant agents (CO and SO) with a correlation coefficient (R²) higher than 0.927 and mean square error (MSE) lower than 8.9%. By the external validation process, the LCC/DSC approach estimates the adulterant agent concentrations with a R² (estimated vs. real adulterant agent concentration) greater than 0.921 and a MSE less than 4.9%.