Effects of temperature and water content on the formation of 3-chloropropane-1,2-diol fatty acid esters in palm oil under conditions simulating deep fat frying

The influence of NaCl addition, water content, heating temperature and heating time on the formation of 3-chloropropane-1,2-diol fatty acid esters (3-MCPD esters) in palm oil simulating deep fat frying was examined in this study. The results in our study showed that all those four factors had significant effects on the generation of 3-MCPD esters in palm oil during deep fat frying. There was a significant increase in the content of 3-MCPD esters formed in palm oil when heating time was 2 h. The effect of water content was the most evident in 3-MCPD esters formation. The heating process imparted an accretion of up to 130 % from 1,260 to 2,950 mg/kg with increasing the water dosage from 7 to 10 %. In addition, 3-MCPD esters were decomposed when heated at high temperatures for a long time (longer than 2 h).     

28份国产特级初榨橄榄油中多酚含量及其变化规律北大核心CSCD

为了对我国油橄榄产业提供基础数据支持,采用国际油橄榄理事会推荐的HPLC法检测特级初榨橄榄油中的多酚含量,分析了我国不同产地的28份市售食用特级初榨橄榄油样品的多酚含量,并对不同生产年度和不同产地单果级特级初榨橄榄油中多酚含量变化规律进行了分析。结果表明:市售国产特级初榨橄榄油中均含有较为丰富的多酚类化合物,多酚含量范围为(63.885±2.345)mg/kg~(307.325±6.865)mg/kg;特级初榨橄榄油中多酚含量受贮存时间的影响较大,同时不同产地中适合生产高多酚含量特级初榨橄榄油的品种具有差异。不同特级初榨橄榄油样品之间多酚含量波动较大,需要通过多种方法来防止油脂中多酚类化合物的降解,以保证油品的质量,并因地制宜对油橄榄品种进行优化筛选。     

玉米油精炼过程氯离子含量变化及其对3-氯丙醇酯和缩水甘油酯含量的影响

对取自安徽、河北、山东等地玉米油加工厂的玉米油毛油、待脱臭油和成品油中的氯离子、3-氯丙醇（3-monochloro-1,2-propanediol,3-MCPD）酯和缩水甘油酯（glycidyl esters,GEs）含量进行检测,并在实验室明确可控的条件下对玉米毛油进行精炼,检测精炼过程氯离子、3-MCPD酯和GEs含量,与玉米油加工厂实际精炼过程的含量变化情况进行对比分析,研究玉米油精炼过程中氯离子含量变化及其对3-MCPD酯和GEs含量变化的影响。结果表明：所检测的所有玉米油样品中均含有氯离子、3-MCPD酯和GEs,其中毛油中氯离子含量最高,为0.628～2.029 mg/kg,毛油中3-MCPD酯和GEs含量分别为0.547～1.083 mg/kg和0.246～0.721 mg/kg;待脱臭玉米油中氯离子含量为0.110～0.374 mg/kg,较毛油中含量明显降低,3-MCPD酯和GEs含量分别为0.933～1.422 mg/kg和0.246～0.432 mg/kg,3-MCPD酯较毛油中含量有所升高,GEs含量变化不明显。脱臭油中3-MCPD酯和GEs含量分别为3.523～4.541 mg/kg和1.501～13.584 mg/kg,较待脱臭油中含量大幅升高,其中一个油样中含量分别增加3.5 倍和32.1 倍,同时该油样中氯离子含量的降幅也最大（0.287 mg/kg）。对实验室精炼过程及工厂精炼过程的玉米油样品检测分析显示,无论是实验室精炼还是工厂实际生产,氯离子含量均随精炼过程逐渐减少,其中降幅最大的是水化脱胶和碱炼脱酸工序（降幅为76.1%～81.3%）;3-MCPD酯和GEs在水化脱胶、碱炼脱酸及吸附脱色过程的含量变化不大,经脱臭后含量大幅升高,同时伴随脱臭过程氯离子含量的降低,并且氯离子含量降幅越大3-MCPD酯的升幅越高。研究结果明确了玉米油精炼过程氯离子和3-MCPD酯及GEs含量的变化规律,以及待脱臭玉米油中氯离子含量对脱臭油脂中3-MCPD酯和GEs含量的影响,对玉米油精炼乃至其他植物油生产中3-MCPD酯和GEs的风险防范和控制都具有指导意义。     

The effects of physical refining on the formation of 3-monochloropropane-1,2-diol esters in relation to palm oil minor components

The formation of 3-monochloropropane-1,2-diol (3-MCPD) esters in refined palm oil during deodorisation is attributed to the intrinsic composition of crude palm oil. Utilising D-optimal design, the effects of the degumming and bleaching processes on the reduction in 3-MCPD ester formation in refined palm oil from poor-quality crude palm oil were studied relative to the palm oil minor components that are likely to be their precursors. Water degumming remarkably reduced 3-MCPD ester formation by up to 84%, from 9.79 mg/kg to 1.55 mg/kg. Bleaching with synthetic magnesium silicate caused a further 10% reduction, to 0.487 mg/kg. The reduction in 3-MCPD ester formation could be due to the removal of related precursors prior to the deodorisation step. The phosphorus content of bleached palm oil showed a significant correlation with 3-MCPD ester formation.     

Occurrence of 3-MCPD and glycidyl esters in edible oils in the United States

Fatty acid esters of 3-monochloropropanediol (3-MCPD) and glycidol are processing contaminants found in a wide range of edible oils. While both 3 MCPD and glycidol have toxicological properties that at present has concerns for food safety, the published occurrence data are limited. Occurrence information is presented for the concentrations of 3-MCPD and glycidyl esters in 116 retail and/or industrial edible oils and fats using LC-MS/MS analysis of intact esters. The concentrations for bound 3-MCPD ranged from below the limit of quantitation (<LOQ) to 0.09 mg kg^?1 (ppm) in 22 unrefined oils and from 0.005 to 7.2 mg kg^?1 (ppm) in 94 refined oils. The concentrations for bound glycidol ranged from <LOQ to 0.03 mg kg^?1 (ppm) in unrefined oil samples and from <LOQ to 10.5 mg kg^?1 (ppm) in processed oil samples. The highest concentrations for both 3-MCPD and glycidol were seen in refined palm oil and palm olein samples. Palm olein samples also contained a higher percentage of 3-MCPD in mono-ester form than any other type of oil.     

Occurrence of bound 3-monochloropropan-1,2-diol content in commonly consumed foods in Hong Kong analysed by enzymatic hydrolysis and GC-MS detection

The aim of this study was to determine the level of bound 3-monochloropropan-1,2-diol in foodstuffs commonly consumed in Hong Kong, China, by an enzymatic hydrolysis indirect method which proved to be free from interferences. A total of 290 samples were picked up randomly from the local market and analysed. About 73% of these samples were found to contain detectable amounts of bound 3-MCPD. Amongst the 73 food items, bound 3-MCPD was not detected in 13 food items, including extra virgin olive oil, beef ball/salami, beef flank, ham/Chinese ham, nuts, seeds, soy sauce, oyster sauce, butter, yoghurt, cream, cheese and milk. For those found to contain detectable bound 3-MCPD, the content ranged up to 2500 µg kg^?1. The highest mean bound 3-MCPD content among the 14 food groups was in biscuits (440 [50–860] µg kg^?1), followed by fats and oils (390 [n.d.–2500] µg kg^?1), snacks (270 [9–1000] µg kg^?1), and Chinese pastry (270 [n.d.–1200] µg kg^?1). Among the samples, the highest bound 3-MCPD content was in a grape seed oil (2500 µg kg^?1), followed by a walnut flaky pastry (1200 µg kg^?1) and a grilled corn (1000 µg kg^?1). Basically, the results of this study agreed well with other published results in peer-reviewed journals, except for cheese, cream, ham, nuts and seeds.     

基于光谱法的特级初榨橄榄油快速鉴伪技术

本文研究了特级初榨橄榄油中掺入不同比例橄榄果榨油(精炼橄榄油)、菜籽油、玉米油和大豆油的光谱特征,采用荧光光谱和紫外光谱,对掺假样品及纯油样品进行了快速检测。结果表明,特级初榨橄榄油的光谱特征与其他植物油之间差异较大,且掺假体积与吸光度之间存在良好的线性关系(R²>0.89),实现了特级初榨橄榄油的定性鉴别与定量检测,建立了特级初榨橄榄油质量控制体系及其掺假检测分析技术,最低检出限为1%,线性范围为5%～100%(v/v)。系统聚类分析将所有特级初榨橄榄油准确地分为一个亚类,也佐证了此方法的稳定性与可靠性。这种简单快捷的检测技术,有助于特级初榨橄榄油实时、在线橄榄油检测分析技术的研发,为我国橄榄油品质鉴定及产业发展提供有利的技术保障。     

Differential scanning calorimeter application to the detectionof refined hazelnut oil in extra virgin olive oil

The potential application of differential scanning calorimetry (DSC) to verify adulteration of extra virgin olive oil with refined hazelnut oil was evaluated. Extra virgin olive oil and hazelnut oil were characterised by significantly different cooling and heating DSC thermal profiles. Addition of hazelnut oil significantly enhanced crystallisation enthalpy (at hazelnut oil ?20%) and shifted the transition towards lower temperatures (at hazelnut oil ?5%). Lineshape of heating thermograms of extra virgin olive oil was significantly altered by hazelnut oil addition: a characteristic exothermic event originated at −27 °C in extra virgin olive oil and progressively disappeared with increasing hazelnut oil content, while the major endothermic peak at −3.5 °C broadened (at hazelnut oil ?40%) and the minor endothermic peak at 8 °C shifted toward lower temperatures (at hazelnut oil ?5%). The preliminary results presented in this study suggest that DSC analysis may be a useful tool for detecting adulteration of extra virgin olive oil with refined hazelnut oil.     

Fatty acid esters of 3-chloropropane-1,2-diol in edible oils.

A series of 25 virgin and refined edible oils, obtained from retailers, was analyzed for levels of free 3-chloropropane-1,2-diol (3-MCPD) and 3-MCPD released from esters with higher fatty acids (bound 3-MCPD). Oils containing free 3-MCPD ranging from <3 microg kg-1 (LOD) to 24 microg kg-1. Surprisingly, bound 3-MCPD levels were much higher and varied between <100 (LOD) and 2462 microg kg-1. On average, virgin oils had relatively low levels of bound 3-MCPD, ranging from <100 (LOD) to <300 microg kg-1 (LOQ). Higher levels of bound 3-MCPD were found in oils from roasted oilseeds (337 microg kg-1) and in the majority of refined oils (<300-2462 microg kg-1), including refined olive oils. In general, it appears that the formation of bound 3-MCPD in oils is linked to preliminary heat treatment of oilseeds and to the process of oil refining. Analysis of unrefined, de-gummed, bleached, and deodorized rapeseed oil showed that the level of bound MCPD decreased during the refining process. However, additional heating of seed oils for 30 min at temperatures ranging from 100 to 280 degrees C, and heating at 230 degrees C (260 degrees C) for up to 8 h, led to an increase in bound 3-MCPD levels. On the other hand, heating of olive oil resulted in a decrease in bound 3-MCPD levels. For comparison, fat isolated from salami was analyzed for intact fatty acid esters of 3-MCPD. This fat contained bound 3-MCPD at a level of 1670 microg kg-1 and the fatty acid esters of 3-MCPD mainly consisted of 3-MCPD diesters; monoesters of 3-MCPD were present in smaller amounts. The major types of 3-MCPD diesters (about 85%) were mixed diesters of palmitic acid with C18 fatty acids (stearic, oleic, linoleic acids). These diesters were followed by 3-MCPD distearate (11%) and 3-MCPD dipalmitate (4%). Generally, very little 3-MCPD existed as the free compound (31 microg kg-1).     

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。     

Effect of cultivar and ripening on minor components in Spanish olive fruits and their corresponding virgin olive oils

Phenolics and volatiles are the compounds mainly responsible for the desirable flavour of extra virgin olive oils and therefore to a large extent determine the degree of consumer preference for this highly regarded product. The effect of both (i) the nature of the cultivar and (ii) the degree of ripening of the olive fruit on the biophenolic and volatile profiles of six different Spanish varieties (Arbequina, Cornicabra, Morisca, Picolimón, Picudo and Picual) and their corresponding virgin olive oils was determined in this study. A clear and statistically significant difference was observed for the oleuropein content, the main phenolic component found in the olive varieties studied. Demethyloleuropein was only found in the Arbequina variety and its content doubled during the ripening process. Verbascoside steadily increased throughout fruit maturation and cyanidin 3-O-rutinoside was the most abundant anthocyanin in all the varieties studied. Within the same cultivar a relationship between the oleosides content in the fruit and the presence of secoiridoids in the virgin olive oils was observed; however, the ratio between biophenols content in the olive fruit and in the virgin olive oil varied significantly for each of the cultivars studied (ranging from 2.3 for Picudo and 28 for Picolimon). The major volatile component was the C6 aldehyde fraction whose content varied greatly between the different varieties studied: E-2-hexenal content ranged from 20.5 mg of internal standard (4-methyl-2-pentanol) per kg of oil in the Arbequina variety to 3.1 mg/kg for Cornicabra; the amount of hexanal ranged from 1.75 mg/kg in Morisca to 0.70 mg/kg for Picual samples.     

初榨橄榄油挥发性风味成分的鉴定

采用顶空固相微萃取-气质联用(HS-SPME-GC/MS)分离鉴定了陇南市武都初榨橄榄油和西班牙特级初榨橄榄油中的挥发性风味成分。结果表明,在7个不同品种油橄榄的国产初榨橄榄油中共鉴定出86种化合物,主要是C6的醛和醇,以及它们相应的酯,还有一些烯烃和萜烯类化合物。其中(E)-2-己烯醛相对质量分数为7.14%~46.22%;在6个西班牙特级初榨橄榄油中共鉴定出101种化合物,其中(E)-2-己烯醛质量分数(1.76%~5.25%)低于国产初榨橄榄油,而(Z)-乙酸-3己烯酯(7.53%~13.76%)和(E)-2-十二碳烯(5.47%~34.75%)相对质量分数较高。试验结果还表明,初榨橄榄油挥发性风味成分很大程度上取决于油橄榄品种和产地。     

Estimated US infant exposures to 3-MCPD esters and glycidyl esters from consumption of infant formula

A dietary exposure assessment was conducted for 3-monochloropropane-1,2-diol (3-MCPD) esters (3-MCPDE) and glycidyl esters (GE) in infant formulas available for consumption in the United States. 3-MCPDE and GE are food contaminants generated during the deodorisation of refined edible oils, which are used in infant formulas and other foods. 3-MCPDE and GE are of potential toxicological concern because these compounds are metabolised to free 3-MCPD and free glycidol in rodents and may have the same metabolic fate in humans. Free 3-MCPD and free glycidol have been found to cause adverse effects in rodents. Dietary exposures to 3-MCPDE and GE from consumption of infant formulas are of particular interest because formulas are the sole or primary food source for some infants. In this analysis, US Food and Drug Administration data on 3-MCPDE and GE concentrations (as 3-MCPD and glycidol equivalents, respectively) in a small convenience sample of infant formulas were used to estimate exposures from consumption of formula by infants 0–6 months of age. 3-MCPDE and GE exposures based on mean concentrations in all formulas were estimated at 7–10 and 2 µg/kg bw/day, respectively. Estimated mean exposures from consumption of formulas produced by individual manufacturers ranged from 1 to 14 µg/kg bw/day for 3-MCPDE and from 1 to 3 µg/kg for GE.     

Extra-Virgin Olive Oil and Cheap Vegetable Oils: Distinction and Detection of Adulteration as Determined by GC and Chemometrics

Refined oils including corn, sunflower, soybean, and palm oils as well as low-quality olive oil such as refined lampante and pomace olive oils are commonly used for extra-virgin olive oil (EVOO) adulteration. Indeed, K ₂₇₀ could be used as a parameter for the detection of EVOO fraud for each type of the studied refined oils, 10 % olive, 4 % pomace olive, 10 % palm, 5 % corn, and 2 % soybean oils. Moreover, the adulteration could also be detected by the increase of the trans fatty acid contents with 10 % pomace olive, 3 % soybean, 3 % sunflower, 2 % corn, and 10 % palm oils. Actually, stigmasta-3,5-diene content is one of the most effective means of detecting refined oils in EVOO at low levels: 2 % olive, 0.4 % pomace olive, 1 % palm, 0.2 % soybean, 0.5 % sunflower, and 0.1 % corn oils. Finally, the application of linear discriminant analysis could represent an alternative and innovative tool for faster and cheaper evaluation of EVOO adulteration.     

油脂脱臭过程氯离子含量对3-氯丙醇酯和缩水甘油酯的影响

对油脂脱臭用直接蒸汽水源中氯离子含量和待脱臭油脂中氯离子含量进行检测分析,并采用不同氯离子含量的直接蒸汽对油脂进行蒸馏脱臭,检测脱臭前后油脂中3-氯丙醇酯（3-monochloro-1,2-propanediol ester,3-MCPD酯）和缩水甘油酯（glycidyl esters,GEs）含量及氯离子含量,研究油脂脱臭过程氯离子含量对脱臭油脂中3-MCPD酯和GEs的影响。结果表明：油脂脱臭用直接蒸汽中氯离子含量随其水源中氯离子含量增加而升高,水源中氯离子含量在对应饱和蒸汽中的保留率约为0.1%;当油脂脱臭用直接蒸汽水源中氯离子质量浓度达到50～200?mg/L时,脱臭油脂中3-MCPD酯含量大幅升高至低质量浓度氯离子水源（1～10?mg/L）脱臭油脂中含量的2.6?倍,但脱臭油脂中氯离子含量并未升高;待脱臭油脂中氯离子含量升高会导致脱臭后油脂中3-MCPD酯和GEs含量的升高。在待脱臭油脂中添加质量浓度为100?mg/L的氯化钠溶液0.5～5?mL时（相当于油脂中添加量1～10?mg/kg）,脱臭后油脂中3-MCPD酯和GEs生成量分别为4.49～7.84?mg/kg和14.88～19.84?mg/kg,是待脱臭油脂含量的5.5～9.5?倍和5.8～7.7?倍。因此,控制和减少油脂脱臭过程氯离子含量对降低脱臭油脂中3-MCPD酯和GEs含量有重要作用。     

气相色谱-质谱联用法测定食用油中3-MCPD脂肪酸酯

本研究在德国油脂科学协会(DGF)标准检测方法的基础上进行方法优化,利用气相色谱-质谱联用(GC-MS)技术,建立了油脂中3-氯-1,2-丙二醇(3-MCPD)脂肪酸酯的分析方法。根据结果可知,该方法线性相关性良好,检出限为0.022 5 mg/kg,定量限为0.076 0 mg/kg,线性范围为0.05~5.0 mg/kg,回收率为95.36%~101.18%,相对标准偏差为1.36%~8.14%。试验中同时利用该方法对7种常见油脂中3-MCPD脂肪酸酯进行了检测。结果表明:该分析方法定性定量准确、灵敏度高、重现性好,能满足油脂中3-MCPD脂肪酸酯分析检测的要求。     

食用植物油中3-MCPD酯GC-MS测定方法研究

建立了甲醇钠-甲醇水解,固相萃取柱净化,HFBI衍生结合气相色谱-质谱(GC-MS)方法对食用植物油中3-MCPD酯含量进行测定。该方法在0.50～2. 50 mg/L范围内线性关系良好(r~2=0.988 5),检出限为0. 025 5 mg/kg,定量限为0. 093 3 mg/kg。3-MCPD酯的平均加标回收率在94. 80%～104. 62%之间,RSD 1.47%～5.23%。本方法操作简单、灵敏度高、重复性好,能够很好地适用于食用植物油中3-MCPD酯的检测。采用该方法对新疆几种市售食用植物油中的3-MCPD酯进行测定。新疆市售的几种食用植物油中均检测出浓度不等的3-MCPD酯。其中菜籽油、亚麻籽油、番茄籽油、花生油以及葡萄籽油受3-MCPD酯污染严重,3-MCPD酯含量都高于0.4 mg/kg。而核桃油、大豆油、红花籽油中3-MCPD酯的含量都低于0.4mg/kg。     

Influence of rosemary (Rosmarinus officinalis, L.) on plant sterol oxidation in extra virgin olive oil

The objective of this study was to investigate the potential role of rosemary compounds in inhibiting the plant sterol oxidation in extra virgin olive oil during heating. The stability of plant sterols was measured by quantification of plant sterol and sterol oxide formation upon 6 h of heating in both the extra virgin olive oil and its respective oil at 10% rosemary concentration (ROE). The total sterol and sitosterol oxide contents were determined by GC-flame ionization detection (GC-FID) and GC-MS techniques, respectively. Heating experiments were carried out at 180 degrees C for 0, 1, 3 and 6 h. The total sterol content in the extra virgin olive oil was 255 mg/100 g and that in the ROE 270 mg/100 g. Sitosterol was the most abundant sterol in both samples (50% of total sterol). The ROE showed a lower content of sitosterol oxides with respect to the extra virgin olive oil during heating: after 6 h of heating only 6.1% of sitosterol oxides were formed, while up to 11.5% of sitosterol oxidized in the extra virgin olive oil. Our findings suggested that rosemary compounds were able to counteract the oxidation of plant sterols in the extra virgin olive oil during heating, preventing formation of potentially harmful compounds to human health.     

Quality assessment of edible vegetable oils used as liquid medium in canned tuna

An experimental investigation was conducted to assess the quality of vegetable oils used as liquid medium in preserved fish. Sixteen tuna preserves were tested, including two in extra virgin olive oil, nine in olive oil (refined olive oil plus virgin olive oil) and five in refined seed oil. Next to the traditional routine analyses prescribed by the EEC Regulation N° 2568/91 (useful for a preliminary characterisation of oils used as liquid medium), the content of trans isomers of unsaturated fatty acids was determined and the analysis of polar compounds was performed by HPSEC (high performance size-exclusion chromatography). The acid composition showed the presence of highly unsaturated fatty acids, typical of fish lipids. Trans isomers were always absent in extra virgin olive oils, whereas they were always present in olive oils and in refined seed oils. Triglyceride oligopolymers, oxidised triglycerides and diglycerides, measured by means of the HPSEC analysis of polar compounds, ranged within 0.13-1.07%, 0.51-2.36% and 0.96-4.02%, respectively. The HPSEC analysis of polar compounds and the determination of trans isomers enabled better assessment of the quality of different types of oils used as liquid medium for canned tuna.     

Detection of hazelnut oil in virgin olive oil by a spectrofluorimetric method

The possibilities of a spectrofluorimetric method joined to multivariate analysis to assess the genuineness of olive oil in admixtures with hazelnut oils were studied. Virgin olive, virgin hazelnut and refined hazelnut oil samples and admixtures between them at 5, 10, 15, 20, 25 and 30% adulteration were analysed at _ex=350 nm. The precision of the method, in terms of repeatability and internal reproducibility, was established by means of the analysis of a virgin olive oil sample under different conditions, the RSD showing values less than 10%. Raw data of the spectra were subjected to mathematical treatment by calculation of the first derivative, selection of the maximum values and application of one-way ANOVA, to assess the most prominent variables in the discrimination process. The response to the addition of adulterant was linear, adjusted-R²=0.99 for virgin olive and refined hazelnut oil mixtures, and 0.98 for virgin olive and virgin hazelnut oil mixtures. Stepwise linear discriminant analysis applied to each admixture separately and to the whole set of samples allowed 100% correct classifications.