Effect of Pretreatment with Dehulling and Microwaving on the Flavor Characteristics of Cold‐Pressed Rapeseed Oil by GC‐MS‐PCA and Electronic Nose Discrimination

Raw and dehulled rapeseeds were treated with microwave energy (800 W) from 1 to 8 min with 1‐min intervals at a frequency of 2450 MHz to investigate the influence of microwaving and dehulling pretreatment on the flavor characteristics of rapeseed oil extracted by pressing. Headspace solid phase microextraction was used to isolate the volatile compounds of rapeseed oil, which were then identified by gas chromatography‐mass spectrometry analysis. The results indicated that microwave and dehulling pretreatment of rapeseed can significantly influence the kinds and content of volatile compounds. The key flavor compounds in rapeseed oil were oxidized volatiles, heterocyclic compounds, and degradation products of glucosinolates. A pungent compound, 4‐isothiocyanato‐1‐butene, was reduced by 97% in rapeseed treated for 3 min with microwaves energy when compared to the rapeseed oil without any treatment. The pyrazine compounds in the oil appeared after 6 min of microwave pretreatment and give a pleasant roasting flavor when compared to crude oils. Principal component analysis was able to differentiate between oils obtained using 4 pretreatment processes based on volatile compounds and electronic nose. The results showed that dehulling pretreatment could improve the flavor, yet microwaving had a greater effect on the flavor of rapeseed oils.     

不同制备工艺菜籽油的风味成分比较研究

采用传统工艺(蒸炒、压榨工艺和蒸炒、压榨、脱胶工艺)和美拉德生香工艺分别制备菜籽油(菜籽油甲、菜籽油乙和菜籽油丙),采用顶空固相微萃取与气相色谱-质谱联用对3种工艺菜籽油的挥发性风味成分进行分析,采用气味活度值和相对活度值确定对3种菜籽油风味贡献最大的物质。结果发现:菜籽油甲、菜籽油乙、菜籽油丙分别鉴定出18、29、21种挥发性成分;菜籽油甲、菜籽油丙的整体风味评分接近,略高于菜籽油乙;菜籽油甲、菜籽油乙风味成分中腈类物质的含量明显高于菜籽油丙,而吡嗪类和醛类物质含量明显低于菜籽油丙;对菜籽油甲、菜籽油乙、菜籽油丙风味贡献最大的物质分别为2-噻吩甲醛、3,5-二乙基-2-甲基吡嗪和3-甲基丁醛。     

基于全二维气相色谱-飞行时间质谱法鉴定冷榨菜籽油的挥发性风味成分

以甘蓝型、白菜型和芥菜型3种不同基因型菜籽为原料,采用全二维气相色谱-飞行时间质谱法对冷榨菜籽油中挥发性风味成分进行鉴定,结合嗅觉检测器对其进行气味分析,并通过感官评定构建冷榨菜籽油风味轮廓图。研究表明:全二维气相色谱-飞行时间质谱法共分离共鉴定出156种挥发性成分,其中38种物质具有特征气味,主要包括异硫氰酸酯、含硫化合物、醇类、醛类、酸类、酮类、内酯和杂环类化合物;对于不同基因型原料而言,异硫氰酸酯和含硫化合物是冷榨菜籽油中风味差异的关键组分,甘蓝型、白菜型和芥菜型3种冷榨菜籽油的异硫氰酸酯总量分别为6. 94%、40. 86%和54. 94%,含硫化合物总量分别为2. 7%、0.44%、1.73%;通过感官评定,3种冷榨油中甘蓝型菜籽油中的辛辣味最弱,卷心菜味最强,白菜型菜籽油中青草味最明显,芥菜型中的酸味最明显;3个不同品种间种子味、坚果味、腐败味、发霉味、苦味差异不显著(P0.05)。     

基于电子鼻和气相色谱-质谱法结合相对气味活度值分析植物油对红油辣椒气味的影响

目的 为探究植物油对红油辣椒气味的影响。方法 采用电子鼻、气质联用技术(gas chromatography-mass spectrometry,GC-MS)结合正交偏最小二乘判别分析(orthogonal partial least squares discriminant analysis,OPLS-DA)和相对气味活度值(Relative Odor Activity Value,ROAV)等分析方法探究不同品种的植物油对红油辣椒气味物质的影响。结果 电子鼻检测结果结合OPLS-DA分析表明不同品种的植物油制备的红油辣椒其整体气味轮廓差异明显。GC-MS检测结果表明5种植物油制备的红油辣椒共检测到101种挥发性物质,其中醇类29种、醛类30种、烃类12种、硫醚类3种、酯类6种、酸类2种以及其他化合物19种；醇类、醛类、硫醚类是红油辣椒的主要挥发性物质。ROAV分析表明A样品(精炼菜籽油)的关键性化合物是：苯乙醛、反-2-壬醛、二甲基硫醚；B样品(大豆油)的关键性化合物是：1-庚烯-3-酮、二甲基硫醚；C(花生油)、E(菜籽油)样品的关键性化合物是：二甲基硫醚; D(玉米油)样品的关键性化合物是：二甲基硫醚、(Z)-2-壬烯醛、1-辛烯-3-酮。结论 不同品种的植物油制备的红油辣椒的主要挥发性物质有一定差,二甲基硫醚是红油辣椒的共有关键性化合物。     

马铃薯煎炸过程中食用油稳定性的研究

采用马铃薯作为食材,菜籽油、胡麻油和米糠油3种常用食用油作为煎炸用油,测定不同煎炸温度、不同煎炸时间下3种食用油酸值、碘值、过氧化值,评价不同食用油煎炸过程中的稳定性.结果 表明:经过5h的连续加热,3种食用油的酸值、过氧化值含量都随加热温度和加热时间的增大有逐渐上升的趋势,碘值随着加热温度和加热时间的增大逐渐下降,3...     

微波加热对食用油品质及脂肪酸成分的影响

研究微波加热对食用油品质及脂肪酸成分影响,为家庭健康烹调提供理论依据。用家用微波炉的不同加热档位,对菜籽油、大豆油等8种常用食用油加热不同时间,用滴定法测定加热后油脂的酸价和过氧化值,GC-MS测定油脂的脂肪酸成分,并以这些指标评价微波加热对食用油品质的影响。在实验所用加热条件下,8种食用油的酸价和脂肪酸成分均未发生明显改变。不同食用油的过氧化值变化曲线有所不同,菜籽油、大豆油、花生油、芝麻油、调和油的过氧化值随着微波功率和时间增加而上升,玉米油、橄榄油和葵花籽油的过氧化值随着微波功率和时间增加先上升后下降。微波加热虽然改变了食用油的过氧化值,但酸价尚未发生改变,认为油脂尚未发生酸败,微波加热也没有破坏食用油原有的脂肪酸组成。从微波加热对食用油的品质和脂肪酸成分影响的结果看,可以认为微波加热是日常生活中安全和健康的加热方式。     

Application of a new sampling device for determination of volatile compounds released during heating olive and sunflower oil: sensory evaluation of those identified compounds

This work has applied a system for characterizing volatile compounds generated during the heating of oils, based on solid-phase extraction–gas chromatography–mass spectrometry. The system has been applied to sunflower and extra virgin olive oil at kitchen conditions, heating from room temperature to 80° above their smoking point. The work identified twenty-three compounds, mainly saturated and unsaturated aldehydes, and alkanes; carboxylic acids were present in lower concentrations. During heating, the stability of each oil was found to be different. The alkanals were produced in greater quantities in the sunflower oil. Alkanes were found in higher concentration in the olive oil and showed no significant variation in either of the oils as the temperature changed. And a relationship between the quantity of aldehydes released at the highest temperature and the percentage of fatty acids from which those aldehydes originated in each oil was found. The importance of the unsaturated aldehydes in the deep-fried odor was also exposed in this study.     

Chemical composition,antioxidant and cytotoxicity activities of the essential oils of Myristica fragrans and Morinda citrifolia

BACKGROUND: In this study the chemical composition, antioxidant activities and cytotoxic effect of the essential oils of Myristica fragrans (nutmeg) and Morinda citrifolia (mengkudu) were determined. RESULTS: Thirty‐eight compounds in nutmeg oil and six compounds in mengkudu oil were identified by gas chromatography–mass spectrometry. The free radical scavenging activity of nutmeg oil was superior of that mengkudu oil. The MTT assay of nutmeg oil on human colorectal carcinoma (HCT‐116) and human breast carcinoma (MCF‐7) cell lines showed IC₅₀ values of 78.61 and 66.45 µg mL^?1, respectively. The mengkudu oil exhibited IC₅₀ values of 91.46 and 78.15 µg mL^?1 for HCT‐116 and MCF‐7, respectively. CONCLUSION: The results showed that nutmeg oil can be developed as potent anti‐cancer and antioxidant drugs. Copyright © 2011 Society of Chemical Industry     

基于主成分和聚类分析评价国产不同批次肉豆蔻挥发油的质量

本文对16批次肉豆蔻样品的挥发油进行化学成分分析鉴定，对其共有化学成分采用主成分分析和聚类分析，从而对肉豆蔻挥发油进行综合质量评价。通过对其形状、气味、色泽等性状进行记录，采用水蒸气蒸馏法提取肉豆蔻挥发油，通过气相色谱-质谱联用色谱仪（GC-MS）所得挥发性成分，结合NIST08系列标准谱库、人工检索等方式对其进行鉴定分析，利用主成分分析和聚类分析对16批次肉豆蔻样品进行综合评价。16批次肉豆蔻多为卵圆形或椭圆形、香气浓烈、灰棕色；从肉豆蔻挥发油化学成分中共筛选出17个共有成分，经主成分分析概括为4个主成分，包含源信息量的86.26%；聚类分析结果显示，16批次肉豆蔻样品可聚为两大类，S15批次聚为一类，S1-S14，S16批次聚为一类；两种分析结果达成一致。通过主成分分析和聚类分析，同时结合性状品质与安全性分析，可以建立肉豆蔻挥发油的质量评价体系，为肉豆蔻挥发油的药食两用以及其他方面的进一步开发研究提供参考依据，该评价方法综合性强、全面性高。     

Application of an electronic nose for determination of pre-pressing treatment of rapeseed based on the analysis of volatile compounds contained in pressed oil

The article presents an attempt to use an electronic nose together with a new three-parameter method for generation of a digital smellprint in order to specify the mode of processing of rapeseed based on the analysis of volatile compounds contained in cold-pressed rapeseed oil. Prior to the pressing process, the seeds were roasted or improperly stored to obtain oil samples with varied technological quality. The quality of pressed oils was evaluated by determination of the acid value. Furthermore, changes in oil colour were assessed with the use of an imaging colorimeter. Volatile compounds were determined with the use of gas chromatography and an electronic nose with a metal oxide semiconductor (MOS) sensor matrix. It was found that the mode of seed pre-treatment before pressing did not change the colour of the oil significantly. However, it influenced the profile of volatile organic compounds and changed their proportions. Ketones represented the largest proportion of volatile compounds determined for roasted samples and those pressed from seeds moistened up to 25% (w.b.). Alcohols dominated in samples moistened up to 10 and 12%, terpenes were the dominant volatile compounds in samples roasted at 140 °C, and other volatile compounds dominated in samples moistened up to 10 and 20% (w.b.). In turn, esters and aromatic compounds accounted for the lowest proportion in the analysed samples. The results shown by the electronic nose were correlated with the presence of particular groups of volatile compounds in rapeseed oil.     

脱胶与脱酸对菜籽油挥发性组分的影响

采用气相色谱-质谱联用法研究传统脱胶和脱酸工艺对冷榨和热榨菜籽油中挥发性组分的影响,发现冷榨油与热榨油中的挥发性组分及风味差异较大,热榨油中的挥发性组分比冷榨油更为复杂,且脱胶和脱酸工艺可以降低菜籽油中挥发性组分的复杂性;主成分分析结果表明脱酸工艺对冷榨油和热榨油的挥发性组分影响较大,而脱胶工艺的影响程度相对较小。通过测定各阶段菜籽油中酸价和过氧化值的变化,发现脱胶工艺对菜籽油的酸价没有显著影响;脱胶和脱酸工艺对冷榨油的过氧化值均有显著影响,但对热榨油的过氧化值没有显著影响。     

不同产地浓香菜籽油中特征风味物质的研究

以贵州、四川、安徽、湖北、湖南、江苏和内蒙7省油菜籽为原料,经烘炒热榨制取浓香菜籽油,采用顶空固相微萃取(HS-SPME)和气相色谱-质谱(GC-MS)联用技术对浓香菜籽油中风味物质进行萃取和分离鉴定,在此基础上引入相对活度值法(ROAV)对鉴定出的风味物质进行活度分析,提取其中的特征风味物质。结果显示:甲烯丙基氰、4-异硫氰酸酯-1-丁烯、壬醛、2,3,5,6-四氟苯甲醚、2,5-二甲基吡嗪是不同产地浓香菜籽油的共同特征风味物质。同时因产地不同浓香菜籽油又表现出风味差异,贵州、四川菜籽油中硫甙降解产物含量较高,表现出浓郁的辛辣味;湖北菜籽油中吡嗪类化合物含量较高,表现出浓郁的焙烤香味。     

油菜籽品种对浓香菜籽油风味及综合品质的影响

分别以双低油菜籽及传统油菜籽为原料,在相同条件下制取浓香菜籽油,采用溶剂辅助蒸发装置结合气相色谱-质谱联用仪对两种菜籽油中挥发性成分的种类和含量进行测定,并利用偏最小二乘判别分析（partial least squares discriminant analysis,PLS-DA）、气味活度值（odor activity value,OAV）对挥发性成分进行数据分析,确定导致两种菜籽油感官风味差异的关键挥发性风味成分,同时结合感官评价、脂肪酸组成、氨基酸组成、营养成分等指标分析比较两种菜籽油综合品质的差异。结果显示,双低菜籽油及传统菜籽油中分别检出12 类82 种和11 类90 种挥发性成分,总量分别为22 377.88、157 512.98 μg/kg,其中硫苷降解产物总量分别为3 311.07、146 492.82 μg/kg,酚类物质总量分别为12 125.47、4 613.03 μg/kg。利用PLS-DA结合OAV最终确定了13 种最重要的特征风味物质,分别为6-甲基硫基己腈、5-甲硫基戊腈、苯代丙腈、3-丁烯基异硫氰酸酯、苯乙腈、反-2-癸烯醛、正己醇、芳樟醇、乙基苯、苯乙醇、椰子醛、4-乙烯基-2,6-二甲氧基苯酚、3-甲基巴豆腈,其中6-甲基硫基己腈、苯乙腈、芳樟醇、5-甲硫基戊腈、苯代丙腈、3-丁烯基异硫氰酸酯6 种成分均对菜籽油独特的辛辣味具有贡献,且苯乙腈、芳樟醇仅在传统菜籽油中检出;正己醇、苯乙醇、椰子醛则在双低菜籽油中含量更高,对菜籽油的甜味具有重要影响;感官评价表明双低菜籽油的甜味优于传统菜籽油,而传统菜籽油辛辣味更强。双低菜籽油中未检出芥酸,而传统菜籽油中芥酸含量高达30.25%;双低菜籽油中VE和甾醇总含量均高于传统菜籽油。研究结果为不同香型浓香菜籽油的生产提供了原料选择和气味标识的支持。     

Production,Characterization, and Stability of Orange or Eucalyptus Essential Oil/β‐Cyclodextrin Inclusion Complex

The aim of this study was to produce and characterize inclusion complexes (IC) between β‐cyclodextrin (β‐CD) and orange essential oil (OEO) or eucalyptus essential oil (EEO), and to compare these with their pure compounds and physical mixtures. The samples were evaluated by chemical composition, morphology, thermal stability, and volatile compounds by static headspace‐gas chromatography (SH‐GC). Comparing the free essential oil and physical mixture with the inclusion complex, of both essential oils (OEO and EEO), it was observed differences occurred in the chemical composition, thermal stability, and morphology. These differences show that there was the formation of the inclusion complex and demonstrate the necessity of the precipitation method used to guarantee the interaction between β‐CD and essential oils. The slow loss of the volatile compounds from both essential oils, when complexed with β‐CD, showed a higher stability when compared with their physical mixtures and free essential oils. Therefore, the results showed that the chemical composition, molecular size, and structure of the essential oils influence the characteristics of the inclusion complexes. The application of the β‐CD in the formation of inclusion complexes with essential oils can expand the potential applications in foods.     

不同植物油对植物肉风味及感官特性的影响

为探究不同脂肪酸组成的植物油对植物肉风味及感官品质的影响,将常用于食品加工且脂肪酸组成差异较大的5种植物油(菜籽油、大豆油、花生油、葵花籽油、棕榈油)添加到植物肉中,采用顶空固相微萃取-气相色谱-质谱联用技术(HS-SPME-GC-MS)对其进行风味分析,结合感官评价和质构分析等方法对5组植物肉进行对比。实验结果表明,5组植物肉的挥发性成分、感观属性、质构特性等存在显著差异。5组样品中共鉴定出79种挥发性组分,其中30种可被嗅闻到,主要包括吡嗪类、呋喃类、醛类、含硫类化合物。2,3,5-三甲基吡嗪、2-戊基呋喃、3-甲硫基丙醛等化合物的嗅闻强度最大。与其他样品相比,添加花生油的样品C和添加菜籽油的样品A中挥发性化合物种类和含量较多,但样品C的香气轮廓中油脂味较为突出,且该组样品的硬度与胶黏性较差,并不适用于植物肉的生产制作。样品A以肉香味为主,其硬度、弹性较大。研究结果表明,含芥酸、油酸较多的菜籽油更适用于植物肉的加工生产,对植物肉的风味、质构等感官品质具有明显增强作用。     

焙炒处理对不同植物油品质特性的影响北大核心CSCD

为了研究焙炒对植物油品质的影响,以油菜籽、亚麻籽、花生、葵花籽和芝麻为原料,经焙炒处理后采用液压压榨法制油(热榨油),分析植物油的理化指标(酸值、过氧化值、水分及挥发物、色泽)、主体组分(脂肪酸组成及含量、甘三酯组成及含量、挥发性组分)和总酚含量,并与未焙炒处理直接压榨制取的油(冷榨油)作对比。结果表明:热榨油酸值和过氧化值显著高于冷榨油(p<0.05),其中,热榨亚麻籽油酸值(KOH)最高(0.96 mg/g),热榨菜籽油过氧化值最高(1.02 mmol/kg);冷榨油水分及挥发物含量显著高于热榨油(p<0.05),其中冷榨花生油水分及挥发物含量最高(0.16%);热榨油的色泽较冷榨油深,其中热榨菜籽油的色泽最深(R1.1,Y31);焙炒对植物油脂肪酸和甘三酯组成及含量无显著影响(p>0.05);热榨油中醇类、醛类和酸类等挥发性组分较少,但杂环类物质较多;热榨菜籽油、亚麻籽油、花生油、葵花籽油和芝麻油总酚含量分别是其冷榨油的1.38、1.57、1.51、1.80倍和1.27倍。因此,焙炒对植物油品质影响较大,应根据生产需要选择合适的预处理方式。     

Extraction and separation of volatile and fixed oils from seeds of Myristica fragrans by supercritical CO₂: chemical composition and cytotoxic activity on Caco-2 cancer cells

Isolation of volatile and fixed oils from nutmeg have been obtained by supercritical fractioned extraction with carbon dioxide. Extraction experiments were carried out at pressures of 90 and 250 bar and temperature of 40 °C. The extraction step performed at 90 bar produced a volatile fraction mainly formed by myristicin (32.8%), sabinene (16.1%), α-pinene (9.8%), β-pinene (9.4%), β-phellandrene (4.9%), safrole (4.1%) and terpinen-4-ol (3.6%). The oil yield relative to this step of the process was 1.4% by weight of the charge. The last extraction step at 250 bar produced a butter-like material (nutmeg butter). The yield of this step was 14.4% by weight. The most represented fatty acids of fixed oil from nutmeg were 14:0 (79.2%), 18:1 n-9 (7.4%) and 16:0 (6.1%), and in particular the unsaturated fatty acids 18:1 n-9 averaged 32.96 μg/mg of oil. The level of myristicin in the nutmeg essential and fixed oils was also directly quantified by reversed HPLC-DAD. Moreover, the essential oil obtained from nutmeg, as well as myristicin, showed a significant in vitro inhibitory effect on the growth of a colon cancer cell line (undifferentiated Caco-2 cells). PRACTICAL APPLICATION: In this study, the chemical characterization and the anticancer activity of nutmeg oils obtained by supercritical extraction with carbon dioxide were investigated. This is important for their potential application in food and pharmaceutical industries.     

Comparative studies of different heat treatments on quality of fried shallots and their frying oils

The objectives of this study were to compare the quality of shallot-flavoured frying oil from microwave heat treatment with that from gas heat treatment. Frying of shallot pieces by the microwave treatment required shorter heating time to obtain the same colour quality as through gas treatment. The amount of total volatile compounds of shallot-flavoured frying oil obtained from microwave treatment was greater than that from gas treatment. Oil-frying of shallots by microwave heating showed better oil quality, with lower acid and peroxide values than after frying by gas heating. In storage tests these two differently treated oils at 25°C, the acid value (AV) showed no significant increase during storage for 80 days. However, the peroxide value (PV) of these two oils increased in parallel as storage time increased. The effect of moisture content, of the shallots, on the quality of resultant shallot-flavoured frying oil was studied. Slight moisture reduction of shallot pieces from 72 to 63%, by a toasting pretreatment gave the highest amount of total volatile compounds of the shallot-flavoured frying oil. However, this total volatile compounds decreased if the moisture content of shallot pieces was less than 63%.     

A novel approach to monitor the oxidation process of different types of heated oils by using chemometric tools

The oxidative stability of seven oils with different fatty acid profiles was assessed. Oxidation at 0, 2 and 4 h at 180 °C was monitored by measuring the absorbance of thiobarbituric acid reactive substances (TBARS) along the absorption spectrum (300–600 nm), the volatile aldehydes (HS-SPME–GC–MS) and the fatty acid profile (FID-GC).TBARS absorption spectrum behavior depended on the lipid composition of heated oils. Higher absorbance increments during heating were noticed at 390 nm compared to 532 nm (from 2 to 21 fold higher depending on the oil), pointing to its better sensitivity to detect oxidation. Furthermore, a close relationship between ABS₃₉₀, the loss of polyunsaturated fatty acids and their corresponding oxidation compounds (volatile aldehydes) was revealed by Principal Component Analysis.Multiparametric equations allowed predicting the formation of volatile aldehydes of heated oils by measuring only two parameters: TBARS₃₉₀ during their heating, and the lipid profile in unheated oils (MUFA, ω-3 and ω-6). Results pointed out the interest of choosing ABS₃₉₀ when the oxidative evolution of vegetable oils under heating is assessed by the TBARS test.