Effect of extraction techniques on the chemical composition and antioxidant activity of Eucalyptus camaldulensis var. brevirostris leaf oils

 The volatile oil compositions of Eucalyptus camaldulensis var. brevirostris leaves obtained by hydrodistillation (HD) and supercritical fluid extraction methods (SFE) were analysed qualitatively and quantitatively by GLC-MS. Ninety different components were separated and most of them identified. In both extracts the main constituents were found to be β-phellandrene (8.94 and 4.09%), p–cymene (24.01 and 10.61%), cryptone (12.71 and 9.82%) and spathulenol (14.43 and 13.14%). The yield of the monoterpene hydrocarbons in HD oil (0.288 g/100 g fresh leaves) was slightly higher compared with that in the SFE extract (0.242 g/100 g fresh leaves). The SFE extract possessed higher concentrations of the sesquiterpenes, light oxygenated compounds and heavy oxygenated compounds than the HD oil. The relationship between the antioxidant activity and chemical composition of the extracted oils was investigated. The significant amounts of p–cymen-7-ol and thymol are responsible for the antioxidative activity of both extracts. The concentration of both compounds, but especially that of p–cymen-7-ol (2.25%), is higher in the SFE extract. This corresponds with the higher antioxidative activity of the SFE compared with the HD extract. p–Cymen-7-ol, a compound newly identified in leaves of Eucalyptus species, exhibited superior antioxidant activity in comparison with that of butylated hydroxyanisole. Received: 30 April 1998     

Improvement of bixin extraction yield and extraction quality from annatto seed by modification and combination of different extraction methods

Bixin from annatto seed was extracted by submerging the seeds in acetone and by combined extractions using sodium hydroxide and soybean oil in the dark to improve extraction yield and reduce content of volatile compounds in annatto extracts. The exclusion of light from acetone extraction did not significantly improve bixin extraction yield (68.5%) compared to the process carried out under daylight (67.3%), but it remarkably reduced contents of toluene and m‐xylene in annatto extracts. Combined extraction using sodium hydroxide solution at 50 °C for 40 min and soybean oil at 100 °C for 20 min resulted in very low level of volatile compounds. Significantly higher extraction yield (53.7%) could be achieved by such a process as compared to a single extraction sodium hydroxide (31.8%) or soybean oil (42.9%) alone. In conclusion, the exclusion of light from acetone extraction and combined extraction significantly reduced concentration of undesirable volatile compounds. The combined extraction significantly improved bixin yield compared to the original extraction methods.     

Effect of extraction techniques on the chemical composition and antioxidant activity of Eucalyptus camaldulensis var. brevirostris leaf oils

 The volatile oil compositions of Eucalyptus camaldulensis var. brevirostris leaves obtained by hydrodistillation (HD) and supercritical fluid extraction methods (SFE) were analysed qualitatively and quantitatively by GLC-MS. Ninety different components were separated and most of them identified. In both extracts the main constituents were found to be β-phellandrene (8.94 and 4.09%), p–cymene (24.01 and 10.61%), cryptone (12.71 and 9.82%) and spathulenol (14.43 and 13.14%). The yield of the monoterpene hydrocarbons in HD oil (0.288 g/100 g fresh leaves) was slightly higher compared with that in the SFE extract (0.242 g/100 g fresh leaves). The SFE extract possessed higher concentrations of the sesquiterpenes, light oxygenated compounds and heavy oxygenated compounds than the HD oil. The relationship between the antioxidant activity and chemical composition of the extracted oils was investigated. The significant amounts of p–cymen-7-ol and thymol are responsible for the antioxidative activity of both extracts. The concentration of both compounds, but especially that of p–cymen-7-ol (2.25%), is higher in the SFE extract. This corresponds with the higher antioxidative activity of the SFE compared with the HD extract. p–Cymen-7-ol, a compound newly identified in leaves of Eucalyptus species, exhibited superior antioxidant activity in comparison with that of butylated hydroxyanisole.     

五种方法提取的牡丹皮挥发油成分比较

本研究通过采用气相色谱-质谱联用（GC-MS）法结合保留指数（RI）对牡丹皮蒸馏法、水蒸气蒸馏法、水蒸气加酒精灯加热蒸馏法、乙醚超声波萃取法和超临界CO2萃取法这五种提取方法所制备的挥发油进行分析,通过比较挥发油得油率、化合物成分和丹皮酚提取率,选出最佳提取方法。五种方法的得油率分别为：1.03%、2.97%、4.45%、2.85%、0.63%,确定所得化合物的种类依次为21、22、22、23和22种,主要包括酚、烷烃、酸、酯、酮、醇和醛类等成分。五种方法获得的丹皮酚含量分别为：76.34%、72.49%、91.54%、60.04%和75.90%。以得油率和丹皮酚提取率为指标,水蒸气加酒精灯加热蒸馏法提取牡丹皮挥发油的提取率最高,可用于牡丹皮挥发油的提取;以化合物成分为指标,则超临界CO2萃取法和乙醚超声波萃取法,鉴别出的成分更全面。     

微波辅助提取-气相色谱-质谱联用快速分析花椒挥发油

建立微波辅助提取-气相色谱-质谱联用快速分析花椒挥发油的方法。采用微波辅助提取-水蒸气蒸馏法(MAE-SD)提取挥发油,正交试验设计优化微波辅助提取条件,气相色谱-质谱联用分析挥发油的化学成分和理化性质,同时将微波辅助提取与传统水蒸气蒸馏法进行比较。结果表明：MAE-SD的最佳工艺为微波功率400W、加水量15mL/g、浸泡30min,提取20min;经GC-MS分析,分离得到137种成分,质谱鉴定相似度在90%以上的化合物59种;根据峰面积归一法,相对含量较高的成分有桧萜(3.72%)、β-月桂烯(8.34%)、枞萜(15.15%)、松油烯(3.65%)、桉树脑(6.25%)、α-蒎烯(4.95%)、β-芳樟醇(3.05%)、4-萜品醇(10.48%)、松油醇(3.55%)、α-松油醇酯(4.09%);与水蒸气蒸馏法相比,挥发油的成分种类和理化性质接近,但相对含量存在一定差异。MAE-SD可快速高效提取挥发油类成分,联合GC-MS可对挥发油进行快速分析。     

制油工艺对澳洲坚果油营养品质及挥发性风味成分的影响

研究压榨法和水剂法2种制油工艺对澳洲坚果油品质及挥发性风味成分的影响,分别比较2种制油工艺对澳洲坚果油甘油三酯组成、甾醇组成、脂肪酸组成、挥发性风味成分、生育酚及矿质元素含量的影响。结果表明:制油工艺对澳洲坚果油的脂肪酸组成、甘油三酯组成和生育酚含量没有显著影响,澳洲坚果油中脂肪酸主要为油酸、棕榈-烯酸、棕榈酸,占86%以上;甘油三酯共检出18种,其中OOO、POS、POO占53%以上;水剂法制得的澳洲坚果油中甾醇含量较高,为1 439.79 mg/kg;压榨法制得的澳洲坚果油中矿质元素含量较高,挥发性风味物质成分较多,共分离出41种,主要包括烯类、醛类、酚类、醇类、酯类、烃类和酮类共7类化合物,其中相对含量较高的是烯类化合物和醇类化合物,占总挥发性成分的82.1%,是构成压榨澳洲坚果油的主要风味物质。     

Analysis of volatile compounds in edible oils using simultaneous distillation-solvent extraction and direct coupling of liquid chromatography with gas chromatography

 Identification of volatile compounds in different edible oils (i.e. olive oil, almond oil, hazelnut oil, peanut oil and walnut oil) was performed using simultaneous distillation-solvent extraction followed by gas chromatographic-mass spectrometric analysis. An alternative approach which allows the direct injection of the oil sample (i.e. without any kind of pre-treatment) and involves the use of on-line coupled reversed phase liquid chromatography-gas chromatography (RPLC-GC) was also considered and the advantages of avoiding off-line preseparation for the analysis of volatile compounds were underlined regarding difficulties associated with the lipophilic nature of most volatile compounds and, hence, with the reliability of their analysis. Received: 14 June 1999 / Revised version: 3 August 1999     

Walnut (Juglans regia L.): genetic resources,chemistry, by‐products

Walnut (Juglans regia L.) is the most widespread tree nut in the world. There is a great diversity of genotypes differing in forestry, productivity, physical and chemical nut traits. Some of them have been evaluated as promising and may serve as germplasm sources for breeding. The nutritional importance of the nut is related to the seed (kernel). It is a nutrient‐dense food mainly owing to its oil content (up to 740 g kg^?1 in some commercial varieties), which can be extracted easily by screw pressing and consumed without refining. Walnut oil composition is dominated largely by unsaturated fatty acids (mainly linoleic together with lesser amounts of oleic and linolenic acids). Minor components of walnut oil include tocopherols, phospholipids, sphingolipids, sterols, hydrocarbons and volatile compounds. Phenolic compounds, present at high levels in the seed coat but poorly extracted with the oil, have been extensively characterised and found to possess strong antioxidant properties. The oil extraction residue is rich in proteins (unusually high in arginine, glutamic and aspartic acids) and has been employed in the formulation of various functional food products. This review describes current scientific knowledge concerning walnut genetic resources and composition as well as by‐product obtainment and characteristics. Copyright © 2010 Society of Chemical Industry     

Effect of different technological processes on the chemical composition of myrtle (<Emphasis Type="Italic">Myrtus communis</Emphasis> L.) alcoholic extracts

Several technological processes were applied to improve the extraction efficiency in the production of myrtle (Myrtus communis L.) liqueur. The variations in the chemical composition of myrtle hydroalcoholic extracts were monitored in a laboratory scale for 40 days after the application of: double dose of berries; ultrasonic extraction; enzymes, to improve either the color or aroma extraction; and atmosphere saturated with nitrogen to improve the stability against oxidative degradations during extraction. Moreover, freezing at −20 °C was applied to myrtle berries as a technological strategy to prolong the use of berries, and macerates were obtained after 4, 8, and 12 months. Chemical investigation of macerates was performed using different analytical methods such as GC and GC-MS for the volatile compounds, HPLC-PDA for free anthocyanins, and spectrophotometric analysis for CIE L*a*b* coordinates and total anthocyanins. Dry matter and pH were also monitored during maceration. Among the different technological processes, the nitrogen-modified atmosphere was the most suitable technique to be applied in industrial scale. An industrial trial was applied with this process and alcoholic extracts and liqueurs have been obtained. The liqueur maintained a higher amount of anthocyanins, better CIE L*a*b* parameters and superior organoleptic characteristics compared to the traditional storage.     

The influence of skin contact during alcoholic fermentation on the aroma composition of Ribolla Gialla and Malvasia Istriana Vitis vinifera (L.) grape wines

Grapes from the Vitis vinifera (L.) varieties Ribolla Gialla and Malvasia Istriana were subjected to two skin contact procedures: pomace maceration and whole berry maceration during alcoholic fermentation. Wine free volatile compounds were determined using two extraction techniques coupled to GC; odour activity values were calculated and compared to control wines without skin contact. The highest concentrations of esters and relative fruity impacts were determined in the control wines for both varieties. Pomace maceration was found to be an effective procedure for the extraction of varietal aroma compounds like terpenes, but only in the Malvasia Istriana was their higher impact on floral odour determined. Pomace maceration resulted in higher total phenol and methanol content. Whole berry maceration was less efficient in terpene extraction, and its impact on general wine composition was not so radical. Control wines were chosen as preferred wines for odour and overall impression.     

芜菁子挥发油、多糖的组成及挥发油抗菌活性的研究

目的用3种方法提取芜菁子挥发油,对挥发油的抗菌作用进行定性和定量分析,并对芜菁子挥发油及多糖的组成进行分析。方法采用水蒸气蒸馏法、溶剂萃取法和同时蒸馏萃取法提取芜菁子挥发油,气相色谱-质谱联用法分析挥发油的组成。运用滤纸片扩散法和二倍稀释法检验芜菁子挥发油对大肠杆菌、金黄色葡萄球菌和绿脓杆菌的抑菌作用。利用水提醇沉法提取残渣中的多糖,酸水解后进行薄层分析。结果 3种方法提取的挥发油分别鉴别出21、7、14种成分。水蒸气蒸馏法提取挥发油中异硫氰酸酯类化合物占45.95%,同时蒸馏萃取法的为31.35%,溶剂萃取法提取挥发油无异硫氰酸酯类化合物。定性定量的抑菌实验结果显示,3种方法所得的挥发油对大肠杆菌、金黄色葡萄球菌和绿脓杆菌均有良好的抑制作用,水蒸气蒸馏法提取的挥发油的抑菌效果最好。在高效G板上,以乙酸乙酯:异丙醇:水=26:14:7(V:V:V)为展开剂,芜菁子多糖的分离效果较好,可鉴别出芜菁子多糖中的果糖和半乳糖。结论芜菁子挥发油对大肠杆菌、金黄色葡萄球菌、绿脓杆菌均有一定的抑制作用,可能与其中含有异硫氰酸酯类和腈类化合物有关。     

同时蒸馏萃取法提取花生油挥发性物质的研究

采用同时蒸馏萃取法结合气相色谱-质谱分析技术（SDE-GC-MS）,对水酶法制备的花生油挥发性物质进行提取和分析,优化同时蒸馏萃取条件。结果表明：花生油总挥发性化合物种类及吡嗪类化合物相对含量均随样品量的增加而增加;二氯甲烷作为萃取溶剂萃取得到的总挥发性化合物种类及吡嗪类化合物相对含量较乙醚多;在花生油用量为30 g时,采用二氯甲烷可以萃取出66种化合物,经质谱分析可鉴定出42种化合物,其中吡嗪类化合物有6种,占总挥发性成分6.73%。     

白豆蔻精油超临界CO2萃取工艺优化及挥发性成分分析

以白豆蔻为原料,利用水蒸气蒸馏（SDE）法和超临界流体萃取（SFE）法提取白豆蔻精油。以萃取率为评价指标,采用单因素试验及正交试验优化萃取工艺,并采用气质联用（GC-MS）法分析两种提取方法所得白豆蔻精油的组成。结果表明,最佳萃取工艺条件为：萃取压力25 MPa、萃取温度50 ℃、CO2流量14 mL/min、提取时间4.0 h。在此优化条件下,SFE提取白豆蔻精油得率为6%,为SDE提取精油的1.5倍。GC-MS分析结果表明,共检出挥发性化合物158种,其中SDE和SFE提取精油中分别检出97种、111种,独有化合物分别有47种、61种,共有化合物有50种。两种提取方法所得精油的组成相似,主要成分有桉叶油醇、α-蒎烯、4-异丙基甲苯、顺式十五烯酸、棕榈酸等,但含量差异较大。结果表明SFE是提取白豆蔻精油的有效方法。     

The composition of the essential oil of dried Nigerian ginger (Zingiber officinale Roscoe)

 The essential oil composition of dried Nigerian ginger (Zingiber officinale Roscoe) was determined by means of gas chromatography and gas chromatography-mass spectrometry techniques. The ginger was hydrodistilled; the oil yield was 2.4% and consisted of 64.4% sesquiterpene hydrocarbons, 6.6% carbonyl compounds, 5.6% alcohols, 2.4% monoterpene hydrocarbons and 1.6% esters. The main compounds were zingiberene (29.5%) and sesquiphellandrene (18.4%). A number of constituents not previously reported in ginger oil were identified. These include 2,6-dimethyl hepten-l-ol, α-gurjunene, linalool oxide, isovaler-aldehyde, 2-pentanone, cadinol, α- and γ-calacorene, eremophyllene, t-muurolol, α-himachallene, α-cubebene acetic acid, pinanol, α-santalene, geranyl propionate, geranoic acid, (E,E)-α-farnesene, n-methyl pyrrole and geranic acid. Received: 14 December 1998 / Revised version: 4 February 1999     

Effect of γ-irradiaton on the volatile compounds of licorice (Glycyrrhiza uralensis Fischer)

The volatile compounds of non-irradiated and 1, 3, 5, 10 and 20 kGy γ-irradiated roots of licorice (Glycyrrhiza uralensis Fischer) were isolated by simultaneous distillation–extraction (SDE) technique and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 61 volatile compounds belonging to the chemical classes of acid (2), alcohol (16), aldehyde (8), ester (6), furan (2), hydrocarbon (14), ketone (10) and N-containing compounds (3) were identified in non-irradiated licorice. The prime volatile compound of licorice was 2-ethoxy-1-propanol, which makes up to 22.82% of the total composition. Over a dose of 1 kGy, another compound, benzaldehyde appeared, whereas other compounds, 3,5-dimethyl octane and phenethyl alcohol, disappeared at the dose of 20 kGy. Though the content of several volatile compounds increased after γ-irradiation, the content of major volatile compounds such as 4-terpineol, myrtenal, tetramethylpyrazine, hexanoic acid, azulene and p-cymene decreased. In comparison to non-irradiated licorice, 10 kGy dose of irradiation induced the maximum level of total yield of volatile compounds by 12%, but slightly decreased at 20 kGy. Therefore, the application of γ-irradiation is feasible without major qualitative and quantitative loss of volatile compounds when exposed at 10 kGy.     

Influence of the type of fiber coating and extraction time on foal dry-cured loin volatile compounds extracted by solid-phase microextraction (SPME)

Extraction of dry-cured loin volatile compounds by solid-phase microextraction (SPME) was optimized. Two different fiber coatings: carboxen/polydimethylsiloxane (CAR/PDMS) and divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS), and three extraction times (15, 30 and 45 min) were assayed. Between the fibers tested, CAR/PDMS coated fibers extracted between two and three times more total amount of volatile compounds than the DVD/CAR/PDMS coating (1314 × 10⁶ vs. 526 × 10⁶ area units). Fifty five compounds were extracted by the CAR/PDMS fiber, while only 48 of these were found with the DVB/CAR/PDMS fiber. On the other hand, 6 additional volatile compounds were extracted by the CAR/PDMS coating, all of them being of low molecular weight. Three of the major compounds extracted, hexanoic acid, methyl ester; butanoic acid, 3-methyl-, methyl ester and hexanal, were found in high proportion in both fiber coatings. The effect of exposure time was more marked for the DVD/CAR/PDMS fiber than for the CAR/PDMS coating. Fifteen minutes of extraction provided a volatile compounds profile with lower area counts for most compounds and significantly different to that obtained with 30 and 45 min of extraction. The extraction yields of dry-cured loin volatile compounds varied according to the fiber coating used and the time of exposure. Therefore, extraction conditions should be selected depending on the objective of the study. Finally, it can be concluded that both porous fibers tested, CAR/PDMS and DVB/CAR/PDMS, provide a similar volatile compounds profile for dry-cured foal loin.     

Determination of fresh onion (Allium cepa L.) volatiles by solid phase microextraction combined with gas chromatography-mass spectrometry

 Solid-phase microextraction (SPME) was used for the extraction of the volatiles of yellow onions (Allium cepa L.), where the primary volatiles are produced enzymatically after rupture of the plant cells. The SPME-GC analysis of successive samples at timed intervals provided information comparable with that obtained previously by headspace techniques; however, SPME was more convenient and faster to perform. Moreover, the SPME-GC-MS system employed permitted easy monitoring of the fast changes in the volatile composition. Because ambient temperatures were used in the analysis, the method described should produce only minor artefacts during the absorption and desorption steps of SPME. The most important compound found in the headspace of sliced onions by SPME-GC-MS after 1 min emission of volatiles was thiopropanal S-oxide. Also, some dipropenyl disulphides and propenyl propyl disulphides were identified. After 30 min, most of the thiopropanal-S-oxide disappeared, and other sulphur and non-sulphur compounds appeared in the GC chromatograms. The major constituents were diprop(en)yl disulphides. Similar constituents were also found in the water-slurred onions by headspace and direct SPME. Received: 8 January 1998     

超临界CO2-分子蒸馏纯化蒜油与水蒸气蒸馏法制取蒜油挥发性成分分析

采用分子蒸馏技术(MD)将超临界CO2(SFE)萃取的蒜油进行纯化,以顶空固相微萃取气质联用技术(HSSPME-GC-MS)分析蒜油中的挥发性成分,确定最佳工艺：进样速度1 滴/s,蒸馏温度60℃,刮膜转速250r/min。纯化的蒜油挥发性成分仅有4 种,二烯丙基二硫醚和二烯丙基三硫醚、2- 乙烯基-1,3- 二硫杂-4- 环己烯和3- 乙烯基-1,2- 二硫杂-5- 环己烯;与水蒸气蒸馏法制得的新鲜蒜油(F-GO)比较,SFE 法是一种理想的制取蒜油的方法;蒜油放置30d(S-GO)后有效成分含量下降,导致品质下降。     

Determination of fresh onion (Allium cepa L.) volatiles by solid phase microextraction combined with gas chromatography-mass spectrometry

 Solid-phase microextraction (SPME) was used for the extraction of the volatiles of yellow onions (Allium cepa L.), where the primary volatiles are produced enzymatically after rupture of the plant cells. The SPME-GC analysis of successive samples at timed intervals provided information comparable with that obtained previously by headspace techniques; however, SPME was more convenient and faster to perform. Moreover, the SPME-GC-MS system employed permitted easy monitoring of the fast changes in the volatile composition. Because ambient temperatures were used in the analysis, the method described should produce only minor artefacts during the absorption and desorption steps of SPME. The most important compound found in the headspace of sliced onions by SPME-GC-MS after 1 min emission of volatiles was thiopropanal S-oxide. Also, some dipropenyl disulphides and propenyl propyl disulphides were identified. After 30 min, most of the thiopropanal-S-oxide disappeared, and other sulphur and non-sulphur compounds appeared in the GC chromatograms. The major constituents were diprop(en)yl disulphides. Similar constituents were also found in the water-slurred onions by headspace and direct SPME. Received: 8 January 1998     

Investigation on the aroma of wines from seven clones of Monastrell grapes

 Analysis of the volatile compounds of wines from seven clones of Monastrell grapes was performed using ultrasound extraction of the compounds. Significant differences were found for some of the compounds and these compounds were used in order to characterize and differentiate among the clones. Linear discriminant analysis allowed some grouping of the clones, showing that differentiation among clones of a neutral grape variety is possible. Received: 21 April 1998 / Revised version: 19 November 1998