Pyrrolizidine alkaloid content in crude and processed borage oil from different processing stages

The pyrrolizidine alkaloid content of crude borage oil and borage oil from different processing stages was determined by GC-MS. The results showed that no pyrrolizidine alkaloids were present above a detection limit of 20 ppb. The reduction factors for pyrrolizidine alkaloids at various stages in the oil refining process were determined by means of spiking experiments using the commercially available pyrrolizidine alkaloid crotaline. It was shown that the pyrrolizidine content in crude borage oil was reduced overall by a factor of about 30,000 in the refining process.     

Enrichment of γ-linolenic acid from evening primrose oil and borage oilvia lipase-catalyzed hydrolysis

Lipase-catalyzed selective partial hydrolysis of evening primrose (Oenothera biennis L.) seed oil and borage (Borago officinalis L.) seed oil led to an increase in the level of γ-linolenic acid (GLA; 18∶3n−6) in the unhydrolyzed acylglycerols. Thus, in evening primrose oil, the GLA level could be raised from 9.4% in the starting material to 46.5% in the unhydrolyzed acylglycerols by means of a lipase fromCandida cylindracea. Selective hydrolysis of borage oil with Pancreatin led to an increase in the GLA content from 20.4% in the oil to 33.5% in the unhydrolyzed acylglycerols. Partial hydrolysis of borage oil with lipase fromC. cylindracea raised the GLA content of the acylglycerols to 47.8%.     

Supercritical extraction of borage seed oil coupled to conventional solvent extraction of antioxidants

This paper describes the extraction of borage seed oil by supercritical carbon dioxide (SC-CO₂) and the further extraction of antioxidants from the SC-CO₂-defatted borage meal with organic solvents (water, methanol, ethanol and ethyl acetate). The optimal conditions for oil extraction were obtained at 303 and 323 K at 200 bar, 2.5 h and a continuous flow of CO₂ of 1.5 L/h introduced through the bottom when the operating pressure and temperature were reached, attaining a yield of 60%. Borage oil is rich in unsaturated fatty acids; oleic acid, linoleic acid and linolenic acid accounted for 74% of the total fatty acid content under the above conditions. The highest extraction yield was achieved using water or methanol as extracting solvent from the SC-CO₂-defatted borage meal at 303 K and pressures of 200 and 150 bar for water and methanol, respectively. The most potent extracts, according to all methods tested, were obtained with water and methanol.     

Kinetics of supercritical carbon dioxide extraction of borage and evening primrose seed oil

In the present work, high‐pressure extraction of borage (Borago officinalis L.) and evening primrose (Oenothera biennis L.) seed oil, containing the valuable γ‐linolenic acid (GLA), has been investigated. Extraction was performed with supercritical carbon dioxide on a semi‐continuous flow apparatus at pressures of 200 and 300 bar, and at temperatures of 40 and 60 °C. A constant flow rate of carbon dioxide in the range from 0.17 to 0.20 kg/h was maintained during extraction. The extraction yields obtained using dense CO₂ were similar to those obtained with conventional extraction using hexane as solvent. The composition of extracted crude oil was determined by GC analysis. The best results were obtained at 300 bar and 40 °C for both seed types extracted, where the quality of oil was highest with regard to GLA content. The evening primrose seed oil extracted with supercritical fluid extraction was particularly rich in unsaturated fatty acids: up to 89.7 wt‐% of total free fatty acids in the oil. The dynamic behavior of the extraction runs was analyzed using two mathematical models for describing the constant rate period and the subsequent falling rate period. Based on the experimental data, external mass transfer coefficients, diffusion coefficients and diffusivity in solid phase were estimated. Results showed good agreement between calculated and experimental data.     

γ-Linolenic acid concentrates from borage and evening primrose oil fatty acidsvia lipase-catalyzed esterification

γ-Linolenic acid (GLA, all-cis 6,9,12-octadecatrienoic acid) has been enriched from fatty acids of borage (Borago officinalis L.) seed oil to 93% from the initial concentration of 20% by lipase-catalyzed selective esterification of the fatty acids withn-butanol in the presence ofn-hexane as solvent. The immobilized fungal lipase preparation, Lipozyme, used as biocatalyst, preferentially esterified palmitic, stearic, oleic and linoleic acids and discriminated against GLA, which was thus concentrated in the unesterified fatty acids fraction. In the absence of hexane, concentrate containing about 70% GLA was obtained. When the reaction conditions, optimized for borage oil fatty acids, were applied to fatty acids of evening primrose (Oenothera biennis L.) oil, concentrates containing 75% GLA were obtained. From both oils, GLA concentrates were prepared efficiently in short reaction times (1–3 h) at 30–60°C. The process can be applied for the production of GLA concentrates for dietetic purposes.     

花椒挥发油成分GC-MS分析

采用GC-MS技术初步分析和鉴定花椒中的挥发油成分。采用水蒸汽蒸馏法提取花椒中的挥发油,气相色谱-质谱联用分离并鉴定化学成分。从花椒中共鉴定出56个化合物,相对含量占挥发油总量的88.375%,。其中主要成分为乙酰丁香酮(12.711%)、(-)-4-萜品醇(11.911%)、4-甲基-1-(1-甲基乙基)-二环[3.1.0]己-2-烯(8.866%)、萜品烯(5.922%)、芳樟醇(5.777%)、桉叶油醇(4.483%)、4,7,7-三甲基二环[4.1.0]庚-4-烯(4.312%)、β-水芹烯.(3.745%)、柠檬烯(3.434%)、α-松油醇(3.349%)、邻-异丙基苯(3.149%)。花椒中鉴定出的挥发油成分比较多,为进一步实验研究提供理论依据。     

Characterization of γ-linolenic acid geometrical isomers in borage oil subjected to heat treatments (deodorization)

Heating of borage oil, either under vacuum as a model or during steam-vacuum deodorization, produces artifacts that are geometrical isomers of γ-linolenic acid (cis-6,cis-9,cis-12 18∶3 acid). In a first approach, we have studied the behavior of these fatty acids in the form of either methyl or isopropyl esters on two capillary columns (CP-Sil 88 and DB-Wax). From this study, it appears that the DB-Wax capillary column is the best suited analytical tool to study in some detail γ-linolenic acid geometrical isomers. In a second approach, the structure of these isomers was formally established by combining several analytical techniques: Argentation thin-layer chromatography, comparison of the equivalent chainlengths with those of isomers present in NO₂-isomerized borage oil on two different capillary columns, partial hydrazine reduction, oxidative ozonolysis, gas chromatography coupled with mass spectrometry and gas chromatography coupled with Fourier transform infrared spectroscopy. The two main isomers that accumulate upon heat treatments are thetrans-6,cis-9,cis-12 andcis-6,cis-9,trans-12 18∶3 acids with minor amounts ofcis-6,trans-9,cis-12 18∶3 acid. One di-trans isomer, supposed to be thetrans-6,cis-9,trans-12 18∶3 acid, is present in low although noticeable amounts in some of the heated oils. The content of these artificial fatty acids increases with increasing temperatures and duration of heating. The degree of isomerization (DI) of γ-linolenic acid is less than 1% when the oil is deodorized at 200°C for 2 h. Heating at 260°C for 5 h increases the DI up to 74%. Isomerization of γ-linolenic acid resembles that of α-linolenic (cis-9,cis-12,cis-15 18∶3) acid in several aspects: The same kinds and numbers of isomers are formed, and similar degrees of isomerization are reached when the octadecatrienoic acids are heated under identical conditions. It seems that the reactivity of a double-bondvis-à-vis cis-trans isomerization is linked to its relative position, central or external, and not to its absolute position (Δ6, 9, 12 or 15).     

银杏叶中甾醇的GC-MS分析

通过对银杏叶中的甾醇进行分离,重结晶纯化,得到了高纯度的植物甾醇.采用GC-MS联用技术对甾醇进行了分析.色谱条件:HP-5色谱柱(30 m×0.25 mm×0.25μm);载气为高纯度N2,体积流量1 mL/min;进样温度300℃;柱温285℃,每分钟升高5℃,320℃保持30 min;电离方式EI,电子能量70 eV;接口温度250℃;离子源温度200℃;检测电压350 V;进样量1μL.经GC-MS确定了其中丰度较大的5种物质及其结构,分别为菜油甾醇、豆甾-4,22-双烯-3β-醇、β-谷甾醇、豆甾-3β-醇和岩藻甾醇.该方法简便、结果可靠,可用于分析银杏叶中甾醇的化学成分.     

不同溶剂萃取对烟丝中甾醇含量降低效果的影响

以95%乙醇、乙酸乙酯、纯化水、石油醚为溶剂萃取烟丝,通过气质联用定量测定萃取后烟丝主要游离甾醇的含量。结果表明：①95%乙醇、乙酸乙酯和石油醚3种有机溶剂都具有不同程度降低烟丝中甾醇含量的效果,甾醇降低量大小顺序为：乙酸乙酯〉石油醚〉95%乙醇,尤其是乙酸乙酯萃取后的烟丝中各甾醇类化合物含量降低最为明显,其中胆甾醇、豆甾醇和β-谷甾醇含量分别降低了24.67%,64.63%,44.03%;②水萃取烟丝后甾醇含量比正常烟丝还要高,这是由于水是良好的极性溶剂,萃取烟丝后导致烟丝中大部分化学成分含量降低,单位质量的烟丝增多,因此单位质量烟丝的甾醇含量反而上升。     

Purification of γ-linolenic acid from borage oil by a two-step enzymatic method

γ-Linolenic acid (GLA) was purified from borage oil by a two-step enzymatic method. The first step involved hydrolysis of borage oil (GLA content, 22.2 wt%) with lipase, Pseudomonas sp. enzyme (LIPOSAM). A mixture of 3 g borage oil, 2 g water, and 5000 units (U) LIPOSAM was incubated at 35°C with stirring at 500 rpm. The reaction was 91.5% complete after 24 h. The resulting free fatty acids (FFA) were extracted from the reaction mixture with n-hexane (GLA content, 22.5 wt%; recovery of GLA, 92.7%). The second step involved selective esterification of borage-FFA with lauryl alcohol by using Rhizopus delemar lipase. A mixture containing 4 g borage-FFA/lauryl alcohol (1:2, mol/mol), 1 g water, and 1000 U lipase was incubated at 30°C for 20 h with stirring at 500 rpm. Under these conditions, 74.4% of borage-FFA was esterified, and the GLA content in the FFA fraction was enriched from 22.5 to 70.2 wt% with a recovery of 75.1% of the initial content. To further elevate the GLA content, unesterified fatty acids were extracted, and esterified again in the same manner. By this repeated esterification, GLA was purified to 93.7 wt% with a recovery of 67.5% of its initial content.     

Fatty acid selectivity of lipases: γ-linolenic acid from borage oil

The γ-linolenic acid (Z,Z,Z-6,9,12-octadecatrienoic acid, GLA) present in borage oil free fatty acids was concentrated in esterification reactions that were catalyzed by several preparations of the acyl-specific lipase ofGeotrichum candidum. In this manner, a 95% recovery of the GLA originally present in borage oil (25% GLA) was obtained as a highly enriched fatty acid fraction with a GLA content of >70%. Other fatty acids concentrated in this fraction were the monounsaturated fatty acids with chainlengths of C-20 and longer that were present in the oil. An immobilized preparation ofG. candidum on silica gel also was used for the enrichment of GLA in borage oil. In this instance, a 75% recovery of GLA was obtained, and the supported lipase was reusable (three cycles) with minimal loss in activity. Presented in part at the 84th Annual Meeting of the American Oil Chemists’ Society, Anaheim, California, May 1993.     

GC-MS联用技术分析厚朴挥发油化学成分

采用GC-MS联用技术,结合程序升温保留指数,对湖南和四川两个产地的厚朴(分别简称湘朴和川朴)挥发油成分进行分析。共定性出111种挥发油化学成分,湘朴为89种,川朴为88种,分别占二者挥发油总含量的87.74%和92.72%,共有组分66种。厚朴的挥发油主要成分为桉叶醇及其同分异构体。湘朴与川朴挥发油中,α-桉叶醇的含量分别为7.91%和13.34%,β-桉叶醇的含量分别为23.88%和15.75%,γ-桉叶醇的含量分别为10.60%和9.68%。湘朴和川朴挥发油成分中含各自的特有组分,分别为23种和22种。二者挥发油成分在化合物含量和种类上存在较大差别。     

Concentration of sterols and tocopherols from olive oil with supercritical carbon dioxide

A process based on the use of a semicontinuous countercurrent supercritical fluid extraction has been developed to isolate and concentrate minor compounds, such as sterols and tocopherols, from olive oil. In the present work, an evaluation of the efficiency of different random packing materials (Raschig rings, Dixon rings, Fenske rings, and glass beads) to selectively separate sterols and tocopherols from olive oil has been performed. Parameters such as recovery, enrichment, and selectivity vs. TG are discussed. Considering the importance of supercritical fluid extraction as a clean processing technology and the interest in minor compounds with nutraceutical properties from olive oil, the process studied represents an alternative to the reuse of low-quality olive oil to extract high added-value products.     

青皮挥发油化学成分的GC-MS分析

采用水蒸气蒸馏法提取青皮挥发油,通过气相色谱-质谱联用技术从青皮挥发油中分离鉴定出22种化学成分,相对含量最高的化合物为右旋柠檬烯,占挥发油总量的45.76%,其中,α-芹子烯、R)-(-)-对薄荷-1-烯-4-醇、1-甲基-4-(1-甲基乙烯基)-苯、2-(二乙氨基)-3-氟苯甲酸乙酯、正二十烷等10多种成分为首次从青皮中检出,为其进一步的研究利用提供了参考。     

Selective hydrolysis of borage oil with Candida rugosa lipase: Two factors affecting the reaction

A 46% γ-linolenic acid (GLA)-containing oil was produced by selective hydrolysis of borage oil (GLA content, 22%) at 35°C for 15 h in a mixture containing 50% water and 20 units (U)/g reaction mixture of Candida rugosa lipase. The GLA content was not raised over 46%, even though the hydrolysis extent was increased by extending the reaction time and by using a larger amount of the lipase. However, 49% GLA-containing oil was produced by hydrolysis in a reaction mixture with 90% water. This result suggested that free fatty acids (FFA) that accumulated in the mixture affected the apparent fatty acid specificity of the lipase in the selective hydrolysis and interfered with the increase of the GLA content. To investigate the kinetics of the selective hydrolysis in a mixture without FFA, glycerides containing 22, 35, and 46% GLA were hydrolyzed with Candida lipase. The result showed that the hydrolysis rate decreased with increasing GLA content of glycerides, but that the release rate of GLA did not change. Thus, it was found that the apparent fatty acid specificity of the lipase in the selective hydrolysis was also affected by glyceride structure. When 46% GLA-containing oil was hydrolyzed at 35°C for 15 h in a mixture containing 50% water and 20 U/g of the lipase, GLA content in glycerides was raised to 54% at 20% hydrolysis. Furthermore, GLA content in glycerides was raised to 59% when the hydrolysis extent reached 60% using 200 U/g of the lipase. These results showed that repeated hydrolysis was effective to produce the higher concentration of GLA oil. Because film distillation was found to be extremely effective for separating FFA and glycerides, large-scale hydrolysis of borage oil was attempted. As a result, 1.5 kg of 56% GLA-containing oil was obtained from 7 kg borage oil by repeated reaction.     

Oxidative stability of stripped and nonstripped borage and evening primrose oils and their emulsions in water

Oxidative stability of stripped and nonstripped borage and evening primrose oils and their emulsions in water was evaluated. The results indicated that column chromatographic techniques provide an effective means for stripping vegetable oils of their minor components. However, some minor components may be retained in the stripped oils. The minor components in borage and evening primrose oils significantly (P<0.05) influenced their oxidative stability in the dark. In contrast, the behavior of endogenous antioxidants in borage and evening primrose oil-in-water emulsions, according to the “polar paradox” theory, was difficult to evaluate. Correlations existed between peroxide value (PV) and conjugated dienes (CD) (P<0.05) as well as 2-thiobarbituric acid-reactive substances (TBARS) and hexanal content (P<0.01) for most oils and emulsion systems. Therefore, CD and TBARS may generally be used to assess the oxidative stability of borage and evening primrose oils and their oil-in-water emulsions in addition to or in place of PV and headspace volatiles, respectively.     

Influence of the vegetable oil refining process on free and esterified sterols

The influence of the refining process on the distribution of free and esterified phytosterols in corn, palm, and soybean oil was studied. Water degumming did not affect the phytosterol content or its composition. A slight increase in the content of free sterols was observed during acid degumming and bleaching due to acid-catalyzed hydrolysis of steryl esters. A significant reduction in the content of total sterols during neutralization was observed, which was attributed to a reduction in the free sterol fraction. Free sterols probably form micelles with soaps and are transferred into the soapstock. The steryl ester content remained constant during all neutralization experiments, indicating that hydrolysis of steryl esters did not take place during neutralization. During deodorization, free sterols are distilled from the oil, resulting in a gradual reduction in the total sterol content as a function of the deodorization temperature (220–260°C). A considerable increase in the steryl ester fraction was found during physical refining, probably owing to a heat-promoted esterification reaction between free sterols and FA.     

朱蕉叶挥发油的GC-MS分析

采用水蒸气蒸馏法提取朱蕉叶的挥发油,运用气质谱联用（GC-MS）技术对挥发油成分进行分析,并采用峰面积归一化法确定各成分的相对百分含量。结果表明,共鉴定出67种成分,占总离子流出峰面积的89.48%。朱蕉叶挥发油主要有1-辛烯-3-醇（22.98%）,甜没药醇（5.21%）,7-（1,1-二甲基乙基）-2,3-二氢-3,3-二甲基-1H-茚-1-酮（4.60%）,棕榈酸（3.51%）和乙酸叶醇酯（3.17%）。