碱催化法衍生化气相色谱/质谱法分析青海湖裸鲤鱼油中的脂肪酸

用碱催化法将青海湖裸鲤鱼油甲酯化,以气相色谱/质谱法分析鱼油中的脂肪酸。青海湖裸鲤可食用部分中鱼油含量为25.13%。从鱼油中共鉴定出47种脂肪酸,包括直链、单支链、多支链饱和脂肪酸,单不饱和、多不饱和脂肪酸,环丙烷基、呋喃基脂肪酸等。不饱和脂肪酸含量为73.6%,其中多不饱和脂肪酸含量为25.4%,以C18∶2(4.9%),C18∶3(3.1%),C20∶4(1.3%),C20∶5(二十碳五烯酸（EPA）, 9.4%)和C22∶6(二十二碳六烯酸（DHA）, 6.7%)为主。单不饱和脂肪酸含量为48.2%,主要由C16∶1(20.3%),C18∶1(25.9%)构成。饱和脂肪酸含量为25.7%,主要有C14∶0(3.4%),C16∶0 (19.4%)和C18∶0(1.1%)。青海湖裸鲤鱼油中还存在不常见的环丙烷基和呋喃基脂肪酸及多种奇数碳链和支链脂肪酸。因此,青海湖裸鲤是功能性脂肪酸的重要膳食来源。     

黑蚂蚁的脂肪酸及抗氧化性能的分析

对黑蚂蚁中脂肪酸的组成和含量进行测定。采用索氏提取法提取其脂肪酸,再进行甲酯化处理,以气相色谱-质谱联用仪进行了分离和鉴定。由黑蚂蚁中分离鉴定出11种脂肪酸,占脂肪酸总量的99.78%,不饱和脂肪酸占脂肪酸总量的80.65%,饱和脂肪酸占脂肪酸总量的19.13。通过流动注射化学发光法分析了黑蚂蚁的抗氧化性能,结果表明,黑蚂蚁具有较强的抗氧化性能。     

稻谷副产品中脂肪酸的气相色谱-质谱分析

对稻谷副产品脂肪酸的组成和含量进行分析测定. 采用索氏提取法提取了稻谷副产品中的脂肪油, 再进行甲酯化处理, 利用气相色谱-质谱法对其脂肪酸组成及含量进行了分析测定. 结果表明, 从稻糠、稻叶、稻秆中鉴定出的脂肪酸分别占其总检出量的96.72%、 71.77%和92.63%, 不饱和脂肪酸含量分别为72.88%、 45.26%和66.96%.     

扁桃油中脂肪酸组成的GC-MS法分析

以正己烷为提取剂,采用超声法提取油脂,经KOH-甲醇甲酯化处理后,以气相色谱-质谱(GC-MS)联用技术鉴定出陕西蒲城3个品种扁桃油中的脂肪酸主要组成为:油酸、亚油酸、9-十六碳烯酸、硬脂酸、棕榈酸,其中不饱和脂肪酸总量占91.4%以上,主要成分油酸占73.3%以上。     

白马骨挥发油的GC-MS分析

采用水蒸气蒸馏法从白马骨中提取挥发油,再通过气-质联用(GC-MS)技术对所提取的挥发油的化学成分进行分离鉴定,共测定了其中的36种成分.已成功鉴定的成分占样品总量的93.39%,其主要成分为脂肪酸,占挥发油总量的74.23%,其次为烷烃化合物8.54%,酯类化合物3.96%,酮类化合物2.36%,烯烃化合物1.95%,醇类化合物1.71%,其它化合物(1个)仅占0.71%.     

酶解法制备方格星虫多肽及其抗氧化作用研究

采用木瓜蛋白酶酶解制备方格星虫多肽,通过单因素实验研究了加酶量、酶解温度、酶解时间、酶解pH值和料液比等因素对羟自由基清除率的影响。通过正交试验确定了木瓜蛋白酶对方格星虫最佳的酶解工艺条件为:加酶量300 U/g,酶解温度50℃,酶解时间60 min,酶解液pH值7.0,料水比1∶3。在此条件下酶解方格星虫获得多肽的羟自由基清除率为95.42%,表明方格星虫酶解物具有较明显的抗氧化能力。由高效体积排阻色谱(HPSEC)法测得方格星虫多肽的分子量为5868。     

气相色谱同位素比质谱测定不同产地鱼油中5种不饱和脂肪酸碳同位素比值

以IAEA-600咖啡因(δ13C-27.771‰)作为溯源标准,建立了气相色谱同位素质谱技术测定鱼油中功能因子亚油酸(LIA)、亚麻酸(LNA)、花生四烯酸(ARA)、二十碳五烯酸(EPA)、二十二碳六烯酸(DHA)等5种不饱和脂肪酸碳稳定同位素比值δ13C的分析方法。鱼样品先经HCl水解,乙醚液液萃取脂肪,提取的脂肪在2 mol/L KOH-甲醇溶液中反应生成脂肪酸甲酯,采用强极性毛细管气相色谱柱(Sil-88 100 m×0.25 mm×0.2μm)分离,稳定同位素比质谱测定。方法经日内、日间和人员比对验证,表明测定结果稳定,标准偏差小于0.82%。收集了不同产地的241个淡水鱼和深海鱼,对于提取的天然鱼油进行5种不饱和脂肪酸同位素比值分析,测得天然鱼油中5种不饱和脂肪酸同位素比值(δ13C)在-32.87‰~27.07‰之间,经计算,鱼油中不饱和脂肪酸δ13C值与硬脂酸δ13C值之比在-5.79~1.88之间,同时测得了相同的产地、品种鱼油中不饱和脂肪酸δ13C的分布范围,构建了天然鱼油的同位素指纹特征数据库,用于鉴定鱼油真伪。将不同浓度玉米油添加至天然金枪鱼油中进行测定,证明δ13C值的变化与掺入C4植物油量呈良好的线性关系,方法可根据δ13C值的变化鉴别掺假的鱼油。     

8种云南植物油脂肪酸的气相色谱-质谱测定

采用气相色谱-质谱联用(GC-MS)方法测定了8种云南植物油脂肪酸含量并对其差异性进行了分析。植物油经甲酯化处理后,用GC-MS方法测定其脂肪酸含量。通过与标准样品保留时间比较和检索NIST标准谱库定性,峰面积归一化法定量。山茶油和辣木籽油含油酸(C18:1)较高,油酸含量分别为80.47%和71.90%;核桃油和假酸浆籽油含亚油酸(C_(18:2))较高,含量分别为60.75%和70.78%;香薷油和藿香籽油含α-亚麻酸(C_(18:3))较高,含量分别为47.13%和55.08%。橡胶树籽油中硬脂酸(C_(18:0))含量9.22%,油酸(C_(18:1))24.07%,亚油酸(C_(18:2))37.17%,α-亚麻酸(C18:3)19.72%,几种脂肪酸分布较为均匀。藿香籽油中不饱和脂肪酸(UFA)含量最高为93.75%。辣木籽油饱和脂肪酸(SFA)含量最高为23.29%;辣木籽油中花生酸(C_(20:0))、二十碳烯酸(C_(20:1))、榆树酸(C_(22:0))和木蜡酸(C_(24:0))含量分别为3.94%、2.73%、6.41%和1.10%,均远远高于其他7种植物油相对应的脂肪酸含量,可作为鉴定辣木籽油的重要依据。     

质谱特征结合等效链长定性分析植物油中的脂肪酸

建立了质谱特征结合等效链长快速定性植物油中脂肪酸的方法。首先根据质谱特征判断脂肪酸的类型并鉴定出其中的饱和脂肪酸甲酯,然后利用它们的保留时间信息计算得到不饱和脂肪酸甲酯的等效链长值,与已建立的脂肪酸甲酯数据库对照实现不饱和脂肪酸甲酯的结构鉴定。用NaOH-甲醇对5种常见植物油(花生调和油、茶籽调和油、菜籽油、葵花籽油、大豆油)中的脂肪酸进行衍生和提取,采用DB-23石英毛细管柱(30m×0.25mm×0.25μm)分离脂肪酸甲酯的同系物和异构体,气相色谱质谱法(GC/MS)测定,结果表明,5种样品油中所含不饱和脂肪酸的组成和含量上均存在明显差异。本方法无需标准品即可快速定性检测脂肪酸同系物及异构体,适用于油脂、食品中脂肪酸的成分分析。     

柽柳实脂肪酸成分的分析

本文研究维药柽柳实中脂肪酸的化学成分。采用石油醚和乙醚两种溶剂提取柽柳实中的脂肪酸,经甲酯化后,使用气质联用技术对脂肪酸的组成及含量进行检测。结果表明,两种方法分别鉴定出18种和17种脂肪酸成分,占提取成分总峰面积的99.33%和89.65%,两者所包含的成分基本一致,但含量有一定的差异。石油醚和乙醚提取物中分别鉴定出棕榈酸(35.61%和32.77%),亚油酸(27.26%和18.76%)和油酸(11.33%和9.15%)等脂肪酸,其中不饱和脂肪酸含量分别占总脂肪酸含量的38.59%和27.91%。维药柽柳实中富含不饱和脂肪酸,具有很好的开发利用价值。     

Novel approach of corn fiber utilization

The corn wet milling process produces a 10% (w/w of the processed corn) byproduct called corn fiber, which is utilized worldwide as a low-value feedstock for cattle. The aim of this study was to find a higher value use of corn fiber. The main fractions of corn fiber are: 20% starch, 40% hemicellulose, 14% cellulose, and 14% protein. Extraction of the highly valuable, cholesterol-lowering corn fiber oil is not feasible owing to its low (2% w/w) concentration in the fiber. The developed technology is based on simple and inexpensive procedures, like washing with hot water, dilute acid hydrolysis at 120°C, enzymatic hydrolysis of cellulose, screening, drying, and extraction. The main fractions are sharply separated in the order of starch, hemicellulose, cellulose, lipoprotein, and lignin). The lipoprotein fraction adds up to 10% of the original dry corn fiber, and contains 45% corn fiber oil, thus yielding more oil than direct extraction of the fiber. It is concluded that the defined method makes the extraction of the corn fiber oil economically feasible. The fractionation process also significantly increases the yield of cholesterol-lowering substances (sterols and sterolesters). At the same time clear and utilizable fractions of monosaccharides, protein, and lignin are produced.     

Simultaneous Determination of 2- and 3-Monochloropropan-1,3-diol Esters in Foods by Enzymatic Hydrolysis and GC–MS Detection

A simple, reliable and accurate method for simultaneous determination of 2- and 3-monochloropropan-1,3-diol fatty acid esters (2- and 3-MCPD esters) in food by enzymatic hydrolysis and gas chromatography mass spectrometry was developed and validated. The extraction of lipids in food was conducted by mixed with hexane and homogenized for 2 min. After extraction, the lipids were directly transferred to enzymatic hydrolysis and the content was determined by gas chromatography mass spectrometry. The main advantage of the proposed method is that it can simultaneously analyse both 2- and 3-MCPD esters in foods and preserve their structural integrity. The limits of detection (LODs) of 2- and 3-MCPD esters in edible oil were 40 and 20 μg kg⁻¹ as 2- and 3-MCPD, respectively. For low fat foods containing less than 3 % fat, the LOD of 2- and 3-MCPD esters were lowered to 1.2 and 0.6 μg kg⁻¹ as 2- and 3-MCPD, respectively. Quantitative recoveries of different fatty acid esters of 2- and 3-MCPD esters were obtained after spiked corresponding standards into blank matrices.

     

Novel approach of corn fiber utilization

The corn wet milling process produces a 10% (w/w of the processed corn) byproduct called corn fiber, which is utilized worldwide as a low-value feedstock for cattle. The aim of this study was to find a higher value use of corn fiber. The main fractions of corn fiber are: 20% starch, 40% hemicellulose, 14% cellulose, and 14% protein. Extraction of the highly valuable, cholesterol-lowering corn fiber oil is not feasible owing to its low (2% w/w) concentration in the fiber. The developed technology is based on simple and inexpensive procedures, like washing with hot water, dilute acid hydrolysis at 120 degrees C, enzymatic hydrolysis of cellulose, screening, drying, and extraction. The main fractions are sharply separated in the order of starch, hemicellulose, cellulose, lipoprotein, and lignin). The lipoprotein fraction adds up to 10% of the original dry corn fiber, and contains 45% corn fiber oil, thus yielding more oil than direct extraction of the fiber. It is concluded that the defined method makes the extraction of the corn fiber oil economically feasible. The fractionation process also significantly increases the yield of cholesterol-lowering substances (sterols and sterolesters). At the same time clear and utilizable fractions of monosaccharides, protein, and lignin are produced.     

Selective multistage extraction process of biomolecules from vine shoots by a combination of biological,chemical, and physical treatments

A multistep extraction process was proposed to recover polyphenols, reducing sugars, and soluble lignin from vine shoots. A physical pretreatment by high voltage electrical discharges (HVED) was followed by an enzymatic hydrolysis and a final delignification step by alkaline hydrolysis. HVED before enzymatic hydrolysis enhanced the extraction of polyphenols (+72%), reducing sugars (+43%), and soluble lignin (+104%) as compared to control experiments (enzymatic hydrolysis). HVED also reinforced the subsequent delignification process by reducing 10% lignin content in exhausted residues. Identification and quantification of ferulic acid, resveratrol, p-coumaric acid, and hydroxybenzoic acid were carried out using high-performance liquid chromatography.     

HPLC Quantification of astaxanthin and canthaxanthin in Salmonidae eggs

Astaxanthin and canthaxanthin are naturally occurring antioxidants referred to as xanthophylls. They are used as food additives in fish farms to improve the organoleptic qualities of salmonid products and to prevent reproductive diseases. This study reports the development and single‐laboratory validation of a rapid method for quantification of astaxanthin and canthaxanthin in eggs of rainbow trout (Oncorhynchus mykiss ) and brook trout (Salvelinus fontinalis М.). An advantage of the proposed method is the perfect combination of selective extraction of the xanthophylls and analysis of the extract by high‐performance liquid chromatography and photodiode array detection. The method validation was carried out in terms of linearity, accuracy, precision, recovery and limits of detection and quantification. The method was applied for simultaneous quantification of the two xanthophylls in eggs of rainbow trout and brook trout after their selective extraction. The results show that astaxanthin accumulations in salmonid fish eggs are larger than those of canthaxanthin. As the levels of these two xanthophylls affect fish fertility, this method can be used to improve the nutritional quality and to minimize the occurrence of the M74 syndrome in fish populations.     

Comparison of methods with respect to efficiencies, recoveries, and quantitation of mercury species interconversions in food demonstrated using tuna fish

Eight different analytical extraction procedures commonly used to extract mercury species from biological samples were evaluated by analyzing Tuna Fish Tissue Certified Reference Material (ERM-CE464) certified for the content of total mercury and methylmercury. Speciated isotope dilution mass spectrometry (SIDMS; US Environmental Protection Agency’s method 6800) was utilized to evaluate and effectively compensate for potential errors during measurement and accurately quantify mercury species using all the extraction methods. SIDMS was used to accurately evaluate species transformations during sample pretreatment, preparation and analysis protocols. The extraction methods tested in this paper were based on alkaline extraction with KOH or tetramethylammonium hydroxide; acid leaching with HCl, HNO₃ or CH₃COOH; extraction with l-cysteine hydrochloride; and enzymatic digestion with protease XIV. Detection of total mercury and mercury species from all extraction methods was carried out by inductively coupled plasma mass spectrometry (ICP-MS) and high-performance liquid chromatography–ICP-MS, respectively. Microwave-assisted extraction and ultrasound-assisted extraction were found to be the most efficient alkaline digestion protocols that caused the lowest levels of transformation of mercury species (6% or less). Extraction with 5 M HCl or enzymatic digestion with protease resulted in the second-highest extraction efficiency, with relatively lower transformation of methylmercury to inorganic mercury (3 and 1.4%, respectively). Despite frequent use of acid leaching for the extraction of mercury species from tuna fish samples, the lowest extraction efficiencies and the highest mercury species transformation were obtained when microwave-assisted extraction with 4 M HNO₃ or CH₃COOH was used. Transformations as high as 30% were found using some literature protocols; however, all the extractions tested produced accurate quantitation when corrected in accordance with the SIDMS method standardized in the US Environmental Protection Agency’s method 6800. Figure Determinative CRM Tuna Fish Tissue Methylmercury Calibration vs. Determinative Calculation.     

Free and Glycosidically Bound Volatiles of Mentha longifolia Growing in Croatia

The glycosides of volatile compounds and the essential oil were isolated from wild Mentha longifolia. After the enzymatic hydrolysis of glycosides, fourteen volatile aglycones were identified by GC/MS. The main aglycones were eugenol, 2-phenylethanol, benzyl alcohol, lavandulol, trans- and cis-carveol, 3-octanol, and 3-hexen-1-ol. The content of aglycones was 40.85 mg kg^-1 of dried plant material. The main components of the essential oil (yield 0.93 w/w) were carvone, piperitenone oxide, limonene, and -caryophyllene. Eugenol, carveol, 3-octanol, and -terpineol were identified in the aglycones and in the essential oil.     

Quality Control of Krill Oil by Nuclear Magnetic Resonance (NMR) Spectroscopy: Composition and Detection of Foreign Species

Krill oil is currently among the most highly promoted products in the dietary supplement market, which, due to its high price, can be potentially adulterated with fish species and artificial oil. For a holistic control of krill oil quality, ¹H, ¹³C, and ³¹P nuclear magnetic resonance (NMR) spectroscopies were used. The fatty acid and phospholipid composition as well as secondary ingredients, such as homarine, amino acids, and chitin, were examined. The following phospholipid species were detected: phosphatidylcholine (75–85?mol %), phosphatidylethanolamine (4–7?mol%) and their lyso derivatives 1-lysophosphatidylcholine (1–2?mol%)–2-lysophosphatidylcholine (10–16?mol%) and lysophosphatidylethanolamine (1?mol%). In the -2 position of phospholipids, the content of eicosapentaenoic acid (mean 68.23%; relative standard deviation 2.23%) was twice as high as the content of docosahexaenoic acid (mean 31.77%; relative standard deviation 4.79%). ¹³C NMR spectroscopy was used to distinguish between krill and fish oil-based dietary supplements. The adulteration of krill oil can be detected by fatty acid distribution in the sn-2 triacylglycerol position. The sensitivity of the method is about 10% (w/w) of fish content in blends, which is enough to detect deliberate adulteration. The same methodology can be used to recognize synthetically modified krill oil. The method was successfully applied to 30 commercially available krill and fish oil supplements.     

Optimization of a microwave-coupled enzymatic digestion process to prepare peanut peptides

The best enzyme to prepare peanut peptides, papain, coupled with microwave irradiation was selected from five common proteases according to the results of the yield of peanut peptides [nitrogen solution index (NSI) in trichloroacetic acid (TCA), TCA-NSI] and the degree of hydrolysis (DH). The main factors that influenced the microwave-coupled enzymatic digestion method were optimized by response surface analysis. The optimal conditions obtained were as follows: microwave extraction time, 9.5 min; power, 600 W; substrate concentration, 4%; enzymatic reaction temperature, 50 °C; enzyme quantity, 6,500 U/g; pH, 7.1 (phosphate buffer, 0.05 mol/L). Under these conditions, TCA-NSI was 62.00% and DH was 25.89%, which is higher than that obtained with either protease hydrolysis or microwave hydrolysis alone.