油菜蜂花粉中黄酮的分离纯化及结构鉴定

研究油菜蜂花粉黄酮的组成,采用乙醇提取,石油醚萃取脱脂和柱层析分离方法对油菜蜂花粉黄酮进行研究,得3个黄酮类化合物,经1 H-NMR、13 C-NMR,分别鉴定出3个黄酮类化合物化学结构为山奈酚-3-O-β-D-吡喃葡萄糖苷、山奈酚-3-O-β-D吡喃葡萄糖基(1→2)-β-D-吡喃葡萄糖苷和槲皮素-3-O-β-D-吡喃葡萄糖苷,与HPLC-MS检测结果一致。     

新疆药桑叶中黄酮类化合物的分离与鉴定

采用色谱分离技术从药桑叶醇提物的乙酸乙酯萃取部分分离黄酮类化合物,通过核磁共振(NMR)和高效液相-串联质谱(HPLC-MS-MS)鉴定其结构。分离得到四个黄酮类化合物,结构表征为芦丁(1)、槲皮素-3-O-葡萄糖苷(2)、金丝桃苷(3)、山奈酚-3-O-β-D-吡喃葡萄糖(4)。其中化合物(3)、(4)首次从新疆药桑叶中分离得到。     

枸杞叶黄酮提取物的组成及初步结构表征

本文采用高温乙醇回流法得到一种枸杞叶黄酮提取物,经硝酸铝-亚硝酸钠比色法测定该提取物的总黄酮含量为347.00 mg/g。采用紫外-可见光谱(UV-Vis)和傅里叶变换红外光谱(FT-IR)对其进行初步结构表征,发现枸杞叶黄酮提取物的UV-Vis谱图中含有A-环苯甲酰和B-环肉桂酰系统的特征吸收峰,其FT-IR谱图也显示有C=C、羟基、酚羟基、甲氧基以及甲基等多种特征官能团的振动吸收峰,具有黄酮类化合物的典型结构。通过高效液相色谱(HPLC)测定枸杞叶黄酮提取物中各黄酮类化合物的组成与含量,得出该提取物含有芦丁、绿原酸、槲皮素、咖啡酸、对香豆酸、山奈酚6种黄酮类化合物,含量分别为100.74、0.31、23.59、42.83、2.94、0.08 mg/g,表明提取物是一种富含芦丁、绿原酸和槲皮素的天然黄酮类物质,在天然食品添加剂和功能食品原料等方面具有开发利用价值。     

油菜蜂花粉中粗黄酮提取物成分分析

为了明晰油菜蜂花粉中黄酮类物质的组成及脉冲电场辅助提取效果,试验采用TLC—DPPH和HPLC等方法对油菜蜂花粉的乙醇提取物及其酸解产物进行了详细的组分分析。结果表明,油菜蜂花粉的乙醇提取物中槲皮素和山奈酚因含量过低而未能检出,但该提取物经酸水解后,则会形成大量槲皮素和山奈酚,故可初步推断油菜蜂花粉中的黄酮类化合物主要以黄酮苷的形式存在。未经脉冲电场破壁处理的蜂花粉乙醇提取物的酸解物中,槲皮素含量为764.39μg/g,山奈酚含量为1 647.97μg/g,而经破壁处理后,槲皮素含量达867.93μg/g,对比提高了13.55%,山奈酚含量达1 924.03μg/g,对比提高了16.75%。该结果充分证明了脉冲电场预处理对油菜蜂花粉细胞具有良好的破壁效果。     

洋甘菊抑制酪氨酸酶活性成分研究

研究了罗马洋甘菊乙醇提取物对蘑菇酪氨酸酶活性的影响并对有效成分进行分离纯化。实验中以L-酪氨酸为底物,空白对照,采用比色法测定了罗马洋甘菊乙醇提取物不同乙醇浓度的洗脱物对蘑菇酪氨酸酶的抑制作用。结果表明:MCI30%(体积分数)乙醇浓度洗脱物对酪氨酸酶活性的抑制率最灵敏。该部分洗脱物经MCI、ODS-A柱分离,得到了3个单体化合物:山奈酚-3-O-β-D-吡喃葡萄糖苷、异鼠李素-3-O-β-D-吡喃葡萄糖苷、山奈酚-3-O-(6"-3-羟基-3-甲基-戊二酰基)-β-D-吡喃葡萄糖苷。     

白鲜皮黄酮类物质分析、富集及在卷烟中的应用

建立了白鲜皮提取物中芦丁、槲皮素、木犀草素、山奈酚和异鼠李素5种黄酮物质通过高效液相色谱法检测的方法,来分析白鲜皮来源对其黄酮物质含量的影响;并采用AB-8型大孔树脂对白鲜皮提取物中黄酮类成分进行富集,评价富集后的白鲜皮提取物在卷烟中的应用效果。试验采用ZORBAX ECLIPSE PLUS C18色谱柱(250mm×4.6 mm,5μm),流动相A相为0.35%乙酸水溶液,流动相B相为75%甲醇水溶液,梯度洗脱,流速为0.80 m L/min,VWD检测波长为283 nm,柱温为35℃。检测方法显示:5种黄酮物质测得的线性范围为0.05~500 mg/L;检出限(S/N=3)在0.004~0.08 mg/kg之间,加标回收率(N=6)在85.96%~107.52%之间,检测方法灵敏有效。检测结果表明,不同来源白鲜皮得到的白鲜皮提取物中芦丁、槲皮素、木犀草素、山奈酚、异鼠李素5种白鲜皮提取物黄酮物质的总含量以辽宁朝阳产白鲜皮提取物最高。经大孔树脂富集后,各产地白鲜皮黄酮类物质含量显著增加。卷烟加香应用结果表明,辽宁朝阳产白鲜皮提取物经大孔树脂富集后,能与烟香协调,增加烟气圆润、绵长感,改善余味。     

不同产地苦荞麦中黄酮类成分的含量测定与分析

建立苦荞麦中芦丁、槲皮素、山奈酚、山奈酚-3-o-芸香糖苷4种黄酮类成分的含量测定方法,比较不同产地苦荞麦中黄酮类成分的含量差异。采用高效液相色谱法(high performance liquid chromatography,HPLC)测定不同产地苦荞麦样品中黄酮类成分的含量,采用统计学方法分析不同产地4种成分含量的差异。方法学考察中线性范围、精密度、稳定性、重复性及加标回收试验均符合规定,云南产苦荞麦中槲皮素、山奈酚含量明显高于其他产地,芦丁、山奈酚-3-o-芸香糖苷含量相差不大。该方法可用于苦荞麦中黄酮类成分的含量测定,为苦荞麦原料的采购提供技术依据。     

太白韭对金黄色葡萄球菌的抑制作用

采用二倍稀释法和牛津杯法测定太白韭乙醇提取物对金黄色葡萄球菌的抑菌活性,采用原子吸收光谱法、扫描电子显微镜技术等分析太白韭乙醇提取物对金黄色葡萄球菌胞外金属离子含量、生物大分子(蛋白质、核酸、多糖)含量、电导率、细胞壁完整性、菌体超微结构等的影响,采用高效液相色谱法分析太白韭乙醇提取物的化学组成,探讨其抑菌机理。太白韭乙醇提取物对金黄色葡萄球菌的最小抑菌质量浓度为15 mg/mL。用太白韭乙醇提取物处理后,金黄色葡萄球菌胞外K+、Ca2+、Na+、Mg2+离子含量显著增加,胞外蛋白质、核酸、多糖含量显著升高,菌体培养液电导率也显著增大。太白韭乙醇提取物能够严重破坏金黄色葡萄球菌的细胞形态,使部分菌体之间出现粘连、聚合现象。在太白韭乙醇提取物中共检出大蒜素和蒜氨酸2种含硫类化合物,尿苷、β-胸苷、腺苷和2'-脱氧腺苷4种含氮类化合物,以及芦丁、山柰酚、槲皮素和异鼠李素4种黄酮类化合物。太白韭乙醇提取物对金黄色葡萄球菌的抑菌活性可能与其中所含芦丁、槲皮素、大蒜素、山柰酚等化合物有关。     

蜂花粉中黄酮类化合物的鉴定和含量测定

以24种不同蜂花粉为材料,对其中微量特征成分黄酮类化合物进行鉴定和归纳。建立一种高压液相色谱-串联三重四级杆质谱法快速测定蜂花粉中8种黄酮类化合物的方法。破壁的试样经乙醇溶液提取后加酸水解,经反相色谱分离,质谱定性并测定8种黄酮类化合物含量,外标法定量。该方法线性良好,R2均大于0.999,检出限为0.15~3.0 mg/kg,精密度为3.2%~6.6%,回收率在91.2%~100.2%,此方法操作简便,抗基质干扰、结果可靠。分析结果证实,蜂花粉中黄酮类化合物通常有槲皮素、山奈酚、芦丁等。可为识别蜂花粉的植物来源,鉴别真伪和建立相应的指纹图谱提供研究方法和实验依据。     

HPLC法同时测定枣叶中5种黄酮的含量

建立了一种枣叶中黄酮类成分定量分析的HPLC方法,并对14个品种的大枣及酸枣叶中这5种黄酮的含量进行了分析。结果得到采用Hypersil BDS C18色谱柱,以乙腈与0.1%甲酸水溶液为流动相梯度洗脱,流速1 m L/min,柱温30℃,检测波长360 nm,实现了槲皮素-3-O-洋槐糖苷、芦丁、槲皮素-3-O-β-D-葡萄糖苷、山奈酚-3-O-芸香糖苷、槲皮素-3-O-α-L-阿拉伯糖-(1→2)-α-L-鼠李糖苷5种黄酮苷的同时检测,最低检出限为1.44~2.59μg/m L,加标回收率在93.8%~105.9%之间。5种黄酮苷的含量测定结果表明不同品种的枣叶中黄酮类成分的组成和含量差异较大,其中芦丁和槲皮素-3-O-洋槐糖苷的含量较高,平均为7.83 mg/g D.W和4.61 mg/g D.W;8个品种枣叶中检测到槲皮素-3-O-α-L-阿拉伯糖-(1→2)-α-L-鼠李糖苷,平均5.32 mg/g D.W;而槲皮素-3-O-β-D-葡萄糖苷和山奈酚-3-O-芸香糖苷的含量较低,分别为0.14 mg/g D.W和0.41 mg/g D.W。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.