银杏酚酸的分离鉴定及其抗菌活性研究

本文以银杏外种皮为原料,研究了吸附树脂分离纯化银杏酚酸的方法和银杏酚酸的抗菌活性,并对其结构进行了鉴定。结果表明:非极性树脂D4020和弱极性树脂AB-8对银杏酚酸具有较好的吸附能力,银杏酚酸粗提液经两种树脂吸附,不同浓度乙醇梯度洗脱后,产物纯度可达90%,得率为0.91%,利用树脂精制银杏酚酸成本低、效率高,是一种有效的分离方法;通过LC/DAD/MS分析表明,银杏酚酸由五种异构体(C13:0,C15:1,C17:2,C15:0,C17:1)组成,其中C15:1含量最高,其次是C17:1;银杏酚酸主要抑制革兰氏阳性菌,对蜡状芽孢杆菌、枯草芽孢杆菌和金黄色葡萄球菌有很好的抑制作用,而对大肠杆菌等革兰氏阴性菌无抑制作用,酚酸的烷基侧链在抑菌中起了重要作用。     

银杏种仁蛋白分离纯化及其抑菌活性

从银杏种仁中分离纯化具有抑菌活性的蛋白质,并分析其抑菌活性。结合抑菌活性分析,采用硫酸铵分级盐析、透析、纤维素DE-52阴离子交换柱层析及Sephadex G-75凝胶过滤柱层析对银杏种仁蛋白（Ginkgo bilobaseed protein,GBSP）进行分离纯化,得到一种抑菌蛋白GBSPⅠ-A。十二烷基磺酸钠-聚丙烯酰胺凝胶电泳（sodiumdodecyl sulfate polyacrylamide gel electrophoresis,SDS-PAGE）检测结果显示,该蛋白呈单一条带,其分子质量约为42.80 kD;Superdex G-75柱层析结果显示GBSPⅠ-A呈单一对称峰,高效凝胶渗透色谱测定其分子质量为39.32 kD;该蛋白对肺炎克雷伯氏菌、金黄色葡萄球菌、戴尔有孢圆酵母及黑曲霉的最小抑菌浓度（minimum inhibitory concentration,MIC）分别为20、20、20、12 mg/mL。     

苹果籽油中甾醇物质的提取工艺及抑菌活性研究

本实验采用薄层层析法对苹果籽油中的植物甾醇进行纯化,采用K-B纸片法研究甾醇纯化物的菌制活性及pH值、温度等对抑菌性的影响,并且测定其最低抑菌浓度(MIC)。结果表明,分离纯化植物甾醇的最佳薄层层析条件为：展开剂为乙醚-石油醚(3:7,V/V),显色剂为三氯化铁溶液。抑菌实验结果表明,甾醇对金黄色葡萄球菌及枯草芽孢杆菌具有很好的抑制作用,最低抑菌浓度分别为18μg/ml和30μg/ml,对大肠杆菌及蜡样芽孢杆菌有抑制作用,对黑曲霉没有抑制作用。在pH5～6 条件下其抑菌效果最佳;一定温度内热处理不影响苹果籽油中甾醇的抑菌活性。苹果籽油中植物甾醇有广谱和常温的抑菌活性。     

桫椤茎中牡荆素的抑菌活性

从体外试验的角度观察牡荆素的抑菌作用。以大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌为供试菌种,采用滤纸片法和试管内药液2倍稀释法测定牡荆素的抑菌圈直径和最低抑菌浓度(Minimal inhibitive concentration,MIC)。牡荆素对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌均有明显的抑制作用,对大肠杆菌的最低抑菌浓度(MIC)为100μg/mL,对金色葡萄球菌的最低抑菌浓度(MIC)为25μg/mL,对枯草芽孢杆菌的最低抑菌浓度(MIC)为100μg/mL。牡荆素具有良好的体外抑菌作用。     

鱼腥草中天然防腐剂的提取方法及其抑菌作用研究

本文研究了鱼腥草中天然防腐剂的提取方法和抑菌作用,结果表明,用食用乙醇提取鱼腥草中防腐物质的最佳提取工艺参数为:固液比1∶15,提取温度80℃,提取时间为10h。鱼腥草醇提取物对实验用常见食品污染菌有较强的抑制作用,对大肠杆菌和枯草芽孢杆菌的最低抑菌浓度(MIC)为6·25mg/mL,对金黄色葡萄球菌为12·5mg/mL,对汉逊氏酵母菌为25mg/mL,对黑曲霉及青霉等均为50mg/mL,对金黄色葡萄球菌、大肠杆菌和枯草芽孢杆菌的抑菌活性pH范围均为47,对汉逊氏酵母菌为46。     

柠檬醛和辛醛混合物对指状青霉的抑制作用

本研究采用琼脂稀释培养法测定柠檬醛、辛醛以及柠檬醛+辛醛混合物(V/V,4:1)对指状青霉菌丝体生长的影响,并对柠檬醛+辛醛混合物抑菌机制进行初步探讨。结果表明,柠檬醛+辛醛混合物(V/V,4:1)能明显抑制指状青霉菌丝体生长,最小抑菌浓度(minimal inhibitory concentration,MIC)和最小杀菌浓度(minimal fungicidal concentration,MFC)均为2.50μL/m L,而柠檬醛的MIC和MFC分别为2.50μL/m L和5.00μL/m L,辛醛的MIC和MFC分别为0.63μL/m L和2.50μL/m L。扫描电镜结果显示,经MIC(MFC)的柠檬醛+辛醛混合物处理后,指状青霉菌丝体表面发生严重塌陷和多重褶皱,菌丝结构发生不规则扭曲,表明细胞完整性遭到严重破坏。此外,指状青霉菌丝体胞外p H、胞外电导率以及260 nm处的吸光度值均随柠檬醛+辛醛混合物(V/V,4:1)浓度增加显著增加。本研究结果表明,柠檬醛+辛醛混合物(V/V,4:1)能破坏指状青霉细胞结构的完整性,增加细胞膜通透性,导致细胞内物质泄漏,从而导致菌丝体死亡。     

白刺果实提取物的体外抑菌活性研究

探讨白刺果实提取物的体外抑菌活性,以期为白刺果实的综合利用及天然食品防腐剂的开发提供依据。用石油醚、氯仿、乙酸乙酯和正丁醇分别对白刺果实95%乙醇提取物进行萃取,纸片法测定各萃取部分对大肠杆菌、枯草芽孢杆菌、金黄色葡萄球菌、酵母菌、青霉、根霉和黑曲霉7种常见的食源性污染菌的抑菌效果,并通过倍比稀释法测定乙酸乙酯部分对其中3种细菌的最低抑菌浓度。结果表明:白刺果实乙酸乙酯部分、乙醇部分和氯仿部分对3种供试细菌均有抑菌作用,其中乙酸乙酯部分抑菌效果最好,且乙酸乙酯部分对3种细菌的抑制强弱顺序为:枯草芽孢杆菌>大肠杆菌>金黄色葡萄球菌;其中乙酸乙酯部分对枯草芽孢杆菌和金黄色葡萄球菌的最低抑菌浓度(MIC)均为25mg/mL,对大肠杆菌的MIC是50mg/mL。各萃取部分对供试真菌均无明显抑制作用。     

银杏渣中类胡萝卜素的提取及柱层析研究

以银杏渣为原料,通过单因素和正交实验探讨了溶剂种类及其配比、料液比、提取温度、提取时间等因素对类胡萝卜素提取的影响.确定了银杏渣中类胡萝卜素的最佳提取工艺:丙酮:石油醚(V/V=1:2).料液比1:20,67.5℃水浴回流提取2次,每次提取2h,类胡萝卜素提取率达119.25μg/g.提取液经硅胶柱层析分离,梯度洗脱得到3个馏分;石油醚洗脱馏分经紫外-可见光吸收光谱和高效液相色谱分析,初步证实为β-胡萝卜素.此工艺可为银杏渣的再利用提供一种新的途径.     

当归总黄酮醇提液的体外抑菌作用研究

研究当归总黄酮醇提液的体外抑菌作用。采用乙醇回流法对当归总黄酮进行提取,滤纸片法、最低抑菌浓度(MIC)法测定醇取液的抑菌作用,并与食品中常用的防腐剂苯甲酸钠进行比较。试验结果表明:当归总黄酮醇提液对大肠杆菌、沙门氏菌、金黄色葡萄球菌、枯草芽孢杆菌、青霉、黑曲霉、热带假丝酵母具有抑菌作用,其抑菌能力依次为:沙门氏菌金黄色葡萄球菌大肠杆菌枯草芽孢杆菌青霉黑曲霉热带假丝酵母。其最低抑菌浓度(MIC):沙门氏菌和金黄色葡萄球菌为0.5mg·m L-1,其余均为1.0mg·m L-1,其MIC与苯甲酸钠溶液的作用强度基本相当,抑菌效果明显,是一种良好的中草药天然抑菌剂。     

拮抗扩展青霉菌株的筛选及其抗菌活性物质分离

从甘肃中部干旱生境土壤中分离筛选到一株对扩展青霉(Penicillium expansum)具有显著抑制作用的拮抗菌A1,通过Biolog法对其种属鉴定为枯草芽孢杆菌(Bacillus subtilis);通过对该菌株抑菌活性物质进行分离纯化,经拮抗实验证明,其中一种单峰化合物具有抑菌活性,其对扩展青霉(P.expansum)和金黄色葡萄球菌(Staphylococcus aureus)的抑菌最低浓度为1μg/mL。该活性物质对引起农产品及食品腐败变质的多种微生物有明显抑菌效果,抗菌谱较广,尤其对扩展青霉(P.expansum)和金黄色葡萄球菌(Staphylococcus aureus)表现出较高的抑菌活性,具有良好应用开发前景。     

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.     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the