嗜冷菌对牛乳货架期的影响

采用Azocasein法和碱式滴定法对嗜冷茵产蛋白酶和脂肪酶的活力进行了测定.研究了嗜冷茵在原料乳中的生长规律.结果表明,嗜冷茵产蛋白酶和脂肪酶的最佳pH值为7.0,最适培养温度在30℃,产酶高峰分别出现在30 h和24 h,在最适培养条件下嗜冷茵数的动态增加与蛋白酶和脂肪酶活力变化趋势大致相同.原料乳在低温贮藏过程中,嗜冷茵数与蛋白质、脂肪、水分、密度、pH值也存在有数学相关性.     

10-HDA对体外培养大鼠小脑细胞增殖的影响

目的:探讨不同浓度的10-HDA对体外培养大鼠小脑神经细胞的增殖和存活的影响。方法:将不同浓度的10-HDA加到原代培养的新生大鼠小脑神经细胞中,使其终浓度分别为0.1μmol/L、1.0μmol/L、10μmol/L、通过BrdU染色,尼氏染色,MTT的方法来检测10-HDA对体外培养大鼠小脑神经细胞增殖和存活的影响。结果:不同浓度的10-HDA均能促进小脑细胞的增殖和存活,并且有一定的浓度依赖关系。中浓度组(10-HDA终浓度为1.0μmol/L)的效果最为显著,与对照组相比有显著性差异(p<0.01)。结论:10-HDA有助于小脑神经细胞的增殖和存活。     

蜂王浆产品中10-羟基-2-癸烯酸的稳定性比较

10-羧基-2-癸烯酸(10-HDA)是蜂王浆特有的不饱和脂肪酸,在其质量标准中特别规定了含量要求.采用纳米技术制备纳米脂质体可提高其稳定性,以包封率为评定指标,采用乙醇注入-超声法制备了10-HDA纳米脂质体,并用液相色谱测定其中的10-HDA含量,比较5种蜂王浆产品中10-HDA的含量稳定性.结果发现,10-HDA纳米脂质体包封率可达98.3％,同时其含量最为稳定,而其它4种蜂王浆产品中10-HDA含量不稳定,随着时间的延长呈下降趋势.     

蜂王浆冻干粉体外抗氧化作用

对青海、陕西、安徽和浙江产油菜蜂王浆的冻干粉中水溶性蛋白、总酚和10-羟基-2-葵烯酸(10-HDA)含量进行测定,并通过DPPH法和FRAP法评价蜂王浆冻干粉的抗氧化活性。结果表明：不同产地油菜蜂王浆的冻干粉中总酚含量无显著性差异,但青海产油菜蜂王浆的冻干粉中水溶性蛋白含量最高(190.32mg/g),10-HDA含量最高的为陕西产油菜蜂王浆的冻干粉(4.28%);不同产地油菜蜂王浆的冻干粉均具有良好的DPPH自由基清除能力和总抗氧化能力,且样品的总抗氧化能力与其所含有的水溶性蛋白(r＝0.88)和总酚含量(r＝0.95)间呈显著正相关。     

红曲米中凝乳酶产生菌的筛选及液态发酵条件的优化

红曲米是我国古代流传下来的一种传统添加剂,红曲米中微生物所产凝乳酶具有凝乳作用.采用酪蛋白平板法和Arima时间法筛选出了1株产生凝乳酶能力强的菌株M5.通过正交试验,对该霉菌产凝乳酶发酵条件进行了初步优化, 结果表明,PDA 培养基是该霉菌产凝乳酶的最佳培养基,最佳培养条件为温度30℃、转速为160 r/min、振荡培养72 h,凝乳活力可达到150.6 SU.     

多菌种根霉菌圆盘制曲的生产研究

利用圆盘制曲技术进行多菌种根霉曲生产,确定圆盘自动化生产工艺,根霉M1、G1和G3复合菌种比例分别为50%～70%、20%～30%、10%～20%,接种量为1‰～3‰;圆盘培养分为两个阶段,1h～20h为菌丝大量繁殖期,培养温度为30℃～34℃,通风量为10Hz～15Hz;20h～32h为产酶期,培养温度为34℃～36℃,通风量为20Hz～25Hz。多菌种根霉曲产质量稳定,糖化作用与产酸能力较强,比单菌种根霉曲相比,试饭糖分、酸度分别提高20.5%、89.6%。     

产右旋糖酐酶埃氏交替单胞菌的筛选、鉴定及酶活分析

从连云港港口海泥样本筛选到一株产右旋糖酐酶的埃氏交替单胞菌A.espejiana YSN412,对其所产的右旋糖酐酶AesDEX酶学性质进行了分析,对其产酶条件进行了摸索AesDEX最适反应温度为30℃,最适pH值为8在30 ℃下保温2.5h.残余相对酶活在95％以上,而在50℃下保温2.5h后只有14％的残余酶活力.该菌株产酶培养的最佳碳源和氮源,分别是纤维二糖和酵母粉,最适产酶培养温度为30℃,NaCl浓度为2％,初始pH为8时培养液酶活力最高.该菌株培养12h时培养液酶活力达到最高值9U/mL本实验筛选到的4.espejiana YSN412菌株产酶较为迅速,所产的右旋糖酐酶AesDEX酶活最适温度较低,在工业生产上具有潜在降低成本、提高生产效率的优势.     

从蜂王浆中提取蜂王酸的研究

目的 探讨从蜂王浆中提取蜂王酸(10-HAD)的工艺.方法 二次有机溶剂提取,二次调pH,用高效液相色谱法对10-HDA进行定性分析.结果 蜂王浆中10-HDA的最佳提取条件为:蜂王浆水溶液pH 10,加入乙醚提取杂质,再调PH 2加入乙醚提取10-HDA.结论 此法可从蜂王浆中高效提取10-HDA.     

生产蜂王酸(10-HDA)菌株的筛选与评价

从新鲜的蜂王浆、蜂巢以及其他可能含有脂肪酸的物质中筛选出3株菌株——QYF005、QYF017、QYF024,依据它们产蜂王酸的重现率,确定QYF005作为进一步研究的对象.通过稀释涂布平板的方法,将菌株在30℃培养60h后,选择平板上的单菌落,在160r/min摇床中30℃培养64h,提取产品,用HPLC和GC-MS方法检测该菌株是否在发酵过程中产生蜂王酸.检测结果显示菌株QYF005能够产生蜂王酸,产量达到25mg/L.     

10-羟基-2-癸烯酸在桶装小麦啤酒中的抑菌作用

10-羟基-2-癸烯酸(10-HDA)是一种非常重要的不饱和脂肪酸,在自然界中只能从蜂乳中得到。天然的10-HDA具有多种生物活性如抗癌性及时抗急性辐射性损伤。本研究中建立了一种从蜂乳中提取10-HDA的方法,并通过流式细胞仪和抑菌(纸片分析)实验研究了10-HDA对啤酒腐败细菌及酵母的抑菌活性,通过倍比稀释法确定了10-HDA的最低抑菌浓度。结果显示10-HDA对啤酒中常见的细菌如短乳杆菌属和足球菌属具有抑制作用,但对酵母没有抑制作用。作者开发了一种应用上面酵母菌株303和下面酵母菌株308发酵桶装小麦啤酒的新方法。啤酒在桶中进行二次发酵,酒中仍有活酵母存在,不能进行巴氏杀菌,要保持啤酒在发酵和桶装过程中洁净、不被污染是十分困难的。本实验中将10-HDA加入嫩啤酒中,提高了桶装啤酒的清洁度、微生物稳定性和啤酒的货架期,经证实10-HDA起了抗微生物剂的作用。     

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.     

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.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

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.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

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