一株纳豆芽孢杆菌的产酶条件优化

从一株实验室保藏的产纳豆激酶细菌出发,先对其液体发酵产酶的培养基和培养条件进行优化,在此优化基础上,利用Plackett-Burman试验筛选出影响纳豆芽孢杆菌产酶的3个主要因素:胰蛋白胨添加量、MgSO4添加量、发酵温度,利用Box-Behnken进行响应面试验设计,优化得到最优发酵条件。发酵培养基条件(g/L):胰蛋白胨26.6、乳糖10.0、Na2HPO45.0、NaH2PO41.0、CaCl20.2、MgSO41.35;发酵条件:种龄12h、接种量2%、发酵温度33℃、发酵时间56h、装液量50mL/250mL。此发酵条件下发酵液的纳豆激酶酶活力为743.65U/mL,比优化前提高了232.33U/mL。     

芽孢杆菌混合发酵工艺条件的优化

为提高饲料用芽孢杆菌中性蛋白酶的活力,考察了多种芽孢杆菌混菌发酵产蛋白酶的协同作用效果,并在单因素试验的基础上,采用响应面分析的中心组合试验设计对多芽孢杆菌的混合发酵工艺条件进行了优化。通过优化确定了混合发酵体系的最佳发酵条件为培养基最初pH值7.17,装液量50mL/250mL,接种量3%,发酵温度35.4℃,摇床转速200r/min,发酵周期100h。在优化的工艺条件下,芽孢杆菌混合发酵产蛋白酶的活力单位可达到2 986U/mL。     

响应面法优化西藏黄牛源产纤维素酶菌株发酵条件

在单因素试验基础上,采用Plackett-Burman试验得出麸皮添加量、蛋白胨添加量及发酵温度是影响菌株产酶的3个最重要的 因素。利用Box-Behnken试验设计对类芽孢杆菌（Paenibacillus）N30发酵生产纤维素酶的产酶条件进行响应面优化。 结果表明,单因 素试验优化结果为麸皮添加量2.5%、蛋白胨添加量0.5%、初始pH值为7.0、发酵温度37℃、接种量1.5%、转速150r/min、装液量 125mL/250mL、种龄32h、KH2PO4 0.2%;响应面优化后发酵条件为麸皮添加量2.8%,蛋白胨添加量0.5%,发酵温度38℃。 在此优化条 件下,纤维素酶酶活为42.5U/mL,是优化前酶活（12.1 U/mL）的3.5倍。     

枯草芽孢杆菌高产中性蛋白酶发酵条件的优化

通过单因素试验和正交试验对枯草芽孢杆菌10075菌株发酵产中性蛋白酶的培养基组分及培养条件进行优化,达到提高菌株中性蛋白酶产量的目的。结果表明,发酵培养基的最佳组分：添加麦芽糖8.0%、蛋白胨4.0%、MgSO4 0.08%;最适发酵条件为发酵温度37 ℃、初始pH 7.0、发酵时间42 h,酶活力由最初的98.36 U/mL 提高到353.45 U/mL。     

浓香型酒醅中一株高产蛋白酶菌株的鉴定及产酶条件的优化

菌株J-1为实验室保存的高产蛋白酶菌株，分离自浓香型发酵酒醅。经过形态学及分子生物学鉴定菌株J-1为解淀粉芽孢杆菌。以蛋白酶活力为指标，通过单因素实验优化产酶条件得出：选用牛肉膏蛋白胨培养基、摇床转速200 r/min、培养温度37℃的实验条件，解淀粉芽孢杆菌所产蛋白酶活力最高，可达到39.6 U/mL。在最优条件下测定蛋白酶最适p H值和最适温度，结果显示：解淀粉芽孢杆菌所产蛋白酶的最适p H值为4.0、最适温度为30℃，并在此条件下蛋白酶活力为45.3 U/mL。结果表明：通过对解淀粉芽孢杆菌产酶条件的优化，提高了菌株蛋白酶活力。期望通过对糟醅中蛋白酶及其产酶条件的研究，能够为白酒酿造生产提供科学理论指导。     

虫源性细菌纤维素酶发酵条件的均匀优化研究

采用U15·(157)均匀试验对虫源性的蜡状芽孢杆菌产纤维素酶发酵条件进行逐步回归分析:以DNS法测定酶活力,确定了该菌株的最优产酶条件.试验结果表明,在自然供氧条件下,发酵74h时酶活性最高;蛋白胨对纤维素酶活力有促进作用.最佳组合条件为:在100mL三角瓶中装入20mL液体培养基,初始pH值为7.5,0.5%CMC-Na,1.2%蛋白胨,最大酶活为233.4711μg/(mL·min).进一步的酶学特性研究显示,酶促反应的最适pH值为8.5,最适温度为25℃～60℃,范围内酶活可保持60%以上.     

甲基营养芽孢杆菌SK21.002产果聚糖蔗糖酶的发酵条件优化

通过研究甲基营养芽孢杆菌SK21.002产果聚糖蔗糖酶的发酵条件,通过单因素实验和正交实验确定其最适产酶的发酵培养基为:蔗糖80g/L,酵母提取物10g/L,胰蛋白胨10g/L,K2HPO48g/L,MgS041g/L,NaCl2g/L;最适产酶的发酵条件为:初始pH6.5,发酵温度30℃,装液量30％,接种量2％,发酵周期21h.在以上条件下发酵培养,果聚糖蔗糖酶活力可达到9.76U/mL,是优化前的3.75倍.     

鹰嘴豆纳豆液态发酵高产蛋白酶的培养基及发酵条件优化

为了提高纳豆中的蛋白酶活力,以纳豆芽孢杆菌为菌种,对鹰嘴豆纳豆液态发酵进行优化。以蛋白酶活力为指标,采用Plackett-Bnrmao法筛选出三个对蛋白酶活力影响最大的因素:装液量、转速和鹰嘴豆粉添加量。通过响应面优化鹰嘴豆纳豆液态发酵的培养基和发酵条件,建立二次回归模型的拟合度良好,对提高蛋白酶活力影响显著(p<0.005),所得最佳培养基为鹰嘴豆粉添加量5.9%,豆粕粉1.0%,葡萄糖0.6%,氯化钠0.5%,最佳发酵条件为:转速250 r/min,装液量76 mL/500 mL,温度37℃,发酵时间48 h。该条件下发酵所得蛋白酶活力达(3558.0±1.5) U/mL,相对于对照培养基的(2491.4±2.8) U/mL提高了42.8%,且纤维蛋白平板法验证的纳豆激酶溶解圈面积提高了108.6%。结果表明,优化后的鹰嘴豆纳豆液态发酵能有效提高蛋白酶活力。     

蜡样芽孢杆菌高产新型中性蛋白酶发酵条件的优化

目的:优化蜡样芽孢杆菌发酵生产新型中性蛋白酶的培养条件。方法:采用Plackett-Burman试验设计,筛选影响蜡样芽孢杆菌高产新型中性蛋白酶酶活力的关键因子;通过Box-Behnken响应面试验设计获得新型中性蛋白酶发酵的最佳工艺条件。结果:筛选出影响蜡样芽孢杆菌高产新型中性蛋白酶的主要因子为葡萄糖、蛋白胨和pH值。获得的最优化发酵培养基组成和培养条件:葡萄糖35 g/L,蛋白40.38 g/L,氯化钠15 g/L,硫酸镁1.5 g/L,Tween-8010 g/L,装液量50 mL/250 mL,pH 7.15,菌龄12 h,发酵时间36 h。在上述条件下,蜡样芽孢杆菌发酵生产新型中性蛋白酶的酶活力高达696.51 U/mL,是未优化前的1.93倍。结论:研究结果为新型中性蛋白酶的产业化生产和应用提供了良好基础。     

甲基营养芽孢杆菌SK21.002产果聚糖蔗糖酶的发酵条件优化

通过研究甲基营养芽孢杆菌SK21.002产果聚糖蔗糖酶的发酵条件,通过单因素实验和正交实验确定其最适产酶的发酵培养基为:蔗糖80g/L,酵母提取物10g/L,胰蛋白胨10g/L,K₂HPO₄ 8g/L,MgSO₄ 1g/L,NaCl 2g/L;最适产酶的发酵条件为:初始pH6.5,发酵温度30℃,装液量30%,接种量2%,发酵周期21h。在以上条件下发酵培养,果聚糖蔗糖酶活力可达到9.76U/mL,是优化前的3.75倍。      

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.     

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.     

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.     

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