保加利亚乳杆菌胞外多糖合成条件的优化及其在发酵乳中的应用研究

研究了不同碳源、氮源、碳氮比及发酵条件等因素对保加利亚乳杆菌Y5菌株产胞外多糖的影响。结果表明,以果糖为碳源时,胞外多糖的产量是55．46mg／L。显著高于用半乳糖作为碳源时的产量（29．59mg／L）;以鱼蛋白胨作为氮源为时,胞外多糖产量可达到46．89mg／L,明显高于用胰蛋白胨作为氮源时的产量（P〈0．01）;当碳氮比为2：1时,Y5菌株产生的胞外多糖最多,可这50．10g／L,显著高于碳氮比为1：2时的产量（P〈0．01）。培养温度为40℃,发酵时间为16h,初始pH值为6．0,葡萄糖添加量为2％的发酵条件是Y-5菌株产胞外多糖的最佳工艺条件,其胞外多糖水平可达105．36g／L。与采用ST和LB菌株的发酵乳相比,应用Y5菌株生产的发酵乳,其乳清析出量仅为7mL（P〈0．01）：冷藏30d后,Y5菌株制备的发酵乳仍能维持10^7mL^-1以上的活菌数,明显高于对照菌株的存活数量（P〈0．01）。     

保加利亚乳杆菌G6高产胞外多糖影响因素研究

研究保加利亚乳杆菌G6高产胞外多糖的影响因素。通过改变其营养基质和发酵条件,采用单因素试验和正交试验,确定出保加利亚乳杆菌G6高产胞外多糖的最佳工艺条件。结果表明:葡萄糖、蛋白胨和磷酸氢二钾为保加利亚乳杆菌G6高产胞外多糖的最适碳源、氮源和磷酸盐,当其质量浓度分别为30,10,3.0 g/L,而初始pH值为5.5,发酵温度为34℃,发酵时间36 h时,该菌株胞外多糖合成量为425.7 mg/L,比优化前提高了36.57%。验证实验结果表明,此工艺条件具有合理性和稳定性,并可为高产胞外多糖乳酸菌的开发和应用提供理论依据。     

一株融合菌株G23产胞外多糖的流变学特性

融合菌株G23是由植物乳杆菌C88和发酵乳杆菌F6通过原生质体融合获得的菌株.采用动态流变仪,在不同多糖质量浓度、温度、pH值务件下测定融合菌株G23所产生的胞外多糖的流变学性质.所产胞外多糖溶液是典型的非牛顿流体,胞外多糖质量浓度的增大可提高溶液体系的黏度.在10～80℃的较大温度范围内黏度变化较小,在所测温度范围内溶液黏度基本保持不变.在不同pH值条件下,胞外多糖溶液均表现为剪切力作用下黏度迅速下降趋势.胞外多糖加入脱脂乳溶液中能够明显的增加脱脂乳的黏度,且溶液的黏度下降变慢.在试验的频率范围内,随着胞外多糖溶液质量浓度的增加,对应的交叉频率的值相应变大,胶体特征越明显.     

产胞外多糖乳杆菌的菌种鉴定及其发酵条件优化

采用苯酚-硫酸法从45株乳酸菌中筛选得到1株产胞外多糖的乳酸菌NM18,对其进行形态特征观察为杆状细菌,通过16S rDNA基因序列分析对该菌株进行了菌种鉴定,PCR扩增得到1478 bp序列,PCR产物序列通过Blast软件在NCBI网站中进行同源性比较,通过MEGA 5.0软件绘制系统发育树,菌株NM18鉴定为植物乳杆菌。通过单因素试验和正交试验确定其最佳发酵条件:初始pH值6.5、发酵温度37℃、发酵时间34 h、最佳接种量1.5%,此条件下菌株NM18的胞外多糖合成量为206.8 mg/L,与基础培养基相比胞外多糖合成量提高15.2%。     

植物乳杆菌胞外多糖发酵条件的优化

目的：对植物乳杆菌胞外多糖的发酵条件进行优化。方法：采用Plackett-Burman法从影响植物乳杆菌胞外多糖(EPS)产量的14个因素中筛选出3个主要影响因素,然后通过响应面法探讨最优工艺参数。结果：影响植物乳杆菌胞外多糖产量的主要因素是蔗糖质量浓度、接种量以及发酵温度,其最佳条件为蔗糖质量浓度34g/L、接种量5%、发酵温度31℃,在此条件下发酵的植物乳杆菌胞外多糖产量达425.16mg/L。结论：应用Plackett-Burman设计和响应面法进行植物乳杆菌胞外多糖发酵条件的优化是可行的。     

植物乳杆菌YW11生产胞外多糖的发酵条件研究

对实验室从西藏灵菇中筛选出的一株植物乳杆菌YW11发酵产胞外多糖的条件进行优化。首先通过单因素实验对发酵条件进行初步优化,然后利用二水平正交试验直观分析确定影响因素的主次顺序。以胞外多糖产量作为响应值,采用3因素3水平的响应面分析法,建立二次多项式回归方程的预测模型,从而确定植物乳杆菌YW11产胞外多糖的最优条件。单因素实验结果表明,发酵时间为18 h、碳源为乳糖(质量浓度为15 g/L)、氮源为大豆蛋白胨(质量浓度为15 g/L)、发酵温度为32℃、接种量为3%、p H值为6.0。直观分析确定影响植物乳杆菌YW11产胞外多糖主要发酵因素为大豆蛋白胨质量浓度、p H值、接种量,响应面法优化其较佳值为:大豆蛋白胨质量浓度为13.50 g/L,接种量为2.70%,p H值为6.27。验证实验表明,在优化的发酵条件下得到植物乳杆菌YW11胞外多糖产量为131.26 mg/L,与理论预测值(129.915 mg/L)相接近。     

高产胞外多糖的植物乳杆菌直投发酵菊芋泡菜的研究

采用自主研发的高产胞外多糖的植物乳杆菌直投式泡菜发酵剂制备菊芋泡菜,研究其发酵过程中泡菜液pH、总酸、活菌数、维生素C、氨基酸态氮和可溶性固形物含量的变化,同时探讨菊芋主要成分菊粉对植物乳杆菌生长的影响,并测定该菌胞外多糖的产量。结果表明,菊粉可促进植物乳杆菌的生长,37℃培养24 h,该菌胞外多糖产量高达471 mg/L。与自然发酵相比,直投发酵的菊芋泡菜各项指标均优于自然发酵,其泡菜液pH达到3.46、总酸含量达到0.36%,活菌数保持在4.3×108CFU/mL、维生素C含量为16.92%、氨基酸态氮含量为0.033%、可溶性固形物含量达到15%。得到的菊芋泡菜酸度适宜,呈诱人乳白色,活菌含量高,且富含植物乳杆菌胞外多糖,为老少皆宜的益生泡菜产品。     

植物乳杆菌YM-2菌株胞外多糖生物合成工艺优化

对从云南传统发酵豆豉分离得到的植物乳杆菌YM-2(Lactobacillus plantarum YM-2)菌株胞外多糖(exopolysaccharide,EPS)生物合成条件进行优化。首先对培养基成分中的碳源、氮源种类进行筛选;然后利用单因素试验分析碳源含量、氮源含量、培养时间以及培养温度对EPS产量的影响;最后采用Box-Behnken法进行四因素三水平响应面分析以确定其最优工艺条件。结果表明,植物乳杆菌YM-2菌株生物合成EPS最佳条件为碳源(葡萄糖)含量30 g/L、氮源(酵母粉)含量30 g/L、培养时间30.05 h、培养温度36.36℃,在此工艺条件下,植物乳杆菌YM-2 EPS产量为257.362 mg/L。     

Cellulomonas sp.GJT07产果聚糖的发酵工艺研究

以Cellulomonassp.GJT07作为发酵菌株,对其胞外多糖的发酵工艺进行了研究,考察了不同碳源、氮源、培养基初始pH、发酵温度、通气量等因素对菌种产糖的影响,建立和优化了胞外多糖摇瓶发酵培养基配方、发酵工艺及发酵条件,胞外多糖实际产量达15 g/L。研究了发酵过程中菌体生物量、pH值、产物多糖积累量的动态变化。多糖组成分析实验表明,该菌株所产胞外多糖为果聚糖。     

乳酸乳杆菌胞外多糖的发酵条件优化

对乳酸乳杆菌发酵生产胞外多糖的发酵条件进行了优化。在确定Elliker培养基为最适培养基的基础上,利用Plackett-Burman试验设计,筛选出对胞外多糖产量有显著影响的因素,即酵母粉、发酵时间、初始pH值,然后针对这3个关键因子,用单因子试验及中心组合试验优化得到最佳发酵条件。结果表明:当酵母粉为17.35 g/L,初始pH 5.85,发酵时间23.18 h时,乳酸乳杆菌胞外多糖实际产量可达3.910 g/L。     

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.     

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.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

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

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

The Ministry of Environmental Protection Issued "Feasible Technology Guidelines for Pollution Prevention and Control in Wood Pulping Process of the Paper Industry (Trial)" and Two Other Guiding Technical Documents

On December 27t＂, 2013, the Ministry of Environmenta Protection announced that, in order to implement ＂The Environmental Protection Law of the People＇ s Republic of China＂, improve the working system in environmenta protection technologies, and promote technologica advancement in pollution prevention, the Ministry of Environmental Protection sponsored the formulation of three guiding technical documents including ＂Feasible Technology Guidelines for Pollution Prevention and Contro n Wood Pulping Process of the Paper Industry （Trial）＂     

1~(st) Intelli-Tissue~ EcoEc Tissue Machine Supplied by PMP Group Successfully Put into Operation in China

正On April 29th,2014,Intelli-Tissue EcoEc tissue machine supplied by PMP Group successfully put into operation at Hebei Xuesong Paper Co.,Ltd.,this is the first such kind of paper machine of PMP Group in China.