纤维素酶催化大豆异黄酮的水解

为充分发挥大豆异黄酮生物价值,采用纤维素酶催化糖苷型大豆异黄酮水解制备游离苷元型大豆异黄酮。通过考察10种纤维素酶对糖苷型大豆异黄酮总水解率和苷元型大豆异黄酮总转化率的影响,筛选得到一种成本较低且水解效果较好的纤维素酶,用于催化水解糖苷型大豆异黄酮,优化了该纤维素酶在水解工艺中底物质量浓度、酶添加量、反应体系pH、酶解温度、酶解时间等参数。结果表明：选择来源于Trichoderma viride的纤维素酶作为大豆异黄酮水解用酶;底物质量浓度0.8～2.0 mg/mL、酶添加量7%～11%、反应体系pH 5.0、酶解温度55℃、酶解时间5～6 h是较经济有效的水解工艺参数,实验优化过程中,大豆异黄酮总水解率超过90%,总转化率接近60%。因此,采用纤维素酶催化水解大豆异黄酮可显著增加游离苷元含量,提高大豆异黄酮利用价值。     

里氏木霉β-葡萄糖苷酶水解大豆异黄酮糖苷的工艺研究

研究了里氏木霉β-葡萄糖苷酶的酶学性质,及其水解大豆异黄酮糖苷能力.该酶反应的最适温度为50℃,最佳pH为5.0;此酶在pH 4.5～5.5之间和低于60℃下酶较稳定,在80℃基本无活力.采用里氏木霉β-葡萄糖苷酶水解的方法,将大豆异黄酮糖苷转化为苷元,以染料木苷水解率为检测指标.通过正交试验确定了该酶水解大豆异黄酮的工艺条件为反应温度50℃、水解时间90 min、水解介质pH4.5、加酶量20U,大豆异黄酮中染料木苷的水解率为99%.     

酶水解对大豆异黄酮粗提物中苷元含量的影响

采用β-葡萄糖苷酶水解的方法将大豆异黄酮糖苷转化为苷元,以染料木素和大豆苷元含量为指标,通过单因素试验对水解过程中的不同影响因素进行了考察。以染料木素含量为指标,运用正交试验优化了β-葡萄糖苷酶水解大豆异黄酮的工艺条件为反应温度40℃、水解时间1.5h、水解介质pH4.5、水解底物浓度10mg/mL,在此条件下,水解得到的大豆异黄酮苷元中染料木素的含量可达到22.91%。     

大豆异黄酮糖苷水解工艺的研究

通过正交试验得到了大豆异黄酮糖苷水解为大豆异黄酮苷元的最佳工艺条件。最佳酸法水解工艺条件为:盐酸浓度3 mol/L,水解温度80℃,水解时间180 min,酸法水解率为81.31%;最佳酶法水解工艺条件为:pH 6.0,酶解温度38℃,酶解时间90 min,加酶量为0.9 mg(50 mg糖苷型大豆异黄酮提取物),酶法水解率为82.54%。酶法水解的效果优于酸法水解的效果。     

两步水解酶法制备大豆异黄酮苷元初探

利用二步水解法制备大豆异黄酮苷元。经弱碱水解丙二酰基大豆异黄酮为糖苷型大豆异黄酮,再经果胶酶进一步水解获得富含苷元的大豆异黄酮。采用单因素试验和正交试验,得到果胶酶制备大豆异黄酮苷元的较优工艺条件:果胶酶水解时间20 min,水解温度47.5℃,水解pH值4.2,酶-底物质量比为0.80%。苷元水解得率为87.37%。     

响应面法优化酶法水解大豆异黄酮的条件

在单因素试验基础上,利用响应面分析(response surface analysis,RSA)法中Plackett-Burman和Box-Behnken进行设计,得出β-葡萄糖苷酶水解大豆异黄酮物质的最佳条件为:水解时间55 min,水解温度57℃,pH3.5.在最佳条件下,用β-葡萄糖苷酶水解大豆异黄酮得到大豆苷元,其得率达到39.05%.     

β-葡萄糖苷酶水解、分离纯化大豆异黄酮甙元工艺研究

研究以低纯度的商品大豆异黄酮为原料,采用β-葡萄糖苷酶水解技术制备高纯度的大豆异黄酮甙元产品.比较系统地研究酶的用量、反应时间、反应温度、反应体系pH值、底物浓度等因素对酶水解效果的影响,最终得到酶水解制备工艺的最佳工艺参数.实验结果表明,采用该分离纯化工艺制备大豆异黄酮甙元产品,其产品得率、异黄酮回收率和产品纯度分别为12.12%、77.16%和92.78%,分离纯化效果比较理想.     

大豆异黄酮水解物的制备

利用黑曲霉产酶发酵培养基制备β-葡萄糖苷酶,再利用β-葡萄糖苷酶水解大豆异黄酮粉制备异黄酮苷元。研究结果表明,较优产酶发酵培养基的C/N为6∶4,加水量1.4倍,培养基中不添加诱导物。水解500 mg40%大豆异黄酮粉的最佳条件为:加酶量100 U,水解温度50℃,水解时间1 h。     

裂褶菌发酵转化大豆异黄酮的条件优化

利用裂褶菌发酵β–葡萄糖苷酶将大豆异黄酮糖苷转化为苷元,研究底物浓度、pH、温度和时间对糖苷转化率的影响,采用正交试验优化转化条件。结果显示:最佳条件为底物浓度15g/100mL、温度50℃、转化时间20h,此时测得大豆苷和染料木苷的转化率分别为99.14%和98.57%。     

大豆异黄酮糖苷酶法水解工艺研究

通过正交试验及方差分析,得到大豆异黄酮糖苷酶法水解为大豆异黄酮苷元最佳工艺条件:在pH 6.0缓冲液体系中,酶解温度为38℃,酶解时间为90 min,加酶量为4.0 mg(4%),酶法水解率为82.55%。     

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.