盐藻多糖提取工艺研究

目的探讨盐藻多糖提取工艺流程。方法应用均匀设计实验确定优化提取条件。结果最终确定的条件为20倍水,pH值8,90℃水浴,提取10 h。同法提取2次,每次平行做2份,盐藻多糖得率为22.7%。结论均匀设计的结果与实际相吻合,为今后盐藻多糖的开发利用提供依据。     

杜氏盐藻多糖提取工艺的优化

针对杜氏盐藻多糖的提取,通过单因素试验选取实验因素与水平,根据Box-Benhnken的中心组合实验设计原理,在单因素试验的基础上采用三因素三水平的响应面分析法,以多糖提取率为响应值作响应面,并进行回归分析。结果表明,杜氏盐藻多糖提取的理想工艺条件为:提取温度81℃,提取液pH8.80,提取时间210min;液料比为25∶1(v/w)时,杜氏盐藻多糖的提取率达到8.77%。红外光谱等分析结果显示,在该工艺条件下提取的杜氏盐藻多糖产品中含有酸性多糖,并含有一定量的硫酸酯多糖,糖苷键主要是α型。     

超声辅助提取雨生红球藻渣多糖工艺优化

以提取过虾青素后的雨生红球藻渣为原料,采用超声辅助热水浸提法提取藻多糖。在单因素实验基础上,通过正交实验设计对雨生红球藻多糖提取工艺进行优化,并与传统的热水浸提工艺进行对比。结果表明,雨生红球藻多糖的最佳提取工艺为:超声功率400 W,超声时间30 min,水浴温度90℃,水浴时间3 h,料液比1∶25,在此条件下多糖得率为3.48%,得率比传统法提高了27%。超声辅助热水浸提法是雨生红球藻多糖提取的有效途径,为藻多糖的进一步研究提供基础,为雨生红球藻渣的综合开发利用提供理论依据。     

不同方法提取香蕉皮中果胶的研究

香蕉皮经不同方法提取而得果胶提取液,分别以乙醇沉淀法和盐析法从提取液中沉淀果胶。研究并取得了不同提取方法的最佳提取条件,比较了不同提取方法的乙醇消耗量,探索了不同方法对果胶提取得率和品质的影响。结果表明:酸解醇析法所消耗的乙醇量几乎为盐析法乙醇消耗量的两倍;盐析法省去稀酸提取液浓缩工序和减少乙醇回收量,节省能耗,降低生产成本,并能保证较高的提取得率和果胶品质。     

正交法优化海带岩藻多糖提取工艺

目的 研究岩藻多糖的提取工艺.方法 采用正交优化法,以海带为原料,最佳组合为料液比(1 g:20mL),温度80℃,提取3次,提取时间10 h.结果 岩藻多糖得率25%,经柱层析纯化,纯度达93%.结论 此工艺操作简便,成本较低.     

低砷岩藻多糖的制备技术

介绍一种低砷含量的岩藻多糖制备技术:以羊栖菜为原料,在传统酸提岩藻多糖工艺的基础上,增加去除浸泡酸溶液及乙醇沉淀纯化岩藻多糖2个步骤,并对这2个步骤进行条件优化。去除浸泡酸溶液的最佳处理条件为使用5倍体积、浓度1%的柠檬酸溶液浸泡藻体,浸泡温度50℃、浸泡4 h后去除浸泡酸溶液,并使用等量的纯水洗涤一遍,然后补充等量的纯水。乙醇沉淀纯化岩藻多糖的最佳条件是:向浓缩液中加入乙醇,使乙醇浓度达到35%,静置30 min,即可离心去除沉淀,上清液浓缩去除乙醇后直接喷雾造粒。使用优化后的工艺进行提取,岩藻多糖中总砷含量由传统酸提工艺的40 mg/kg降低到(0.5~1)mg/kg,且产品得到进一步纯化,L-岩藻糖含量由20%提高到35%以上。     

正交法优化海带岩藻多糖提取工艺

目的 研究岩藻多糖的提取工艺.方法 采用正交优化法,以海带为原料,最佳组合为料液比(1 g:20mL),温度80℃,提取3次,提取时间10 h.结果 岩藻多糖得率25%,经柱层析纯化,纯度达93%.结论 此工艺操作简便,成本较低.     

苹果渣果胶提取工艺条件的研究

以苹果渣为原料,分别采用盐析法和醇沉法研究提取果胶的最佳工艺.盐析法提取果胶的条件为:酸提液pH为2.0,酸提时间1.0h,以硫酸锌为盐析用盐,添加量2%,脱盐液(10%HCl,70%乙醇)用量100mL.醇沉法从苹果渣中提取果胶的条件为:酸提液pH为1.5,料液比为1∶15,酸提时间为1.5 h,乙醇用量150mL.从产品得率和质量比较均为醇沉法提取果胶较好.     

关于盐藻多糖的研究

本文对海洋浮游藻类──盐藻的开发和利用进了研究与探讨，介绍了盐藻多糖的提取和纯化工艺及其相关生物技术，并在实验基础上说明盐藻复合物对提高机体免疫功能的作用，展示其在医药化工等行业的应用价值。     

关于盐藻多糖的研究

本文对海洋游藻类－盐藻的开发和利用进了研究与探讨，介绍了盐藻多糖的提取和纯化工艺及其相关生物技术，并在实验基础上说明盐复合物对提高机体免疫功能的作用，展示其在医药化工等待业的应用价值。     

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.     

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.     

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.     

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.     

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.