菊芋菊糖的提取、聚合度分布及抗氧化活性的研究

以新鲜菊芋为原料,比较热水浸提、酶法、超声和微波辅助热水浸提4种提取方法对菊芋菊糖的提取率、聚合度、抗氧化能力的影响。采用不同截留相对分子质量的超滤管对提取液中菊糖聚合度分布进行分析,通过清除1,1-二苯基-2-三硝基苯肼(DPPH)、羟基自由基(·OH)和超氧阴离子自由基(O2-·)试验来研究菊糖体外抗氧化活性。结果表明,菊芋菊糖最佳提取工艺为:料液质量体积比1 g∶20 m L,微波功率800 W,间歇式辅助处理6 min,提取温度80℃,提取时间120 min,菊糖得率为15.35%。酶法辅助提取对菊糖聚合度基本没有影响,超声和微波辅助造成菊糖平均聚合度下降,其中聚合度30DP60的菊糖样品比例由32.5%分别下降到28.6%和16.5%,聚合度DP60的菊糖比例由13.6%下降到6.8%和3.6%。不同体外抗氧化体系中,4种方法提取所得菊糖均表现出一定的抗氧化能力,且与其质量浓度呈明显量效关系。其中,微波辅助提取法所得菊糖对活性氧自由基的清除作用最强,显示出较强的抗氧化活性。     

菊芋菊糖的提取与纯化

重点研究了菊芋菊糖的提取与纯化。选择提取温度、提取时间、料液比、提取次数进行单因素实验,确定条件范围,再采用正交实验优化提取条件,得到菊芋菊糖提取最佳工艺条件为温度70℃、提取时间90min、料液比1∶15,菊糖提取率可达90.76%。提取液80℃保温1h菊糖保留率高达95.88%且除去60%以上蛋白质。经过D218离子交换树脂脱色处理,菊糖液色泽澄清,呈白色,蛋白质基本除去。最后冷冻干燥得产品,总糖含量达98%以上,其中菊糖含量为96.23%。     

菊芋菊糖的超声波提取、纯化及HPLC法纯度检测

重点研究了菊芋菊糖的超声波提取、纯化工艺和利用高效液相色谱技术进行纯度检测.其中,超声波提取菊芋菊糖最佳工艺条件为:超声功率112W,提取温度70℃,提取时间20min,料液比1:20,菊糖得率为57.3%.菊糖提取液经石灰乳法和醇沉法除杂,再经S-8大孔吸附树脂脱色处理后色泽澄清,真空冷冻干燥得白色粉末,经高效液相色谱法检测,其纯度为96.2%.     

菊芋多糖提取过程中的pH控制策略研究

采用未漂洗和漂洗过的菊芋做原料,在pH5.0～9.0,85℃、固液比1:10下提取,并在60～120min每隔10min取样分析,得出如下结论:pH越低,提取液中的还原糖含量越高;pH越高,提取液中的蛋白质的含量越高;菊糖含量在100min左右达到最高值。考虑还原糖及蛋白质等杂质、脱色及菊糖的含量,未漂洗的原料最佳提取条件为pH7.0,提取110min,其菊糖含量为88.43g/L,菊糖提取率为76.46%;漂洗过的原料最佳提取条件则是pH7.0,提取100min,其菊糖含量为86.10g/L,菊糖提取率为72.65%。     

菊粉分离纯化工艺的研究

以菊糖的保留率为指标,考察了除杂实验中菊糖溶液pH、除杂时间、水浴温度的影响,及其脱色实验中活性炭用量、温度、脱色时间等因素对保留率的影响,并利用正交试验对菊糖的除杂脱色工艺进行了优化,最后对产品采取分离纯化试验.试验结果表明,菊芋中菊糖除杂的优化工艺条件为:除杂温度70℃、水浴时间20 min、溶液最适pH=9;脱色的优化工艺条件为:脱色温度90℃、水浴时间20 min、活性炭用量4％(按体积百分含量加活性炭),然后抽滤除去活性炭,对滤液进行真空浓缩后在50℃条件下干燥,在以上综合条件下得到的菊糖纯度可达92％.     

菊芋中提取菊粉的纯化工艺研究

采用石灰乳-磷酸法除杂和脱色剂脱色,对菊芋菊粉粗提液进行纯化研究。结果表明:石灰乳-磷酸法对菊粉粗提液除杂的最佳工艺条件为:pH12.0,温度60℃,时间10min,在此最佳条件下体系的透光率从46.5%上升到87.3%;比较几种脱色剂的脱色效果,活性炭的脱色效果最好;当活性炭用量为0.7g/100mL(除杂液),脱色温度80℃,脱色时间30min,透光率高达96.7%;当活性炭用量为0.3g/100mL(除杂液),脱色温度40℃,脱色时间10min,菊粉损失率仅为4.05%。     

菊芋提取液的皮状丝孢酵母发酵产油脂试验研究

以皮状丝孢酵母为产油脂菌种,研究其发酵菊糖提取液产油脂情况。首先研究了从菊芋中提取菊糖的条件,获得最适提取条件为:温度85℃,时间80 min,菊芋粉质量浓度70 g/L,在此最优提取条件下,菊糖提取率达95%;然后考察了pH值、接种量、培养温度和氮源对皮状丝孢酵母发酵菊糖提取液产油脂的影响,获得最优条件为:初始pH值5.5、培养温度30℃、接种量10%。在此优化条件下,5 L发酵罐分批扩大培养,其生物量、出油率和油脂得率分别达到13.93 g/L、34.73%和4.89 g/L。补充添加氮源对生物量、出油率和油脂得率的提高不显著。气相色谱法测定脂肪酸成分主要是C16和C18系列,其中80.2%以上是C16:0、C18:1和C18:2,尤其是C18:1(43%),其油酸、棕榈酸和亚油酸占总脂肪酸的比例和植物油脂非常接近。     

菊芋菊糖、山楂、菊花复合饮料的研制

采用热水浸提法对菊糖进行提取,通过正交试验确定了提取菊糖的最佳条件为:料水比1∶25(g/g),温度90℃,提取时间60 min,菊糖提取率为79.98%。以菊芋菊糖、山楂、菊花为主要原料,添加白砂糖、蜂蜜等辅料。针对其关键技术进行了探讨,采用单因素和正交试验设计,以产品感官评价为指标,确定菊芋菊糖、山楂、菊花复合饮料的最佳工艺配方。结果表明:山楂和菊花提取液比为2∶3(m L/m L)、菊芋菊糖2%、白砂糖4%、蜂蜜3%、最佳稳定剂为0.05%海藻酸钠和0.1%CMC-Na。该复合饮料具有营养、保健的功能,色泽、香味、口感俱佳。     

菊芋苦荞山药复合功能膏的制备与工艺流程

研究菊芋苦荞山药复合功能膏的制备方法与工艺流程。将菊芋、苦荞和山药在一定条件下烘干、粉碎、过滤成粉,将菊芋粉放在一定条件下提取菊糖,提取方法采取温度、时间、料液比三因素正交试验,并将菊糖溶液与苦荞、山药按照一定比例混合。然后在菊芋苦荞山药复合溶液里添加一定浓度的果糖、果胶和CaCl_2,并控制一定的pH值。菊芋烘干温度80℃、时间10 h,过40目;山药烘干温度60℃、时间8 h,过100目;苦荞烘干温度60℃、时间8 h,过100目,最后制备的复合膏口感质地最好;采用热水浸提法对菊糖进行提取,通过正交试验确定了提取菊糖的最佳条件为:料水比1:40(g/mL),温度80℃,提取时间50 min,菊糖提取率为75.32%;添加果糖终浓度15%,低脂果胶1.2%,添加CaCl_20.06%;终pH控制在6.4,制备的复合膏的质感和口感达到理想状态。菊芋苦荞山药粉化后,以每100 mL菊糖液中加入0.4%山药粉、0.1%苦荞粉的比例混合,经果胶调制可以制备口感质感优良的多功能复合膏。     

超声波辅助复合酶提取菊糖工艺优化

以菊芋块茎为原料,采用超声波辅助复合酶酶解法进行菊糖提取工艺研究。首先通过单因素试验和Plackett-Burman筛选试验确定菊糖提取工艺中影响显著的3 个因素--超声温度、超声时间和加酶量,再利用Box-Behnken试验及响应面分析法优化最佳提取工艺条件。结果表明：最佳提取工艺条件为料液比1∶20（g/mL）、超声温度51 ℃、加酶量120 μg/g（m（果胶酶）∶m（纤维素酶）=1∶4）、超声时间25 min、pH 5.5,优化后菊糖得率为72.2%。     

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.     

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.