超声辅助酶解法提取仙人草多糖的工艺研究

以仙人草为原料,采用超声辅助酶解法提取仙人草多糖。通过单因素法考察了单一酶种类和浓度、复合酶浓度和配比、酶解温度、酶解时间、酶解pH值对多糖提取率的影响。利用正交实验优化了超声辅助酶解法提取仙人草多糖的工艺条件。结果表明,超声波辅助酶解法提取仙人草多糖的最佳提取条件为复合酶(纤维素酶∶果胶酶=1∶1)浓度5%、酶解温度50℃、酶解时间2 h、酶解pH值7,在此条件下仙人草多糖的提取率为6.60%。     

超声波辅助酶法制备山核桃油的工艺研究

以临安山核桃仁为原料,结合超声波辅助,研究水酶法提取山核桃油的加工工艺。结果表明,复合酶酶解制取山核桃油的最佳工艺条件：纤维素酶、半纤维素酶、果胶酶、中性蛋白酶4种酶配比为2∶5∶2∶4,料水比1∶5,加酶量1.6%,酶解温度45℃,酶解pH值为7.0,酶反应时间3h。在最佳工艺条件下,山核桃油得率为54.23%。     

超声波辅助复合酶法提取Iota卡拉胶工艺优化

目的：优化Iota卡拉胶提取工艺，以期提高Iota卡拉胶产率。方法：采用超声波辅助复合酶技术从刺麒麟菜中提取Iota卡拉胶。通过单因素和正交试验，确定最佳复合酶（纤维素酶、半纤维素酶、木瓜蛋白酶）配比和复合酶酶解条件，并优化超声处理条件和煮胶工艺条件。结果：最佳复合酶配比为纤维素酶0.50%、半纤维素酶1.25%、木瓜蛋白酶0.20%；最佳酶解条件为酶解温度60 ℃，酶解pH 5.5、酶解时间2.5 h、酶解料液比1∶30 （g/mL）；最佳超声处理工艺为超声功率350 W、超声时间25 min、超声温度40 ℃；最佳煮胶工艺为煮胶温度90 ℃、六偏磷酸钠（SHMP）添加量0.04%、煮胶时间3 h。结论：在最优工艺条件下，提取的Iota卡拉胶产率高，可达到47.17%。     

响应面法优化复合酶提取雨生红球藻中虾青素的工艺

本文研究了纤维素酶、果胶酶以及复合酶对雨生红球藻破壁效果,并通过响应面优化酶解破壁辅助提取虾青素的工艺。结果表明,当纤维素酶和果胶酶酶活力配比1:1(U/U),加酶量7000 U/mL时,优化的最佳酶解条件为:酶解pH4.9,酶解温度49℃,酶解时间为6 h,理论提取率为70.21%,实际提取率为71.08%±0.26%,相对误差为1.2%。综上,复合酶法辅助提取方法简单、条件温和、绿色安全、效率高,可在雨生红球藻虾青素实际提取工艺中得到应用。     

微波辅助酶法提取绞股蓝皂苷工艺优化

为改善传统水提法提取得率低的问题,研究微波辅助酶法提取绞股蓝皂苷工艺。采用响应面法筛选酶法提取中复合酶的最佳配比,确定了复合酶最佳配比为果胶酶-半纤维素酶-纤维素酶质量比为4∶5∶5,再利用单因素试验结合Box-Behnken设计法优化提取工艺。结果表明：影响微波辅助酶法提取绞股蓝皂苷主要因素为复合酶添加量、酶解温度、酶解时间、微波时间,优化得到的最佳工艺参数为复合酶添加量1.8%、酶解温度52 ℃、酶解时间2 h、微波时间4 min,此工艺条件下绞股蓝皂苷得率为7.88%。该提取方法与传统水提法相比,产品得率增加了68%,且提取温度较低,工艺可操作性强。     

响应面法优化复合酶辅助超声波提取柚子皮总黄酮工艺

本研究以马家柚柚子皮为研究对象,采用复合酶法辅助超声波法优化了柚子皮中总黄酮的提取工艺。首先研究复合酶(纤维素酶:果胶酶)的配比、复合酶的用量、pH、料液比、酶解温度、酶解时间、超声功率和超声时间共8个要素因子对柚子皮中总黄酮得率的影响。在此基础上,先选用Plackett-Burnman试验设计确定了具有显著性影响的因子为:复合酶的用量、酶解温度、超声功率和超声时间,再选用Box-Behnken试验设计优化了柚子皮中的总黄酮提取条件。结果表明,酶法辅助超声波法提取柚子皮中总黄酮的提取条件为:复合酶的配比(纤维素酶:果胶酶)为3:2、复合酶的用量1.70%、pH4.5、料液比1:20 g/mL、酶解温度55.0℃、酶解时间60 min、超声功率183.00 W、超声时间41.00 min,在此条件下柚子皮中总黄酮得率为2.19%。     

混料设计优化水酶法提取西瓜籽油的工艺研究

以西瓜籽为原料,研究水酶法提取西瓜籽油的最优工艺并对其脂肪酸组成、理化特性进行分析。在单因素实验基础上,采用混料设计对复合酶不同配比进行优化。得到的最优分步酶解条件为:首先采用复合酶(纤维素酶、果胶酶、半纤维素酶)配比0.68∶0.22∶0.10,复合酶添加量2.0%,在p H 5.0、酶解温度50℃、液料比7∶1条件下酶解2 h;然后加入1.5%的碱性蛋白酶,在p H 7.5、酶解温度55℃条件下继续酶解2 h。在最优分步酶解条件下,西瓜籽油提取率为91.45%。所得西瓜籽油色泽淡黄,澄清透明,富含不饱和脂肪酸,其理化指标符合国家食用油卫生标准。     

莲花蜂花粉酶解破壁工艺条件优化

为研究莲花蜂花粉的最佳酶解破壁条件,通过单因素试验确定纤维素酶-果胶酶-木聚糖酶-木瓜蛋白酶4种酶制剂的比例,在酶解破壁条件的单因素试验基础上,采用二次回归正交旋转组合设计试验方法对酶解条件进行优化,建立酶解pH值、复合酶加入量、酶解温度、料水比与破壁率之间的经验数学模型。复合酶中各种酶制剂的最适配比为4:2:1:3。莲花蜂花粉酶解破壁的最佳条件为酶解pH4.0、复合酶加入量12‰、酶解温度45℃、料水比1:14(g/mL),破壁率89.21%。     

超声波辅助复合酶法提取松茸多糖的工艺研究

以松茸多糖得率为评价指标,采用单因素试验和正交试验,确定最佳提取工艺参数。结果表明,超声波提取优化工艺条件为超声温度90 ℃,料液比1∶15（g∶mL）,超声时间10 min。在此最佳超声提取条件下松茸多糖得率为11.18%。在超声波优化结果的基础上,进行复合酶处理,最佳酶解工艺参数为酶解温度50 ℃,酶解时间60 min,复合酶（木瓜蛋白酶∶纤维素酶∶果胶酶为1∶1∶1）添加量4.0%,酶解pH值6.0,此优化条件下松茸多糖得率为19.56%。复合酶超声辅助法比超声波法提取松茸多糖提高了8.38%。结果表明,复合酶超声辅助提取法提取松茸多糖是一种科学有效的方法,可显著提高松茸多糖得率。     

复合酶对草莓出汁率和澄清度的影响

为提高草莓的出汁率和草莓汁的澄清度,该文以新鲜草莓为原料,研究单一酶（果胶酶、纤维素酶、木聚糖酶）和复合酶对出汁率和澄清度的影响。在单因素试验基础上,对复合酶添加量、复合酶质量比、酶解温度、酶解时间进行响应面优化,得到最佳酶解条件,并对酶解的草莓汁进行感官评价。结果表明,果胶酶和纤维素酶具有协同作用,可明显提高草莓的出汁率和澄清度,出汁率从64.16%（对照组）提高到87.38%,澄清度从2.34%提高到72.83%;经响应面优化试验,得到草莓汁最佳酶解条件为复合酶添加量0.17%、复合酶（果胶酶∶纤维素酶）质量比3∶1、酶解温度41℃、酶解时间35 min,此条件下草莓的出汁率为90.84%,草莓汁的澄清度为84.61%;与对照组相比,复合酶组的感官评分最高,整体风味及口感更优,表明果胶酶和纤维素酶可以有效提高草莓的出汁率和澄清度,且所得草莓清汁感官风味更佳。     

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.     

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.     

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.     

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.