pH和钙离子促进采摘后蕨菜中类黄酮积累的初步研究

初步研究了pH和Ca2+对采摘后蕨菜中类黄酮积累的影响。结果表明,pH 5.0~8.0的柠檬酸-磷酸缓冲液或50~200μmol/L的CaCl2溶液浸泡处理能显著促进采摘后蕨菜细胞中类黄酮的合成和积累,而且效果与处理时间密切相关。采用pH 6.6的缓冲液泡处理4 h或150μmol/L的Ca2+溶液处理3 h效果最佳,可使蕨菜总黄酮的含量分别比对照增加287.8%和325.3%,然而pH和Ca2+2种因素共处理时没有明显的累加效应。实验结果显示,采摘后的新鲜植物组织在一定条件下对环境信号刺激仍然具有响应能力,通过生物技术处理能够促进采摘后植物细胞的次生代谢,从而提高天然活性物质的产量,这为植物性食品的深加工提供了新思路。     

采摘后芦笋中γ-氨基丁酸生物合成影响因素的初步研究

初步研究了pH缓冲液、钙离子浸泡溶液处理以及L-谷氨酸底物饲喂对采摘后新鲜芦笋中1-氨基丁酸（1-aminobutyric acid，GABA）合成和积累的影响。结果表明：pH7．0的磷酸氢二钠-柠檬酸缓冲溶液或者100trmol／L的氯化钙溶液浸泡处理2h能分剐使芦笋材料GABA含量比对照增加73％和62-23％。效果最显著的是L-谷氨酸底物饲喂处理，采用50trmol／L的谷氨酸底物饲喂处理24h能使芦笋GABA含量比对照增加3．38倍，达到0．5108mg／g#｜。为研究开发富含GABA的蔬菜功能食品提供了新思路：     

从小麦麸皮中提取植酸钙的生产工艺

采用稀酸萃取加碱中和沉淀法从小麦麸皮中提取植酸钙。利用正交法找出了最佳工艺条件:反应温度30℃、水料浸提比8∶1、浸泡酸度pH为2~2.5、絮凝剂为5%的氯化钠、浸泡时间为6h~8 h、中和剂采用Ca(OH)2和10%的NaOH溶液、中和酸度为先用Ca(OH)2中和pH至5,再加10%的NaOH溶液中和pH至7.5左右。     

三阶段负压贮藏条件下钙处理调控绿芦笋的衰老

将采后绿芦笋分别放入质量分数为0.5%、1.0%、1.5%、2.0%的氯化钙(CaClz)溶液,浸泡处理10 min,以蒸馏水浸泡10 rain为对照,然后进行温度为24～4℃,相对湿度为85%～95%,真空压力(绝对压力)入库前3 d控制在10℃20 kPa,其后7 d控制在20～30 kPa,以后保持在35～50 kPa的"高-中-低,,三阶段负压贮藏.研究了4种不同质量分数的CaClM2处理对绿芦笋衰老效应的调控作用.结果表明,用适当质量分数的钙处理可显著降低绿芦笋的呼吸强度、乙烯释放量、MDA含量、相对电导率及衰老指数,提高绿芦笋的抗坏血酸含量、叶绿素含量及商品率;但对降低木质素含量效果不显著.其中钙处理以1.5%的CaCl2效果最佳.     

真空冷冻干燥绿芦笋护绿工艺研究

色泽是评价真空冷冻干燥绿芦笋质量的重要指标,本实验从漂烫和护绿剂浸泡处理两个环节对真空冷冻干燥绿芦笋的护绿工艺进行研究。运用U12(122×6)均匀实验研究不同漂烫条件对绿芦笋营养成分的影响,利用L16(45)正交实验研究不同护绿处理的护绿效果,最终得出真空冷冻干燥绿芦笋较优护绿工艺条件为:切分长度5～6cm,85～90℃条件下漂烫3.5～4min;0.3mol/L的Na2CO3溶液浸泡40s;护绿剂pH7.5、Zn(CH3COO)2浓度200mg/kg、CuSO4浓度50mg/kg,浸泡时间8h。     

芦笋下脚料中黄酮类物质最佳提取工艺的探讨

对芦笋下脚料中类黄酮类物质提取的最佳技术参数进行了探讨。结果表明,芦笋下脚料中类黄酮物质的最佳提取条件为乙醇浓度为90%,固液比为1∶10,在70℃条件下提取3h。     

不同贮藏方式对芦笋黄酮类物质含量的影响

采用普通冷藏、气调贮藏、化学试剂前处理后冷藏等几种方式保存绿芦笋,研究不同贮藏方式对芦笋中黄酮类物质含量的影响。结果表明,各贮藏方式黄酮含量整体均呈下降趋势,至28 d,各组黄酮含量保存率为35.4%～53.1%。100%O2气调包装和200μmol/L的CaCl2溶液浸泡2 h后冷藏可延缓整个贮藏过程中黄酮类物质含量的下降。     

海藻酸钙纤维的溶胀性研究

研究海藻酸钙纤维所含Ca2+与Na+、K+等离子的交换而导致纤维溶胀甚至溶解的现象.用不同条件下的KCl溶液、NaCl溶液分别处理海藻酸钙纤维,通过处理后纤维增重率的变化及处理液所含Ca2+含量的变化,探讨离子交换对海藻酸钙纤维溶胀性能的影响.结果表明:溶液pH值对海藻酸钙纤维溶胀性影响显著,在pH7,温度60～ 65℃,质量分数25％(相对纤维质量)的盐溶液中浸泡20 min时具有最大溶胀性.浸泡纤维后的处理液所含Ca2的浓度与纤维溶胀性变化趋势一致,并且K+溶液处理对海藻酸钙纤维溶胀性能的影响高于Na+.研究表明海藻酸钙纤维的溶胀主要是由于处理液中Na+、K+等离子与纤维所含Ca2的交换导致基于钙离子复合而成纤维的复合结构解体所致.     

产中性蛋白酶菌种的选育及其在玉米淀粉生产浸泡工艺中的应用

从玉米淀粉生产企业的玉米浸泡水中筛选出可在中性pH值条件下降解蛋白质的菌种;经对该菌种进行原生质体紫外诱变处理,其蛋白酶活性提高了198%;将不同浓度的发酵液添加到玉米淀粉生产的浸泡水中,替代SO2。方差分析表明,菌液的作用时间和SO2含量对淀粉得率的影响显著。得到的优化组合为:玉米先在添加0.1%SO2的浸泡液中浸泡18h,然后在pH值7.0条件下加入20%的蛋白酶发酵液,继续浸泡10h。改进方法后获得的淀粉得率为67.71%,总的浸泡时间缩短至28h。     

Ca2+激活生物酶对苎麻纤维脱胶的工艺参数优化

利用Ca2+对生物酶进行有效激活,以提高苎麻生物酶脱胶效果,优化脱胶工艺中Ca2+浓度、pH值、通气量等工艺参数,经过Box-Behnken试验设计和SAS软件分析,得出最优工艺条件为:果胶酶、半纤维素酶浓度分别为12、4 mg/mL,酶处理时间5 h,酶处理温度50°C,Ca2+浓度4.23 mg/mL,pH值4.8,通气量9.2 dm3/min.利用最优工艺处理后的精干麻的残胶率为1.96%,断裂强力为64.5 cN,纤维平均细度为0.457 tex.     

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.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the