避雨栽培条件下红地球葡萄不同物候期光合特性初探

本试验主要研究了避雨栽培条件下红地球葡萄果实膨大期、转色期和成熟期的光合特性.结果表明:葡萄叶片的净光合速率(Pn)日变化呈双峰曲线,具有明显的光合“午休”现象;光饱和点(LSP)分别为1387.50、1335.71、1342.86 μ mol/(m2·s),光补偿点(LCP)分别为60.76、24.64、39.87μmol/(m2·s); CO2饱和点(CSP)分别为1095、1230、1035μmol/mol,CO2补偿点(CCp)分别为57.23、66.79、44.56 μ mol/mol.     

光照强度对雨生红球藻细胞生长和虾青素积累的影响

初步研究了不同光照强度(40~200μmol/m2·s)对雨生红球藻(Haematococcus pluvialis)细胞生长及虾青素积累的影响。结果表明,雨生红球藻在培养初期细胞干物质积累较少,虾青素含量较低;而在整个培养后期细胞干物质积累较多,虾青素含量较高。细胞生长进入对数生长期的时间随光照强度增加而减少。中等光照强度条件(80μmol/m2·s)最适于藻细胞生长,该条件不利于虾青素的积累;而高光强条件(200μmol/m2·s)明显抑制藻细胞生长(P<0.05),但虾青素含量明显提高(P<0.05);继续增加光照强度(240μmol/m2·s),单个细胞中的虾青素含量显著增加。     

不同光强LED黄光对滇重楼生长、光合特性和皂苷含量的影响

为探究发光二极管(LED)黄光不同光强对滇重楼光生物学特性和品质的影响,同时为LED光源在滇重楼生产上的应用提供理论依据。本研究以3年生滇重楼种苗为试验材料,采用波长为590 nm±5 nm的黄光为照射光源,设置了25、50、75、100μmol/(m~2·s)4个光强梯度处理,对滇重楼生物学鲜重、叶片光合荧光特性及根茎皂苷含量进行了研究。结果表明,75μmol/(m~2·s)处理滇重楼叶片净光合速率、荧光指标、气孔导度、蒸腾速率均为最高。25μmol/(m~2·s)处理的荧光指标最低。100μmol/(m~2·s)处理下重楼根茎皂苷含量最高,25μmol/(m~2·s)处理下皂苷含量最低。综合分析滇重楼叶片光合荧光特性和根茎皂苷含量,黄光75μmol/(m~2·s)对促进滇重楼叶片的光合作用最有利,黄光100μmol/(m~2·s)对增加滇重楼根茎皂苷含量最有利。建议在滇重楼栽培上将黄光光强控制在75~100μmol/(m~2·s)为宜。     

氮源、光照对缺刻缘绿藻总脂、花生四烯酸和色素积累的影响

以缺刻缘绿藻(Parietochloris incisa)为试验材料,采用差量法、超声波萃取法、气相质谱仪分析法和分光光度法等方法,研究了氮源和光照强度对缺刻源绿藻生长、总脂、花生四烯酸和色素含量变化的影响。结果表明:无氮源,35μmol photons/(m2·s)低光强下可降低缺刻源绿藻的生长速度和生物量。而在有氮源、280μmol photons/(m2·s)高光强下,缺刻源绿藻的生物量达到最大值,为7.23 g/L。无氮源、光强度均能不同程度的提高藻细胞总脂肪及花生四烯酸的含量,且在无氮源、280μmol photons/(m2·s)高光强条件下油脂量最高,约为38.02%,在缺氮源、135μmol photons/(m2·s)中光强条件下花生四烯酸含量最高,约为16.10%。色素含量在缺氮条件下随着光强的上升而下降,在有氮源、135μmol photons/(m2·s)中光强条件下达到最大值,约为150.00 mg/L。类胡萝卜素含量无论是在有氮源还是无氮源培养基中,135μmol photons/(m2·s)中光强条件均较高。     

茉莉酸甲酯对葡萄砧木‘SA17’耐NaHCO3胁迫的影响

为了探讨外源茉莉酸甲酯(MeJA)对葡萄碱性盐(NaHCO₃)耐性的影响,以葡萄砧木‘SA17’[V.amurensis×(V.berlandieri×V.riparia)]为试材,测定了不同浓度(0、2、20、200 μmol/L)的MeJA浇施处理对葡萄NaHCO₃胁迫(100 mmol·L^-1)耐性的影响。结果表明:碱性盐胁迫下低浓度外源MeJA处理提高了葡萄根系活力、SOD和POD酶活性,降低了MDA含量,高浓度的MeJA则相反。其中,以20 μmol·L^-1 MeJA处理缓解NaHCO₃胁迫效果最为显著。此外,20 μmol·L^-1 MeJA处理浓度显著提高了NaHCO₃胁迫不同时间点(0、3、9、12 d)的葡萄根系活力、 SOD和POD酶活性,降低了MDA含量。并且,20 μmol·L^-1 MeJA有助于维持碱性盐胁迫下氧化还原对比值[AsA/DHA、GSH/GSSG、NAD(P)H/NAD(P)]...     

LED红蓝光照射强度对采后西兰花保鲜品质的影响

以西兰花为试材,重点探究温度为4℃、相对湿度为90%时光强分别为10、20、30μmol/m~2·s的发光二极管(Light-emitting diode,LED)红蓝光照射对采后西兰花相关品质指标的影响,并以黑暗处理为对照。结果表明:不同强度的光照处理对各指标的优劣影响不同。随着光照强度增加,失重率缓慢增大,10μmol/m~2·s光强下失重率最小为23.75%;叶绿素含量损失则逐渐减少,30μmol/m~2·s光强下的损失比仅为10μmol/m~2·s光强下的0.31倍;Vc含量损失比也呈现整体下降趋势,其中20μmol/m~2·s光强下最小,是10μmol/m~2·s光强下的0.62倍;色差值则呈现先增加后降低的趋势,10μmol/m~2·s光强下的色差损失比最小为2.18。选取(20~30)μmol/m~2·s之间的LED红蓝光,由于光合作用保持的营养成分含量远大于蒸腾作用导致的失水率,对采后西兰花可达到较好的保鲜效果。     

基于遗传算法的设施葡萄光合优化调控模型研究

光合作用是葡萄进行物质生产的重要生理过程,光合速率是描述这一过程的重要指标。葡萄光合速率主要受到温度和光合有效辐射的影响,如何快速实现不同温度条件下光饱和点的动态获取,是葡萄生产中需要解决的重要问题。本文利用温度、光合有效辐射、光合速率数据,构建以温度、光合有效辐射耦合的光合速率多元非线性回归模型,借助Matlab软件基于遗传算法的光合速率模型寻优方法,获得了不同温度下最优净光合速率和对应的光饱和点,并建立了以光饱和点为目标的葡萄光合优化调控模型。模型验证表明,实测值与通过模型计算值的相关性较高,决定系数为0.949,拟合直线的斜率为1.0341,模型具有较高的精度。     

培养条件对湛江等鞭金藻生长和油脂产率的影响

为提高微藻油脂产率和优化培养条件,以湛江等鞭金藻(Isochrysis zhanjiangensis)为研究对象,探讨了营养方式、光强和NaNO_3浓度对微藻生长和产物积累的影响以及培养过程中氮消耗与微藻生长间的关系。结果表明,湛江等鞭金藻生长越快,对氮的吸收越多,兼养较光自养和光异养消耗更多的氮以满足生长需要。充足的氮源和兼养培养条件下,蛋白质积累较多;氮浓度和光强较低条件下,油脂积累较多。光强为100μmol/(m2·s)、NaNO_3质量浓度为75 mg/L、光异养条件下油脂含量最高为46%,生物量质量浓度为0. 46 g/L;光强为100μmol/(m2·s)、NaNO_3质量浓度为750 mg/L、兼养培养时生物量质量浓度最高为2. 20 g/L,油脂含量为32. 77%。综合考虑油脂产率和节约成本等因素,湛江等鞭金藻最高油脂产率80. 06 mg/(L·d),在光强为100μmol/(m2·s)、NaNO_3质量浓度为375 mg/L、兼养培养条件下获得,此时多不饱和脂肪酸占总脂肪酸含量也较高(30. 82%),因此是生产微藻油脂的合适条件。     

CaCl_2对强光胁迫下烤烟光合特性的影响

为分析外源CaCl_2对旺长期间强光胁迫下烤烟叶片色素、光合、荧光参数的影响,以及对叶片光合机构的保护作用,以盆栽烟草为试验材料,连续4 d施30 m mol·L-1 CaCl_2后转至人工气候室进行10 d强光处理,测定叶片光合、荧光参数。结果表明:喷施CaCl_2的烤烟叶片与喷施蒸馏水的对照相比,叶绿素含量显著提高,类胡萝卜素有所下降,气孔导度和净光合速率分别增加47.57%和23.21%,碳同化速率显著提高,使光系统Ⅱ保持了较高的开放程度,PSII最大光化学效率(Fv/Fm)、PSII实际光化学效率(ΦPSII)、光化学猝灭系数(qP)均显著提高,非化学猝灭系数(NPQ)降低。说明预施外源CaCl_2可以有效保护烟草光合机构免于强光的伤害,减轻光抑制。     

蓝光协同茴香精油对鲜切苋菜的保鲜机理

研究不同光量子通量密度（10、20、30 μmol/（m2·s））发光二极管（light emitting diode，LED）蓝光和最佳茴香精油剂量（0.35 μL/mL）处理鲜切苋菜的保鲜效果及机理。以T1（0 μmol/（m2·s）蓝光LED＋0.35 μL/mL茴香精油）、T2（10 μmol/（m2·s）蓝光LED＋0.35 μL/mL茴香精油）、T3（20 μmol/（m2·s）蓝光LED＋0.35 μL/mL茴香精油）、T4（30 μmol/（m2·s）蓝光LED＋0.35 μL/mL茴香精油）为处理组，以不作处理为对照组（CK），测定各组菌落总数、理化指标及抗氧化酶活力，并进行感官评价。结果表明：30 μmol/（m2·s）蓝光LED和0.35 μL/mL茴香精油复合处理可较好地保持鲜切苋菜叶绿素、VC和可溶性固形物的含量；抑菌效果由强到弱依次为T4＞T3＞T2＞T1；460 nm LED蓝光和茴香精油复合处理鲜切苋菜的超氧化物歧化酶、过氧化酶活力明显高于茴香精油处理组，可以有效抑制丙二醛和亚硝酸盐的积累，提高感官评分，将鲜切苋菜货架期延长至10 d。综上，LED460 nm蓝光和茴香精油复合处理是延缓鲜切苋菜衰老、保持其品质的有效方法。     

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