Glucosinolate metabolism,functionality and breeding for the improvement of Brassicaceae vegetables

Unique secondary metabolites, glucosinolates (S-glucopyranosyl thiohydroximates), are naturally occurring S-linked glucosides found mainly in Brassicaceae plants. They are enzymatically hydrolyzed to produce sulfate ions, D-glucose, and characteristic degradation products such as isothiocyanates. The functions of glucosinolates in the plants remain unclear, but isothiocyanates possessing a pungent or irritating taste and odor might be associated with plant defense from microbes. Isothiocyanates have been studied extensively in experimental in vitro and in vivo carcinogenesis models for their cancer chemopreventive properties. The beneficial isothiocyanates, glucosinolates that are functional for supporting human health, have received attention from many scientists studying plant breeding, plant physiology, plant genetics, and food functionality. This review presents a summary of recent topics related with glucosinolates in the Brassica family, along with a summary of the chemicals, metabolism, and genes of glucosinolates in Brassicaceae. The bioavailabilities of isothiocyanates from certain functional glucosinolates and the importance of breeding will be described with emphasis on glucosinolates.     

树脂酸烯丙酯UV光固化反应性能研究

研究了树脂酸烯丙酯作为单体进行UV光固化反应的影响因素及其固化产物性能。采用红外光谱法对双键转化率进行了表征和分析,并对固化膜性能进行测试。结果表明,双键转化率随光照时间的增加而增加,随引发剂含量增加先上升后下降;固化过程中,表干时间随引发剂用量、光照强度的增加及光照距离的减小而变短,即相对固化速率增加;在较佳条件UV光照距离4.5 cm、光照强度100%下,以8%米氏酮(商品名MK)为引发剂、光照时间250 s时乙烯基双键转化率为97.9%,以5%2羟-基-2-甲基苯丙酮(商品名Darocure 1173)为引发剂、光照时间300 s时乙烯基双键转化率达97.6%;固化膜具有很好的柔韧性、耐冲击强度及附着力,具有较好的硬度及耐酸、耐碱、耐盐、耐水性。     

西兰花中硫代葡萄糖苷的提取及抑菌试验初报

采用甲醇法提取西兰花中硫代葡萄糖苷,利用重量法测定其中硫代葡萄糖苷的含量,得出硫代葡萄糖苷最佳提取条件,并对硫代葡萄糖苷提取液进行酸水解,通过抑菌圈实验,分析了西兰花中硫代葡萄糖苷水解产物异硫氰酸酯类的抑菌性。其结果表明,采用80％甲醇溶液、料液比为10：40（w／v）、80℃为提取的最佳条件。西兰花花蕾中硫代葡萄糖苷的含量最高,达到39．90μmol／g;花茎中为18．28μmol／g：叶中为11．86μmol／g。实验结果表明异硫氰酸酯类对金黄色葡萄球菌（Staphylococcus aureus）、白葡萄球菌（White staphylococcus）、枯草芽孢杆菌（Bacillus subtilis）大肠杆菌（Escherichia coli）的抑菌作用均较明显。     

Modification of protein structure and dough rheological properties of wheat flour through superheated steam treatment

Native (NF, 13.5% w.b) and moistened (MF, 27% w.b) wheat flours were treated with superheated steam (SS) at 170 °C for 1, 2 and 4 min, and their protein structure as well as dough rheological properties were analyzed. Confocal laser scanning microscopy (CLSM) and SDS-PAGE patterns indicated the formation of protein aggregates with reduced SDS extractability after treatment. Farinograph and dynamic rheometry measurements showed that the strength as well as elastic and viscous moduli of the dough made from SS-treated flours progressively increased with SS treatment time. And both the improvements were more pronounced for superheated steam-treated moistened flours (SS-MF) than for superheated steam-treated native flours (SS-NF). Size-exclusion high performance liquid chromatography (SE-HPLC) analysis demonstrated that dough rheological parameters have positive correlations with SDS unextractable polymeric proteins (UPP) contents. SS treatment on flours led to a transition of protein secondary structures to more ordered form (α-helix and β-sheet). Additionally, free sulfhydryl (SH) contents decreased after treatment, which implied that disulfide bonds accounted for protein extractability loss and dough rheological properties improvement. Elevated moisture level promoted the modification of both protein structure and dough behaviors of flours during SS treatment.     

异硫氰酸烯丙酯及其包合物在冷却牛肉片保藏中的应用

该文研究了异硫氰酸烯丙酯及其包合物对冷却牛肉片中大肠杆菌和腐败细菌的抑制作用。结果表明,添加异硫氰酸烯丙酯或其环糊精包合物(4 μL/g),可以有效抑制冷却牛肉片中大肠杆菌和腐败细菌,明显延长保鲜期。环糊精包合物在牛肉中可缓释异硫氰酸烯丙酯,强化杀菌的效果,同时增加肉品的持水性。但异硫氰酸烯丙酯包合物的加入会对冷却牛肉片的色泽产生较大影响,可能更适合于添加到对牛肉原有色泽要求不严格的加工类产品中。     

辣根素对绿豆象不同虫态的熏蒸活性研究

利用三角瓶熏蒸法,测定了辣根素在28℃下对绿豆象不同虫态的熏蒸效果。结果表明:在28℃下,熏蒸处理24h后,辣根素对绿豆象卵、幼虫、蛹、成虫的LC50值依次为:0.071μL/L,0.618μL/L,0.576μL/L,0.115μL/L。辣根素对绿豆象的亚致死效应明显。经过辣根素熏蒸后的绿豆象幼虫、蛹,其发育总历期无论雌虫、雄虫均显著延长。在幼虫阶段经过熏蒸后,辣根素对整个种群性比影响显著;在超过0.49μL/L剂量后,其种群性比明显低于对照以及其他各个剂量处理。     

二乙基烯丙基胺的合成

以烯丙基氯作烷基化试剂，在常压、不加催化剂的情况下合成了二乙基烯丙基胺，并对原料配比、水浴温度、加料方式与时间、以及沸腾反应时间对产率的影响进行了研究。结果表明，在烯丙基氯与二乙胺摩尔比为1．1：1、总加料时间2h及沸腾反应1h时，二乙基烯丙基胺的产率可达78％。     

Effectiveness of allyl acetate as a fumigant against five stored grain beetle pests

Five esters, butyl acetate, allyl acetate, ethyl acetoacetate, isopropyl acetate and propyl acetate, were screened as fumigants in the laboratory for 24 h at 27 (+/-2) degrees C against the adults of Rhyzopertha dominica (F), Sitophilus oryzae (L) and Tribolium castaneum (Herbst). Of the compounds tested, allyl acetate was the most toxic, with LD(99) values of 7.56, 12.81 and 11.42 mg litre(-1) against R dominica, S oryzae and T castaneum, respectively. Tests with allyl acetate against mixed-age cultures of Cryptolestes ferrugineus (Stephens), Oryzaephilus surinamensis (L), R dominica, S oryzae and T castaneum revealed that doses of 50-150 mg litre(-1) with 24-120-h exposures were necessary to achieve 100% mortality of all life stages. Cryptolestes ferrugineus was the most tolerant insect tested, whilst R dominica was highly susceptible. The insect toxicity data indicates that allyl acetate has potential as a fumigant of stored food grains.     

Fumigant distribution in forest nursery soils under water seal and plastic film after application of dazomet, metam-sodium and chloropicrin

Adequate concentration, exposure time and distribution uniformity of activated fumigant gases are prerequisites for successful soil fumigation. Field experiments were conducted to evaluate gas phase distributions of methyl isothiocyanate (MITC) and chloropicrin (CP) in two forest-tree nurseries. Concentrations of MITC and CP in soil air were measured from replicated microplots that received dazomet, metam-sodium and CP. Half of the plots were covered with high-density polyethylene tarp immediately after fumigation; the other half were not covered but received daily sprinkler irrigation for 1 week to create and maintain a water seal. The magnitude of MITC concentrations was similar between nurseries for metam-sodium in both tarp and water seal treatments and for dazomet in the tarp treatment. Consistently greater MITC and CP concentrations were found in the upper 30 cm of soil in the tarped plots compared with the water-sealed plots. Despite potential environmental and economic benefits with the water seal method, tarp covers were more reliable for achieving and maintaining higher MITC and CP concentrations and less prone to variations due to irrigation/rain, soil bulk density and other environmental conditions.     

Fumigant activity of plant essential oils and components from horseradish (Armoracia rusticana), anise (Pimpinella anisum) and garlic (Allium sativum) oils against Lycoriella ingenua (Diptera: Sciaridae)

Plant essential oils from 40 plant species were tested for their insecticidal activities against larvae of Lycoriella ingénue (Dufour) using a fumigation bioassay. Good insecticidal activity against larvae of L. ingenua was achieved with essential oils of Chenopodium ambrosioides L., Eucalyptus globulus Labill, Eucalyptus smithii RT Baker, horseradish, anise and garlic at 10 and 5 microL L(-1) air. Horseradish, anise and garlic oils showed the most potent insecticidal activities among the plant essential oils. At 1.25 microL L(-1), horseradish, anise and garlic oils caused 100, 93.3 and 13.3% mortality, but at 0.625 microL L(-1) air this decreased to 3.3, 0 and 0% respectively. Analysis by gas chromatography-mass spectrometry led to the identification of one major compound from horseradish, and three each from anise and garlic oils. These seven compounds and m-anisaldehyde and o-anisaldehyde, two positional isomers of p-anisaldehyde, were tested individually for their insecticidal activities against larvae of L. ingenua. Allyl isothiocyanate was the most toxic, followed by trans-anethole, diallyl disulfide and p-anisaldehyde with LC(50) values of 0.15, 0.20, 0.87 and 1.47 microL L(-1) respectively.