HPLC法检测玉米中痕量单端孢霉烯属族毒素

以对酞内酰胺苯甲酰氨（４－（２－ｐｈｔｈａｌｉｍｉｄｙ１）ｂｅｎｚｏｙ１ ｃｈｌｏｒｉｄｅ，简称ＰＩＢ－ＣＩ）为衍生试剂，建立了一种快速、灵敏分析单端孢霉烯属族毒素中脱氧雪腐镰刀菌烯醇的新方法，对衍生反应条件，衍生物分离及定量检测条件都进行了研究，衍生物用ＯＤＳ柱分离，紫外检测器检测（λ＝３００ｎｍ）乙腈＋水（５８＋４２Ｖ＋Ｖ）作流动相，检出限为６ｐｍｏｌ。用于分析玉米中的痕量ＤＯＮ，简化了样品处     

快速基质分散净化-超快速液相色谱-串联质谱法同时测定玉米中22种三嗪类除草剂残留

建立了玉米中扑灭津、莠去津、敌草净、特丁通等22种三嗪类除草剂多残留的分析方法。样品以乙腈为提取剂,经高速匀浆方法提取并浓缩后,以增强型脂质去除净化剂(EMR-Lipid)净化,除去了样品中的脂质,有效地降低了样品中的复杂基质所带来的背景干扰,净化液再经增强型脂质去除萃取剂(EMR-Polish)盐析萃取,以 Kinetex XB-C18柱为分离柱,用乙腈和0.1%甲酸溶液进行梯度洗脱,电喷雾正离子(ESI+)多反应模式监测,超快度液相色谱-串联质谱(UFLC-MS/ MS)测定,基质匹配标准曲线法定量。加标水平为5,10和20μg/ kg 时,22种农药的回收率为72%~105%,相对标准偏差小于15%。22种农药的检出限为0.16~1.8μg/ kg,在1.0~50μg/ L 范围内线性关系良好(r>0.993)。本方法具有快速、准确、灵敏度高等优点,能够准确测定玉米中22种三嗪类除草剂的残留量。     

基于近红外光谱和仿生模式识别玉米品种快速鉴别方法

文章提出了一种采用近红外光谱快速鉴别玉米品种的新方法,并对不同品种的玉米种子建立了相应的鉴别模型。对7个玉米品种共140个样本,通过近红外光谱仪扫描获得4 000～12 000 cm-1波段范围内的光谱数据。为了消除噪声、提高数据处理效率,对原始数据进行了归一化预处理,采用固定尺寸移动窗口渐进因子法(fix-sized moving window evolving factor analysis)寻找特征波段,使用主成分分析(PCA)方法得到能反映玉米种子99.96%光谱信息的5个主成分,进而利用仿生模式识别(biomimetic pattern recognition)方法建立玉米品种的鉴别模型。对于每个品种中的20个样本,随机挑选10个样本作为训练样本,其余10个样本作为第一测试集,其他品种共120个样本作为第二测试集。在对第二测试集平均正确拒识率达到99.1%的情况下,对第一测试集中的样本取得了94.3%的平均正确识别率。该方法具有较高的鉴别准确度,可以作为一种快速无损的玉米品种鉴别方法。     

A Study of Bioactivity of Corn Peptides with Low Molecular Weight Ⅱ： Effect on Plasma Free Amino Acid Concentrations in Rats

The effects of the ingestion of corn peptides with a low molecular weight(LMCP) prepared from zein on some plasma free amino acid concentrations in rats that had taken ethanol were investigated. LMCP(1.0g/kg body weight) in 15~ ethanol(10 mL/kg body weight) was given to Wister rats by intragastrical administration. The amino acid analysis showed that the concentrations of aianine, leucine, and proline in the plasma reached their maximum levels at 30 min for the LMCP-intake group. They are 582.39, 99.60 and 272.51 μg/L, respectively. But in the control group, the plasma free amino acid levels were not changed obviously.Therefore, LMCP could cause an increase in concentration of some free amino acids such as alanine, leucine and proline etc. in plasma of the rats that have taken ethanol.     

Enzyme recovery and recycling following hydrolysis of ammonia fiber explosion-treated corn stover

Both cellulase and cellobiase can be effectively recovered from hydrolyzed biomass using an ultrafiltration recovery method. Recovery of cellulase ranged from 60 to 66.6% and for cellobiase from 76.4 to 88%. Economic analysis shows that cost savings gained by enzyme recycling are sensitive to enzyme pricing and loading. At the demonstrated recovery of 60% and current loading of 15 Filter paper units of cellulase/g of glucan, enzyme recycling is expected to generate a cost savings of approx 15%. If recovery efficiency can be improved to 70%, the savings will increase to >25%, and at 90% recovery the savings will be 50%.     

Comparison of microbial inhibition and enzymatic hydrolysis rates of liquid and solid fractions produced from pretreatment of biomass with carbonic acid and liquid hot water

This research quantified the enzymatic digestibility of the solid component and the microbial inhibition of the liquid component of pretreated aspen wood and cornstover hydrolysates. Products of liquid hot water and carbonic acid pretreatment were compared. Pretreatment temperatures tested ranged from 180 to 220°C, and reaction times were varied between 4 and 64 min. Both microbial inhibition rates and enzymatic hydrolysis rates showed no difference between pretreatments containing carbonic acid and those not containing no carbonic acid. Microbial inhibition increased as the reaction severity increased, but only above a midpoint severity parameter of 200°C for 16 min. Both the rates and yields of enzymatic hydrolysis displayed an increase from the lowest tested reaction severity to the highest tested reaction severity.     

Production of lactic acid from cheese whey by batch and repeated batch cultures of Lactobacillus sp. RKY2

The fermentative production of lactic acid from cheese whey and corn steep liquor (CSL) as cheap raw materials was investigated by using Lactobacillus sp. RKY2 in order to develop a cost-effective fermentation medium. Lactic acid yields based on consumed lactose were obtained at more than 0.98 g/g from the medium containing whey lactose. Lactic acid productivities and yields obtained from whey lactose medium were slightly higher than those obtained from pure lactose medium. The lactic acid productivity gradually decreased with increase in substrate concentration owing to substrate and product inhibitions. The fermentation efficiencies were improved by the addition of more CSL to the medium. Moreover, through the cell-recycle repeated batch fermentation, lactic acid productivity was maximized to 6.34 g/L/h, which was 6.2 times higher than that of the batch fermentation.     

A capillary electrophoresis-tandem mass spectrometry methodology for the determination of non-protein amino acids in vegetable oils as novel markers for the detection of adulterations in olive oils

A new analytical methodology based on capillary electrophoresis-mass spectrometry (CE-MS(2)) is presented in this work, enabling the identification and determination of six non-protein amino acids (ornithine, β-alanine, GABA, alloisoleucine, citrulline and pyroglutamic acid) in vegetable oils. This methodology is based on a previous derivatization with butanol and subsequent separation using acidic conditions followed by on-line coupling to an ion trap analyzer for MS(2) detection established through an electrospray-coaxial sheath flow interface. The electrophoretic and interface parameters were optimized obtaining the separation of all compounds in less than 15 min and with resolutions higher than 5. The proposed method was validated by assessing its accuracy, precision (RSD<7% for corrected peak areas), LODs and LOQs (between 0.04-0.19 ng/g and 0.06-0.31 ng/g, respectively) and linearity range (R(2)>0.99), and it was used in order to identify the selected non-protein amino acids in soybean oils, sunflower oils, corn oils and extra virgin olive oils. MS(2) experiments performed the fingerprint fragmentation of these compounds allowing to corroborate ornithine and alloisoleucine in seed oils but not in olive oils. The method was applied to identify and quantify olive oil adulterations with soybean oil detecting in a single run the amino acids in mixtures up to 2% (w/w). The results showed a high potential in using these compounds as novel markers for the detection of adulterations of extra virgin olive oils with seed oils. Thus, the developed method could be considered a simple, rapid and reliable method for the quality evaluation of extra virgin olive oil permitting its authentication.     

玉米品种近红外光谱的DFT特征分析方法

提出了一种基于离散傅里叶变换(discrete Fourier transform,DFT)的玉米品种特征分析新方法.实验数据为37个玉米晶种种子的近红外漫反射光谱数据,波段范围为4 000～12 000 cm-1.文中通过对原始数据进行分析,发现扫描频率较高的部分噪声也比较大.文中首先定义了一种类间、类内差异度Qm的...     

融合冠层水分特征的光谱参数NCVI及反演玉米LAI

精确反演农作物冠层叶面积指数对指导作物管理和作物估产具有非常重要的意义。以吉林市郊区玉米种植区为试点,考虑冠层叶片水分含量对LAI的贡献,在NDVI的基础上结合表征冠层叶片水分含量的植被指数DSWI,提出一种归一化综合植被指数NCVI,以此建立模型反演LAI,并对模型进行检验。结果表明:NCVI模型反演LAI值与实测值之间存在良好的对应关系,此模型突破了传统经验模型对稠密冠层LAI反演的局限,对LAI值大于3的冠层反演效果良好;另外,NCVI模型对土壤水环境十分敏感,在干旱半干旱地区的反演效果明显优于一般区域。