Separation of Monovinyl and Divinyl Protochlorophyllides Using C30 Reverse Phase High Performance Liquid Chromatography Column: Analytical and Preparative Applications

A new, high performance liquid chromatography method has been developed for the separation of monovinyl- and divinyl-protochlorophyllides, using commercially available, C₃₀ reverse phase column and isocratic elution. This method can be used both for analytical applications and preparative scale purification of monovinyl- and divinyl-protochlorophyllides using the same column where submilimolar concentrations of the crude protochlorophyllide extract can be separated in one run. The purity of the obtained protochlorophyllides was demonstrated by spectroscopic methods, as well by the formation of aggregates in toluene.     

人体血清微量元素与环境中，微量元素相关关系研究

运用灰色系统理论中的关联度分析方法，研究了人体血清微量元素与土壤，水、辕食(小麦)中微量元素关联度的大小．结果表明，血清微量元素与土壤中微量元素的关联程度最大．     

Fermentation characteristics and the dynamic trend of chemical components during fermentation of Massa Medicata Fermentata

As a representative of traditionally fermented Chinese medicine, Massa Medicata Fermentata (MMF) shows the functions of invigorating the spleen and stomach and promoting digestion, which plays an important role in the treatment of gastrointestinal diseases. The fermentation mechanism and the key factors that affect the quality of MMF have not been revealed yet, which has become an urgent issue that limits its clinical application. This article aims to systematically and comprehensively reveal the transformation of physical properties and the dynamic trend of chemical components including substrate components, volatile components, and lactic acid as anaerobic fermentation product during MMF fermentation. Along with obvious hyphae growth observed for MMF, the weight of MMF decreased, and the moisture and temperature increased. Through the quantified 14 components from substrate, ferulic acid increased from 45.53 ± 6.94 to 141.89 ± 78.40 μg/g, while glycosides and phenolic acids declined except caffeic acid. Also, within the 66 volatile components analyzed, alcohols and acids increased, while aldehydes and ketones decreased. Lactic acid was not detected in the fermentation substrate, but an apparent increase in lactic acid content was observed along with the increased fermentation days, resulting in 2.54 ± 0.15 mg/g on day 8. Based on the tested components, the fermentation process of MMF was discriminated into three distinct stages by principal component analysis, and an optimal fermentation time of four days was proposed. The results of this study will be of great significance to clarify the characteristics of fermentation and conduce to improving quality standards of MMF.     

4,4′-Dihydroxy-3,3′,5,5′-tetramethoxyazodioxybenzene: an unexpected dimer formed during hydroxylamine extractions of wheat flour

Neutral hydroxylamine extracts of wheat contained a product that was colourless at pH<5 (λ_max 340 nm) and yellow at pH>9 (λ_max 400 nm). ESI-MS showed a major ion m/z 184.0 and a possible parent ion m/z 367.2 (MH⁺) suggesting that the product resulted from the reaction of 2,6-dimethoxy-p-quinone with hydroxylamine. However, mass spectral and other spectroscopic data indicated that the compound was neither of the 2,6-dimethoxy-p-quinone oximes. A product with identical absorbance, mass spectrum, electrophoretic mobility and HPLC retention time as the pigment from hydroxylamine extracts of flour was observed amongst the reaction products of hydroxylamine and 1,4-dihydroxy-2,6-dimethoxybenzene. The structure of this product was identified by NMR, 2D NMR and IR as 4,4′-dihydroxy-3,3′,5,5′-tetramethoxyazodioxybenzene.     

倍数光度滴定法测定微量过氧化苯甲酰

联合应用BPO与KIO3(在KI存在下)的倍增反应和光度滴定数据的二阶导数法处理,使面粉中微量BPO测定的灵敏度较常规碘量法提高了200倍,方法的检出限可达0.1 mg.L-1。在面粉实样分析中,测定结果的RSD值在1.3%~2.8%之间,加标回收率在98.6%~102.2%之间。提出的方法所得测定结果与国标法(GB/T 18415-2001)所得结果一致。     

Ethanol production from steam-explosion pretreated wheat straw

Bioconversion of cereal straw to bioethanol is becoming an attractive alternative to conventional fuel ethanol production from grains. In this work, the best operational conditions for steam-explosion pretreatment of wheat straw for ethanol production by a simultaneous saccharification and fermentation process were studied, using diluted acid [H₂SO₄ 0.9% (w/w)] and water as preimpregnation agents. Acid-or water-impregnated biomass was steam-exploded at different temperatures (160–200°C) and residence times (5, 10, and 20 min). Composition of solid and filtrate obtained after pretreatment, enzymatic digestibility and ethanol production of pretreated wheat straw at different experimental conditions was analyzed. The best pretreatment conditions to obtain high conversion yield to ethanol (approx 80% of theoretical) of cellulose-rich residue after steam-explosion were 190°C and 10 min or 200°C and 5 min, in acid-impregnated straw. However, 180°C for 10 min in acid-impregnated biomass provided the highest ethanol yield referred to raw material (140 L/t wheat straw), and sugars recovery yield in the filtrate (300 g/kg wheat straw).     

Explorative data analysis of two-dimensional electrophoresis gels

Methods for classification of two-dimensional (2-DE) electrophoresis gels based on multivariate data analysis are demonstrated. Two-dimensional gels of ten wheat varieties are analyzed and it is demonstrated how to classify the wheat varieties in two qualities and a method for initial screening of gels is presented. First, an approach is demonstrated in which no prior knowledge of the separated proteins is used. Alignment of the gels followed by a simple transformation of data makes it possible to analyze the gels in an automated explorative manner by principal component analysis, to determine if the gels should be further analyzed. A more detailed approach is done by analyzing spot volume lists by principal components analysis and partial least square regression. The use of spot volume data offers a mean to investigate the spot pattern and link the classified protein patterns to distinct spots on the gels for further investigation. The explorative approach in analysis of 2-D gels makes it possible, in a fast and convenient way, to screen many gels in order to determine the protein patterns that form clusters and could be selected for further examination.     

Development of Near-Infrared Reflectance Spectroscopy Models for Quantitative Determination of Water-Soluble Carbohydrate Content in Wheat Stem and Glume

Water-soluble carbohydrate (WSC) reserved in stem is an important agronomic trait for crop improvement. The intact samples and pieces of chipped samples were employed to determine WSC content by near-infrared reflectance spectroscopy (NIRS). Three NIRS models were developed to predict WSC content in wheat stem lower internode, upmost internode, and wheat glume, respectively. Moreover, a mixed model was developed for WSC quantitative analysis in the mixed sample of the three wheat organs. Statistics analysis indicated that the four models showed a high determination coefficient (R² ≥ 0.97) and ratio of standard deviation to RMSECV (RPD ≥ 5.99). The NIRS models would allow rapid and high throughout assessments and selections of WSC contents in wheat genetics and breeding programs.     

Identification,quantification and Chrastil modelling of wheat straw wax extraction using supercritical carbon dioxide

Supercritical carbon dioxide (scCO₂) can be used as a “green” selective solvent for extractions of wheat straw waxes. For the first time, the crude extraction yields of wheat straw waxes and the yields of a single high value group of components (wax esters) using various scCO₂ conditions (305.15 to 373.15 K and 7.5 to 40 MPa) have been modelled using the Chrastil equation (Chrastil, 1982). The model accurately predicts both the crude yield and percentage of valuable wax esters within the extracts enabling maximum extraction efficiency. The key compounds within the waxes (fatty acids, sterols, fatty alcohols, wax esters, β-diketones and alkanes) have been identified and quantified. This study highlighted that, 14,16 hentriacontanedione was extracted at critical temperature and pressure in concentrations of 1000 μg.g⁻¹ straw. This molecule could demonstrate significant potential as a natural chelate for metal recovery and also in the formation of super-hydrophobic coatings.     

Efficient barrier properties of mechanically enhanced agro-extracted cellulosic biocomposites

The objective of this work was to prepare the mechanically stable hydrophobic biocomposites by incorporating the cellulose fibers into the polymer matrices for their applications in biomedical and food packaging. Herein, two different types of biocomposites were prepared by mixing polylactic acid (PLA) and polyhydroxybutyrate (PHB) with the agro-extracted cellulose, separately at 170 °C. The influence of the cellulose fibers on the thermal, mechanical, and barrier properties of polymer matrices (PLA and PHB) was observed. With an increase in the cellulose content in PLA and PHB, the tensile strength of the biocomposite materials significantly improved with the enhancement of 24.45% and 32.08%, respectively, compared with the pure PLA and PHB. Furthermore, a decrease of 74.16% and 73.49% in the water vapor transmission rate and oxygen transmission rate, respectively, was observed for cellulose/PHB biocomposites. This study highlights that adding cellulose fibers significantly improves the mechanical and the barrier properties of PLA and PHB, suggesting their biocomposites for use in biodegradable polymer industries.