高效液相色谱-二极管阵列检测法测定小麦粉及面粉改良剂中福美双

福美双是重要的二硫代氨基甲酸酯(DTC)杀菌剂,在小麦中使用限量以1 mg/kg二硫化碳(CS2)计.目前我国相关检测方法是针对二硫代氨基甲酸酯一类的化合物,二硫代氨基甲酸酯通过与酸反应生成CS2,采用光谱法或色谱法测定CS2,间接实现二硫代氨基甲酸酯测定.该方法无法特异性实现对福美双的检测,因此开展小麦粉中福美双检测...     

Newly Generated Atractylon Derivatives in Processed Rhizomes of Atractylodes macrocephala Koidz

Thermally processed rhizomes of Atractylodes macrocephala (RAM) have a long history of use in traditional Chinese medicine (TCM) for treating various disorders, and have been an integral part of various traditional drugs and healthcare products. In TCM, herbal medicines are, in most cases, uniquely processed. Although it is thought that processing can alter the properties of herbal medicines so as to achieve desired functions, increase potency, and/or reduce side effects, the underlying chemical changes remain unclear for most thermally processed Chinese herbal medicines. In an attempt to shed some light on the scientific rationale behind the processes involved in traditional medicine, the RAM processed by stir-frying with wheat bran was investigated for the change of chemical composition. As a result, for the first time, five new chemical entities, along with ten known compounds, were isolated. Their chemical structures were determined by spectroscopic and spectrometric analyses. The possible synthetic pathway for the generation of such thermally-induced chemical entities was also proposed. Furthermore, biological activity evaluation showed that none of the compounds possessed cytotoxic effects against the tested mammalian cancer and noncancer cell lines. In addition, all compounds were ineffective at inhibiting the growth of the pathogenic microorganisms.     

Measurement of water absorption capacity in wheat flour by a headspace gas chromatographic technique

The purpose of this work is to introduce a new method for quantitatively analyzing water absorption capacity in wheat flour by a headspace gas chromatographic technique. This headspace gas chromatographic technique was based on measuring the water vapor released from a series of wheat flour samples with different contents of water addition. According to the different trends between the vapor and wheat flour phase before and after the water absorption capacity in wheat flour, a turning point (corresponding to water absorption capacity in wheat flour) can be obtained by fitting the data of the water gas chromatography peak area from different wheat flour samples. The data showed that the phase equilibrium in the vial can be achieved in 25 min at desired temperature (35°C). The relative standard deviation of the reaction headspace gas chromatographic technique in water absorption capacity determination was within 3.48%, the relative differences has been determined by comparing the water absorption capacity obtained from this new analytical technique with the data from the reference technique (i.e., the filtration method), which are less than 8.92%. The new headspace gas chromatographic method is automated, accurate and be a reliable tool for quantifying water absorption capacity in wheat flour in both laboratory research and mill applications.     

Calorimetric and rheological properties of wheat flour suspensions and doughs: Effects of wheat types and milling procedure

Three types of wheat were submitted to two different milling procedures, giving rise to six flours which differed by some physico-chemical characteristics such as particle size, level of damaged starch and protein content. Differential scanning calorimetry was used for monitoring heat-induced structural changes in flour aqueous dispersions 80% water and in doughs 45% water. Differences between the thermal behaviour of the flour dispersions and doughs were explained mainly by differences in protein content. This result was confirmed after partial substitution of flour by gluten. Dynamic mechanical analysis performed at 20°C on the flour doughs indicated, as expected, a linear increase in the elastic modulus with increasing protein content. The results did not bring any evidence that, under these experimental conditions, starch damage might affect gluten hydration.This revised version was published online in November 2005 with corrections to the Cover Date.     

稀土元素在植物中的分异机制 (I) 小麦不同器官中的稀土元素分异模式及形成机制

以小麦为植物材料，利用外源稀土添加、营养液培养等人工控制手段，研究了稀土元素在植物体内的分异效应，并探讨了分异效应产生的机制。结果表明，稀土元素在小麦不同器官中出现显著分异。根系出现中稀土(MREE)富集特征和“M”型四重效应，分析是由稀土元素与PO4^3-的选择性沉淀造成。小麦地上部分稀土元素分布出现“W”型四重效应，分析也是由根部磷沉淀造成。与此同时，小麦茎部相对富集轻稀土(LREE)，叶中相对富集重稀土(HREE)。运用VMINTEQ程序计算了木质部溶液中稀土元素的结合形态主要有LnEDTA^-和Ln^3 (Ln指稀土元素)，但仅有LnEDTA^-表现出HREE相对富集特征，其他形态则表现出LREE相对富集特征。分析叶部LREE／HREE分异是吸收LnEDTA^-造成，而茎部LREE／HREE分异则是吸收Ln^3 和其他形态稀土的结果。细胞壁对Ln^3 的吸附也是导致以上分异特征的重要因素。     

Availability of crop residues as sustainable feedstock for bioethanol production in North Carolina

The amount of corn stover and wheat straw that can be sustainably collected in North Carolina was estimated to be 0.64 and 0.16 million dry t/yr, respectively. More than 80% of these crop residues are located in the coastal area. The bioethanol potential from corn stover and wheat straw was estimated to be about 238 million L (63 million gal/yr) in North Carolina. The future location of ethanol plant in North Carolina was estimated based on feedstock demand and collection radius. It is possible to have four ethanol plants with feedstock demand of 400, 450, 500, and 640 dry t/d. The collection radii for these four ethanol plants are 46, 60, 42, and 67 km (28, 37, 26, and 42 miles), respectively. The best location for a bioethanol plant includes four counties (Beaufort, Hyde, Tyrrell, and Washington) with feedstock demand of 500 t/d and collection radius about 26 mile.     

Effects of processing on five selected metals in the durum wheat food chain

The concentration levels of five metals, namely Cd, Cr, Fe, Ni and Pb, were investigated along the durum wheat processing chain, from grain to the final product. Cadmium and Pb are well-known toxic elements and their levels in wheat grain are regulated by the European legislation. Chromium, Fe and Ni were included in the study as markers of metal release from equipment during processing. Durum wheat grain, semolina and pasta were sampled at an industrial plant for milling and pasta making. Samples were taken at different stages along processing in order to elucidate the influence of each stage on the element content. Samples of the water used for grain tempering and dough preparation were also collected. The whole analytical procedure, from sampling to final analytical determinations, was carried out according to a pre-established quality assurance protocol. Analyses were performed by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES).Milling was the key process influencing the concentrations of the studied elements and reduced the metal levels according to a definite element-specific pattern. Purity of the water used as ingredient, element deposition from plant air and metal release from equipment were identified as critical issues in contamination control during processing. In the conditions of this study, it was found that a simple relationship can be established between the original concentrations in durum wheat grain and those in pasta for Cd and Fe, while for Pb, Cr and Ni, a greater uncertainty in the estimation of the levels in the final product is expected.     

Quantitative Label-Free Comparison of the Metabolic Protein Fraction in Old and Modern Italian Wheat Genotypes by a Shotgun Approach

Wheat represents one of the most important cereals for mankind. However, since wheat proteins are also the causative agent of several adverse reactions, during the last decades, consumers have shown an increasing interest in the old wheat genotypes, which are generally perceived as more “natural” and healthier than the modern ones. Comparison of nutritional value for modern and old wheat genotypes is still controversial, and to evaluate the real impact of these foods on human health comparative experiments involving old and modern genotypes are desirable. The nutritional quality of grain is correlated with its proteomic composition that depends on the interplay between the genetic characteristics of the plant and external factors related to the environment. We report here the label-free shotgun quantitative comparison of the metabolic protein fractions of two old Sicilian landraces (Russello and Timilia) and the modern variety Simeto, from the 2010–2011 and 2011–2012 growing seasons. The overall results show that Timilia presents the major differences with respect to the other two genotypes investigated. These differences may be related to different defense mechanisms and some other peculiar properties of these genotypes. On the other hand, our results confirm previous results leading to the conclusion that with respect to a nutritional value evaluation, there is a substantial equivalence between old and modern wheat genotypes. Data are available via ProteomeXchange with identifier <PXD024204>.     

Estimation of Winter Wheat Biomass Using Visible Spectral and BP Based Artificial Neural NetworksSCIEI北大核心CSCD

The objective of this study was to evaluate the feasibility of using color digital image analysis and back propagation (BP) based artificial neural networks (ANN) method to estimate above ground biomass at the canopy level of winter wheat field. Digital color images of winter wheat canopies grown under six levels of nitrogen treatments were taken with a digital camera for four times during the elongation stage and at the same time wheat plants were sampled to measure above ground biomass. Canopy cover (CC) and 10 color indices were calculated from winter wheat canopy images by using image analysis program (developed in Microsoft Visual Basic). Correlation analysis was carried out to identify the relationship between CC, 10 color indices and winter wheat above ground biomass. Stepwise multiple linear regression and BP based ANN methods were used to establish the models to estimate winter wheat above ground biomass. The results showed that CC, and two color indices had a significant correlation with above ground biomass. CC revealed the highest correlation with winter wheat above ground biomass. Stepwise multiple linear regression model constituting CC and color indices of NDI and b, and BP based ANN model with four variables (CC, g, b and NDI) for input was constructed to estimate winter wheat above ground biomass. The validation results indicate that the model using BP based ANN method has a better performance with higher R-2 (0.903) and lower RMSE (61.706) and RRMSE (18.876) in comparation with the stepwise regression model.     

A New Green Thermoplastic Polymer with Improved Hydrophobic Character

Summary: A green thermoplastic polymer based on wheat flour was modified by the addition of a natural crosslinker genipin. Films of the polymer modified with different composition of genipin were prepared by extrusion. Free surface energy using contact angle method, moisture absorption test and hardness test were used to characterize the products. From moisture absorption and contact angle measurements, it was seen that for genipin amounts higher than 0.2% w/w, a hydrophobic character is achieved. Results obtained indicate enhancement in hydrophobic properties of the films.