用人工神经网络处理谷物成分分析

本文用人工神经网络处理谷物的付立叶变换近红外漫反射光谱,对谷物中含量在10~(-1)～10~(-3)的蛋白质、脂肪和6种人体必需氨基酸定量分析数据进行了解析,分析结果与经典化学方法没有系统偏差,且优于逐步回归分析法的结果。     

Preprocessed barley,rye, and triticale as a feedstock for an integrated fuel ethanol-feedlot plant

Rye, triticale, and barley were evaluated as starch feedstock to replace wheat for ethanol production. Preprocessing of grain by abrasion on a Satake mill reduced fiber and increased starch concentrations in feedstock for fermentations. Higher concentrations of starch in flours from preprocessed cereal grains would increase plant throughput by 8–23% since more starch is processed in the same weight of feedstock. Increased concentrations of starch for fermentation resulted in higher concentrations of ethanol in beer. Energy requirements to produce one L of ethanol from preprocessed grains were reduced, the natural gas by 3.5–11.4%, whereas power consumption was reduced by 5.2–15.6%.     

pH-controlled dispersive liquid–liquid microextraction for the analysis of ionisable compounds in complex matrices: Case study of ochratoxin A in cereals

A new sample preparation procedure, termed pH-controlled dispersive liquid–liquid microextraction (pH-DLLME), has been developed for the analysis of ionisable compounds in highly complex matrices. This DLLME mode, intended to improve the selectivity and to expand the application range of DLLME, is based on two successive DLLMEs conducted at opposite pH values. pH-DLLME was applied to determination of ochratoxin A (OTA) in cereals. The hydrophobic matrix interferences in the raw methanol extract (disperser, 1 mL) were removed by a first DLLME (I DLLME) performed at pH 8 to reduce the solubility of OTA in the extractant (CCl₄, 400 μL). The pH of the aqueous phase was then adjusted to 2, and the analyte was extracted and concentrated by a second DLLME (extractant, 150 μL C₂H₄Br₂). The main factors influencing the efficiency of pH-DLLME including type and volume of I DLLME extractant, as well as the parameters affecting the OTA extraction by II DLLME, were studied in detail. Under optimum conditions, the method has detection and quantification limits of 0.019 and 0.062 μg kg⁻¹, respectively, with OTA recoveries in the range of 81.2–90.1% (n = 3). The accuracy of the analytical procedure, evaluated with a reference material (cereal naturally contaminated with OTA), is acceptable (accuracy of 85.6% ± 1.7, n = 5).     

Cell wall polysaccharides in cereals: chemical structures and functional properties

β-Glucans and arabinoxylans are the two primary cell wall structural components in cereals, such as wheat, oat, barley and rye. The relative amounts of the two polysaccharides vary with species and growing environments. The cell walls of barley and oats are generally rich in β-glucan, whereas rye and wheat cell walls contain higher levels of arabinoxylans. Cereal β-glucan is a mix linked (1 → 3) (1 → 4)-β-d-glucan composed of two major building blocks: a trisaccharide and a tetrasaccharide unit: the combination of the two units is over 90%. The ratio of the two building blocks is used as a fingerprint for each β-glucans: it is 4.5, 3.3, 2.2 for wheat, barley and oat β-glucan, respectively. Of the two types of cell wall polysaccharides in cereals, β-glucan received greater attention due to its proved beneficial physiological effect as an excellent source of soluble dietary fibre for significantly attenuating blood glucose and insulin levels and its demonstrated ability to reduce low-density lipoprotein cholesterols (LDL) in serum. The ability of cereal β-glucan to attenuating blood glucose, insulin levels is linked to the viscosity produced by cereal β-glucans in a linear relationship. It is also demonstrated that the functional properties of cereal β-glucans are determined by their structural features and molecular weight: a higher trisaccharide to tetrasaccharide ratio favours gel formation and faster gelation process, and ultimately, gives stronger gels. Cereal β-glucan also demonstrated an unusual behaviour by forming gel faster and yielding stronger gels at lower molecular weight (above minimum gelation molecular weight). Such a structure–function relationship was established based on rheological, light scattering and computer modelling studies which cover both dilute and concentrated concentration regimes: high tri/tetra ratio gives high proportion of consecutive trisaccharide unit which favours the intermolecular association of β-glucan chains; on the other hand, low molecular weight chains have higher mobility that promotes intermolecular chain–chain interactions, hence, lead to faster gelation process and formation of stronger gels. Research also revealed that processing and storage conditions, such as temperature, pH, extrusion, baking and frozen before eating, have significant effects on the bioavailability of cereal β-glucans, hence, its ability to reduce blood glucose and cholesterol levels.     

A 150 micron id packed column for the separation of soybean proteins by elution gradient mu-HPLC: simultaneous separation of soybean proteins from cereal and milk proteins

Mu-HPLC has previously been used to increase the resolution and sensitivity of protein separations but never for the analysis of soybean proteins. In this work, soybean proteins were, for the first time, separated using a capillary column with an internal diameter of 150 microm packed with a Genesis C18 stationary phase (4 microm, 300 angstroms) and UV detection. TFA and acetic acid were investigated as ion-pairing reagents in order to optimise water-ACN gradients to achieve this separation. The column showed good selectivity enabling the separation of soybean proteins from other vegetable proteins such as cereal (wheat, rice and corn) and also from milk proteins. The developed method was applied to the detection of soybean proteins in commercial products elaborated with mixtures of vegetable proteins.     

Isolation and determination of carbendazim residue from wheat grain by matrix solid‐phase dispersion and HPLC

Carbendazim residues were analyzed by column‐switching high‐performance liquid chromatography (HPLC) with photodiode array detection (PDA). The active ingredient was extracted by matrix solid‐phase dispersion (MSPD) from wheat grain on an acidic silica gel column using a methanol‐dichloromethane mixture. The recovery rate for fortified samples was 87.3 ± 3.3% with a standard deviation (SD) of 2.9%. The detection limit was 0.02 μg/mL. The method was applied to the determination of carbendazim residues in wheat grain samples from a treated field.     

谷物中噻吩甲氯残留量的气相色谱-质谱测定

应用气相色谱－ 质谱法确证及测定谷物（ 糙米、玉米） 中噻吩甲氯的残留含量, 试样采用水－ 丙酮提取,提取液经与石油醚液－ 液分配后, 再以硅酸镁载体（Ｆｌｏｒｉｓｉｌ） 柱净化, 气相色谱－ 质量选择检测器选择离子监测方式（ ＧＣ－ ＭＳＤ－ ＳＩＭ） 进行测定和阳性确证。噻吩甲氯选择监测离子的种类为ｍ／ ｚ ２８７ 、２８８ 、３２３ , 其丰度比约为４６ ∶１００ ∶１１ 。采用外标法定量, 方法检出限为０ ．０１０ ×１０ － ６ 。     

Kinetic modelling of ultrasound-assisted extraction of phenolics from cereal brans

Cereal brans are by‐products of the milling of cereal grains, which are mainly used as low value ingredients in animal feed. Wheat and oat bran is a rich source of bioactives and phytochemicals, especially phenolic compounds. Within this study, the application of ultrasound (US) technology to assist the extraction of phenolics from oat and wheat bran was investigated (20–45 kHz). Peleg’s mathematical model was used to study the kinetics of ultrasound-assisted extraction (UAE) and subsequent stirring of total phenolic compounds (TPC). The surface morphology of cereal brans after extraction was studied using SEM analysis. The excellent agreement was determined between the values of TPC calculated from Peleg’s mathematical model and actual experimental results. The constant that represents a time required for the initial phenolic concentration to be extracted to one-half of its initial value has been introduced (K_1/2). It was shown that the TPC extraction kinetics was dependent only on K_1/2 enabling fast kinetics fitting and comparison between extraction rates. Moreover, different values of K_1/2 constant could indicate the differences in brans composition and consequently different influence of US pretreatment on these samples.     

A novel method for the determination of trace copper in cereals by dispersive liquid-liquid microextraction based on solidification of floating organic drop coupled with flame atomic absorption spectrometry

A novel,simple,rapid,efficient and environment-friendly method for the determination of trace copper in cereal samples was developed by using dispersive liquid-liquid microextraction based on solidification of floating organic drop(DLLME-SFO) followed by flame atomic absorption spectrometry.In the DLLME-SFO,copper was complexed with 8-hydroxy quinoline and extracted into a small volume of 1-dodecanol,which is of low density,low toxicity and proper melting point near room temperature. The experimental parameters affecting the extraction efficiency were investigated and optimized.Under the optimum conditions, the calibration graph exhibited linearity over the range of 0.5—500 ng/mL with the correlation coefficient(r) of 0.9996.The enrichment factor was 122 and the limit of detection was 0.1 ng/mL.The method was applied to the determination of copper in the complex matrix samples such as rice and millet with the recoveries for the spiked samples at 5.0 and 10.0 u,g/g falling in the range of 92.0-98.0%and the relative standard deviation of 3.9-5.7%.     

高效液相色谱-三重四极杆串联质谱测定谷物中T-2毒素和HT-2毒素

建立了快速分析谷物样品中T-2毒素和HT-2毒素的高效液相色谱-三重四极杆串联质谱( HPLC-MS/MS)分析方法.样品经乙腈-水(80:20,V/V)混合溶剂提取,免疫亲和柱净化后,采用HPLC-MS/MS测定.T-2毒素和HT-2毒素的检测线性范围均为0.20 ～20.00 μg/kg,定量下限为0.20 μg/...