Diode laser absorption spectroscopy for studies of gas exchange in fruits

Gas exchange in fruits, in particular oxygen transport in apples, was studied non-intrusively using wavelength modulation diode laser absorption spectroscopy at about 761 nm, applied to the strongly scattering intact fruit structure. The applicability of the technique was demonstrated by studies of the influence of the skin to regulate the internal oxygen balance and of cling film in modifying it by observing the response of the signal from the internal oxygen gas to a transient change in the ambient gas concentration.Applications within controlled atmosphere fruit storage and modified atmosphere packaging are discussed. The results suggest that the technique could be applied to studies of a large number of problems concerning gas exchange in foods and in food packaging.     

Identification of the Flavone in the Flower Bud of Panax Quinquefolium and Its Content Determination in the Different Parts

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Stereoisomeric flavour compounds XXXVIII: Direct chirospecific analysis of γ-lactones using on-line coupled LC-GC with a chiral separation column

Summary Chiral -lactones from the raw flavour extract of strawberries and commercially available fruit-containing products are stereoanalyzed directly by on-line coupling of liquid chromatography (LC) to gas chromatography (GC) and enantiomer separation with 2,6-di-O-pentyl-3-O-acetyl--cyclodextrin as the chiral stationary phase.     

New home-made assembly for hollow-fibre membrane extraction of persistent organic pollutants from real world samples

Nowadays, hollow fibre membrane extraction techniques are widely used but they are usually applied to water or very simple matrices such as water. In this paper, we propose a new assembly that allows the extraction of forty persistent organic pollutants in real world samples, namely orange juice, porcine plasma and tomatoes. The limits of detection obtained are very low even in the analysis of real samples (9-182 ng L(-1)). The relative standard deviations vary from 1 to 18% and the averaged recoveries in the spike experiments are very high (65-120%) in the different types of samples studied. The new assembly allows a very good precision overcoming in one of the most important shortcomings of membrane extraction techniques. A central composite design has been performed to get optimal extraction conditions for the analytes and also the combined response of all the analytes has been obtained to attain the simultaneous optimum.     

高效液相色谱法同时测定蔬菜和水果中8种农药残留

建立了同时测定蔬菜和水果中8种农药残留的反相高效液相色谱分析方法.通过乙腈提取,LC-NH2柱净化,C18柱分离,梯度洗脱,检测波长275 nm.8种农药在0.2～10.0 mg/L浓度范围内线性关系良好;检出限在0.01～0.04 mg/kg范围;平均加标回收率在80.1%～103.7%范围,相对标准偏差(RSD)在...     

Investigation of Trace Metals Content and Carbon Isotopic Composition on the Soil Leaf-Fruit Chain from Some Transylvanian Areas

Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Isotopic Ratio Mass Spectrometry (IRMS) were used in this study to trace heavy metal and isotopic content of soil into the fruit juices. This work presents a preliminary study on the carbon isotope signature and trace metal content investigated on the soil-plant-fruit pulp chain. The samples were collected from Transylvanian areas. Our results for fruit juices are compared with allowable limits for drinking water in the United Kingdom (NS30). The results for soil samples were compared with the maximum value reported for normal range values of natural soils cited by the EEA (European Environment Agency) report. The results obtained for δ¹³C values on the soil - leaf - fruit pulp chain for grape, pear, and apple samples show depletion in ¹³C isotope, as the trend of the values reported in literature for the soil–leaf–fruit chain.     

近红外光谱技术在水果产业中的最新应用

综述了近红外光谱技术在水果产业中的最新应用,系统阐述了NIR在果树栽培调控、果实品质检测、果实贮藏三方面的最新研究进展,并对其发展前景提出了展望。     

模式识别技术用于果酸混合物分析

研究了偏最小二乘法和人工神经网络法用于水果的紫外可见多组分光度分析。当混合物中诸组分存在相互作用，光谱加和性受到 扰动时，ＰＬＳ法和ＡＮＮ法用于混和物的分析仍能得到较满意的结果。     

气相色谱-质谱联用法测定水果中4,6-二硝基邻甲酚

利用气质联用（GC-MS）技术建立了水果中4，6-二硝基邻甲酚（DNOC）的测定方法。以二氯甲烷提取水果样品中DNOC残留，并使用N-（特丁基二甲基硅）-N-甲基三氟乙酰胺对提取DNOC残留进行衍生化，利用GC-MS选择离子模式（SIM）测定残留DNOC衍生化产物，在苹果和梨中DNOC的添加回收率在70％～110％之间，相对标准偏差RSD〈9％（n=10），方法的检出限为10μg/kg。