A method for the determination of acrylamide in bakery products using ion trap LC-ESI-MS/MS

Acrylamide levels of bakery products, e. g., bread and bread rolls, are usually below 100 microg/kg , often even below 50 microg/kg. Therefore, usual analytical methods which have an LOQ greater, not dbl equals 25 microg/kg are not sensitive enough for detailed investigations on acrylamide formation within these commodities. An improved method for trace level determination of acrylamide in bakery products was developed using ion trap LC-ESI-MS/MS. Samples were divided into crumbs and crusts to achieve an initial concentration by removing the crumbs since these are devoid of acrylamide. After sample extraction and clean-up using multimode SPE cartridges, further analyte enrichment was accomplished by solid-phase-supported liquid-liquid extraction with ethyl acetate prior to LC-MS/MS analysis. The method was evaluated using bread, bread rolls, alkali-baked bread rolls, and toast. LOQ was calculated from the confidence interval of the calibration curve and found to be 1.7 ng/mL, corresponding to 17 microg/kg of product. When crumbs and crusts were separated, an LOQ of 10.2 microg/kg of bakery product could be obtained. As demonstrated in preliminary comparative analyses, accuracy of the method met the requirements for determination of trace level acrylamide formation in bakery products. Mean recovery was 102.4% (CV 4.5%), intermediate reproducibility revealed a CV of 2.1%, and a repeatability of CV 6.0%.     

Apple pomace as a potential ingredient for the development of new functional foods

Extruded snacks and baked scones were formulated with increasing levels (0–30%) of apple pomace (AP). The incorporation of up to 20% of AP in extruded snacks and in baked scones does not change significantly (P < 0.05) the proximate composition of the final products, except for the content of starch of baked scones. At this level of incorporation, the fibre content, phenolic content and antioxidant capacity (DPPH radical scavenging activity, ferric reducing antioxidant power (FRAP) and β‐carotene/linoleic acid system) increased when compared to the products to which no AP was added. Chlorogenic acid and quercetin were the major phenolic compounds found in the products. Loss of phenolic compounds during heat treatment occurred; however, the DPPH radical scavenging activity of final products was not affected.     

Metabolomics reveals consistency of the shoot system in Medicago truncatula by HPLC‐UV‐ESI‐MS/MS

Flavonoids not only play crucial roles in plant development and resistance, but also provide one of the major natural sources in human nutrition. To investigate the distribution of flavonoids in the shoot system of Medicago truncatula, a high‐performance liquid chromatography coupled with electrospray ionisation tandem mass spectrometer (HPLC‐ESI‐MS/MS) method was established and then applied to determine the quantitation of flavonoids in different parts of the plant. There were twenty‐two, fifteen and eleven different kinds of flavonoids identified from the flower, leaf and stem of M. truncatula, respectively. The identified constituents were either aglycone or glycosides of the typical flavonoid backbones, such as myricetin, quercetin, luteolin, kaempferol, tricin, apigenin and laricitrin. It was found that the shoot system of M. truncatula can be differentiated by flavonoids in terms of structures and contents. Our results provide instruction to utilise the shoot system of legume crops as fodder and herb medicine in the future.     

Phenolic Profile and Biological Activities of the Pepino (Solanum muricatum) Fruit and Its Wild Relative S. caripense

The pepino (Solanum muricatum) is an edible and juicy fruit native to the Andean region which is becoming increasingly important. However, little information is available on its phenolic composition and bioactive properties. Four pepino varieties (37-A, El Camino, Puzol, and Valencia) and one accession (E-7) of its close wild relative S. caripense were characterized by HPLC-DAD-MSⁿ/ESI. Twenty-four hydroxycinnamic acid derivatives were detected (5 to 16 compounds per variety or accession), with differences of more than two-fold for their total content among the materials studied. The major phenolics in the pepino varieties were chlorogenic acids and derivatives, while in S. caripense a caffeoyl-synapoyl-quinic acid was the major compound. The in vitro antioxidant capacity (DPPH (2,2-diphenyl-1-picrylhydrazyl hydrate), ORAC (oxygen radical absorbance capacity), and TRC (total reducing capacity) tests) was higher in S. caripense. Pepino and S. caripense extracts were not toxic for RAW 264.7 macrophage cells, and the raw extracts inhibited NO production of the lipopolysaccharide (LPS)-stimulated macrophages by 36% (El Camino) to 67% (37-A). No single variety ranked high simultaneously for hydroxycinnamic acids content, antioxidant activity and biological activity. We suggest the screening of large collections of germplasm or the use of complementary crosses between Puzol (high for hydroxycinnamic acids and biological activity) and S. caripense E-7 (high for antioxidant activity) to select and breed pepino varieties with enhanced properties.     

一种用于ESI离子源的可控高压直流电源的研究

介绍了一种用于电喷雾离子源的可控高压直流电源。分析了它的电场控制原理,讨论了它的硬件组成,具体给出了它的功能原理电路及其电路功能的实现。     

Assessment of phenolic profile of Turkish honeys

In this study, phenolic profile and antioxidant activity of 60 Turkish honey samples of nineteen different floral origins were evaluated by ultra-performance liquid chromatography with electrospray ionization coupled to tandem mass spectrometry, providing the identification of 32 phenolic compounds. Thyme (1051.58 mg/kg), pine (994.18 mg/kg), carob (935.03 mg/kg), eucalyptus (814.46 mg/kg), rhododendron (680.71 mg/kg), heather (562.59 mg/kg), cedar (561.83 mg/kg), and euphorbia (501.64 mg/kg) present significantly high phenolic content. Moreover ferulic, homogentisic, gentisic, syringic, 3,4-dihydroxybenzoic, caffeic, vanillic, p-coumaric, 4-hydroxy benzoic, and trans-2-hydroxy cinnamic acids were the most abundant of the determined compounds. The antioxidant activities of the honeys were evaluated by β-carotene-linoleic acid inhibition, DPPH free radical scavenging activity and ABTS⁺ cation radical scavenging activity which were measured as IC₅₀: 10.87 – 48.23 µg/mL, SC₅₀: 54.33 – 99.40 µg/mL and SC₅₀: 10.33 – 41.20 µg/mL, respectively. Phenolic compounds are considered antioxidant constituents, and they could be stated as components that account for antioxidant activity in Turkish honeys.     

Non‐galloylated and galloylated proanthocyanidin oligomers in grape seeds from Vitus vinifera L. cv. Graciano,Tempranillo and Cabernet Sauvignon

Non‐galloylated and galloylated flavan‐3‐ol composition in seeds from Vitis vinifera L. var. Graciano, Tempranillo and Cabernet Sauvignon grapes harvested in 2000, 2001 and 2002 at the same geographical area were determined using normal‐phase HPLC coupled with electrospray ionization mass spectrometry (LC/ESI‐MS) detection. Non‐galloylated and monogalloylated flavan‐3‐ols up to octamers, and di‐, and trigalloylated flavan‐3‐ols up to heptamers were identified in all grape seeds. Comparisons of the flavan‐3‐ol composition in three grape varieties harvested in three different years indicate that levels of non‐galloylated flavan‐3‐ols decrease as the degree of polymerization increased, whereas the monogalloylated dimers were present in the highest levels in all varieties and vintages. The levels of other monogalloylated flavan‐3‐ols varied in different vintages. Tempranillo contained the lowest levels of non‐galloylated and monogalloylated flavan‐3‐ols, whereas Graciano contained the highest levels, with the exception of non‐galloylated flavan‐3‐ols in vintage 2001, and non‐galloylated monomers in vintages 2000 and 2002. Grape seeds from vintage 2000 contained the highest levels of both non‐galloylated and galloylated structures. Statistical analyses indicate that the distribution of the flavan‐3‐ols is primarily determined by genetic factors and is also strongly influenced by climate conditions. Copyright © 2006 Society of Chemical Industry     

真空辅助成型工艺的数值分析与模拟

真空辅助工艺是一种双移动边界的工艺过程，既有厚度方向的压缩，又有平面内的树脂流动，利用通用有限元软件难以实现模拟分析，本文借助达西定律，建立了压缩模型和渗透率模型，并与专业数值模拟软件相结合，实现了简单2．5维薄壳结构的流动模拟，模拟结果与分析结果相吻合，对于生产工艺具有一定的指导意义。     

ESI contrast analysis: a new approach for element analysis with energy-filtering transmission electron microscopy (EFTEM)

Element microanalysis with energy-filtering transmission electron microscopy can be performed in different ways. Electron energy-loss spectroscopy (EELS) records the intensity as a function of the energy loss from selected regions. Elemental mapping with electron spectroscopic imaging (ESI) uses energy-filtered images at an element-specific energy loss from which a background image has to be subtracted. A combination of these two approaches is Image-EELS, which records a series of energy-filtered images, each at a different energy loss and measures the intensity of selected regions as a function of the energy loss. As an additional procedure ESI contrast analysis is introduced; with this we can investigate the image contrast as a function of the energy loss. The contrast can be measured for the total image or for selected regions as the standard deviation of the grey levels divided by the mean grey level. This procedure is added as a new feature to the existing Image-EELS program, so that EELS intensity spectra and the contrast can be directly compared. Alternatively, the contrast can be calculated step by step from individually recorded electron spectroscopic images, so that only simple equipment for image analysis is sufficient to realize this new method. Inner shell ionizations produce characteristic, but often weak element edges in energy-loss spectra which can be detected more sensitively and reliably as a rapid increase in contrast. Regional analysis of the contrast as a function of the energy loss, combination of data from different regions and the possibility to increase the intensity during recording of the images expand the application range of this new analytical method which bridges the gap between ESI and EELS analysis. With ESI contrast analysis it is possible to discriminate between faint element signals and artefacts in elemental mapping. This new approach for element detection is especially advantageous for biological objects which usually contain very small amounts of the interesting elements in heterogeneous and complex objects. As an example, nervous tissue of a fish was analysed after cytochemical precipitation of endogenous calcium.