170,208 research outputs found
Cereal bran fractionation: processing techniques for the recovery of functional components and their applications to the food industry
No full textBran is the outer part of cereal grains that is separated during the cereals de-hulling and milling processes. It was considered in the past a by-product of cereal industry employed mainly as animal feed. Cereal bran, being particularly rich in different functional biopolymers, bio-active compounds and essential fatty acids, attracted the interest of pharmaceutical and food industry. Furthermore, the peculiar techno-functional properties of brans together with their particular physiological and nutritional aspects have led to a great interest in their incorporation as main or secondary components in different groups of food products including bakery and confectionery products, breakfast cereals and extruded foodstuffs, emulsions and functional dairy products and pasta products. In the first part of the present work the main fractionation processes, bran fractions properties and their physicochemical and technological properties are briefly reviewed. In the second part, relevant applications, with emphasis on patents, in food industry are reviewed as well
Effect of the pig rearing system on the final volatile profile of Iberian dry-cured ham as detected by PTR-ToF-MS
No full textThe volatile compound profile of dry-cured Iberian ham lean and subcutaneous fat from pigs fattened outdoors on acorn and pasture (Montanera) or on high-oleic concentrated feed (Campo) was investigated by proton transfer reaction time-of-flight mass spectrometry. In addition to the usual proton transfer ionization we implemented the novel switchable reagent ions system which allows the use of different precursor ions (H3O+, NO+ and O2+). The analysis of the lean and subcutaneous fat volatile compounds allowed good sample discrimination according to the diet. Differences were evident for several classes of compounds: in particular, Montanera hams showed higher concentrations of aldehydes and ketones and lower concentrations of sulfur-containing compounds compared to Campo hams. The use of NO+ as precursor ion confirmed the results obtained with H3O+ in terms of classification capability and provides additional analytical insights.Fil: Sanchez del Pulgar, J.. Fondazione Edmund Mach. Research and Innovation Centre; Italia. Universidad de Extremadura. Facultad de Veterinaria; ArgentinaFil: Soukoulis, S.. Fondazione Edmund Mach. Research and Innovation Centre; ItaliaFil: Carrapiso, A. I.. Universidad de Extremadura. Escuela de Ingenierías Agrarias; EspañaFil: Cappellin, L.. Fondazione Edmund Mach. Research and Innovation Centre; ItaliaFil: Granitto, Pablo Miguel. Universidad Nacional de Rosario; ArgentinaFil: Aprea, E.. Fondazione Edmund Mach. Research and Innovation Centre; ItaliaFil: Romano, A. Fondazione Edmund Mach. Research and Innovation Centre; ItaliaFil: Gasperini, F.. Fondazione Edmund Mach. Research and Innovation Centre; ItaliaFil: Biasioli, F.. Fondazione Edmund Mach. Research and Innovation Centre; Itali
PTR-TOF-MS and data-mining methods for rapid characterisation of agro-industrial samples: influence of milk storage conditions on the volatile compounds profile of Trentingrana cheese
No full textProton transfer reaction-mass spectrometry (PTR-MS), a direct injection mass spectrometric technique based on an efficient implementation of chemical ionisation, allows for fast and high-sensitivity monitoring of volatile organic compounds (VOCs). The first implementations of PTR-MS, based on quadrupole mass analyzers (PTR-Quad-MS), provided only the nominal mass of the ions measured and thus little chemical information. To partially overcome these limitations and improve the analytical capability of this technique, the coupling of proton transfer reaction ionisation with a time-of-flight mass analyser has been recently realised and commercialised (PTR-TOF-MS). Here we discuss the very first application of this new instrument to agroindustrial problems and dairy science in particular. As a case study, we show here that the rapid PTR-TOF-MS fingerprinting coupled with data-miningmethods can quickly verify whether the storage condition of themilk affects the final quality of cheese and we provide relevant examples of better compound identification in comparison with the previous PTR-MS implementations. In particular, ‘Trentingrana’ cheese produced by four different procedures for milk storage are compared both in the case of winter and summer production. It is indeed possible to set classification models with low prediction errors and to identify the chemical formula of the ion peaks used for classification, providing evidence of the role that this novel spectrometric technique can play for fundamental and applied agro-industrial themes.Fil: Fabris, Alessandra. Instituto Agrario San Michele All'adige Fondazione Edmund Mach; ItaliaFil: Biasioli, Franco. Instituto Agrario San Michele All'adige Fondazione Edmund Mach; ItaliaFil: Granitto, Pablo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y Sistemas; Argentina. Universidad Nacional de Rosario; ArgentinaFil: Aprea, Eugenio. Instituto Agrario San Michele All'adige Fondazione Edmund Mach; ItaliaFil: Cappellin, Luca. Instituto Agrario San Michele All'adige Fondazione Edmund Mach; Italia. Universidad de Innsbruck; AustriaFil: Schuhfried, Erna. Universidad de Innsbruck; AustriaFil: Soukoulis, Christos. Instituto Agrario San Michele All'adige Fondazione Edmund Mach; ItaliaFil: Märk, Tilmann D.. Universidad de Innsbruck; AustriaFil: Gasperi, Flavia. Instituto Agrario San Michele All'adige Fondazione Edmund Mach; ItaliaFil: Endrizzi, Isabella. Instituto Agrario San Michele All'adige Fondazione Edmund Mach; Itali
Analysis of resonant responses of split ring resonators using conformal mapping techniques
No full textWe report a novel method for modeling the resonant frequency response of infra-red light, in the range of 2 to 10 microns, reflected from metallic spilt ring resonators (SRRs) fabricated on a silicon substrate. The calculated positions of the TM and TE peaks are determined from the plasma frequency associated with the filling fraction of the metal array and the equivalent LC circuit defined by the SRR elements. The capacitance of the equivalent circuit is calculated using conformal mapping techniques to determine the co-planar capacitance associated with both the individual and the neighbouring elements. The inductance of the equivalent circuit is based on the self-inductance of the individual elements and the mutual inductance of the neighboring elements. The results obtained from the method are in good agreement with experimental results and simulation results obtained from a commercial FDTD simulation software package. The method allows the frequency response of a SRR to be readily calculated without complex computational methods and enables new designs to be optimised for a particular frequency response by tuning the LC circuit
Extending the dynamic range of proton transfer reaction time-of-flight mass spectrometers by a novel dead time correction
No full textProton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) allows for very fast simultaneous monitoring of volatile organic compounds (VOCs) in complex environments. In several applications, food science and food technology in particular, peaks with very different intensities are present in a single spectrum. For VOCs, the concentrations range from the sub-ppt all the way up to the ppm level. Thus, a large dynamic range is necessary. In particular, high intensity peaks are a problem because for them the linear dependency of the detector signal on VOC concentration is distorted. In this paper we present, test with real data, and discuss a novel method which extends the linearity of PTR-TOF-MS for high intensity peaks far beyond the limit allowed by the usual analytical correction methods such as the so-called Poisson correction. Usually, raw data can be used directly without corrections with an intensity of up to about 0.1 ions/pulse, and the Poisson correction allows the use of peaks with intensities of a few ions/pulse. Our method further extends the linear range by at least one order of magnitude. Although this work originated from the necessity to extend the dynamic range of PTR-TOF-MS instruments in agro-industrial applications, it is by no means limited to this area, and can be implemented wherever dead time corrections are an issue
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Monitoring the effect of high pressure and transglutaminase treatment of milk on the evolution of flavour compounds during lactic acid fermentation using PTR-ToF-MS
No full textIn this study, the effects of thermal or high hydrostatic pressure (HHP) treatment of a milk base in the absence or presence of a transglutaminase (TGase) protein cross-linking step on the flavour development
of yoghurt were investigated. The presence of several tentatively identified volatile flavour compounds (VOCs), both during the enzymatic treatment and the lactic acid fermentation of the milk base, were monitored using a proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS). The formation of the major flavour compounds (acetaldehyde, diacetyl, acetoin, and 2-butanone) followed a sigmoidal trend described by the modified Gompertz model. The HHP treatment of milk increased significantly
the volatile compound formation rate whereas it did not affect the duration of the lag phase of formation, with the exception of acetaldehyde and diacetyl formation. On the contrary, the TGase cross-linking of milk did not significantly modify the formation rate of the volatile compounds but shortened the duration of the lag phase of their formatio
Soukoulis, “Self-consistent calculation of metamaterials with gain,”
No full textWe present a computational scheme allowing for a self-consistent treatment of a dispersive metallic photonic metamaterial coupled to a gain material incorporated into the nanostructure. The gain is described by a generic four-level system. A critical pumping rate exists for compensating the loss of the metamaterial. Nonlinearities arise due to gain depletion beyond a certain critical strength of a test field. Transmission, reflection, and absorption data as well as the retrieved effective parameters are presented for a lattice of resonant square cylinders embedded in layers of gain material, and split ring resonators with gain material embedded into the gaps. 78.20.Ci, 41.20.Jb The field of metamaterials [1, 2] is driven by fascinating and far-reaching theoretical visions such as, e.g., perfect lenses For reference, the best fabricated negative-index material operating at around 1.4 µm wavelength In this paper, we apply a detailed computational model to the problem of metamaterials with gain. The generic fourlevel atomic system tracks fields and occupation numbers at each point in space, taking into account energy exchange between atoms and fields, electronic pumping and non-radiative decay
Rheological, textural, physicochemical and sensory profiling of a novel functional ice cream enriched with Muscat de Hamburg (Vitis vinifera L.) grape pulp and skins
No full textThe scope of the present work was the development of an ice cream containing substantial amount of phenolic compounds by substituting sucrose by a Muscat de Hamburg grape pulp and skin matter (GPSM)-enriched bulking agent at the level of 25 to 100% w/w. Sucrose replacement by GPSM reinforced the pseudoplastic and thixotropic character of the ice cream mixes imparting weak gel-like properties (G′ > G′′). Oscillatory thermo-mechanical analysis revealed the occurrence of a β-relaxation peak at − 17 to − 12.8 °C, whilst a slight depression of the freezing point was observed. The increase in GPSM solids resulted in a significant increase in the instrumental hardness and overrun of ice cream samples, whilst it enhanced their meltdown resistance. Although GPSM boosted the nutritional value and flavour profile of the ice cream, when sucrose substitution exceeded 50%, undesirable sensory characteristics, such as coarse/grainy texture, bitterness and astringency, were detecte
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