1,721,088 research outputs found
Procedure di convoluzione e deconvoluzione mediante trasformata di Fourier nella sintesi e nell'analisi di responsi voltammetrici
No full textStudio elettrochimico e spettroelettrochimico di complessi di rame con fenantroline sostituite
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Preliminary RP-HPLC approaches to the characterization of nutraceutical components in Stevia rebaudiana Bertoni leaves
No full textRole of the caffeic acid oxidation products on the iron mobilization at the soil-root interface
Full text linkPrevious results show that the reduction of Fe(III) by caffeiic acid (CAF) is strongly influenced by the pH
of the reaction medium (DEIANA et al., 1995). In particular, it has been found that al pH > 3.8 the
reducing activity of CAF towards the Fe(III) ions in solution is low, but it increases when Fe(III) is
complexed as Fe(III)-polygalacturonate. The mobilization of the Fe(II) ions, which form upon the Fe(III) reduction, has been shown to depend mainly on the nature of the Fe(III)-polygalacturonate complexes (DEIANA et al., 1994a). In particular, it bas been observed a high redox activity of CAF towards Fe(III) when the metal ion is coordinated by the carboxilic groups of the macromolecule. The Fe(III) reduction has been found to decrease when an oxydrilic group was inserted in the Fe(III) coordination sphere. The
Fe(II) produced partly diffuses into the external solution and partly is still strongly held by the polysaccharidic matrix. The oxidation of CAF by Fe(III) gives rise to the formation of products (OP) with different polymerization degree, some of which are similar to those found in natural systems (DEIANA et al., 1994b). In order to determine the role of these products in the Fe(III) reduction as well as
in the mobilization of the Fe(II) produced it was set up an electrochemical method to synthetize these products (DEIANA et al., 1994b). Here are reported some results about the interaction which establish between the CAF oxidation products and iron in both oxidized and reduced form
A study on the evolution of 5-hydroxymethyl-2-furaldehyde in royal jelly stored at different conditions
No full textRoyal jelly (RJ) constitutes one of the most renowned products from beekeeping. It is secreted from the cephalic glandular system of young worker bees to feed the queen throughout her whole life and it is considered as the main responsible for the caste differentiation inside the beehive[1,2].
Many functional properties have been attributed to RJ and several biologically and pharmacologically active substances have been identified in its chemical composition[3,4]. Therefore, its commercial appeal has considerably grown in the last years and it can be nowadays considered as one of the most valuable nutraceutical products.
One of the main aspects related to RJ quality is represented by freshness. Improper storage conditions may cause modifications on the chemical composition of RJ affecting its health-promoting properties and its economic value. For this reason, it is generally recommended to keep RJ refrigerated during storage[5].
Several studies have been dedicated to the identification of a freshness marker for RJ but many of the proposed parameters are influenced by a large number of factors and don’t fit for purpose[5].
In the past our research group developed and validated a rapid RP-HPLC method for the determination of 5-hydroxymethyl-2-furaldehyde (HMF) in RJ [6]. In this study, the evolution of HMF in RJ stored at different conditions (RT, 4 °C and -18 °C) was investigated. Our results suggest that HMF could be very useful to discriminate between spoiled and fresh samples. Moreover a very good correlation (R2=0.9791) between HMF content and RT storage time was observed.
1. R Krell, Value-added products from beekeeping, 1996, FAO Agricultural Service Bulletin no.124, Food and Agriculture Organization of the United Nations Rome, http://www.fao.org/docrep/w0076E/w0076E00.htm, accessed 26 June 2014
2. M Kamakura, Nature, 473, 478, 2011
3. M Viuda-Martos, Y Ruiz-Navajas, J Fernàndez-Lopéz, J Pérez-Alvaréz, Journal of Food Science, 73, R117-R124, 2008
4.MF Ramadan, A Al-Ghamdi, Journal of Functional Foods, 4, 39-52, 2012
5.E Marconi, MF Caboni, MC Messia, G Panfili, Journal of Agricultural and Food chemistry, 50, 2825-2829, 2002
6. M Ciulu, R Farre, I Floris, VM Nurchi, A Panzanelli, MI Pilo, N Spano, G Sanna, Analytical Methods, 5, 5010-5013, 201
Electrochemical synthesis and characterization of terpyridine-tethered polythiophene bearing ethynyl bridge
No full textEPR and electrochemical study of copper complexes with phenanthrolines and cinnamate ligands.
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