1,721,007 research outputs found
Sugar determination via the homogeneous reduction of Au salts : a novel optical measurement
No full textA novel optical assay for sugar determination based on the catalytic and biocatalytic growth of gold nanoparticles (AuNPs) is presented. The reaction of carbohydrates with these Au salts in alkaline media generates AuNPs at room temperature (RT) without the need for Au seeds in the solution or fibrous mesh. The optical properties of the resulting AuNPs relates to the total reducing sugar content of the samples analyzed. The development of such inexpensive optical assay was evaluated qualitatively and quantitatively on food beverages and honey samples. Its application can be of help to control the glucose content of the diet or easily extended in a host of industrial, biomedical and clinical fields
Optical nanoprobes based on gold nanoparticles for sugar sensing
No full textA novel optical nanoprobe for sugar sensing is reported. The assay used an electrospun polyamide mesh containing Au salts. The reaction of carbohydrates with these Au salts in alkaline media generates gold nanoparticles (AuNPs) at room temperature without the need for Au seeds. The optical properties of the resulting AuNPs relate to the total reducing sugar content of the samples analysed. The development of such inexpensive disposable optical nanoprobes could find applications in a host of industrial, biomedical and clinical fields
Olive Oil and Electronic Nose
No full textExtra virgin olive oil (EVOO) is a typical product of the Mediterranean diet that plays a major role for its health benefits and excellent organoleptic properties linked to the peculiar chemical composition. One of the most significant improvements in the olive oil industry in recent years is the development of intelligent sensing systems, so-called "electronic noses," that allow rapid, direct, and highly sensitive online monitoring of food aromatic profiles. In this chapter we show the capability of two commercial electronic noses based on two different working principles-metal oxide and field effect sensors array (MOS/MOSFET) and proton transfer mass spectrometry (PTR-MS)-to characterize EVOO. The capability of these two systems to analyze EVOO was verified with four different case studies that investigated: (1) the oxidation stage of EVOO during storage, discrimination of EVOO samples based on (2) MOS/MOSFET (3) PTR-MS electronic nose, and (4) process monitoring by PTR-MS
Nanotechnology and Food Quality Control
No full textThe preparation and attractive performance of nanomaterials for innovative detection schemes of food related compounds are described. Nickel nanowires growths by the template procedure were used for magnetoswitchable control of electrochemical processes of sugar-like compounds at the electrode surface. Gold nanoparticles were also prepared by reducing a gold solution with different phenolic compounds. The different antioxidant power of these compounds allow to modulate the kinetic growth of gold nanoparticles. Finally, an index of the antioxidant power based on the growth of gold nanoparticle is reported
Tecnica combinata acustico-meccanica per la caratterizzazione di prodotti da forno a bassa umidità
No full textLa fraiabilità è un attributo importante di qualità per molti prodotti da forno a bassa umidità. La friabilità è una percezione sensoriale che deriva dalla combinazione di stimoli meccanici ed acustici. La tecnica strumentale combinata acustico-meccanica , unitamente all'analisi dell'immagine, viene proposta in questo lavoro per caratterizzare campioni di cinque tipologie di fette biscottate commerciali. Lo scopo del lavoro è dimostrare l'efficacia dell'analisi combinata acustico-meccanica come metodo strumentale oggettivo per analizzare e classificare prodotti fiabili, utilizzando come supporto statistico tecniche avanzate di analisi multivariata
Nanofibrous membrane based tyrosinase-biosensor for the detection of phenolic compounds
No full textA tyrosinase-modified electrode is described to be used as amperometric biosensor for the detection of phenolic compounds in food. The enzyme has been immobilized by drop-coating on a glassy carbon electrode covered by a polyamidic nanofibrous membrane prepared by electrospinning. With respect to others, the selectivity of the designed tyrosinase-biosensor resulted modified by the presence of the nanostructured coating which seems to affect the permeability of phenols as a function of the pH of the solution and of their dissociation constants. The biosensor exhibits a response time of 16 s, a detection limit of 0.05 μM, and a linearity up to 100 μM (slope: −304 nA μM−1; intercept: −191 nA, r2 = 0.996, n = 19). Among others, it can be successfully used for monitoring in real time the release kinetics of phenols encapsulated in polymeric microcapsules
Electrochemical Reduction of Ellman's Reagent : A Novel Selective Detection Protocol for Thiol Compounds
No full textHerein we detail a novel approach to the detection of total sulfhydryl thiol species based on an electrochemical adaptation of the classical Ellman's reaction. The ability to electrochemically reduce the nitro moieties of both the parent 5,5-dithiobis(2-nitrobenzoic acid) (DTNB) and the resulting 5-thio-2-nitrobenzoic acid (TNBA) species provides a selective means of detecting thiol compounds. The use of the reductive sweep means that electrode passivation as a result of oxidative electrochemical procedures can be avoided and the selectivity improved through positioning the analytical signal within a region where few interferences reside. The electrochemical protocol enables the detection of the thiols in both acidic and basic media, which the colorimetric method is unable to do
Nanoemulsions for the determination of the antioxidant capacity of oils by an electrochemical method
No full textThe paper describes a rapid and simple method for the evaluation of the antioxidant capacity in oil in water nanoemulsion. This procedure does not require extensive sample treatment and, most important, does not use any organic solvent for dissolution of the fatty matrix. The nanoemulsions were directly injected in a flow injection (FI) system with an electrochemical detector equipped with a glassy carbon working electrode operating amperometrically at a potential of +0.8 V (vs. Ag/AgCl). Results obtained were compared with those obtained by the Oxygen Radical Absorbance Capacity (ORAC) assay
- …
