1,721,283 research outputs found
DOC, DOP e IGP : il legame con il territorio e l’aspetto salutistico del vino e dei frutti rossi
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Evoluzione dello stile di vita e delle abitudini alimentari e ripercussioni sulla salute
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Determination of steviol glycosides in commercial extracts of Stevia rebaudiana and sweeteners by ultra-high performance liquid chromatography Orbitrap mass spectrometry
Full text linkStevia rebaudiana extracts are used as sweeteners in several countries worldwide. Several extracts of diverse composition are available on the market, and their taste depends on the contents of the various steviol glycosides. This study presents an accurate method for the qualitative and quantitative determination of steviol glycosides in 40 Stevia extracts, 7 sweeteners and 3 Stevia-sweetened beverages by a UHPLC coupled to an Orbitrap mass spectrometer. The sub-2 μm amide column provided the separation of all the target analytes in a run time of 30 min with high resolution. The effect of different eluent compositions on the ionisation efficiency of the steviol glycosides was studied. The optimal ionisation conditions were achieved in negative mode using 0.05% formic acid. Under this condition, adducts were not found, [M-H]- were the main ions and the spontaneous loss of a glucose residue at C19 was reduced. The %RSD for intra- and inter-day precision for all eleven analytes varied from 2.1–4.2% and 3.0–5.1%, respectively. The recoveries from spiked Stevia extract samples were greater than 95% for all analytes. Rebaudioside A was the most abundant, ranging from 23–102%. Nine Stevia extracts and one drink were not compliant with the European Regulation. Isosteviol was under the LOD in all samples and steviol was found in four samples in quantities in the range 0.01–0.03%
DIETARY FLAVONOIDS AND INTERACTION WITH ENDOGENOUS ANTIOXIDANTS
No full textGreen tea catechins were given to healthy volunteers under controlled diet for 4 consecutive weeks. Plasma concentrations of ascorbate, urate, -tocopherol, -carotene and blood levels of total glutathione were measured before, after the supplementation and the wash-out period. RBC membranes were assayed for their levels of -tocopherol and phosphatidylcholine PUFA’s. Catechin intake provides antioxidant protection in vivo through a cascade involving endogenous antioxidants, which interact differently according to their redox potentials and polarity. As a final beneficial effect, liposoluble vitamin E and -carotene are spared by catechins, resulting in an overall protection against oxidative modification of RBC membrane PUFA’s
Componente proteica e carboidratica delle globuline di Lupinus Albus: aspetti metodologici per la valutazione
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