1,720,971 research outputs found
Kinetic models for conventional and ultrasound assistant extraction of polyphenols from defatted fresh and distilled grape marc and its main components skins and seeds
No full textKinetic modeling is essential for industrial applications. The applicability of six mathematical models (parabolic diffusion, power law, Weibull's equation, Elovich's equation, second order rate, two- site kinetic models) to describe the kinetics of the conventional (CSLE) and ultrasound assistant extraction (UAE) of polyphenols (TPC) from fresh and distilled grape marc and its components, seeds and skins, after removal of non-polar compounds was studied. The best extraction yield of TPC for all the samples was obtained using UAE with ethanol-water mixture (57:43 v/v) as solvent, 200 W and 26 kHz after 30 min. The two-site kinetic model showed (R2 0.9965–1.000, NRMSD (%) 0.21–2.29) the best agreement with the experimental results. Important proanthocyanidins concentrations and significant antioxidant activity were observed both for fresh and distilled grape marc and its components. Fresh grape skins resulted particularly rich of oligomeric proanthocyanidins and the distilled ones of polymeric proanthocyanidins. These extracts could be used for different healthy purposes
Eau-de-vie de raisin de faible titre alcooométrique. Evaluation de techniques de distillation
No full textUltrasound-assisted extraction of proanthocyanidins from vine-shoots of Vitis vinifera.
No full textProanthocyanidins are high added value polyphenols which have received considerable attention for their health-protective activities. An alternative vine-shoots exploitation as a cheap source of proanthocyanidins obtained by ultrasound-assisted extraction was studied. Amplitude (50–100%), liquid-to-solid ratio (L/S) (50–100 mL/ g) and extraction time (10–30 min) were the variables studied by Box–Behnken design to maximize extraction of oligomeric proanthocyanidins (OPCs) and polymeric proanthocyanidins (PPCs) extracted from vine shoots at 80°C. Under the optimal conditions found and validated the OPCs resulted 89.18 ± 0.08 mg catechin/100 g DM and the PPCs 95.46 ± 0.65 mg catechin /100 g DM. The total proanthocyanidins content found in vine shoots was 1.82 mg/g DM and resulted higher than those reported for barley, whole grain rice and stored vine shoots
Broken and Intact Cell Model for supercritical carbon dioxide extraction of tea Camellia sinensis (L) seed oil
No full textThe model of broken and intact cells was used to fit the experimental data, and it was proved to be able to describe the extraction process of tea seed oil. The extraction rate, observed through the overall extraction curves (OEC), resulted in being faster the higher the pressure whereas the temperature had less influence on the extraction kinetics. The volume mass transfer coefficients in the fluid phase (kfa0) and solid phase (ksas) were used as fitting parameters. The maximum average deviation between measured and calculated oil yield was 4.1%. Mass transfer coefficients in the fluid phase and solid phase varied between 2.40·10−2–2.75·10−2 s−1 and 4.32·10−5–6.90·10−5 s−1, respectively. The outcomes of work showed the highest extraction yield (50.03 ± 0.68% w/w) obtained at 300 bar and 40 °C. Tea seed oil extracted using SC-CO2 presented higher antioxidant capacity and lower UV indices than oil extracted with n-hexane
Applicazione dell'anidride carbonica supercritica per l'estrazione di olio da semi di canapa (Cannabis sativa L.)
No full textEffect of commercial enzymatic preparation with pectolytic activities on conventional extraction and ultrasound-assisted extraction of oil from grape seeds (Vitis vinifera L.)
No full textSummary: Conventional solvent extraction (CE) and ultrasound-assisted extraction (UAE) in hexane for oil from untreated and enzyme-treated grape seeds were investigated and compared. Among the output power tested (50, 100 and 150 W) in UAE on untreated seeds, UAE at 150 W for 30 min with liquid-to-solid ratio 8:1 (v/w) gave oil extraction yield comparable to CE (ca. 14% w/w) for 6 h with liquid-to-solid ratio 12:1 (v/w). CE and UAE at 150 W did not influence the fatty acid profiles of oil. CE oil was found to be the most oxidised. The enzymatic treatments (2, 4 and 6 g per 100 g seeds of Rapidase® Expression) prior to CE enhanced by 2.5% of the oil yield. Enzymatic treatments higher than 2 g per 100 g seeds increased relative value of some fatty acids both in CE and UAE. Enzymatic pretreatment from 2 to 4 g per 100 g seeds significantly improved some physicochemical parameters of oil quality when extracted by CE, but not by UAE. © 2013 The Authors. International Journal of Food Science and Technology © 2013 Institute of Food Science and Technology
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
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