Beta-carotene isomer composition of sub- and supercritical carbon dioxide extracts. Antioxidant activity measurement.
ABSTRACT In the present work sub- and supercritical extraction conditions using carbon dioxide were studied in order to obtain extracts with different compositions from the green microalgae Dunaliella salina. Different compositions of beta-carotene isomers were identified in the extracts by using HPLC-DAD. Also, antioxidant activity of the extracts was measured using a TEAC assay. An experimental design was applied considering two factors, extraction pressure and temperature, in a wide range of values, trying to maximize the extraction yield. Higher yields were obtained at high pressures and low temperatures, that is, at higher CO2 densities. Attempts were made to correlate the antioxidant activity of the extracts with their chemical composition by means of principal component analysis. A certain relationship was found between their antioxidant activity and the isomeric composition of beta-carotenes. As a result, an original equation is proposed to predict the antioxidant activity of extracts from D. salina in terms of the ratio 9-cis-beta-carotene/all-trans-beta-carotene, the concentration of alpha-carotene, and, especially, the concentration of 9-cis-beta-carotene.
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ABSTRACT: In this study, experimental supercritical CO2 extraction of β-carotene from leaf skin of Aloe vera (Aloe barbadensis miller) was investigated and modeling of this system was developed in order to predict the extraction yield as a function of effective operating variables. The results of β-carotene extraction via supercritical CO2 were compared with the conventional Soxhlet extraction from almost 5 g of Aloe vera skin with 100 ml petroleum ether as solvent. The shrinking core model was applied in the simulation which is similar to irreversible desorption of a solute from a porous adsorbent. The modeling predictions are very well compatible with the experimental data. The β-carotene extraction yield was determined as a function of temperature, pressure, CO2 flow rate and dynamic extraction time. The genetic algorithm (GA) was used to determine the optimal operating conditions in which the maximum amount of β-carotene extraction yield was obtained.Journal of Supercritical Fluids The 12/2012; 72:312–319. DOI:10.1016/j.supflu.2012.10.005 · 2.57 Impact Factor
Recent Patents on Engineering 12/2012; 6(3):182-206. DOI:10.2174/187221212804583204
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ABSTRACT: The most abundant carotenoids present in tomato-based products were taken into account. Several samples coming from Italian stores have been analysed by using an RP - HPLC method. These products show a free carotenoids content proportional to the intensity of the manufacturing processes to which their are subjected. Among the carotenoids lycopene isomerises in various cis forms under different chemical - physical conditions. The lycopene antioxidant activity appears to be related to its trans - cis isomerisation degree, and the stability and the relative abundance of the isomers were investigated by applying heating and illumination. The cooking process seems to increase the total lycopene availabili- ty, whereas a prolonged exposure to a light source appears to be the best way to obtain the cis isomers. β-carotene is partially subjected to degradative processes, and do not shows an appreciable isomerisation degree under the same conditions.