The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Ulf Svanberg - One of the best experts on this subject based on the ideXlab platform.
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effects of various traditional processing methods on the all trans β carotene content of orange fleshed sweet potato
Journal of Food Composition and Analysis, 2008Co-Authors: Anton Bengtsson, A Namutebi, Larsson M Alminger, Ulf SvanbergAbstract:Abstract The effects of traditional preparation methods and drying procedures on the provitamin A carotenoid content of orange-fleshed sweet potato (OFSP) roots was determined by a high-performance liquid chromatography (HPLC) method. All-trans-β-carotene was the major provitamin A carotenoid and the mean content of seven improved OFSP cultivars ranged from 108 to 315 μg/g dry matter. The retention of all-trans-β-carotene was 78% when OFSP were boiled in water for 20 min. When OFSP were steamed for 30 min the retention was 77%, whereas deep-frying OFSP roots for 10 min resulted in retention levels of 78%. Drying slices of OFSP roots at 57 °C in a forced-air oven for 10 h reduced the all-trans-β-carotene content by 12%. Solar drying and open-air sun drying OFSP slices to a moisture content of ⩽10% resulted in all-trans-β-carotene losses of 9% and 16%, respectively. The cis-isomer 13-cis-β-carotene was found in noticeable amounts in all processed samples, but not in any raw samples. The formation of 13-cis-β-carotene correlated with the original amount of all-trans-β-carotene found in the raw OFSP root. The high content of all-trans-β-carotene in the investigated improved OFSP varieties and the moderately low losses due to degradation and isomerization renders OFSP a suitable food source of provitamin A.
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Effect of traditional open sun-drying and solar cabinet drying on carotene content and vitamin A activity of green leafy vegetables
Plant Foods for Human Nutrition, 2003Co-Authors: Ulf Svanberg, Generose MulokoziAbstract:Dried green leafy vegetables constitute a major dietary source of provitamin A carotenoids for people living in semi-arid areas of Tanzania. In the present study, eight vegetable varieties commonly consumed in these areas were either traditionally sun-dried or solar-dried, and the amount of provitamin A carotenoids were determined by HPLC. In the fresh blanched leaves, the contents of β-carotene, α-carotene, 9-cis-β-carotene and 13-cis-β-carotene were in the range of 526–917, 12–39, 80–136 and 16–40 μg/g dry matter/basis; dmb, respectively. The average amounts of all-trans-β-carotene in the leaves after blanching, solar drying and open sun-drying were 662, 502 and 353 μg/g dmb, respectively, all significantly different from each other (p
I. P. Terenetskaya - One of the best experts on this subject based on the ideXlab platform.
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Photoisomerization of Provitamin D in Hydrogel Matrix
2013Co-Authors: I. P. Terenetskaya, Yu. M. Samchenko, T. N. Orlova, N. Pasmurceva, P. S. Kapinos, I. E. Boldeskul, Z. R. Ul'bergAbstract:Study of interfacial processes between incorporated biomolecules and hydrogel matrix is of primary importance for the application of synthetic hydrogels as biomaterials, sensors, etc. Their hydrophilic nature, however, hampers fat-soluble biomolecule incorporation. We synthesized N-isopropylacrylamide (NIPAAm)- and Acrylamide (AA)-based hydrogels with hydrophilic-lipophilic balance that under specific conditions permit homogeneous incorporation of Provitamins D3(7-dehydrocholesterol) and D2(ergosterol) dissolved in ethanol. Similarity of Provitamins D photoisomerization in such hydrogel matrices with the photoreaction in ethanol shows great potential of the novel material for personal dosimetry of biologically active ‘antirachitic’ UV radiation.
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Specific features of provitamin D3 photoisomerization in a cholesteric liquid crystal
Optics and Spectroscopy, 2010Co-Authors: T. N. Orlova, I. P. TerenetskayaAbstract:The method of UV absorption spectroscopy is used to study the influence of the cholesteric pitch on the efficiency of previtamin D (photoisomer of provitamin D3) cis-trans isomerization in a cholesteric liquid crystal (nematic + optically active dopant + provitamin D3). It is found that a change in pitch from 14 to 0.364 μm due to an increase in the concentration of an optically active dopant in a wide range (1.6–61 wt %) only slightly reduces the efficiency of the cis-trans isomerization. However, small changes in pitch (0.364–0.368 μm) due to an increase in the provitamin D3 concentration within the range of 0.07–2.2 wt % significantly increase the efficiency. Reducing in the influence of provitamin D3 concentration on the cis-trans isomerization efficiency with an increase in mesophase temperature was found in both nematic and cholesteric liquid crystals up to the disappearing of the concentration dependence in the isotropic phase. Altogether, the obtained results indicate the collective character of cis-trans isomerization in liquid crystals due to the ordering of the medium.
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Limitations of the photostationary approximation in the photochemistry of provitamin D: The ambiguous role of the irreversible degradation channel
Theoretical and Experimental Chemistry, 2008Co-Authors: I. P. TerenetskayaAbstract:The limitations of the generally accepted photostationary approximation in the photochemistry of provitamin D resulting from the strong spectral dependence of the effectiveness of the irreversible channel were established theoretically by a simplified model. The results show clearly that disregard of the irreversible channel with low quantum yield in a system of reversible photochemical reactions over a wide spectral range is not always justified. As a result the approximation according to which the concentration of the main photoisomers of provitamin D is constant only holds in a specific region of the spectrum, and this must be taken into account during concentration analysis of the photoisomeric mixture.
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Specific features of photoisomerization of provitamin D 3 in a nematic liquid crystal
Optics and Spectroscopy, 2006Co-Authors: T. N. Orlova, I. P. TerenetskayaAbstract:Photoisomerization of provitamin D3 (7-dehydrocholesterol) in a nematic liquid crystal (ZLI-1695, Merck) is investigated in detail by UV absorption spectroscopy. It is found that dissolution of chiral molecules of provitamin D3 induces the cholesteric phase in a nematic. The spectral kinetics of photoisomerization in this phase changes significantly from that in an ethanol solution. A sharp nonmonotonic dependence of the increase in accumulation of trans isomer tachysterol in a liquid crystal matrix with a decrease in the induced cholesteric pitch from 2200 to 25 μm is revealed.
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Study of the kinetics and quantum efficiencies in the photochemistry of provitamin D using a tunable laser
Soviet Journal of Quantum Electronics, 1991Co-Authors: S I Gundorov, I. P. Terenetskaya, V A Davydenko, O I YushchukAbstract:An experimental investigation was made of the kinetics of the photoisomerization reactions of provitamin D initiated by a tunable laser at various wavelengths in the 260–305 nm range. The quantum efficiencies of the reversible photoreactions were constant within the provitamin absorption band and substantial changes occurred only when the irradiation was at the long-wavelength wing (λ > 300 nm). In contrast, a nonmonotonic dependence of the quantum efficiencies on the radiation wavelength was exhibited by the irreversible photoreactions.
Delia B Rodriguezamaya - One of the best experts on this subject based on the ideXlab platform.
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occurrence of cis isomers of Provitamins a in brazilian vegetables
Journal of Agricultural and Food Chemistry, 1998Co-Authors: Helena Teixeira Godoy, Delia B RodriguezamayaAbstract:Because cis isomerization lowers provitamin A activity, concern has been raised over the necessity of separating the provitamin A isomers in determining the vitamin A values of foods. Sixteen different raw vegetables and eight cooked vegetables (total of 123 samples) were analyzed to appraise the occurrence of cis isomers. The raw vegetables analyzed, except tomato and carrot, had cis isomers (trace to 3.4 μg/g 13-cis-β-carotene and trace to 4.1 μg/g 9-cis-β-carotene). The trans-β-carotene range was 1.1−38.4 μg/g. Appreciable amounts of α-carotene were found only in carrot (16.5−19.0 μg/g trans-α-carotene) and in a cultivar of squash (0.3 μg/g 13-cis-α-carotene, 17.1 μg/g trans-α-carotene, and 0.1 μg/g 9-cis-α-carotene). The vitamin A values were calculated with and without isomer separation, using currently accepted biological activities, showing overestimations of 10−22% when the isomers were not separated. Cis isomers were found in all samples of cooked vegetables analyzed; the overestimations ranged f...
Anton Bengtsson - One of the best experts on this subject based on the ideXlab platform.
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effects of various traditional processing methods on the all trans β carotene content of orange fleshed sweet potato
Journal of Food Composition and Analysis, 2008Co-Authors: Anton Bengtsson, A Namutebi, Larsson M Alminger, Ulf SvanbergAbstract:Abstract The effects of traditional preparation methods and drying procedures on the provitamin A carotenoid content of orange-fleshed sweet potato (OFSP) roots was determined by a high-performance liquid chromatography (HPLC) method. All-trans-β-carotene was the major provitamin A carotenoid and the mean content of seven improved OFSP cultivars ranged from 108 to 315 μg/g dry matter. The retention of all-trans-β-carotene was 78% when OFSP were boiled in water for 20 min. When OFSP were steamed for 30 min the retention was 77%, whereas deep-frying OFSP roots for 10 min resulted in retention levels of 78%. Drying slices of OFSP roots at 57 °C in a forced-air oven for 10 h reduced the all-trans-β-carotene content by 12%. Solar drying and open-air sun drying OFSP slices to a moisture content of ⩽10% resulted in all-trans-β-carotene losses of 9% and 16%, respectively. The cis-isomer 13-cis-β-carotene was found in noticeable amounts in all processed samples, but not in any raw samples. The formation of 13-cis-β-carotene correlated with the original amount of all-trans-β-carotene found in the raw OFSP root. The high content of all-trans-β-carotene in the investigated improved OFSP varieties and the moderately low losses due to degradation and isomerization renders OFSP a suitable food source of provitamin A.
Guangwen Tang - One of the best experts on this subject based on the ideXlab platform.
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Vitamin A value of plant food provitamin A - evaluated by the stable isotope technologies.
International journal for vitamin and nutrition research. Internationale Zeitschrift fur Vitamin- und Ernahrungsforschung. Journal international de vi, 2020Co-Authors: Guangwen TangAbstract:Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.
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Carotenoids as Provitamin A
Carotenoids, 2020Co-Authors: Guangwen Tang, Robert M. RussellAbstract:In 1930, Moore discovered that β-carotene (3) could be converted in vivo into vitamin A [1]. Since then, the vitamin A values of β-carotene and other provitamin A carotenoids, particularly α-carotene (7) and β-cryptoxanthin (55), have been investigated by various techniques. As discussed in Chapter 9, vitamin A nutrition is of worldwide interest; deficiency of the vitamin remains a problem in developing countries, affecting 75 to 140 million children [2]. Deficiency of vitamin A (VAD) can result in visual malfunction such as night blindness and xerophthalmia [3], and can impair immune function [4], resulting in an increased incidence and/or severity of respiratory infections, gastrointestinal infections [5], and measles [6]. Vitamin A levels in HIV-positive children are lower than those in HIV-negative children [7]. Open image in new window
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Genetic variation of carotenoids, vitamin E and phenolic compounds in Provitamin A biofortified maize
Journal of the Science of Food and Agriculture, 2016Co-Authors: Tawanda Muzhingi, Natalia Palacios-rojas, Alejandra Miranda, Maria L. Cabrera, Kyung‐j. Yeum, Guangwen TangAbstract:Biofortified maize is not only a good vehicle for provitamin A carotenoids for vitamin A deficient populations in developing countries but also a source of vitamin E, tocochromanols and phenolic compounds, which have antioxidant properties. Using high-performance liquid chromatography and a total antioxidant performance assay, the present study analyzed the antioxidant variation and antioxidant activity of 36 provitamin A improved maize hybrids and one common yellow maize hybrid.; Results: The ranges of major carotenoids in provitamin A carotenoids biofortified maize were zeaxanthin [1.2-13.2 µg g-1 dry weight (DW)], β-cryptoxanthin (1.3-8.8 µg g-1 DW) and β-carotene (1.3-8.0 µg g-1 DW). The ranges of vitamin E compounds identified in provitamin A carotenoids biofortified maize were α-tocopherol (3.4-34.3 µg g-1 DW), γ-tocopherol (5.9-54.4 µg g-1 DW), α-tocotrienol (2.6-19.5 µg g-1 DW) and γ-tocotrienol (45.4 µg g-1 DW). The ranges of phenolic compounds were γ-oryzanol (0.0-0.8 mg g-1 DW), ferulic acid (0.4-3.6 mg g-1 DW) and p-coumaric acid (0.1-0.45 mg g-1 DW). There was significant correlation between α-tocopherol and cis isomers of β-carotene (P
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Vitamin A value of plant food provitamin A - evaluated by the stable isotope technologies.
International Journal for Vitamin and Nutrition Research, 2014Co-Authors: Guangwen TangAbstract:Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the...
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Bioconversion of dietary provitamin A carotenoids to vitamin A in humans
The American Journal of Clinical Nutrition, 2010Co-Authors: Guangwen TangAbstract:Recent progress in the measurement of the bioconversion of dietary provitamin A carotenoids to vitamin A is reviewed in this article. Methods to assess the bioavailability and bioconversion of provitamin A carotenoids have advanced significantly in the past 10 y, specifically through the use of stable isotope methodology, which includes the use of labeled plant foods. The effects of the food matrix on the bioconversion of provitamin A carotenoids to vitamin A, dietary fat effects, and the effect of genotype on the absorption and metabolism of β-carotene have been reported recently. A summary of the major human studies that determined conversion factors for dietary β-carotene to retinol is presented here, and these data show that the conversion efficiency of dietary β-carotene to retinol is in the range of 3.6–28:1 by weight. There is a wide variation in conversion factors reported not only between different studies but also between individuals in a particular study. These findings show that the vitamin A value of individual plant foods rich in provitamin A carotenoids may vary significantly and need further investigation.
