B-carotene

COLORANTSFORFOOD,DRUGS,COSTffiTICSANDTffiDICALDEVICES] (Void) b-Carotene pigment [7235-40-7]... 

Fiore, A. et al.. Elucidation of the b-carotene hydroxylation pathway in Arabidopsis thahana, FEBS Lett. 580, 4718, 2006. 

Sun, Z., Gantt, E., and Cunningham, J., Cloning and functional analysis of the b-carotene hydroxylase of Arabidopsis thaliana, J. Biol. Chem. 271, 24349, 1996. 

Carotenoids are present at low levels in tea leaf.60 Neoxanthin, violaxanthin, lutein, and B-carotene are the major components of this group. They enter into reactions that lead to aroma formation.61... 

Johansson, L.B.-A., G. Lindblom, A. Wieslander, and G. Arvidson. 1981. Orientation of b-carotene and retinal in lipid bilayers. FEBS Lett. 128 97-99. 

Mehraban, Z. and Farzaneh, F. (2005) MCM-41 as selective separator of chlorophyll-a from b-carotene and Chlorophyll-a mixture. Micropor. Mesopor. Mater., 88, 84. 

An elegant approach using three bacterial genes overexpressed in Desiree achieved a 20-fold increase in total carotenoids to 114 p-g/G DW and a 3600-fold increase in B-carotene to 47 pg/g DW (Diretto et al., 2007). A 250 g serving of these potatoes was estimated to provide 50% of the RDA of vitamin A. Potatoes engineered to have higher zeaxanthin levels were fed to human subjects and the zeaxanthin was found to be readily bioavailable (Bub et al., 2008). 

Dugas, T.R., Morel, D.W., and Harrison, E.H. 1999. Dietary supplementation with b-carotene, but not with lycopene inhibits endothelial cell-mediated oxidation of low-density lipoprotein. Free... 

Fuhramn, B., Elis, A., and Aviram, M. 1997. Hypocholesterolemic effect of lycopene and b-carotene is related to suppression of cholesterol synthesis and augmentation of LDL receptor activity in macrophage. Biochem. Biophys. Res. Commun. 233, 658-662. 

Many studies have been conducted on the volatile thermal degradation products of carotenoids. Several authors have reported the formation of toluene and xylene as TDP of bixin and capsanthin (18) and B-carotene (10, 11, 18-25), as well as canthaxanthin (26). 

In addition, 2,6-dimethylnaphthalene was reported to be formed from thermally treated carotenoids (11, 17, 20-29). The formation of ionene as a TDP of B-carotene has been reported (11, 19, 22). The presence of a- and B-ionones have also been reported (24, 25). 

Among the other reported volatile TDP of B-carotene include B-cyclo-cltral, 5,6-epoxy-B-ionone and dihydroactinidiolide (25). These compounds were also found by Isoe et al. (30, 31), Wahlberg et al. (32) and Kawakami and Yamanishi (33) as photo-oxygenation products of B-carotene. Volatile thermal degradation of carotenoids has been extensively studied, mainly in nonfood systems. Hence, the objective of this study was to identify the volatile components of the TDP of B-carotene formed in a food model system. 

The second class of volatile products observed were hydrocarbons, namely the ionene compounds. The formation of these hydrocarbons during heating is also reflective of deodorization and frying conditions. The formation of low molecular weight aromatic hydrocarbons results from fragmentation of the carotene molecule. The losses of toluene and ionene compounds from B-carotene yield do-decahexaene and octatetraene, respectively. These nonvolatile degradation products have been previously reported in our laboratory (13, 14). 

To clarify the role of B-carotene to the aroma of roasted green tea, B-carotene was heated in a pyrolyzer at 180°C for 6 minutes. The reaction was carried out under air with and without catechin gallates, a component of tea leaves. The volatile products were trapped in a precolumn cooled by dry ice/acetone. The precolumn was then connected to a GC capillary column and the volatiles then analyzed by GC-MS. 

Table IV. Ionone Related Compounds Identified in the Thermal Degradation of B-Carotene...

The addition of catechins (sample B) greatly reduced these products. Thus catechins show a similar effect on the pyrolysis of B-carotene and L-theanine. (Yamanishi, T. Hamada, T. unpublished.)... 

It has been shown that the aroma of tea is affected by the heat treatment received. Tea aroma and flavor are greatly influenced by catechins and proceeds by more than one pathway. The catechins influence tea aroma and flavor in three ways. First, catechins have a bitter, astringent taste. Second in order to reduce the level of soluble catechins (i.e. in var. assamica), a second heat treatment is required. This refiring produces a stronger roast aroma. Third catechins strongly influence the pyrolysis of B-carotene and L-theanine. 

Since the terminal groups do not affect the electronic excitation characteristics of the polyenes, these dyes are invariably very long, b-carotene involves 11 conjugate bond groups to achieve absorption at a wavelength of450 nm and 478 nm, e=135,000 and 120,000 respectively. Retinol, being much shorter, exhibits a peak absorption at 325 nm, e=52,480 in ethyl alcohol. 

Cancer The increased risk of cancer in vitamin deficiency is thought to be the result of depletion in beta-carotene. Beta-carotene is a very effective antioxidant and is suspected to reduce the risk of cancer is known to be initiated, by the production of free radicals. Of particular interest is the potential benefit of increased b-carotene intake to reduce the risk of lung cancer in smokers. However, caution needs to be taken when increasing the intake of any of the lipid soluble vitamins. 

Novotny JA, Dueker SR, Zech LA. Compartmental analysis of the dynamics of B-carotene metabolism in an adult volunteer. J Lipid Res 1995 36 1825-38. 

---