Carrots carotenoids

The answer is a. (Murray, pp 505—626. Scriver, pp 4029-4240. Sack, pp 121-138. Wilson, pp 287-320.) In mammals, p-carotene is the precursor of retinal, which is the basic chromophore of all visual pigments. Isopen-tenyl pyrophosphate and dimethylallyl pyrophosphate are isoprenoid isomers formed from the repeated condensation of acetyl CoA units. By continued condensation in mammalian systems, cholesterol can be formed. In plant systems, carotenoids are formed. In addition to producing the color of tomatoes and carrots, carotenoids serve as the light-absorbing molecules of photosynthesis. Ketone bodies are derived from condensation of acetyl CoA units but not from isoprenoid units. Vitamin C (ascorbic acid), carnitine, and thiamine (vitamin BO are not derived from isoprenoid units. 

Provitamin A. Carotenoids are a large family of coloured compounds that are abundant in plants. About 10% of carotenoids have the P-ionone ring, which is needed for vitamin A activity, e.g. p-carotene found in carrots. Carotenoids have numerous double bonds that ensme they are efficient free radical scavengers and they can neutralise singlet oxygen. 

Carotenoids are natural pigments characterized by a tail to tail linkage between two C20 units and an extended conjugated system of double bonds They are the most widely dis tributed of the substances that give color to our world and occur m flowers fruits plants insects and animals It has been estimated that biosynthesis from acetate produces approximately a hundred million tons of carotenoids per year The most familiar carotenoids are lycopene and (3 carotene pigments found m numerous plants and easily isolable from npe tomatoes and carrots respectively... 

Fertile sources of carotenoids include carrots and leafy green vegetables such as spinach. Tomatoes contain significant amounts of the red carotenoid, lycopene. Although lycopene has no vitamin A activity, it is a particularly efficient antioxidant (see Antioxidants). Oxidation of carotenoids to biologically inactive xanthophyUs represents an important degradation pathway for these compounds (56). 

Carrot oil—The Hquid or the soHd portion of the mixture, or the mixture itself obtained by the hexane extraction of edible carrots (Daucus carota L.) with subsequent removal of the hexane by vacuum distillation. The resultant mixture of soHd and Hquid extractives consists chiefly of oils, fats, waxes, and carotenoids naturally occurring in carrots. 

An excellent case in point is the coloration of the American lobster, Homarus americanus. The pigment associated with the typical greenish-brown outer layer of the lobster shell is the carotenoid, astaxanthin (Figure A), an oxygenated derivative of p-carotene, also known as the molecule that imparts the orange color to carrots. 

The range (p,g/100 fresh weight) of lycopene and P-carotene in selected tomato cultivars can be 20-62000 and 35-2200 respectively, and of P-carotene and a-carotene in selected carrot cultivars 1100-64000 and 530-36000 respectively. Some of the carotenoids may be present as fatty acid esters (Breithaupt and Bamedi, 2001). More extensive listings can be found (O Neill et al, 2001 van den Berg et al, 2000 Hart and Scott 1995). 

Carrot crt genes from E. herbicola CaMV 35S 2-5 fold increase in root carotenoids Ausich et al., 1991 Hauptmann et al., 1997... 

Carotenoids are lipid-soluble pigments responsible for many of the brilliant red, orange, and yellow colors in edible fruits (lemons, peaches, apricots, oranges, strawberries, cherries, etc.), vegetables (carrots, tomatoes, etc.), fungi (chanterelles), flow-... 

Daily consumption of various fruits, vegetables, and derived juices contributes to human intake of carotenoids. The estimation of carotenoid intakes has been made possible throngh publication of the qnalitative and qnantitative carotenoid contents of commonly consnmed foods. Average intake estimates in the United States are around 6.5 mg/day. In seven conntries in Enrope, the average total carotenoid intake based on the snm of the five carotenoids was approximately 14 mg/day. When dietary source of carotenoids were analyzed, carrots appeared as the major sonrces of p-carotene in all conntries except Spain, where spinach was the main contribntor. 

Specific carotenoid-protein complexes have been reported in plants and invertebrates (cyanobacteria, crustaceans, silkworms, etc.), while data on the existence of carotenoproteins in vertebrates are more limited. As alternatives for their water solubilization, carotenoids could use small cytosolic carrier vesicles." Carotenoids can also be present in very fine physical dispersions (or crystalline aggregates) in aqueous media of oranges, tomatoes, and carrots. Thus these physicochemical characteristics of carotenoids as well as those of other pigments are important issues for the understanding of their bioavailability. 

Hedren, F., Diaz, V., and Svanberg, U., Estimation of carotenoid accessibility from carrots determined by an in vitro digestion method, Eur. J. Clin. Nutr, 56, 425, 2002. 

Among thermal processes, canning caused the largest trans-to-cis isomerization of provitamin A carotenoids, increasing the total cis isomers by 39% for sweet potatoes, 33% for carrots, 19% for collards, 18% for tomatoes, and 10% for peaches 13-di-P-carotene was the isomer formed in highest amonnts. ... 

Canning at 121°C for 30 min was also responsible for the highest losses of carotenoids in carrot juice, reaching 60% for P- and a-carotene, whereas the lutein level decreased 50%, all accompanied by the formation of 13-c -p-carotene in the largest amount, followed by 13-cA-lutein and 15-cA-a-carotene. Canning (T x = 121°C, F = 5) of sweet com resulted in a decrease of lutein by 26% and zeaxanthin by 29%, accompanied by increased amounts of 13-cis- lutein, 13 -CM-lutein, and 13-c/i-zeaxanthin. ° The relative amounts of cis isomers of lutein, mainly the 13-cis, increased by 15% and of 13-di-zeaxanthin by 20% after com canning." ... 

Losses of 45 to 48% in the P-carotene contents and formation of cis isomers were also verified by pasteurization of carrot juice at 110 and 120°C for 30 sec. No significant effects on trans-to-cis isomerization of a- and P-carotene isomers were observed after acidification and heating of carrot juice at 105°C for 25 sec. In addition, an increase of only 3% in the cis isomers of provitamin A carotenoids was observed after orange juice pasteurization. " ... 

The comparison of the light effect on carotenoids in foods is very difficult to carry out because different foods with different isomer compositions are employed at the beginnings of experiments. The presence of large molecules offers some photoprotection to carotenoids in food systems, either by complexation with proteins as found in carrots or acting as a filter to reduce the light incidence. Different storage conditions are often found because different light intensities are used or sometimes they are not even reported and experiments are carried out under air, N2, or in a vacuum. 

Heinonen, M.I., Carotenoids and provitamin A activity of carrot (Daucus carota L.) cultivars, J. Agric. Food Chem., 38, 609,1990. 

Ahneida, L.B. and Penteado, M.V.C., Carotenoids with provitamin A activity of carrots Daucus carota L.) consumed in Sao Paulo, Brazil, Rev. Farm. Bioquim. Univ. S. Paulo, 23, 133, 1987. 

Chen, B.H. and Tang, Y.C., Processing and stability of carotenoid powder from carrot pulp waste, J. Agric. Food Chem., 46, 2312, 1998. 

Chen, B.H., Peng, H.Y., and Chen, H.E., Stability of carotenoids and vitamin A during storage of carrot juice. Food Chem., 57, 497, 1996. 

Kopas-Lane, L.M. and Warthesen, J.J., Carotenoid photostability in raw spinach and carrots during cold storage, J. Food ScL, 60, 773, 1995. 

Fortuitously, the bacterial gene product, CRTI, produces di -trans carotenoids and satisfies the stereo-chemical specificity of LYC B for all-trani substrates while also catalyzing the four desaturation steps from phytoene to lycopene. Nevertheless, over-expression of Crtl has been shown to have only a modest effect (two- to fourfold increases in tomatoes and carrots) in increasing flux through the pathway and some unexpected pleiotropic influences on activities upstream and downstream of the desaturations (reviewed by Fraser and Bramley and Giuliano °). 

Most laboratories now employ C30 columns for separation of carotenoids from complex matrices. There are several examples for separation of carotenoids from foods such as orange, watermelon, mango, camu-camu, carrot, spinach, tomato, " sweet com, and potato. The C30 column systems shown in Table... 

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