Carrots carotenoid pigments

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. 

Investigation of the effects of water activity, salt, sodium metabisulfite, and Embanox-6 on the stability of carotenoids in dehydrated carrots shows that carotenoid pigments were most stable at 0.43a and addition of salt, metabisulfite, and Embanox-6 helped in stabilizing carotenoids in dehydrated carrots (Table 29.9) [71]. 

In leafy vegetables, -carotene usually amounts to 10-20% of total carotenoid content. As in carrots, other carotenoid pigments are various xanthophylls. Lutein, violaxanthin and neoxanthin usually occur in large amounts, while cryptoxanthin, zeaxanthin (the main carotenoid of maize), antheraxanthin and other xanthophylls are found in smaller amounts (Table 9.14). The presence of carotenoids is masked by chlorophylls. Lettuce Lactuca sativa, Asteraceae) is an example of a vegetable accumulating a higher amount of lactucaxanthin. 

Some carotenoid pigments are used as fresh or dried plant parts or extracts (so-called oleoresins) to impart colour to food (e.g. carrots, orange peels, tomatoes, saffron, annatto and paprika, which is made from dried and ground fruits of various Capsicum species and cultivars). Palm oil containing carotenoid pigments is also used for the same purpose. 

As a concrete example of CC separation of carotenoid pigments present in plants, this can be carried out by a prior separation on sUica column using methanol as eluent. In this first separation, three fractions of different polarity (carotenes, mono- and, polyhydroxylated xanthophylls) are obtained. Each fraction can be rechromatographed to give a second separation. Thus, for instance, the carotene fraction of carrots, tomatoes, and maize is separated on a column of MgO-Hyflo Super Cel. Other adsorbents (CaCOs, ZnCOs, polyethylene, cellulose, etc.) have been used to separate the carotenoids of pepper, tomato, carrot, etc. 

Many of the yellow, orange, and red colors of plants and animals are due to carotenoids, pigments similar to those of carrots. The basic structure of carotenoids is a chain of eight isoprenoid units. Certain isoprenoid derivatives with shorter chains (e.g., vitamin A) are also considered carotenoids. Most of the structural differences among carotenoids exist at the ends of the chain. Some carotenoids are hydrocarbons and are known as carotenes, while others contain oxygen and are called xanthophylls. The structures of several carotenoids, along with the foods or tissues in which they are present, are shown in Table I. 

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... 

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. 

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-... 

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. 

Carotenoids were discovered during the nineteenth century. Wachen in 1831 proposed the term carotene for the hydrocarbon pigment crystallized from carrot roots Berzelius called the more polar yellow pigments extracted from autumn leaves xanthophylls and Tswett separated many pigments by column chromatography and called the whole group carotenoids. ... 

Lobster and shrimp dine on carotenoid-containing plankton, and the compounds become concentrated in their shells. Here the carotenoids are bound up with protein molecules, and the carotenoid-protein complex has a dark green color. When the protein is heated, it is denatured. In other words, it breaks down and disassociates from the reddish pigment, astaxanthin, which then becomes visible. To a smaller extent this is also evident in cooked carrots, which become more orange than they were before. This was another experiment my daughter and I decided to try. We cooked up some fresh carrots to see if they would become more orange. They did, but the effect was not as pronounced as it was with the shrimp, because carrots have little protein. 

Many of the colors associated with higher plants (green leaves in the spring and summer, yellow or red leaves in the fall, the orange color of carrots, some colors in flower petals) are due to the presence of pigment molecules such as chlorophylls and carotenoids. In this experiment a mixture of these pigments will be isolated by solvent extraction of plant tissue, separated by chromatography, and the components identified by visible spectrophotometry. 

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