**2.1. Carotenoids**

Due to their intense and striking colors, carotenoids have always been a subject of interest of scientists. The first report of isolation of these substances is from 1831, from the carrot (*Daucus carota* L.), which also gave rise to the name of the class, derived from the English "carrot" [1]. The first separation and purification processes of carotenoids are attributed to the Russian botanist Tswett [2], who invented the liquid chromatography for the separation of carotenoids from colored leaves [5]. Tswett also gave rise to the concept of a family composed of many compounds, carotenoids, among them carotenes (composed only of very apolar carbon and hydrogen molecules, like lycopene, β-carotene, α-carotene) and oxygenated derivatives and xanthophylls composed of oxygenated functions, such as ketones, ethers, hydroxides, epoxides, methoxides, or carboxylic acids (less apolar molecules such as lutein, zeaxanthin, cryptoxanthin).

Carotenoids have aliphatic or acyclic structures (open chain) and alicyclic or cyclic structures (closed chain). Cyclic or alicyclic carotenoids can be monocyclic (when there is a ring) or bicyclic (when there is more than one ring) [5]. β-Carotene is the most commonly found of these compounds, accounting for 25–30% of the total carotenoid content of plants [6] or even more in some of them.

Due to their double-bonded conjugate system, carotenoids exhibit ultraviolet and visible spectral absorption characteristics, and most have maximum absorption at three wavelengths, resulting in a spectrum consisting of three peaks. The greater the number of conjugated double bonds in the carotenoid, the greater the spectrum wavelength [7].

According to Krinsky et al. [8], at least seven conjugated double bonds are necessary for a carotenoid to have color, as in the case of ζ-carotene, which gives a yellow color to passion fruit. As the conjugate system is extended, the color also intensifies. Therefore, lycopene with 11 conjugated double bonds gives rise to the red color of tomatoes (*Solanum lycopersicum*). Cyclization places the double bonds within the rings, outside the plane of those of the polyene chain, decreasing their coloration. Thus, γ-carotene, with a double conjugated ring-located bond, is reddish orange, while β-carotene with two of these ring bonds is orange (carrot), although both have conjugated double bonds as does lycopene.

(*Cucurbita maxima, C. pepo,* and *C. moschata*), as well as orange and yellow sweet potatoes, are usually good sources of carotenoids including α and β-carotene. On the other hand, the yellow sweet and bitter cassava (*Manihot esculenta*) roots were studied by Oliveira et al. [3], which found lower contents of β-carotene. To improve these contents, many efforts have

Carotenoids are chemically defined as C40 tetraterpenoids (naturally occurring hydrocarbons and their derivatives), obtained by the union of eight isoprenoid (C5) units of five carbon

The purpose of this chapter is to offer some information about some raw plant materials

Due to their intense and striking colors, carotenoids have always been a subject of interest of scientists. The first report of isolation of these substances is from 1831, from the carrot (*Daucus carota* L.), which also gave rise to the name of the class, derived from the English "carrot" [1]. The first separation and purification processes of carotenoids are attributed to the Russian botanist Tswett [2], who invented the liquid chromatography for the separation of carotenoids from colored leaves [5]. Tswett also gave rise to the concept of a family composed of many compounds, carotenoids, among them carotenes (composed only of very apolar carbon and hydrogen molecules, like lycopene, β-carotene, α-carotene) and oxygenated derivatives and xanthophylls composed of oxygenated functions, such as ketones, ethers, hydroxides, epoxides, methoxides, or carboxylic acids (less apolar molecules such as lutein,

Carotenoids have aliphatic or acyclic structures (open chain) and alicyclic or cyclic structures (closed chain). Cyclic or alicyclic carotenoids can be monocyclic (when there is a ring) or bicyclic (when there is more than one ring) [5]. β-Carotene is the most commonly found of these compounds, accounting for 25–30% of the total carotenoid content of plants [6] or even

Due to their double-bonded conjugate system, carotenoids exhibit ultraviolet and visible spectral absorption characteristics, and most have maximum absorption at three wavelengths, resulting in a spectrum consisting of three peaks. The greater the number of conjugated dou-

According to Krinsky et al. [8], at least seven conjugated double bonds are necessary for a carotenoid to have color, as in the case of ζ-carotene, which gives a yellow color to passion fruit. As the conjugate system is extended, the color also intensifies. Therefore, lycopene with 11 conjugated double bonds gives rise to the red color of tomatoes (*Solanum lycopersicum*). Cyclization places the double bonds within the rings, outside the plane of those of the polyene

ble bonds in the carotenoid, the greater the spectrum wavelength [7].

been made through the biofortification.

containing high and lower carotenoid contents.

**2. Raw plant materials**

zeaxanthin, cryptoxanthin).

more in some of them.

**2.1. Carotenoids**

atoms [4].

108 Progress in Carotenoid Research

The detection of carotenoids, after separation by liquid chromatography methods, occurs in a characteristic absorption zone between 400 nm and 500 nm wavelength; the detection in cisor *Z*- isomers usually occurs between 330 and 340 nm. The intensity of absorption is affected by the solvent or the composition of the mobile phase used in the analysis [7].

Carotenoids consist of a wide range of substances, with great structural diversity and varied functions, of which more than 600 have already been identified and had their chemical structures elucidated. They are probably the most occurring pigments in nature, and the many different colors we see are the result of the presence and combination of these different compounds [8].

The official nomenclature of carotenoids was established in 1974 by the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Biochemistry [9].

They stand out commercially in the production of rations for breeding sites (fish, crustaceans, and poultry) and are used as food dyes and in aromas. In addition to the food industry, carotenoids play an important role in the pharmaceutical industry due to their nutritional and functional properties, as precursors of vitamin A, antioxidant activity, among others [10].

They can be divided into two groups: carotenes and xanthophylls. Carotenes are pure hydrocarbons, which have an orange to red coloration. This group includes β-carotene, α-carotene, ζ-carotene, δ-carotene, and lycopene. β-Carotene is the most commonly found of carotenes, accounting for 25–30% of the total carotenoid content of plants and even more in some of them [6].

It is also the most active carotenoid, with the highest bioconversibility in the human body, covering 15–30% of all serum carotenoids. β-Carotene is described as a suppressor of tumorigenesis in the skin, lung, liver, and colon, promoting the cessation of the cycle of cell multiplication. It also shows a suppression activity superior to that promoted by α-carotene [11]. Lycopene does not have pro-vitamin A activity but is considered as the carotenoid with the highest singlet oxygen sequestration capacity, possibly due to the presence of two unconjugated double bonds, which make it more reactive [12, 13].

Thermal processing can lead to important changes in the sensory characteristics and the content of antioxidant compounds, altering the antioxidant potential of foods. Conditions such as time, temperature, and style of cooking are determinants for the increase or decrease of the total antioxidant activity [14].

The biological activity of carotenoids depends on their bioaccessibility and solubilization in the gastrointestinal tract. Due to their lipophilic nature, these compounds do not disperse well in the aqueous medium of the gastrointestinal tract. Therefore, it is important to analyze how food matrix and processing affect their bioaccessibility. Rodriguez-Roque et al. [15] formulated beverages with mixtures of fruit juices and water, milk, and soy applying three treatments: high intensity pulse electric fields, high pressure processing, and thermal treatment, to evaluate bioaccessibility of carotenoids and on lipophilic antioxidant activity. Bioaccessibility of carotenoids was reduced after all treatments, except for *cis*-violaxanthin and neoxanthin, which increased 79% in beverages treated with high intensity pulse electric fields and high pressure processing. The thermal treatment presented worst decreasement of the bioaccessibility in 63%. High-intensity pulse electric fields and high pressure processing can be considered as promising technologies to obtain nutritive and functional beverages.

The average found for the centesimal composition in orange flesh sweet potato was moisture—83.91 g 100 g−1, ash—0.52 g 100 g−1; protein—0.69 g 100 g−1; lipids—0.10 g 100 g−1; carbo-

Carotenoids in Raw Plant Materials

111

http://dx.doi.org/10.5772/intechopen.78677

The orange sweet potato pulps have the potential to be used as food-based supplements to reduce vitamin A deficiency since β-carotene is one of the carotenoids with pro-vitamin A activity for human diet, exerting important functions in human physiology, acting as antioxidants, as protective pigments of the human retina, and as precursors of retinoids that influ-

Orange-fleshed sweet potato (OFSP) is a carotenoid-rich vegetable. Thermal treatment to process sweet potatoes can decrease the contents of these compounds in foods, reducing their bioactive properties. Raman spectroscopy can be employed as a fast tool in food analysis, especially to detect low concentrations of carotenoids and to monitor their degradation profile along time. Sebben et al. [28] evaluated two drying methods, hot air and microwave in a rotating drum, coupled to quantitative Raman spectroscopy. A 50% decrease in the carotenoid contents were found for both types of drying methods. The results were reproducible. The best linear correlations were R2 = 0.90 for hot air and 0.88 for microwave dried samples,

Vitamin A deficiency (VAD) is a public health problem in some regions of Brazil. Enhancement of the use of orange-fleshed sweet potatoes as a pro-vitamin A source can be a strategy for prevention of this deficiency. Berni et al. [29] compared the pro-vitamin A contents, vitamin A equivalencies and β-carotene (βC) bioaccessibilities of two varieties (*Beauregard* and Amelia) of home-cooked orange sweet potatoes and two commercial ones. Pro-vitamin A carotenoid content in home cooked *Beauregard* variety was higher than in Amelia variety and in commercial products for babies. All-*trans*-βC was the most abundant carotenoid in all samples (raw, cooked, and commercial) as expected. Boiling and frying decreased total β-carotene. According to them, a portion of 100 g fresh weight of *Beauregard* contained over 100% of the estimated average requirement for children and women and up to 92% estimated average requirement for lactating women. The efficiency of micellarization of all-*trans*-βC after the in vitro digestion was relatively low (4–8%) and significantly less than for *cis*-isomers, the amounts of *trans*-βC captured into micelles from boiled *Beauregard* and fried Amelia varieties were higher than in micelles obtained from the digestion of commercial ones. Bioaccessibility of pro-vitamin A carotenoids in the micelle fraction of digested OFSP was confirmed in assays of Caco-2 human intestinal cells. They suggested that agricultural development of these two varieties: Amelia and *Beauregard* (biofortified), riches in *trans*-βC, and the improvement of home cooking styles can be strategies to increase the consumption of this food to reduce VAD

Islam [27] analyzed total carotenoids and *trans* and cis-β-carotene in different varieties of raw and cooked orange-fleshed sweet potato (OFSP) aiming to reduce VAD using plant-based foods. Intravarietal difference in carotenoids as well as in *trans* and *cis-*β-carotenes were found both in raw and boiled potatoes. Carotenoid content was higher in raw potatoes compared to boiled samples from the same variety, as expected by solids dissolution. Amongst the varieties, Kamalasundari (BARI SP-2) contained the highest amount of carotenoids both in raw and boiled samples. The β-carotene was significantly higher in Kamalsundari and BARI SP-5

hydrates—13.42 g 100 g−1, respectively, with a caloric value of 57.34 kcal 100 g−1 [19].

ence gene expression [27].

respectively.

in Brazil.
