Vol. 62, 2016, No. 10: 474–481 Plant Soil Environ. doi: 10.17221/459/2016-PSE Carotenoids in potatoes – a short overview J. Lachman1, K. Hamouz2, M. Orsák1, Z. Kotíková1 1Department of Chemistry, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czech Republic 2Department of Crop Production, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czech Republic ABSTRACT Carotenoids are one of major lipophilic constituents contributing to total antioxidant activity and provitamin con- tent of potato, a major non-cereal staple food. The review briefly discusses health promoting properties of carot- enoids and especially their contents and composition in different potato cultivars affected by flesh colour (white-, yellow-, purple- and red-fleshed) and the effect of selected factors on carotenoid total and individual levels, such as genotype, breeding, tuber development, heat processing – cooking, storage, effect of year, locality, etc. The aim of the recent research is obtaining potatoes with higher levels of beneficial carotenoids to improve one the most popu- lar vegetables in the world. Keywords: phytonutrients; Solanum tuberosum; xanthophylls; thermal processing and storage Carotenoids are effective antioxidants with 2007, Fernandez-Orozco et al. 2013). The colour of important health-promoting functions such as potato tubers of conventional cultivars depends on provitamin A activity, enhancement of the im- carotenoid content and composition (Hejtmánková mune system and reduction of cardiovascular et al. 2013) and tuber yellow intensity is positively disease or cancer and help in the prevention of correlated with total carotenoid content. In the atherosclerosis (Bonierbale et al. 2009). The higher review main factors affecting carotenoid levels, consumption of carotenoids can protect consum- such as genotype, climate and growing conditions, ers and therefore considerable interest is currently storage and cooking processes, are discussed. being shown in the screening and development of Characteristics of carotenoids by their chemi- food crops with increased concentrations of total cal composition. Carotenoids are an important and individual carotenoids (Stahl and Sies 2005). group of natural organic pigments synthesized Potato is the fourth most important staple food from plants that are naturally occurring in the crop after rice, wheat and maize, and it contains a chloroplasts and chromoplasts of photosynthetic wide range of phytochemicals, including phenolic organisms, such as plants and algae, and some compounds such as chlorogenic acid, anthocyanins fungi and bacteria (Valcarel et al. 2015). All share in purple and red-coloured potatoes and carot- a tetraterpenoid structure of 40 carbon atoms, a enoids (Tierno et al. 2015, Lachman et al. 2016). long conjugated chain of double bonds in the centre Hence, potato tubers are considered an important of the molecule (chromophore) and near symme- source of bioactive compounds, which are highly try around the central double bond. They may be desirable in diet (Ezekiel et al. 2013), although the split into two classes, xanthophylls (which contain concentrations of different phytochemicals are af- oxygen) and carotenes (which are purely hydrocar- fected by cooking and other processes (Lachman bons and contain no oxygen) (Rao and Rao 2007). et al. 2013). In particular, native potato germplasm Carotenoids serve two key roles in plants and algae: can be considered a great source of variability for they absorb light energy for use in photosynthesis, increased tuber nutritional value (Burgos et al. and they protect chlorophyll from photodamage. 474 Plant Soil Environ. Vol. 62, 2016, No. 10: 474–481 doi: 10.17221/459/2016-PSE Role and significance of carotenoids in human be used as a tool to differentiate between white- or nutrition and their health benefits. Higher ani- yellow-fleshed cultivars. Fernandez-Orozco et al. mals are incapable of biosynthesizing carotenoid, so (2013) claimed that the total carotenoid contents these pigments are essentially indigested through for all cultivars ranged from 0.50–15.5 mg/kg the diet as precursors for retinol (vitamin A) DW, although most of the samples had less than biosynthesis. Provitamin A activity is the ability 10.0 mg/kg DW, with an average value of about of carotenoids to form vitamin A (retinol and 4.35 mg/kg DW; however 50% of the RDA of vita- retinal) by the action of carotene dioxygenase. min A can be met by consuming 250 g of enriched Any carotenoid containing at least one unmodified genetically engineered potatoes. β-ionone ring may be cleaved to provide provitamin The different types of xanthophylls show vari- A activity. Thus, provitamin A active carotenoids able concentrations in various potato genotypes include β-carotene, α-carotene, γ-carotene and with lutein predominating and varying amounts β-cryptoxanthin. Although provitamin A activity is of zeaxanthin, violaxanthin, and others reported. the major function of carotenoids, potent antioxi- The main carotenoid was lutein in all cultivars dant activity of carotenoids through singlet oxygen (54–93%); furthermore violaxanthin, neoxan- quenching and deactivation of free radicals play thin, zeaxanthin and β-carotene were identified in important roles in the prevention of certain types most of the analysed samples (Hejtmánková et al. of cancer, cardiovascular diseases, and macular 2013). The carotenoid analysis showed a similar degeneration (Müller et al. 2015). Apart from this, qualitative composition for all potato cultivars, carotenoids play important roles in cellular and with the following substances being identified: organelle function. β-Carotene inhibits inflam- all-trans-neoxanthin, 9’-cis-neoxanthin, all-trans- matory gene expression in lipopolysaccharide- violaxanthin, 9-cis-violaxanthin, antheraxanthin, stimulated macrophages with possible anti-obesity lutein-5,6-epoxide, all-trans-lutein, 9-cis-lutein, positive role (Williams et al. 2013). Generally, ca- 13-cis-lutein, all-trans-β-cryptoxanthin and all- rotenoids are involved in embryonic development, trans-β-carotene (Fernandez-Orozco et al. 2013). gap junction communication, immune modula- Two groups of pigments were assigned to par- tion, cell differentiation, anti-inflammation, bone tially (monoesters for dihydroxy-xanthophylls) metabolism, anti-angiogenesis, anti-proliferation, and totally esterified carotenoids (monoesters hematopoiesis, antioxidant activity, skin health, of monohydroxy-xanthophylls and diesters for apoptosis and good vision (Saini et al. 2015). dihydroxy-xanthophylls). The lack of zeaxanthin Content of total and individual carotenoids in all samples should be remarked, in contrast to in potato tubers. Recent findings suggest that other studies which have reported that zeaxanthin carotenoid pool size is determined, at least in part, is a major carotenoid in many potato cultivars by the activity of carotenoid cleavage dioxygenases (André et al. 2007a,b). Kotíková et al. (2016) re- (Campbell et al. 2010). Higher levels of total ca- ported that yellow cultivars showed a much higher rotenoids were found in the skin of tubers, with average total carotenoid content (26.2 mg/kg DW) maxima values of 28 and 9 mg/kg dry weight (DW) when compared to red/purple-fleshed potatoes in skin and flesh, respectively. Yellow-skinned or (5.69 mg/kg DW). Yellow cultivars were dominated fleshed tetraploid cultivars also had higher con- by antheraxanthin, whereas neoxanthin was the tents than those with paler or white tissues, with main carotenoid in red/purple cultivars. no relationship found for other colours (Valcarel Potato, which usually accumulates lutein and vio- et al. 2015). Carotenoid concentrations in some laxanthin, was modified to accumulate zeaxanthin diploid potatoes were reported up to 22 times (Römer et al. 2002) in yellow-fleshed potato by higher than in white-fleshed potatoes (Haynes et transformation of neoxanthin epoxidase and it may al. 2011). The content of carotenoids is affected by also result in an increase in transcript for protein cultivar and locality. Hamouz et al. (2016) reported fibrillin evolved in carotenoid storage (DellaPenna that the content of total carotenoids in analysed and Pogson 2006). Metabolic engineering was cultivars ranged in 1.10–12.2 mg/kg DW and was recently applied to potato in order to increase the influenced by genotype cultivar, locality and year. provitamin A content (Diretto et al. 2007), with a Breithaupt and Bamedi (2002) suggested that the resulting increase of 20-fold and 3600-fold for total total concentration of carotenoids in potatoes could carotenoid and β-carotene content, respectively, 475 Vol. 62, 2016, No. 10: 474–481 Plant Soil Environ. doi: 10.17221/459/2016-PSE in the biofortified ‘golden potato’. Broad-sense orange flesh. Total carotenoids content was re- heritability estimates were high for total carot- ported in the range of 0.50–3.50 mg/kg FW and enoid (0.81), lutein (0.77), zeaxanthin (0.73), and 8.00–20.0 mg/kg FW, respectively, in white- and the lycopene beta-cyclase pathway carotenoids yellow-fleshed potato cultivars (Brown et al. 2008). (0.73); moderate for neoxanthin (0.42); and low Researchers have been able to increase carotenoids for violaxanthin (0.21) and antheraxanthin (0.13) content considerably using transgenic approaches. (Haynes et al. 2011). Carotenoids and their contents Ducreux et al. (2005) were able to increase tuber reported