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The present characterisation of cultivars and breeding lines with high concentrations of phytochemicals is an important step both to support the consideration of specialty potatoes as a source of healthy compounds, and to obtain new cultivars with positive nutritional characteristics. Moreover, by using near infrared spectroscopy a non-destructive identification and classification of samples with different levels of phytochemicals is achieved, offering an unquestionable contribution to the potato industry for future automatic discrimination of varieties.

Intensely pigmented potato tubers are desired for the speciality potato market because of the health-promoting effects of pigments and other related compounds. Although highly coloured potatoes show higher concentrations of carotenoids and anthocyanins and higher antioxidant capacity, the phytochemical composition is highly dependent on environmental factors. Thus, the effects of genotype, environment and genotype × environment interactions on monomeric anthocyanins, soluble phenolics, carotenoids and hydrophilic antioxidant capacity were evaluated in a set of cultivars selected on the basis of the contrasting flesh colour of tubers. Twenty-one tetraploid potato genotypes were grown in three different field trials at Arkaute and Iturrieta for 2 years. Genotype, environment and genotype × environment interactions were significant for all of the studied parameters (P ≤ 0.01). However, most of the variation was accounted for by clonal variation. Broad-sense heritabilities (and their 95% confidence intervals) were 0.947 (0.832–0.981) for total monomeric anthocyanins, 0.917 (0.852–0.952) for total soluble phenolics, 0.950 (0.911–0.975) for total carotenoids, and 0.887 (0.799–0.945) and 0.850 (0.734–0.927) for hydrophilic antioxidant capacity measured by ABTS and DPPH methods, respectively. Although certain instabilities were recorded for all of the studied traits, the high estimates of heritability support the main role of genetics in phytochemical composition and suggest that sufficient heritable genetic variation exists in tetraploid potato germplasm for the breeding of advanced clones with improved bioactive properties.

A total of four traits related to bioactive potential of the tetraploid potato were studied in a North Carolina II cross‐experiment. The objectives of this study were to estimate genetic parameters for target bioactive compounds in a tetraploid potato population, to determine phenotypic and genotypic correlations and to calculate combining ability effects of cultivars and breeding lines included in the crossing scheme. Total monomeric anthocyanins, phenolics, carotenoids and hydrophilic antioxidant capacity were measured by spectrophotometric methods. The sources of variation female (GCAf), male (GCAm) and their interaction (SCA) were significant for bioactive compounds and antioxidant capacity. Narrow‐sense heritability estimates (h2) were moderate for all the traits (0.413–0.657). Both phenotypic and genotypic correlations were highly significant for phenolic compounds and antioxidant capacity. As regards combining ability, positive and negative GCA and also SCA effects have been identified for bioactive compounds and antioxidant capacity. These results indicate that hybrid breeding lines can be obtained by choosing parents with significant GCA, whose bioactive potential can also be further enhanced if the crosses have a significant SCA.

Color is considered as an important quality trait of food products. The blue, purple or red colors of several fruits and vegetables are due to the presence of anthocyanins. Scientific evidence suggests that these pigments are health‐promoting compounds and there is some research focused on the development of anthocyanin‐based natural colorants. However, anthocyanins levels can be altered through the action of several factors during food processing and storage. In this study, prevention of degradation of anthocyanins in potato extracts through combining the addition of gallic acid as copigment and the presence or absence of light with different temperatures was investigated. The four studied factors were statistically significant (P ≤ 0.01), but genotype showed the major effect, followed by light, temperature and gallic acid addition. The stability of anthocyanins can be increased throughout the combination of low temperature (T = 4C), absence of light and gallic acid addition (pigment : copigment molar ratio 1:50). Practical Applications Besides having important biological roles, such as antioxidant activity, anti‐inflammatory and anticarcinogenic properties, anthocyanin‐rich plant extracts might have potential as food colorants. In fact, colored potatoes have been suggested to be a great source of anthocyanins and a potential source of natural colorants. The major problem of anthocyanin‐based natural colorants is their instability under nonacidic normal processing and storage conditions. With the aim of preventing the degradation of anthocyanins to colorless phenolics and insoluble brown compounds, there have been several studies conducted through the addition of different additives. In the present study, the stability effect of gallic acid as a copigment was investigated in different conditions, considering two important factors that influence the preservation of anthocyanins (temperature and light) in purple and red‐fleshed potato extracts. Our results contribute to the development of preparation processes of food products and colorants derived from colored potatoes with increased anthocyanin content and color intensity.

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Purple- and red-fleshed potato cultivars constitute a great source of phenolic compounds, which may promote human health. Since the characterization of potato germplasm is a key step during the breeding process, the classification of high anthocyanin-producing tetraploid genotypes may facilitate the incorporation of phenolic-related traits in a potato breeding programme. A set of 18 high anthocyanin-producing underutilized tetraploid cultivars, which have been previously classified in terms of phytochemical content, have been characterized by both microsatellite markers (simple sequence repeat, SSR) and morphological descriptors. A wide genetic variability was found using 11 highly discriminatory SSR markers. The collection also displayed a large amount of variation for most morphological traits. The neighbour-joining trees defined by SSR markers and morphological descriptors revealed genetic and phenotypic relatedness of the potato genotypes. Despite the complexity of tetrasomic inheritance, high anthocyanin-producing tetraploid cultivars should be considered for potato breeding since they are adapted to long-day conditions and do not present undesirable characteristics that are found in native accessions or landraces.