Color intensity (E1%), total anthocyanins (CAT), total polyphenol content (TPC) and antioxidant activity (FRAP) in tubers, for selected red flesh potato (INIA RS58-3), purple flesh potato (INIA RQ12-521), blue-violet flesh potato (INIA RÑ98-9) cultivated in Osorno (40°34′26.22”S, 73°8′0.53”W.), Chile during two seasons (2019-2020 and 2020-2021).
The potato is the fourth most important crop in the world in terms of human food, after maize, wheat and rice (FAOSTAT, 2019). The cultivated potato is a vital food-security crop considering its worldwide growth, from latitudes 65° Lat N to 53° Lat S, high yield, and great nutritive value. The potato is a good source of dietary energy and micronutrients, and its protein content is high in comparison with other roots and tubers. The cultivated potato is also a concentrated source of vitamin C and some minerals such as potassium and magnesium. Tuber flesh color generally ranges from white to dark yellow in cultivated potato; however, the high potato diversity shows tuber flesh color varies from white to dark purple. Red and purple-flesh potatoes are an interesting alternative for consumers due to phenolic compounds and antioxidant capacity. The goal of this publication is to show the advances in red and purple flesh potato, in terms of anthocyanin profile, color extraction and stability in simulated in vitro digestion.
- Antioxidant activity
- in vitro digestion
- Red and purple flesh potato
- Solanum tuberosum
The cultivated potato (
2. Color fleshed potatoes high in anthocyanins and antioxidant activity is promising food
2.1 Potato diversity in Chile
Chile is one of the countries with the largest potato diversity in the world and is also recognized as a center of origin (or center of diversity). Potato migration from the Andes to coastal Chile caused its adaptation to long-day conditions, this process contributed to the development of commercial cultivars worldwide . Chile is the origin of the
2.2 Cultivated potato and red-purple fleshed potatoes
Cultivated potato is a high valued crop because of its nutritional properties and biochemical composition, rich in starch, reducing sugars, non-reducing sugars, proteins, and carotenoids. Other important nutrients in potatoes include minerals and vitamins such as potassium, magnesium, vitamin C as well as vitamin B6, among others [10, 11]. Potatoes are a reliable source of ascorbic acid – ranged from to 5.8 to 21 mg of vitamin C per 100 g tuber on a fresh weight (FW) basis–, however several studies have reported changes in the content of vitamin C in potato tubers depending on variety [12, 13]. Potato flesh color ranged from white to dark yellow cultivars are the most common, a recent review showed that the total carotenoids content of tubers is influenced by location, season, genotype, and their interactions, with values between 5 and 10 mg kg−1 FW of total carotenoids, for white-fleshed potatoes, to over 100 mg kg−1 FW of total carotenoids for dark-yellow potatoes . Total carotenoids expression was observed in the mid of the tuber maturation process rather than in ready-to-harvest tubers. The predominant carotenoid forms found in cultivated potato were lutein, violaxanthin, zeaxanthin, and neoxanthin .
Today, with a major market shift for antioxidant-rich foods, the traders are also seeing an increase in the demand for red and purple fleshed potatoes, because these contain an important group of secondary plant metabolites associated with positive health benefits: phenolics, flavonoids, and anthocyanins . Red and purple fleshed potatoes provide a natural source of anthocyanins and antioxidant activity . Anthocyanins are recognized as natural flavonoid colorants ranged from orange-red (pelargonidin), reddish to blue-violet (malvidin), for use in food industry and pharmaceutical ingredients, because of their potential health benefits. The six predominant anthocyanidins found in higher plants (including root and tubers) are cyanidin, delphinidin, pelargonidin, peonidin, petunidin, and malvidin . The phenolics compounds, flavonoids, and anthocyanins are potent antioxidants which contribute to the physiological defense against oxidative and free-radical-reactions. Food containing anthocyanins have been associated with a reduction in inflammation markers and a lower risk of chronic diseases, including obesity, diabetes, cardiovascular disease, and cancer [19, 20]. In addition, a recent study showed that anthocyanins ameliorate neurodegeneration at a molecular and clinical level and dietary anthocyanin’s supplement prevents neurodegenerative diseases . Colored fleshed potatoes contain relatively low amount of total phenolic acids, but its flavonoids and flavones extracts showed high scavenging activities toward oxygen compared to other fruits and vegetables .
In relation to the predominant anthocyanidins, a study in four potato cultivars (“Hermanns Blaue”, “Highland Burgundy Red”, “Shetland Black”, and “Vitelotte”) identified Petunidin derivatives in all of them except in “Highland Burgundy Red”. Malvidin was the predominant on the “Vitelotte” cultivars. “Shetland Black” was the only one containing minor peonidin . The evaluation of anthocyanin phenolic compounds of potato peels from ten colored potato cultivars (red and purple) the most prominent were pelargonidin, peonidin, and malvidin aglycones. All samples revealed antioxidant and antitumor activities, and no toxic effect . Another recent study on colored potato (three red-fleshed, three-purple fleshed, and one marble-fleshed) showed that red and purple-fleshed potatoes are rich sources of anthocyanins. Pelargonidin and petunidin were the main anthocyanidin forms, and all aqueous extracts presented
Because most native color fleshed potatoes have low yield, wide phenotypic variations and uneven flesh color, the INIA Chile’s Potato breeding program has developed new putative color flesh potato cultivars as raw material to food coloring and ingredient extraction, with high anthocyanins flesh concentration and high yield. Table 1 shows significant differences in color intensity (E1%), total anthocyanins (CAT), total polyphenol content (TPC), and antioxidant activity (FRAP), for selected red flesh potato (INIA RS58-3), purple flesh potato (INIA RQ12-521), blue-violet flesh potato (INIA RÑ98-9). Principal component analysis and matrix of correlation coefficients showed a good fit between color intensity (E1%) and total anthocyanins (CAT) with values from 0.63 between E1% and CAT-based in tuber dry weight between 0.90 for E1% and CAT-based in tuber fresh weight. Both red (INIA RS58-3) and blue-violet (INIA RÑ98-9) fleshed potatoes showed higher color intensity and higher total anthocyanins (CAT), also these two potato lines showed higher values in total polyphenol content (TPC), and antioxidant activity (FRAP). Conversely, the light purple flesh potato (INIA RQ12-521) showed lowest color intensity and consequently lower CAT, TPC, and antioxidant activity. Thus, selected red flesh potato (INIA RS58-3) and blue-violet flesh potato (INIA RÑ98-9) are promising raw material for natural color extraction and food coloring ingredients.
|Color flesh Potato selected lines||Skin Color||Flesh Color||Tuber Shape||S.S.|
(mg C3G kg FW−1)
(mg EAG kg FW−1)
(μmol TroloxKg DW−1)
In term of Anthocyanin profile (Table 2), in these color fleshed potatoes, the predominant anthocyanins identified were Pelargonidin-3-glucoside, Peonidin-3-glucóside, Peonidin-3-arabinósido, Delphinidin 3-glucoside, Delphinidin 3-galactoside, Delphinidin 3-rutinoside, Delfinidina-3,5-diglucósido, Delphinidin 3-galactoside, Delphinidin 3-glucoside, Delphinidin 3-rutinoside, Malvidin-3-glucóside, and Malvidin-3,5-diglucóside. The major picks in red flesh potato (INIA RS58-3) were in Peonidin and Delphinidin derivatives, while in blue-violet flesh potato (INIA RÑ98
|Color flesh Potato selected lines||Skin Color||Flesh Color||Tuber Shape||Anthocyanin profile (predominants)|
|INIA RS58-3||RF||RF||Rd||Pelargonidin-3-glucoside, Peonidin-3-glucoside, Delphinidin 3-galactoside|
|INIARQ12-521||PF||PL||O||Peonidin-3-arabinósido, Delphinidin 3-glucoside, Delphinidin 3-galactoside, Delphinidin 3-rutinoside, Malvidin-3-glucóside,|
|INIARÑ98-9.||VB||VB||Rd||Peonidin-3-arabinósido, Delfinidina-3,5-diglucósido, Delphinidin 3-galactoside, Delphinidin 3-glucoside, Delphinidin 3-rutinoside,|
2.3 Stability and Bioaccesibility: potato anthocyanins
The concentration and stability of these anthocyanins are affected by several parameters such as agronomic factors and postharvest storage. However, the stability of acylated anthocyanins is still not well addressed, and few studies in anthocyanins contents (CAT) in colored-flesh potato tubers during processing and digestion have been published [25, 26]. The stability of anthocyanins is affected by pH, temperature, and light. During the digestion process, anthocyanins stability is affected because undergo variation in pH and in digestive enzymatic activity. Therefore, the anthocyanins stabilization is needed to maintain their health effects in the human body and increase its positive effects. The anthocyanins stability could be improved by using micro-encapsulation technology such as spray-drying [26, 27, 28]. Micro-encapsulation is a technique wherein a bioactive compound is encapsulated by a biopolymer, to protect the compound from oxygen, water, or other conditions, thereby improving its stability and release in the desired stage [26, 28]. In order to know bio stabilization of anthocyanins extract from purple flesh cultivated potato, a study was addressed on the encapsulation anthocyanins’ efficiency and bioaccesibility. The anthocyanin extract from INIA purple flesh potato (PPE) was micro-encapsulated by spray-drying  (Figure 1). Maltodextrin (MD) was used as the encapsulating agent, due to its high solubility in water, low viscosity, bland flavor, and colorlessness. Briefly, the mixture (extract PPE-maltodextrin) was fed into spray dryer at 130°C. The encapsulation efficiency (EE) was 86%, due the high anthocyanins-MD interactions caused by hydrogen bonding and/or electrostatic interactions. The total anthocyanins were 1.34 ± 0.02 mg cy-3-glug−1 and antioxidant activity (FRAP) was 10.1 ± 0.6 mg trolox equivalentg−1. The moisture (5.6 ± 0.4%), water activity (aw = 0.225 ± 0.001), and particle size (6.51 ± 0.1 um) were within the range described for anthocyanin encapsulated obtained by spray-drying [27, 30, 31].
PPE-MD encapsulation improved its anthocyanins stability due to anthocyanin extract and encapsulating agent interaction that may occur by hydrogen bonding and/or electrostatic interactions. Reduced damage of active anthocyanins was observed under adverse storage conditions. The time-course of the storage stability assay during 140 days at 60°C showed that encapsulated extract (PPE-MD) showed significantly higher anthocyanins retention than non-encapsulated PPE (Figure 2), thereby extending shelf life, color, and antioxidant capacity . These results agree with earlier reports on use of spray drying technique on black-carrot, black berry, maqui and plum [27, 32, 33, 34].
Other important aspect is the
2.4 Red and purple flesh potato-based food and natural ingredients responding to new global food market trends
The global consumer trend preferences and the health and wellness market in the next coming years, show a promising future for non-traditional color fleshed potato, as red, purple, and blue fleshed potato, because their antioxidant activity and health benefit are capturing the consumers’ attention. Most studies about market trends have projected that “the global health and wellness food market” would grow at a CAGR of over 6% (6–8%) during the next years. This forecast is explained in part, because the world, upon COVID-19 pandemic impact, will face the growing incidences of chronic diseases, stress, obesity, aging and other adverse health conditions, see more detail in [36, 37, 38] reports. In potato, some reports about its market under the COVID-19 pandemic situation shows that potatoes become popular due to their long shelf-life. In relation to global market, most potatoes are consumed as fresh vegetable, however, is shifting from fresh potatoes to processed potato-based foods. Based on application, the processed potato market is segmented into ready-to-cook, snacks, potato flour-gluten free, and other potato-based food additives for soups, gravies, bakery, and desserts driven by urbanization and changes in eating habits among many other factors. Thus, these global food market trends, raises further questions for food industry and R&D institutions, would be capable to develop new color fleshed potato-based foods and potato-based ingredients keeping its nutritional value and color.
A recent research studied how the anthocyanin degradation and anthocyanin profile were influenced in red-fleshed potatoes (cv Herbie 26) after different methods of processing (dried cubes, French fries, chips, semi-finished products, and finished products); most evaluated processes showed losses on anthocyanin content. Chip products showed higher retention anthocyanins. Pelargonidin-3-feruloylrutinoside-5-glucoside, and pelargonidin-3-caffeoylrutinoside-5-glucoside, were most thermally stable . To reduce the loss of effectiveness of plant-based compounds as anthocyanins, and polyphenols from color fleshed potatoes, micro-encapsulation arise as an alternative. This technique allows the development of novel plant-based ingredients able to keep their functionality after processing. However, commercial product development depends on financial and operational viability. In the previous section of this chapter, anthocyanins’ stability and bioaccesibility from color fleshed potatoes were discussed with emphasis in micro-encapsulation for INIA purple flesh potato and
Potato flake is an ingredient with multiple applications in processed food and long shelf life. A recent study compared the convective tray drying method with a refraction-based drying method for producing potato flakes (cv. Kufri Pukhraj, a light yellow to gold flesh potato). The results showed that those flakes obtained by refraction-based drying had better nutritive value, color and acceptability. It recommended its application for the fortification of flour, baby foods, and extruded products . Previously, a study in anthocyanin-rich red potato flakes showed that might improve the antioxidant system by enhancing hepatic SOD (superoxide dismutase) mRNA in mice . The replacement of part of the wheat flour with purple fleshed potato powder (from freeze-dried) and albedo showed an enhancement antioxidant activity of fortified breads, and longer shelf life . In addition to the previous reported health benefits, the purple fleshed potato powder (from freeze-dried) has the potential to aid in the amelioration of ulcerative colitis symptoms, a major form of inflammatory bowel disease .
Potato-based ingredients (flakes, spray dried powder, and freeze-dried powder) were elaborated from red flesh potato (INIA RS58-3), purple fleshed potato (INIA RQ12-521), and blue-violet flesh potato (INIA RÑ98-9) because their application in food industry (Figure 4). The spray dried powder shows better physical properties when compared to the freeze-dried powder. Conversely, freeze-dried powder preserves better the nutritional value such as naturally occurring. And, in spray dried powder the high temperature of heat may cause the loss of nutritional value. Red flesh potato (INIA RS58-3) and purple flesh potato (INIA RQ12-521) were selected for further evaluation because they fresh tubers show greater differences in color intensity. Potato-based ingredients as flakes and freeze-dried powder were compared (Table 3) for color intensity (E1%), total anthocyanins (CAT), and antioxidant activity (FRAP). As expected, freeze-dried powder preserved better the color intensity (E1%), total anthocyanins (CAT) and antioxidant activity (FRAP), however the flakes values were also attractive. These potato-based flakes and freeze-dried powder are food coloring because both ingredients provide color and bioactive compounds, with different applications.
|Potato-based ingredients||Color (E1%) Color intensity||CAT|
(mg C3G g−1) ingredient
(μmol Trolox g-1) ingredient
Red flesh INIA RS58-3
|0.42 ± 0.03 ab||1.9 ± 0.2 b||45.1 ± 1.2 b|
Purple flesh potato INIA RQ12-521
|027 ± 0.02 c||1.2 ± 0.3 c||47.0 ± 1.7 b|
Red flesh INIA RS58-3
|0.47 ± 0.01 a||2.7 ± 0.1 a||56.9 ± 4.9 a|
Purple flesh potato INIA RQ12-521
|0.39 ± 0.01 b||2.2 ± 0.2 ab||46.4 ± 0.6 b|
All these antecedents, suggest that red and purple fleshed potatoes are not only a promising crop for starvation problem, also their consume promote health and may prevent chronic diseases. Anthocyanin-rich extracts from red and purple fleshed potatoes have high potential as natural colorants with multiple applications in food industry. Also, these potatoes contain an important group of secondary plant metabolites associated with antioxidant activity and positive health benefits, as phenolics, flavonoids, and anthocyanins. INIA’s new putative color flesh potato cultivars (red flesh potato (INIA RS58-3), purple flesh potato (INIA RQ12-521), blue-violet flesh potato (INIA RÑ98-9)) are promising raw materials for natural color extraction and food coloring ingredients.
This chapter is a review the latest research on color fleshes potato and recent results of the authors on red to purple fleshed potato foodcoloring ingredients as well. We would like to acknowledge all authors cited in the references.
Acknowledgments to CONICYT-PAI I7817020005 and FIA PYT-2017-0488 grants.
Conflict of interest
The authors declare no conflict of interest.
Appendices and nomenclature
Instituto de Investigaciones Agropecuarias de Chile (Institute of Agricultural Research of Chile).
Compound annual growth rate.