Phenolic Acid Content and Antioxidant Properties of Edible Potato (Solanum tuberosum L.) with Various Tuber Flesh Colours

The aim of the paper was to evaluate the phenolic acid content and antioxidant properties in potato cultivars with coloured flesh and bright flesh. The study material included eight cultivars of edible potato grown in a temperate climate in Poland. Five cultivars were potato tubers with coloured flesh: Rote Emma, Blue Salad, Vitelotte, Red Emmalie, and Blue Congo; and three were potato tubers with bright flesh: Bella Rosa, Lord, and Tajfun. In all potato samples under study, four phenolic acids were identified: chlorogenic acid, gallic acid, p-coumaric acid, and caffeic acid. The predominant acid was chlorogenic acid, the levels of which ranged from 62.95 mg center dot 100 g(-1) FM to 126.77 mg center dot 100 g(-1) FM. The total concentration of the identified phenolic acids was diverse and depended on the genotype of the cultivar and the tuber flesh colour, with coloured-fleshed potatoes having higher phenolic acid contents in comparison to bright-fleshed potato cultivars. The average concentration of phenolic acids in the samples was 89.19 mg center dot 100 g(-1) FM, and the average concentrations of the individual phenolic acids identified were as follows: chlorogenic acid (86.19 mg center dot 100 g(-1) FM), gallic acid (1.18 mg center dot 100 g(-1) FM), p-coumaric acid (0.64 mg center dot 100 g(-1) FM), and caffeic acid (1.18 mg center dot 100 g(-1) FM). In addition, three groups of anthocyanins were identified: pelargonidin-3,5-di-O-glucoside, peonidin-3,5-di-O-glucoside, and petunidin-3,5-di-O-glucoside. Anthocyanins were not found in the Lord or Tajfun varieties characterised by white tuber flesh. The predominant pigment was petunidin-3,5-di-O-glucoside, with an average content of 23.15 mg center dot 100 g(-1) FM, and the highest value was observed in the Vitelotte variety (51.27 mg center dot 100 g(-1) FM). The antioxidant activity of the flesh of the potatoes under study was diverse depending on flesh colour. The FRAP (Ferric Reducing Antioxidant Power) assay indicated higher antioxidant activity of coloured-fleshed potato cultivars. The highest concentration was identified in the Vitelotte cultivar flesh and was 114% higher than in the Lord cultivar. Similar dependencies were found in the case of the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay; however, in this case, the Vitelotte cultivar flesh demonstrated nearly 6.4 times higher antioxidant activity than the Lord cultivar. Summarizing our own research, we can conclude that potato varieties with coloured flesh are characterised by a higher content of biologically active substances, including phenolic acids, and antioxidant properties compared to potato tubers with bright flesh.

Automated summary

The aim of the study was to evaluate the phenolic acid content and antioxidant properties in potato cultivars with coloured flesh and bright flesh. It was found that potato cultivars with coloured flesh had higher levels of phenolic acids and better antioxidant properties compared to bright-fleshed potato cultivars.