EFFECT OF RED AND PURPLE FLESH POTATO VARIETIES ON ENZYMATIC DARKENING OF TUBERS AND ANTIOXIDANT PROPERTIES

Abstract

Background. Colored-flesh potato varieties are becoming more and more popular in Poland. One of the distinctive features of tuber quality is a tendency for the enzymatic darkening of flesh. The aim of the research was to determine the effect of red and purple flesh potato varieties on the change of their color immediately after cutting tubers, one hour and four hours after their cutting, and on the total polyphenol content and antioxidant activity. The research material was three purple flesh potato varieties: Provita, Double Fun, Violet Queen and three red flesh potato varieties: Magenta, Mulberry Beauty, Lily Rose. The raw material came from Polish producers from the 2020 and 2021 growing seasons. Basic chemical composition, total polyphenol content and ABTS+• (μM TROLOX/1g d.m.) and DPPH (μM TROLOX/1g d.m.), as well as antioxidant activity were determined for the potatoes. The color of tuber flesh and its changes were determined calorimetrically using a Minolta CR-200. Results and conclusions. Purple flesh potatoes were characterized by higher total polyphenol content (by 2%) and higher antioxidant activity of ABTS+• and DPPH• (71.2, and 21.0 μM TROLOX/1g d.m. respectively) in comparison to the red varieties (ABTS+• – 60.5 and DPPH – 15.5 μM TROLOX/1g d.m.). The potato varieties tested were characterized by a low tendency for the enzymatic darkening of tubers. The flesh of purple potatoes immediately after cutting was darker (L* 41.8 on average). It was also characterized by a higher share of blue (b* -2.8 on average) and a lower share of red (a* 3.8 on average) than for red flesh potatoes. The flesh of red potatoes after cutting was characterized by a color with a higher proportion of yellow shade (parameter b* was 7.2 on average), which did not change after four hours after cutting.