BIOACTIVE COMPOUNDS IN YELLOW, LIGHT YELLOW, AND CREAM-COLOURED POTATO TUBERS AFTER SHORT-TERM STORAGE AND BOILING

Abstract

This study measured the changes in bioactive compounds [L-ascorbic acid (AA) and total phenolic (TP) compounds] and antioxidant activity (measured in Trolox equivalents, TE) in six potato (Solanum tuberosum L.) varieties with yellow, light-yellow, and cream-coloured flesh after several different treatments. The experimental materials included raw tubers and peeled and unpeeled potato tubers that had been cooked. Analyses were conducted immediately after harvest and after 3 months of storage at 5°C and 8°C. Flesh colour significantly affected the AA and TP contents in tubers. The difference between the AA content in cream- and yellow-coloured tubers was 12.5%, and between cream and light-yellow tubers was 16.5%. Differences in TPs between the different flesh colours did not exceed 33%. Significant losses of AA were found in yellow- and light-yellow-fleshed tubers that had been peeled and cooked after harvest (44 and 46%, respectively). Cooking peeled tubers significantly decreased the antioxidant activity in potatoes regardless of the flesh colour and storage treatment. The unpeeled cooked tubers had significantly higher antioxidant activities than raw tubers after harvest. Irrespective of the flesh colour, high linear correlations were found between (AA)×(TE) for cooked peeled tubers. A significant determination coefficient (R²) was observed between (TPs)×(TE) for raw and cooked unpeeled light-yellow and yellow-coloured tubers. The linear relationship between TPs and TE after cooking was significant for unpeeled tubers. The greatest matching of the model characteristics of the interdependence of features (O²) (AA) x (TE) was 75%, and for the model TPs and TE 80%.