Apparent increase of vitamin C (ascorbic acid) levels in potato (Solanum tuberosum) chips: vitamin C-like additives or impurities

Abstract

Vitamin C (Ascorbic acid) levels in Irish potato (Solanum tuberosum) tubers purchased from shops and open markets in Cardiff, U.K. were determined in the raw, boiled and fried (chips) pieces by 2,6, Dichlorophenolindophenol dye (DCP) method in the laboratory. The chips were prepared in sunflower oil, corn oil and animal fat (Lard with antioxidant E. 321) respectively. Attempt was made to confirm the presence of vitamin C in the chips extracted by thin chromatography (TLC). Results obtained showed that the raw potato pieces contained 7.20–14.53mg vitamin C/100g, boiled pieces contained 3.54–8.88 vitamin C/100g while the chips pieces contained comparatively higher (7.92–17.00mg vitamin C/100g) level of the vitamin. The boiled potato pieces lost for greater amount (63–75%) of the vitamin C than the chips (<25%) cooked for the same length of time probably due to solubility and oxidation of the vitamin. The vitamin C level in the chips prepared in animal fat (Lard with antioxidant E. 321) with a mean value 13.67mg vitamin C/100g was comparatively but not significantly higher than those prepared in sunflower (10.04mg vitamin C/100g) and corn oil (10.65mg vitamin C/100g) respectively. This could probably be because of the additive of other impurities contained in the fat capable of reacting with the 2, 6, Dichlorophenolindophenol dye. The results obtained were generally not significantly (P>0.05) influenced by the oil types used. Results obtained revealed that thin layer chromatography (TLC) method demonstrated the presence of vitamin C in the sample extracts. The vitamin did not, however move freely as the control suggesting that vitamin C in potatoes exist in a bound or combined form. The experiment results revealed that the chips contained higher mean vitamin C (10.9mg vitamin C/100g) than the boiled pieces (6.6mg vitamin C/100g), potato chips may not be a reliable source of vitamin C because of the bound or combined nature of the vitamin.

Keywords: vitaminC, ascorbic acid, potato, Solanum tuberosum

Plant Products Research Journal Vol. 9 2005: 1-5