Changes in phenolic antioxidants during chuño production (traditional Andean freeze and sun-dried potato)

Total antioxidant capacity (TAC), total phenolic compounds (TPH), total flavonoids (TF) and the amounts of individual phenolic compounds were assessed in Bolivian potato cultivars (various Solanum species) before, during and after the traditional freezing and sun-drying of potatoes known as chuños. The TAC of chuños ranged from 0.4 to 2.7 μmol Trolox equivalents/g dry matter using 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) and from 0.7 to 3.0 according to the ferric reduction antioxidant power (FRAP). The values of TAC obtained using FRAP were about 70% lower after freeze-drying while they remained essentially constant when measured using ABTS. High-performance liquid chromatography showed the presence of epicatechin, chlorogenic acid, gallic acid, syringaldehyde and protocatechuic acid in both potato and chuño samples although the values were lower in the chuño samples. The results suggest that the antioxidant capacity and the content of individual phenolics are somewhat decreased but far from eliminated during the process. Chuño can therefore still be considered an important source of antioxidants in the diet.