The effect of thermal treatment on antioxidant capacity and pigment contents in separated betalain fractions
Katarzyna Mikołajczyk-Bator , Sylwia Pawlak
AbstractBackground. Increased consumption of fruits and vegetables signifi cantly reduces the risk of cardio-vascular disease. This benefi cial eff ect on the human organism is ascribed to the antioxidant compounds these foods contain. Unfortunately, many products, particularly vegetables, need to be subjected to thermal processing before consumption. The aim of this study was to determine the eff ect of such thermal treatment on the antioxidant capacity and pigment contents in separated fractions of violet pigments (betacyanins) and yellow pigments (betaxanthins and betacyanins). Material and methods. Fractions of violet and yellow pigments were obtained by separation of betalain pigments from fresh roots of 3 red beet cultivars using column chromatography and solid phase extraction (SPE). The betalain pigment content was determined in all samples before and after thermal treatment (90°C/30 min) by spectrophotometry, according to Nilsson’s method  and antioxidant capacity was assessed based on ABTS. Betalain pigments in the separated fractions were identifi ed using HPLC-MS. Results. After thermal treatment of betacyanin fractions a slight, but statistically signifi cant degradation of pigments was observed, while the antioxidant capacity of these fractions did not change markedly. Losses of betacyanin content amounted to 13–15% depending on the cultivar, while losses of antioxidant capacity were approx. 7%. HPLC/MS analyses showed that before heating, betanin was the dominant pigment in the betacyanin fraction, while after heating it was additionally 15-decarboxy-betanin. Isolated fractions of yellow pigments in red beets are three times less heat-resistant than betacyanin fractions. At losses of yellow pigment contents in the course of thermal treatment reaching 47%, antioxidant capacity did not change markedly (a decrease by approx. 5%). In the yellow pigment fractions neobetanin was the dominant peak in the HPLC chromatogram, while vulgaxanthin was found in a much smaller area, whereas after heating additionally 2-decarboxy-2,3-dehydro-neobetanin was detected. Conclusion. Both groups of betalain pigments (betacyanins and betaxanthins) exhibit antioxidant capacity before and after heating. Violet beatacyjanins are 3 times more stable when heated than yellow betaxanthins.
|Journal series||Acta Scientiarum Polonorum Technologia Alimentaria, ISSN 1644-0730, e-ISSN 1898-9594, (B 15 pkt)|
|Publication size in sheets||0.5|
|Keywords in English||betalain pigments, red beet, thermal treatment, antioxidant capacity|
|Score|| = 15.0, 13-12-2019, ArticleFromJournal|
= 15.0, 13-12-2019, ArticleFromJournal
|Publication indicators||= 2; : 2016 = 0.682|
|Citation count*||11 (2020-08-11)|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.