The eff ect of thermal treatment on antioxidant capacity and pigment contents in separated betalain fractions

Abstract

Background. 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 [1970] 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.

Natural color pigments: oxidative stability and degradation kinetics during storage in thermally pasteurized vegetable purees

“…Pasteurization significantly ( P < 0.05) affected the betalain content of beet puree with a 12.8–13.9% and 10.1–11.1% reduction of betacyanins and betaxanthins, respectively depending upon the film type, with larger losses in the high OTR film. Other studies have reported losses of between 6–81% and 13–73% in betacyanins and betaxanthins, respectively, during thermal treatments of red beets and beet products . According to Herbach et al, betaxanthins are more sensitive to thermal treatment than betacyanins.…”

“…Other studies have reported losses of between 6-81% and 13-73% in betacyanins and betaxanthins, respectively, during thermal treatments of red beets and beet products. [20][21][22][23] According to Herbach et al, 4 betaxanthins are more sensitive to thermal treatment than betacyanins. However, in the present study, betaxanthins showed higher retention than betacyanins.…”

The effect of processing and in vitro digestion on the betalain profile and ACE inhibition activity of red beetroot products

“…The highest percentage of decarboxylated derivatives was found in the peel. This phenomenon could be a result of exposing red beetroots to light and temperature, causing the transformation of betacyanins into decarboxylated forms (Mikołajczyk-Bator & Pawlak, 2016;Wybraniec, 2005).…”

Recovery of Phytochemicals via Electromagnetic Irradiation (Microwave-Assisted-Extraction): Betalain and Phenolic Compounds in Perspective

“…Their presence incites the fluorescence property of betaxanthin [4,38]. From the findings of Mikołajczyk-Bator and Pawlak [41], thermal degradation of red-violet pigments was three times lower than yellow color given compounds despite the antioxidant capacity of the latter, which tends to be higher after heat treatments.…”

“…Those neo-derivatives are of interest due to their yellow color appearance derived from thermal degradation of Beta vulgaris and Opuntia species betanin [37]. Most degradation processes of betacyanin are isomerization, deglycosylation, dehydrogenation, hydrolysis, and decarboxylation [5,37,41]. Betalamic acid which is core structure of betalain, (b) Amino acid which conjugates with betalamic acid to derive betaxanthin, (c) Yellow color giving betaxanthin, (d) Vulgaxanthin I which is a derivative of betaxanthin, (e) cyclo-DOPA which condenses with betalamic acid to give betacyanin, (f) Red-violet color giving betacyanin, and (g) Betanin which is a derivative of betacyanin [2,5,14,27,28,37,42].…”