Effect of pH Changes on Antioxidant Capacity and the Content of Betalain Pigments During the Heating of a Solution of Red Beet Betalains

Abstract

Red beets and their products are mainly consumed after processing. In this study, the effect of pH on changes in antioxidant capacity (AC) and the content of betalain pigments were analysed during the heating of a betalain preparation solution. With pH ranging from 4 to 9 during the heat--treatment, the content of red pigments decreased depending on the pH level of the sample. The losses of red pigments in the investigated betalain preparation solution increased along with rising pH levels of the heated solution. The greatest losses were recorded at pH of 9.0. An opposite correlation was observed for yellow pigments. The content of yellow pigments in the heated betalain preparation solution was increasing along with increasing pH. The most pronounced increase in the content of yellow pigments was found at pH of 6.5 and 7.0. At the same time, the heated betalain preparation solution was shown to exhibit a higher antioxidant capacity at pH of 6.0 (14.9 μmol Trolox/mL) than at pH of 4.0 (12.6 μmol Trolox/mL). It was observed that the increase in the antioxidant capacity in heated betalain preparation solutions with pH in the 6.0-6.5 range occurred as a result of increased concentrations of neobetanin, assessed by HPLC, within the pH range from 5.0 to 6.5.

Betacyanins and Betaxanthins in Cultivated Varieties of Beta vulgaris L. Compared to Weed Beets

“…The stability of these molecules was further increased by glycosylation. Degradation of betalains in beetroots with a subsequent change of color was mainly a result of pH values that were out of the optimal range [ 43 ] or exposure to high temperatures where first order kinetic changes are involved [ 44 , 45 ]. These natural dyes are also sensitive to water content, light, oxygen, and the presence of certain metals [ 6 , 12 ].…”

Emerging technology approach for extractability and stability of betalains from the peel of beetroot (Beta vulgaris L.)

“…Besides, in the medium of pH > 7, the hydrolysis of betanin to betalamic acid and cyclo-dopa-5-O-glucoside can occur with the improvement of the yellowish brown color [11]. Mikołajczyk-Bator and Czapski [37] pointed out the correlational changes of heatinduced betalain pigments along with pH in which the loss of violet color was more intense within a pH range of 4-9; however, the yellow color-giving pigments increased with pH from 6.5 to 7. Probably, the improvement of yellow pigment is due to neo-derivatives of BC diversification via isomerization, deglycosylation, dehydrogenation, hydrolysis, deamination, and decarboxylation [38].…”

Red Beetroot Betalains: Perspectives on Extraction, Processing, and Potential Health Benefits

“…98 Betalains are also significant antiradical ingredients since they are efficient ROS scavengers. 99 The excellent antioxidant activity of betalains is due to their unique molecular structures, which is reflected by their capability to donate hydrogen to reactive species. Compared with betaxanthins, betacyanins have stronger antioxidant activity.…”