Article info.

ABSTRACT

Received 30 Aug 2018
Revised 19 Jan 2019

Accepted 29 Mar 2019

The principle pigments from Vietnamese red dragon fruits (Hylocereus polyrhizus) were investigated qualitatively the first time by liquid chromatography connected to electrospray ionization tandem mass spectrometry approach (LC-ESI-MS/MS). Both betacyanins and betaxanthins were detected from the crude and purified extracts based on the maximum UV absorbance of 540 nm and 480 nm, together with the daughter ions at m/z 389 and 265, respectively. The main betacyanins were identified as betanin/isobetanin ([M+H]⁺ at m/z 551), phyllocactin/isophyllocactin (6’-O-malonylbetanin, [M+H]⁺ at m/z 637) and apiosyl-betanin/apiosyl-isobetanin ([M+H]⁺ at m/z 683) next to the minor derivative of hylocerenin/isohylocerenin ([M+H]⁺ at m/z 695), 2’-apiosyl-phyllocactin/2’-apiosyl-isophyllocactin ([M+H]⁺ at m/z 769) and traces of betanidin 5-O-β-sophoroside/isobetanidin 5-O-β-sophoroside ([M+H]⁺ at m/z 713). The primary yellow indicaxanthin was also recognized at m/z 309. These compounds appeared in different ratios in comparison with other Hylocereus polyrhizus cultivar reported before. Their degradation products of decarboxylation and dehydrogenation, namely decarboxy-betanin ([M+H]⁺ at m/z 507) and neobetanin ([M+H]⁺ at m/z 549) were also found in traces. These artifacts were not found in the fresh fruits and were suspected to be generated through harvesting and processing conditions of high temperature and sunlight.

Keywords

Betalains, betacyanins, betaxanthins, Hylocereus polyhizus (red dragon fruits), LC-ESI-MS/MS

Cited as: Thu, T.T.M. and Quang, D.V., 2019. Studies on betalains chemistry from the Vietnamese red dragon fruits (Hylocereus polyrhizus) by LC-ESI-MS/MS. Can Tho University Journal of Science. 11(1): 87-94.