Evaluation of different methods for betanin quantification in pitaya (Stenocereus spp.)
Spectrophotometry UV-Vis, with calibration curve (SWCC), High-performance liquid chromatography (HPLC), and Spectrophotometry with an extinction coefficient (SWEC) were used for betanin quantification in pulp and peel of pitaya (Stenocereus spp). The concentrations of pulp betanin measured by the three analytical methods did not differ significantly, as assessed by the Scheffe method (P > 0.05). The mean of pulp betanin was 2.092 mg/g dry sample. With respect to the peel samples, there was a significant difference: a lower betanin concentration was obtained by HPLC. Since the SWCC method required a standard solution, and that HPLC was time-consuming, the SWEC method represented the best choice for betanin quantification in pulp in order to reduce cost, time, and wastes.
In the food industry, the use of synthetic dyes (especially the red and yellow ones) has been restricted due to their potential risks for human health (1). Consequently, there has been a growing interest in the development of natural additives. Besides, consumers have been lately inclined to prefer natural products because of their eco-friendliness, apparent lack of toxicity, and nutraceutical properties (2, 3). Some natural colours, as betalains, are antioxidants; these help reduce cardiovascular diseases, cancer, and disorders associated to ageing (4, 5). Betalains have been used as food colourants in gelatines, desserts, confectioneries, dry mixes, poultry, dairy, and meat products (6). Betalains are divided into two groups: betacyanins,that provide red hues and betaxanthins that provide yellow colours. Betanin is the dye that contributes from 75 to 95% to red colour in betacyanins. In order to obtain the desired hue in the product, the amount of betalain to be added, calculated as betanin, does not exceed 150 ppm (7).
Betalains are water-soluble polyphenolic pigments, found in plants related to the order Caryophyllales, which ...