Separation of Pitaya (Stenocereus pruinosus) Betaxanthins, Betacyanins, and Soluble Phenols Through Multistage Aqueous Two-phase Systems

Abstract

Pitaya (Stenocereus pruinosus) fruits, particularly those of the red variant, contain betalains that can be used to pigment foods and provide tonalities in the range of red–purple to orange-yellow. If betalains are separated into betacyanins (Bc) and betaxanthins (Bx), the potential for using them can be improved. Betalains are usually mixed with sugars, which limit their use since sugars can alter sensorial properties, and with other bioactive compounds, such as polyphenols, which can be beneficial due to their antioxidant potential. The objective was to separate betalains and soluble phenols from pitaya fruits and conduct the partition of betalains into Bc and Bx by multistage aqueous two-phase systems (ATPS). Pulp of pitaya fruits (294.25 μg/g betalains, 146.63 μg/g soluble phenols, and 34.31 mg/g sugars) were processed at 25 °C with ATPS prepared with 6.57–34.05% sodium citrate (Na3Cit) and 4.21–60.54% 1-propanol. Soluble phenols and sugars remained mainly in the bottom phases of ATPS with concentrations of 69.33–190.90 μg/mL and 20.89–45.88 mg/mL, respectively. The extraction efficiency of betalains was higher than 90% and these were separated into Bc and Bx, where Bc concentrated in the bottom phase and Bx in the top phase. Fractions with Bx/Bc ratios of 10.25 and 0.46 were obtained through multistage processing of top and bottom phases, which allowed recoveries of 45.94% Bx and 53.93% Bc, although the latter was in mixture with low concentrations of soluble phenols and sugars. ATPS has the potential to separate betacyanins and betaxanthins from pitaya fruits. Kewwords: Aqueous two-phase systems, Betalain partitioning, Pitaya fruit polyphenols, Sugar elimination from pigment