Factors affecting betacyanin stability in juice of LD5 Red-fleshed dragon fruit (Hylocereus polyrhizus)

Abstract

In Binh Thuan province (Vietnam), the red-fleshed dragon fruit (Hylocereus polyrhizus), concretely LD5 variety majorly grows and contains a large amount of betacyanin, a natural colourant that potentially applied to many products in the food industry. In this study, the processing factors possibly influencing the betacyanin stability in the red-fleshed dragon fruit juice were in turn investigated. The heating treatment included 2 factors: temperature (65, 75 and 85oC) and heating time (10, 20 and 30 minutes); while the pH values ranged between 3.0 to 7.0 and the ascorbic acid addition varied in concentrations (0.1, 0.2, 0.3, 0.4 and 0.5% w/w). The processed fruit juice was stored in different packaging materials (plastic and glass) with and without light exposure for 5 weeks to monitor the retained betacyanin. The results showed that the betacyanin was remained with the highest proportion (0.84 ± 0.02) at 0.3% ascorbic acid addition, pH 4.0 and heat treatment at 65oC for 10 minutes. In storage without light exposure, both plastic and glass packaging materials kept efficiently betacyanin in fruit juice. However, the glass material represented better efficiency in the betacyanin remaining than the plastic material did.