Stability Study of Betacyanin Extract from Red Dragon Fruit (Hylocereus Polyrhizus) Peels

Dragon fruit (Hylocereus polyrhizus) or buah naga is one of the tropical fruits under the cactus family, Cactaceae. Dragon fruit becoming popular in Indonesia due to its attractive color, sweet, juicy pleasant taste and also the plant is beautiful. The peels of red dragon fruit is the potential sources of betacyanins which responsible for the red-violet color. The objective of this study was to evaluate the stability of betacyanin extract from red dragon fruit peels. In this study, the betacyanin extract from the peels of red dragon fruit was extracted by methanol and water. The stability of this pigment was evaluated by monitored the effects of storage time and pH by spectrophotometer at wavelength 538 nm. This study was also investigated the kinetics degradation of betacyanin extract using the accelerated reaction method. Results analysis of red dragon fruit peels extract shown that for five hours in room temperature, betacyanin content in methanol extract was decreased about 10.44%, meanwhile betacyanin content in water extract was decreased about 22.58%. Betacyanin content was obtained from peels which extracted by methanol pH 5 (515.20 μg/100 g) higher than betacyanin content in water pH 5 (491.16 μg/100 g). Arhenius data showed that betacyanin extract in water follow the first-order kinetic model with its half life time (t ½) at 25oC was 23 hours and 90%-shelf life was 76 hours.