Dragon fruit is one of the tropical fruits can be grown in Indonesia. The skin of dragon fruit, which is accounted for 30-35% of the whole fruit usually thrown away as waste. This study aims to produce a bioactive extract from extraction of dragon fruit skin that is rich in phenolic and pigment compounds then it used as food additives. The variation that was used in this study includes the application of drying as pre-treatment of dragon fruit skin and the extraction methods (maceration and Soxhlet extraction). The obtained extracts were evaluated for the amount of total phenolic compounds and pigments (anthocyanin and betacyanin). Drying of dragon fruit skin was found to yield lower amounts of bioactive materials, which may occur due to the thermal degradation even though a low drying temperature was used. In addition, the maceration method was found to give a higher amount of bioactive materials compared with the Soxhlet method. The extraction with the highest yield of bioactive materials was obtained by the use of fresh dragon fruit skin and maceration for 240 minutes, which gave amounts of anthocyanin, betacyanin, and total phenolic compounds of 0.08, 0.04, dan 0.35 mg/g fresh dragon fruit skin, respectively.
One of the important food additives used in the food industry is betalain, which is applied as a natural dye. Red beet is the most common resource of betalain. To increase its shelf life, encapsulation followed by drying is commonly carried out. However, betalain is a heat‐sensitive pigment that is susceptible to degradation on thermal exposure. Moreover, drying could affect the color, shape, structure, nutrition, and content of other ingredients in betalain. This review paper provides a discussion of (1) various drying methods such as spray drying, freeze drying, vacuum drying, and their effects on the quality of the dried betalain products; (2) stability and properties of betalain pigment obtained by encapsulation using different carrier agents such as maltodextrin, gum arabic, starch, inulin, and protein; (3) several drying pretreatment and posttreatment processes to improve the recovery and stability of betalain such as extraction and optimum storage conditions. Additionally, a summary and future perspectives for further research are also provided in each section of drying methods.
This study aims to produce natural pigments for food prepared from dragon fruit skin by extraction and freeze-drying and to assess the effect of additional ethanol as extraction solvent on the process yield. During extraction stage, the effect of solvent (pure water and additional ethanol) on the yield of bioactive materials was assessed. Furthermore, during freeze-drying, the effect of maltodextrin addition as carrier agent on the quality of powder has also been evaluated. It has been found that the addition of ethanol as extraction co-solvent may give a positive effect on the yield of bioactive materials in the dragon fruit skin extracts, including the contents of anthocyanin, betacyanin, and total phenolic compounds. Regarding freeze drying, it was found that high recoveries of bioactive materials (84-92%) had been achieved, which indicates that freeze-drying may be suitable for drying such heat-sensitive materials. In addition, it was found that the addition of 10% maltodextrin as carrier agent may decrease the moisture content of the powder significantly, up to 8.162.12%, which is beneficial for its storage stability.Keywords: betacyanin; food additives; dragon fruit; extraction; anthocyanin.
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