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.
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.
One potential utilization of dragon fruit skin is to produce bioactive materials as natural antioxidants and colorants for the food industry by extraction and spray drying. This study investigated the quality (total phenolic compounds/TPC, betacyanin and betaxanthin contents, and antioxidant activity) of the extracts and spray-dried products, and the quantity (powder yield) obtained by the use of different types and amounts of spray drying agents. Two drying agents were introduced during spray drying, i.e. maltodextrin and whey protein isolate (WPI). The result showed that a lower extraction solvent to solid ratio may result in a lower yield of TPC, betacyanin and betaxanthin contents, and also in antioxidant activity of the dragon fruit skin extract. In addition, maltodextrin and WPI were found to be able to significantly increase the yield from spray drying. The highest yield (72.7 ± 8.4%) was obtained with the use of 40% maltodextrin as drying agent, while the control yielded 9.5 ± 1.8%. Furthermore, it was found that the spray-dried product could recover more than 90% of the TPC and betacyanin in the extracts, which indicates that spray drying may be suitable for heat-sensitive materials.
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