Siwatt Thaiudom, Ratchadaporn Oonsivilai, Numphon Thaiwong
This study explores the bioactivity, heavy metal contamination, antimutagenicity, and antioxidation aspects of a colorant powder (CP) derived from dragon fruit peels (DGFP) following a two-step process: extraction and creation of colorant powder. Extraction with deionized water at pH 5.5, 40°C for 20 min provided betacyanin content in the crude extract at 15.21 ± 0.04 mg/g dry weight with betanin and phyllocactin as the main bioactive components. The extract antimutagenicity was found to be 0.522 mg GAE/mL. The extract was mixed with 6% maltodextrin and dried to produce CP using a spray dryer with a feed rate of 6 ml/min and a 160°C inlet temperature. The powder was red and no heavy metal was detected using ICP-OES. The CP was proven to possess antioxidant activity as confirmed by DPPH, ABTS+, and FRAP assay. Thus, DGFPs should be recognized as a valuable by-product with added value as a food colorant.
The crude extract from the dragon fruit peels contained betacyanin at 15.21 ± 0.04 mg/g dry weight. The extract possessing betanin and phyllocactin as the main bioactive compounds was found to be mutagenic safe. After the extract was spray-dried with 6% maltodextrin to produce the colorant powder, the betacyanin content was reduced around twofold from the original content. However, the antioxidant activity still existed in the powder with no heavy metal contamination. Thus, the dragon fruit peels have a high potential for practical application as a safe food colorant.