Ohmic Heating Process for the Extraction of Betacyanin Pigment from Red Dragon Fruit Peel as a Natural Food Colorant Ingredient

The usage of natural food colorants in food processing is increasing nowadays. Red dragon fruit peel is rich in betacyanin pigment. The peel, which is generally categorized as food waste, can be extracted and used as a natural food colorant that produces a red-violet color. Pigment extraction using ohmic heating can shorten the extraction time. Ohmic heating has a very fast heating rate and can avoid excessive thermal damage to pigments. This study aims to determine the effect of solvent type and extraction temperature on chemical and physical characteristics, as well as process parameters (heating time, electrical conductivity, and ohmic heating efficiency) of extracts that have been extracted using the ohmic heating method. The study used a 2-factor group randomized design, namely solvent type (distilled water, citric acid 0.2%, and NaCl 0.2%) and extraction temperature (50, 60, 70, 80, and 90℃). The results showed that the interaction between solvent type and extraction temperature significantly affected betacyanin content. Each factor (solvent type and extraction temperature) had a significant effect on the heating time, electrical conductivity, and extraction yield. NaCl 0.2% solvent can increase electrical conductivity so that the heating time is faster and pigments can be extracted from the cells. Ohmic heating can be used for the extraction process of betacyanin pigment from red dragon fruit peel, which is heat-labile.