EXTRACTION OF FLAVONOIDS FROM KUMQUAT PEEL (CITRUS JAPONICA) AND EVALUATION OF THE ANTIOXIDANT ACTIVITY OF THE SPRAY-DRIED POWDER PRODUCT

Abstract

Flavonoids are a group of natural compounds with diverse biological activities, commonly found in the peels of Citrus species. This study aimed to optimize the extraction conditions of flavonoids from the peel of Citrus japonica using ethanol as the solvent, and to apply spray-drying for powder production. The investigated parameters included ethanol concentration, sample-to-solvent ratio (w/v), sample particle size, extraction temperature, and duration. The appropriate extraction conditions were determined as follows: 75% ethanol, 1:20 (w/v) sample-to-solvent ratio, 0.125mm particle size, extraction at 70°C for 45 minutes. Under these conditions, the extract contained a total flavonoid content of 7.360 ± 0.010mg/g and exhibited DPPH radical scavenging activity with an EC₅₀ value (effective concentration 50%) of 3.240 ± 0.050μg/ml. After spray-drying, the resulting powder had a moisture content of 2.76% and a yield of 53.40%. When reconstituted in water, the powder sample showed a total flavonoid content of 5.809 ± 0.015mg/g and an EC₅₀ value of 5.590 ± 0.030μg/ml. These results highlight C. japonica peel as a promising raw material for the development of flavonoid-rich powders for use in functional foods and natural health products.