Extraction of quercetin from onions and apples

Abstract

Quercetin is a natural flavonoid found abundantly in vegetables, fruits and grains. Red onions and apples are common foods containing appreciable amounts of quercetin. Quercetin is also present in various kinds of honey from different plant sources. The main objective was to see which of the two: green apple peels and dry scales of red onions have a higher amount of quercetin. Quercetin can be extracted using different solvents and forth is study 80% ethanol, 80% methanol, 80% acetone and distilled water were compared. Dry scales of red onion s and green apple peels were dried at 100⁰C for 24hours and ground into a fine powder. 2g of each sample was extracted in 100ml of each solvent for 24hours except distilled water where each sample was extracted by incubation at 100⁰C for 3hours. After extraction, the mixtures were filtered and absorbances measured using a spectrophotometer and colorimeter. A quercetin standard curve for each solvent was generated and used to obtain the amount of quercetin in each extract. From the results obtained, extraction using ethanol gave higher amounts of quercetin. Extraction with water showed the highest amount from onions due to increase in extraction temperature. Dry scales of red onions also show higher amounts quercetin compared to green apple peels from all extracts using the different solvents. The highest amount of quercetin is obtained from onions with extraction using 80% ethanol. The lowest extraction of quercetin is from apples with extraction using methanol as a solvent.