This study analyzed the nutritional components, ursolic acid content and antioxidant activity of different solvent (distilled water, fermented alcohol, methanol) extracts to increase the utilization of apple pomace, which is a by-product after processing of apple. The samples were hot air dried apple pomace and freeze dried apple pomace.
The moisture, carbohydrate, protein, fat, ash and total dietary fiber of hot air dried apple pomace were 3.2%, 88.5%, 3.9%, 2.4%, 2.0% and 28.5%, those of freeze dried apple pomace were 8.2%, 84.2%, 3.4%, 2.4%, 1.8% and 33.0%, respectively. Total polyphenol and total flavonoid contents of hot air dried apple pomace were the highest at 306.7 μg/mL and 950.1 μg/mL in methanol extracts and 277.6 μg/mL and 925.0 μg/mL in methanol extracts of freeze dried apple pomace. DPPH radical scavenging activities of hot air dried apple pomace were 73.3% in methanol extract and 59.4% in fermented alcohol extract and that of freeze dried apple pomace were 76.1% in methanol extract and 66.0% in fermented alcohol extract. Both samples showed the lowest antioxidant activity in distilled water extracts. Similar to DPPH radical scavenging activity, both samples showed higher ABTS radical scavenging activity in the order of methanol, fermented alcohol and distilled water. In case of reducing power, all experimental groups showed stronger reducing power than ascorbic acid (311.5 μg/mL), which was a positive control. In ursolic acid content, ursolic acid was not detected in distilled water extract of both samples. However, in hot air dried apple pomace, methanol extract was 1,753.32 μg/mL and fermented alcohol extract was 1,532.94 μg/mL. In freeze dried apple pomace, methanol extract was 1,407.04 μg/mL, fermented alcohol extract was 1,221.81 μg/mL.