Apple processing to obtain juice produces a great amount of discarded material constituted by peel and seed. Several substances, including phenolic compounds, to which antioxidant activity is attributed, are found in these fractions. This work aimed at evaluating total phenolic compounds and in vitro antioxidant activity of extracts and phenolic fractions (free, soluble esterified and insoluble esterified) of apple, cv. Gala, residues. The methodologies used were DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS [2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid] to evaluate antioxidant activity and gas chromatography to determine phenolic acids. Extraction with 75% acetone (v/v) in water was the most efficient to obtain total phenolic compounds. The antioxidant activity in this extract was 4.83 and 25.46 µmol TEAC.g-1 by the ABTS method and 7.43 and 39.15 µmol TEAC.g-1 by the DPPH method for wet and dry samples, respectively. Flavanol contents in the same samples were 11.05 and 58.20 mg.100 g-1 for wet and dry samples, respectively. A positive correlation between total phenolics and antioxidant activity (r² = 0.9283) was observed. In the three fractions used, the following phenolic acids were identified: salicylic, gallic, propyl gallate and synaptic acid, being the first present in the highest amount in all the fractions studied. The results obtained showed the antioxidant potential of apple pomace.
Gala variety apple pomace; antioxidant activity; phenolic acids
