PROTEIN EXTRACTION FROM UVAIA SEEDS (Eugenia pyriformis) USING ULTRASOUND: IMPACT ON SOLUBILITY, PHENOLICS AND ANTIOXIDANT ACTIVITY

Uvaia (Eugenia pyriformis) is an endemic fruit from the Atlantic forest, with pulp rich in antioxidant compounds and increasing applications. The fruit processing residues are the seeds, which are discarded. Uvaia seeds, like the pulp, have a high content of antioxidant compounds and a high protein content. Ultrasound is considered a green and effective technology for extracting proteins from seeds. Its cavitation process can lead to structural modifications and assist in the extraction of bioactive compounds. In this study, the solubility, phenolic content, and antioxidant capacity of the uvaia seed protein extract obtained by ultrasound (450W for 10 minutes) followed by isoelectric precipitation (pH 3.0) were evaluated. Results were compared to the non-sonicated samples (control). Zeta potential and solubility were assessed within a pH range varying from acid to alkaline (3 to 11), and the soluble protein content was quantified using Bradford. Total phenolic content was determined using the Folin-Ciocalteau reagent, and antioxidant capacity was measured using ABTS and FRAP assays. The protein content of the ultrasonic extract was statistically higher (31.8%) than the control extract (29.8%), which was 3 times higher than the original flour (9.5%). Ultrasound extraction significantly decreased the solubility and zeta potential across the entire pH range. The phenolic content was higher in the ultrasound-untreated extract (p<0.05), indicating that sonication aided in the extraction of phenolics during the protein extraction process, in which the removal supernatant is discarded. However, there was no significant difference (p>0.05) in antioxidant activity by ABTS and FRAP between the extracts. Therefore, the use of ultrasound to extract proteins from uvaia seeds can increase the protein content in the extract, but reduce its solubility and phenolic content without altering its antioxidant capacity.