Effect of solvent mixtures on the ultrasound-assisted extraction of compounds from pineapple by-product

Abstract

Extraction of compounds from pineapple by-products can be affected by operational conditions and solvents. This study aimed to (i) carry out the ultrasound-assisted extraction of phenolic compounds from pineapple peels using different types of solvents and operating conditions and (ii) characterize the extracts obtained. The solvents with the highest efficiency in extracting total phenolic compounds (TPC), namely water, ethanol, and acid solution (1 mol L−1 HCl), were tested in different proportions using a simplex-centroid mixture design. The effects of time (5–45 min), temperature (30–60 °C), and ultrasonic power (0–100 W) were also evaluated. Extracts were assessed for antioxidant potential, phenolic profile, and sugar composition. TPC contents ranged from 219.75 to 405.06 mg GAE 100 g−1, with the highest value obtained in the mixture of ethanol (0.50) and acid solution (0.50). The extract with the highest TPC content and antioxidant activity was obtained at 60 °C, 50 W of ultrasonic power and 30 min. The extract obtained under these conditions contained fructose (7.17 g 100 g−1) and glucose (8.29 g 100 g−1) as major soluble sugars and caffeic acid (217.65 mg 100 g−1) as the major phenolic acid. Therefore, the extraction of compounds under the conditions studied is an alternative to the valorization of pineapple waste.