Recovery of Phenolic Compounds and Antioxidants from Coffee Pulp (Coffea canephora) Waste Using Ultrasound and Microwave-Assisted Extraction

Coffee pulp is a by-product generated from coffee bean production. This waste is a potential source of bioactive compounds, which can be recovered for use as an ingredient for many products. However, this by-product is typically dumped in landfills or made into compost. Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) were employed to recover bioactive compounds from coffee pulp waste. Results showed that time and instrument power significantly affected the recovery yield in both UAE and MAE. The temperature was also a significant factor in UAE. The optimal MAE conditions were a radiation time of 70 min, a power of 700 W, and a 50% (v/v) ethanol solvent to sample ratio of 100:5 (mL/g), approximately 47 mg of phenolic compounds, 36 mg of flavonoid, 8 mg of chlorogenic acid, and 6 mg of caffeine could be recovered from 1 g of the material. The optimal UAE condition were an ultrasonic time of 35 min, a temperature of 60 °C, and a power of 250 W; however, bioactive compounds and antioxidant capacity constituted around one half of MAE. Therefore, MAE is recommended as the extraction technique for the bioactive compound and antioxidant recovery from the coffee pulp.