Green solvents and enzymes combined with advanced extraction techniques for the recovery of bioactive carotenoids and extractable/non-extractable polyphenols from grapefruit peels

The simultaneous extraction of extractable phenolic compounds (EPPs) and carotenoids from grapefruit peels using microwave-assisted extraction (MAE) with biobased solvents was optimized, followed by non-extractable polyphenols (NEPs) extraction. Ethyl acetate:γ-valerolactone (20:80 v/v) yielded the highest antioxidant and anti-inflammatory EPPs at 50 °C in 6 min. From the residue, NEPs were obtained by comparing several methods: ultrasound-assisted extraction (UAE) combined with enzymatic-assisted extraction (EAE), and UAE and MAE with natural deep eutectic solvents (NaDES). UAE (15 min, 30 % amplitude) followed by EAE (70 °C, 40 min) and MAE-NaDES using choline chloride:lactic acid (1:2, 50 % water, 50 °C, 6 min) yielded the most bioactive NEPs. HPLC-DAD-QTOF-MS analysis allowed to identified 19 polyphenols in both extracts, highlighting naringin as the majority, particularly in UAE-EAE extract. Stability tests showed UAE-EAE extracts protect against oxidative damage, potentially extending the shelf life of food products. On the other hand, MAE-NaDES extracts prevent anti-inflammatory compound degradation, indicating their potential application in pharmaceutical formulations. Thus, depending on the purpose, either UAE-EAE or MAE-NaDES can be used.