Bioactive compound extraction from mandarin peel via cloud point extraction and enhanced shelf stability through sodium alginate encapsulation

Abstract

The mandarin peel is a valuable natural source of phenolic compounds known for their high antioxidant properties. Cloud point extraction (CPE) emerges as a groundbreaking technique for harvesting bioactives compounds. The optimal CPE conditions were 8.5 % (v/v) Triton X-114 at 30 °C with pH 4, and 7 % (w/v) salt concentration. At optimal CPE, 93.75 % phenolic compounds and 88.35 % flavonoids were recovered their respective yields of 16.85 mg gallic acid equivalent per gram and 2.45 mg quercetin equivalent per gram of mandarin peel. The micellar mandarin peel extract (MMPE) exhibited 47.05 % antioxidant activity. Further, MMPE was encapsulated in sodium alginate beads to improve its stability. The highest 74.05 % encapsulation efficiency was achieved using 2.5 % sodium alginate. The MMPE beads showed increased hardness due to rigid shell. Structural characterizations also explained more uniform and densely packed internal structure of MMPE beads compared to blank beads. Functional properties and thermal stability assessments showcased superior properties in MMPE beads. Release kinetics studies revealed that 60–70 % of polyphenols were liberated within 30 min under both aqueous and simulated gastric environments. CPE presents a promising avenue for converting mandarin peel waste into valuable bioactives with antioxidant properties.