Ultrasound-enhanced deep eutectic solvent extraction and encapsulation of eggplant peel polyphenols for low-fat mozzarella spread formulation

Abstract

The current study aimed to explore the polyphenols present in eggplant peels, their encapsulation, and application in the low-fat functional mozzarella spread. Eggplant peel extraction was performed with ultrasound-assisted extraction conditions with deep eutectic solvents. The extraction conditions, including ultrasonication time (5–10 min), ultrasonic power (5–10 W), and sample concentration (10–15%), were optimized using a Box Behnken design. W/O/W emulsions were formulated with varying volume fractions of W/O emulsions (10% (E1), 20% (E2), and 30% (E3) (%w/w)) using a fat replacer of aloe vera gel mucilage. W/O and W/O/W emulsions were evaluated in terms of phytochemicals retention capacity, droplet size, creaming, and color stability on 0, 3, 7, and 15 days at 4 °C. Mozzarella spreads were prepared with no emulsion addition (To), 10 mL of W/O (T1), 10 mL of E1 (T2), and 10 mL of E3 (T3) and assessed for 1, 3, and 7 days at 4 °C based on phytochemicals, antioxidant potential, textural, color, and sensory analysis. Optimized extraction parameters were 7.5 min, 8 W, and 13% to attain 21 mg/g polyphenols, 9 mg/g flavonoids, and 64% DPPH activity. W/O emulsions exhibited a decline in polyphenols, flavonoids, antioxidants, and retention capacity over time. E1 presented the highest droplet, bioactive retention, and creaming stability with the lowest color change due to higher plant mucilage concentration, in contrast to E2 and E3. T1 presented higher sensory and functional characteristics in contrast to the control. Overall, the W/O emulsions have the potential for the formulation of mozzarella spread with improved sensorial attributes.

Keywords; Deep eutectic solvent, Eggplant peel, Low-fat cheese spread, Response surface methodology, Ultrasound-assisted extraction, W/O/W emulsions, Antioxidants, Chemical Fractionation, Deep Eutectic Solvents, Emulsions, Polyphenols, Solanum melongena,Solvents, Ultrasonic Waves.