Efficacy of green solvents in pungent, aroma, and color extractions of spice oleoresins and impact on phytochemical and antioxidant capacities

The current study investigated the effect of green solvents (ethanol, acetone, and their mixture) on oleoresin yield, extraction of pungent compounds, volatiles, colorants, and the correlations with phytochemical and antioxidant activities of 5 spices (chili, black pepper, turmeric, ginger, and coriander). The solvents’ polarities and boiling points determined the oleoresin extractability, and the solvent mixture recorded the maximum yield in all spices. A total of 33 volatiles and 8 non-volatile compounds were identified in the essential oil and oleoresin fractions. Curcumin and 6-gingerol contributed to strong antioxidant properties with Pearson correlations of 0.999 and 0.924, respectively. Acetone reported the highest yield of curcumin (244.09 ± 1.71 mg/g) and 6-gingerol (131.98 ± 2.86 mg/g), whereas ethanol was the most effective solvent for capsaicinoids and piperine. Chili oleoresin extracted by ethanol delivered the maximum pungency. Acetone displayed the highest extractability of linalool detected in coriander oleoresin and essential oil. Chili oleoresin contained the highest carotenoid yield, and acetone extracted the maximum red and yellow fractions. Chili and black pepper possessed high Browning Indices and positively correlated with the total flavonoid content. β-caryophyllene dominated the essential oil profile of chili and black pepper, and the solvent mixture reported the maximum yields as 47.43% ± 0.69% and 75.11% ± 0.64%, respectively. Conclusively, the solvent mixture extracted the maximum oleoresin yield; acetone showed the highest affinity for colorants, volatiles, and antioxidants in turmeric, ginger, and coriander, while ethanol was the most efficient solvent in extracting bioactive compounds of chili and black pepper.