Comparative Chemical Composition and Bioactivity of Opuntia ficus-indica Sanguigna and Surfarina Seed Oils Obtained by Traditional and Ultrasound-Assisted Extraction Procedures

Abstract

This study investigates the seed oils obtained from two different varieties of Opuntia ficus-indica (Sanguigna and Surfarina) growing in Sicily, Italy. Soxhlet and ultrasound-assisted extraction procedures are used to obtain the seed oils. The fatty acid profile, γ-tocopherols, carotenoid content, and the bioactivity in terms of the antioxidant effects (using ABTS, DPPH, FRAP, and β-carotene bleaching tests), and carbohydrate-hydrolysing enzyme inhibitory activity (α-amylase and α-glucosidase) are determined. The extraction procedure does not significantly affect the fatty acid composition of the oil, but it does affect the tocopherol and carotenoid contents, as well as the antioxidant and inhibitory activities. All the oil samples are rich in polyunsaturated fatty acids, especially linoleic, and oleic acids. Soxhlet extraction proves to be the best extraction procedure to enrich the oils in γ-tocopherol. Relative antioxidant capacity index (RACI) and global antioxidant score (GAS) analyses are applied to evaluate the antioxidant potential of the Sanguigna variety oil extracted with the Soxhlet apparatus that is shown to be the most active. The same oil also shows the highest α-amylase inhibitory activity (IC 50 value of 40.9 μg mL −1 ), which is better than that reported for acarbose used as a positive control. Practical Applications: This study is the first to evaluate the effect of oil extraction technologies on the bioactive compound levels and antioxidant and hypoglycaemic activities of cactus pear seed oil, which is a by-product of fruit processing. The findings will contribute to the valorization of food by-products. The results provide useful information to select the most valuable technological conditions for oil extraction to preserve the bioactive compounds and the biological activity of the vegetable by-product extracts, such as seed oil. Cactus pear seed oil obtained by the traditional extraction procedure (Soxhlet) represents a promising source of healthy compounds, particularly of carotenoids and γ-tocopherol, used not only as antioxidants to preserve lipid components in food preparation but also as functional ingredients due to their hypoglycaemic effect. Effect of extraction procedure on chemical composition, antioxidant potential, and hypoglycaemic activity of cactus pear seed oils.