ONION (ALLIUM CEPA L.) SEED OIL, EXTRACTION TECHNOLOGIES, BIOACTIVE COMPOSITION, PHARMACOLOGICAL ACTIVITIES AND INDUSTRIAL POTENTIAL - A REVIEW

Abstract

Allium cepa L. (Amaryllidaceae) is among the most economically important bulb crops globally, yet its seed fraction remains a chronically underexplored repository of structurally diverse and pharmacologically potent phytochemicals. Seeds of A. cepa accumulate a compositionally distinct matrix of unsaturated fatty acids, furostanol saponins, organosulphur cysteine sulfoxide derivatives, tocopherols, phytosterols, quercetin glycosides and hydroxycinnamic acid conjugates, a profile that diverges substantially from that of the bulb and that confers a unique spectrum of biological activities. The present review systematically examines the botanical and taxonomic context of A. cepa with emphasis on the seed organ, consolidates quantitative compositional data across extraction methods and genotypes, critically evaluates Soxhlet, cold pressing, oil expeller and supercritical CO₂ technologies and synthesises evidence on physicochemical quality indices including tocopherol, sterol, fatty acid and organosulphur profiles. Pharmacological evidence covering antimicrobial, anti inflammatory, antidiabetic, antihypertensive, anticancer and hepatoprotective activities is evaluated at the mechanistic level and current knowledge gaps in postharvest management of onion seed for oil quality preservation are identified. This review positions onion seed oil as a high-value functional ingredient for food, cosmetic and pharmaceutical applications and underscores the need for standardised extraction protocols, cultivar-specific metabolomic profiling and systematic postharvest research.