Taking control of phenolics in Camellia oleifera seed oil: how processing shapes oil quality and biological functions

Camellia oleifera Abel. is one of the four major woody oil crops in the world. China is its origin and largest producer. The primary value of this species lies in the oil from its mature seeds. Its seeds are rich in phenolic compounds. These phenolics exert multiple health benefits and influence the physicochemical and sensory characteristics of the oil. Therefore, retaining phenolic compounds during oil extraction is critical for producing high-quality functional oils. Oil processing mainly includes pretreatment (e.g., drying), extraction (e.g., pressing), and refining methods (e.g., degumming, deacidification). Phenolic compounds are susceptible to high temperatures and can undergo substantial losses during refining. These effects compromise oil quality and functionality. Thus, processing conditions must be optimized to preserve phenolic compounds. However, oil yield rather than phenolic retention is often the primary concern in current practice. Limited research has addressed how phenolic compounds affect oil quality and functionality. This review systematically summarizes the major types of seed phenolics and clarifies their effects on oil quality. It also reviews advances in their biological functions. The objectives are to provide theoretical guidance for optimizing processing parameters to produce oils with high phenolic content and to support the development of value-added Camellia products.