Changes in Selected Properties of Cold-Pressed Oils Induced by Natural Plant Additives

Cold-pressed oils are becoming increasingly popular. The stability of these oils is the main concern, as changes occur in their organoleptic characteristics during storage, which could affect their suitability for consumption. Various natural plant components with antioxidant properties are added to cold-pressed oils to preserve their freshness for as long as possible. The present study assessed the effect of addition of garlic and chili pepper on the chemical properties of cold-pressed oil extracted from seeds of flax, hemp, and black cumin. First, the moisture level and the fat and protein content in the seeds were determined, and the oil was then extracted. The oil extraction yield was calculated, and the oil was analyzed to determine its fatty acid composition, acid value, peroxide value, and oxidative stability. Three samples were prepared for further analyses: a control sample with pure oil and two samples supplemented with 1 g/100 g of garlic or chili pepper. Changes in the oil samples stored for 2, 4, and 6 weeks were assessed based on the values of some parameters. The additives were found to exert antioxidant properties, as they caused effective inhibition of oxidative changes occurring during storage of the oils. The additives also extended the induction time.