Rosemary (Rosmarinus officinalis) oil: composition and functionality of the cold-pressed extract

Abstract

The aim of this work was to investigate cold-pressed rosemary oil (RO) for its lipid classes, subclasses, fatty acid composition, tocochromanols and total phenolics amount. Antiradical activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH•) and galvinoxyl radicals, antioxidant activity, as measured by the Rancimat test, as well as antimicrobial activity against food-borne bacteria, and dermatophytic fungi of RO were evaluated. In RO, the amount of neutral lipids was highest (ca. 86%), followed by phospholipids (0.92%) and glycolipids (0.88%). The percentages of monounsaturated, polyunsaturated, and saturated fatty acids were 41.7, 42.3, and 15.8%, respectively. Linoleic acid (41.7%) and oleic acid (41.2%) were the major fatty acids while linolenic acid accounted for 1.3% of total fatty acids. The following tocochromanols were detected: α-, β-, γ- and δ-tocopherols, which accounted for 291, 22, 1145, and 41 mg/100 g oil, respectively, as well as α-, β-, γ- and δ-tocotrienols, which accounted for 18, 12, 29, and 158 mg/100 g oil, respectively. RO also contained high levels of phenolic compounds (7.2 mg GAE/g). After 60 min of reaction with free radicals, 67% of DPPH• and 55% of galvinoxyl radicals were quenched by RO. Rancimat test showed that blending RO with sunflower oil increased the induction period (IP) for blends. The IP of the RO: sunflower oil blend (1:9, v/v) was 390 min, and RO: sunflower oil blend (2:8, v/v) was longer (540 min). RO exhibited high antimicrobial potential against food-borne pathogenic bacteria (E. coli, S. enteritidis, and L. monocytogenes) and high antifungal potential against dermatophyte fungi (T. mentagrophytes, and T. rubrum). RO had unique high level of γ-tocopherol, which is a scavenger of reactive nitrogen species making it a promising material in the food, cosmetic and pharmaceutical applications.