Solvent free microwave extraction of orange essential oil (Citrus sinensis), and the effect of the process conditions in its yield, composition and antimicrobial activity

Abstract

Microwave assisted extraction (MAE) is a relatively new ecofriendly technique that has received increasing attention due to its reduced extraction time and energy consump-tion, higher yield and lower solvent consumption; unlike conventional extraction techniques, which involve higher energy costs and greater time. Likewise, industry by-products such as citrus peels are disposed of in large quantities, thus functional properties of their compounds are left unused. In the present investigation, solvent-free microwave extraction (SFME) was used to obtain orange peel essential oil at different power conditions (400, 800 W, and their combinations). The aim was to evaluate the effect of the process on the yield, composition and antimicrobial activity of the essential oil obtained. The highest extraction yields were obtained using powers of 400 and 800/400 W, corresponding the minor energy and CO2 emission generated to the latter. In general, all oils had the same major components (limonene, β-myrcene, linalool and α-pinene), with the oil obtained at 400 W having, in addition, five minor compounds, in amounts less than 0.23%. Regarding antimicrobial activity, in general, greater activity against L. monocytogenes (ATCC 19115) was detected in comparison with E. coli (ATCC 8739) in all treatments.