Extraction of Essential Oil from Waste Grapefruit Peel Using a Pilot-Scale Twin-Screw Extruder

Citrus peels are the richest source of essential oils (EOs). The growing demand for natural products has affected the industrial production of food and beverages (e.g., juices, spirits, energy drinks, and carbonated drinks). EOs are health-promoting substances preferred over synthetic additives. They are "generally regarded as safe" by international regulatory bodies and, therefore, are safe for use as food additives for human consumption. The cosmetics industry uses EOs for manufacturing soaps, creams, gels, and shampoos. Moreover, EOs are used in the pharmaceutical industry because of their antimicrobial properties. This paper describes the technical productivity and feasibility in terms of energy requirement of EOs/extraction from grapefruit peel using a pilot-scale twin-screw extruder. A maximum productivity of 2.21 g EO/(kg dry base peel.min) was achieved with a minimum energy requirement of 0.72 W.h/g EO. These results indicated that the proposed method could be advantageous compared with conventional industrial processes. The produced EO satisfied the highest international quality standards; therefore, the proposed process can be used for producing high-quality EO with commercial value.