Optimization of novel oil extraction technique from canola seeds: lecithin-based microemulsion

Abstract

Nowadays, solvent (hexane) based oil extraction is a widely used commercial technique and there are a number of environmental, economic and health related concerns. Overcoming such serious issues is driving research to develop alternative safe methods. In the present study, a novel technique, using lecithin-based microemulsion system, was developed for canola oil extraction. At first, pseudoternary phase diagrams of canola oil:lecithin:propanol:water microemulsions were constructed and the effect of temperature on microemulsion formation was evaluated. So that, (lecithin:propanol):water microemulsion premixes [(2:1)50:50 and (2:3)80:20] were selected for optimization (temperature, exposure time, premix:canola seeds ratio, and agitation rate) of oil extraction from canola seeds using one factor at a time design. Based on "one factor at a time" design, the highest extraction yield (82.6% wt) achieved at 60°C, 60 min, 6:1 premix:canola seeds ratio without agitation; the premix composition was (lecithin:propanol):water (2:1)50:50. From quality point of views, the microemulsion-based extracted oils had lower peroxide value, higher acidity, as well as low phosphorous and lecithin contents in comparison with hexane extracted one. This technique confirmed its simultaneous extraction, recovery and solubilization capabilities which can be used for oil extraction and food formulation.

Practical applications: For many decades, vegetable oils were commonly extracted by mechanical pressing or extraction with solvents such as hexane. Hexane, a highly volatile and flammable solvent which requires expensive equipment for safe operation, is classified as a hazardous air pollutant and occupational exposure to n-hexane can cause neurological symptoms and other health defects. Overcoming these serious issues is driving research to develop alternative safe methods such as microemulsion technique. This study introduced a novel technique using lecithin-based microemulsion systems for extraction of edible oils from oilseeds. This technique, as a low energy consuming method, has great potency for being used as a safe and green oil extraction technique which is the developing direction for not only the dominant oil resources but also nutrient lipids which can be easily dissolvable in aqueous food and pharmaceutical formulations.

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