Competing Extraction Technologies

There are a number of different processes in use today for the extraction of target compounds from natural sources. The most widely used are:

Generally each of the current extraction processes forces the client to accept a trade-off among these attributes. In mechanical extraction some form of mechanical pressure is used to squeeze the oil out of the solid plant matter, a process that is very energy intensive while also leaving a valuable percentage of the oil behind (low yield). Mechanical extraction is therefore often employed as a first step in the extraction of products with a high natural oil content, such as peanuts and canola or in applications where "solvent free" is a critically valued differentiator.

Steam distillation is a very simple, albeit slow method of extraction used primarily in the flavours and fragrances industry due to its ability to extract volatile oils without damaging the flavour or aroma profile. The process, however, results in inherently low product yields, meaning that much of the valuable target product remains unrecovered. In addition, it suffers from low selectivity, significantly limiting its potential fields of use.

Solvent processing is the most widely used today, but it is not without its limitations. It is diffusion based which drives a number of limitations: active recovery and purity can both be limited by the inherent diffusion characteristics: slow extraction rates can require large capital equipment for a given level of throughput; lengthy exposure to heated solvents can cause product degradation; and the need to re-extract biomass with fresh solvent in multi-stage extractions can result in highsolvent and energy costs.

SFE is a technology that uses a solvent (usually carbon dioxide) with properties between those of a gas and a liquid as the extraction medium. The result is a more efficient process (higher yields) and the ability to do selective extractions. The drawbacks, however, are that in order to create this special "supercritical" fluid, very high pressures are required (e.g. carbon dioxide is only useful as a solvent at pressures in excess of 100 atmospheres), resulting in very high capital equipment and operating costs. Additionally SFE is a batch process which imposes limitations in specific applications. Lastly, the bulk density of the input material has a direct impact on throughput so SFE is most cost effective with high value, high bulk density input applications.