Maceration, infusion, percolation and decoction:
Maceration is a technique use in wine making and has been adopted and widely used in medicinal plants research. Maceration involved soaking plant materials (coarse or powdered) in a stoppered container with a solvent and allowed to stand at room temperature for a period of minimum 3 days with frequent agitation [11].
The processed intended to soften and break the plant’s cell wall to release the soluble phytochemicals.
After 3 days, the mixture is pressed or strained by filtration. In this conventional method, heat is transferred through convection and conduction and the choice of solvents will determine the type of compound extracted from the samples. Infusion and decoction uses the same principle as maceration; both are soaked in cold or boiled water.
However, the maceration period for infusion is shorter and the sample is boiled in specified volume of water (eg. 1:4 or 1:16) for a defined time for decoction [11]. Decoction is only suitable for extracting heat-stable compounds, hard plants materials (e.g. roots and barks) and usually resulted in more oil-soluble compounds compared to maceration and infusion.
Unique equipment called percolator (Figure 1c and 1d) is used in percolation, another method that shares similar fundamental principle.
Dried powdered samples are packed in the percolator, added with boiling water and macerated for 2 hours. The percolation process is usually done at moderate rate (e.g. 6 drops /min) until the extraction is completed before evaporation to get a concentrated extracts