Spices and Condiments (1+1)

Spice oleoresins

 
• The oleoresins represent the total flavouring components of spices in a very concentrated form. They are very close to the flavour of the whole ground spice. Spice oils only give the aroma of the spice, whereas spice oleoresins represent the total flavour of the spice. Oleoresins are prepared by extracting the ground spice with solvents like alcohol, acetone, hexane, methylene chloride, ethylene dichloride and ethyl acetate. Care should be taken to use pure solvents (food grade) that do not leave behind high boiling residues, which affect the flavour adversely. The major advantages with oleoresins are: flavour stability, less storage space requirement and uniformity in flavour strength.
• The main steps involved in the oleoresin process are:

  1. Grinding the spice
  2. Extraction
  3. Distillation of the miscella (extract)
  4. Blending the finished product
• The ground spice is placed in extractors, which are preferably made of stainless steel. The bed of material rests on a perforated false bottom. The solvent is let in at the top. It percolates down the bed of material, carrying with it the solubles like volatile oil, fatty oils, colours, resins and pungent principles. The contact time between the solvent and the spice particles should be sufficient to ensure diffusion and extraction of the flavour constituents. About 4 to 5 volumes of the solvent are required to get most of the solubles out of the ground spice. This volume can be reduced by using countercurrent extraction, where dilute extracts can be used for extracting fresh material.
• The concentrated extract (miscella) is distilled to remove the solvent. A vacuum is used towards the end, to prevent damage by heat and to ensure the complete removal of the solvent. Since food laws require the oleoresin to contain not more than 30 to 60 ppm of solvent residue, the final traces of solvent have to the removed carefully.
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• For obtaining a standard quality oleoresin, it is important that the choice of the solvent, particle size of the spice and the ratio of solvent to spice are properly determined. Attempts have been made to prepare oleoresin by using the super-critical extraction technique. The process is yet to be commercialised. The finished product (oleoresin) is a dark viscous liquid. The flavour or colour strength of the oleoresin can be adjusted to the required standard by dilution with permitted dilutents. It can be fortified with separately distilled essential oils to achieve a balance between pungency and aroma. The yield of oleoresin and the main constituent present in them, from some spices, are given in Table

Table : Yield of oleoresin and the principal constituent

Spice Yield of oleoresin (%) Principal constituent in oleoresin

Pepper	10-12	Piperine (35-60%)
Ginger	4-7	Gingerene (25-30%)
Chillies	12-16	Capsaicin (2-4%)
Turmeric	6-9	Curcumin (20-30%)
Coriander	18-20	D-linalool (1.5-2.0%)

(Source: Spices Board, Cochin)

• As mentioned earlier, the oleoresins are too viscous and concentrated to be used as such in flavour blends or food products. It is customary to disperse them on solid or liquid media to dilute them and make their use more easy.
• Standards for spice oleoresins have been given by the Essential Oil Association of America. Other organisations like the Indian Standards Organisation and the International Standards Organisation have also prescribed such standards.

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