Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2015
Publication Date: 3/11/2015
Publication URL: http://handle.nal.usda.gov/10113/60546
Citation: Evangelista, R.L., Hojilla-Evangelista, M.P., Cermak, S.C., Isbell, T.A. 2015. Dehulling of coriander fruit before oil extraction. Industrial Crops and Products. 69:378-384.
Interpretive Summary: Coriander (Coriandrum sativum L.) is an annual herb crop traditionally grown for use as a fresh green herb (cilantro) or as a spice. It is, however, mainly cultivated for the seeds which are widely used as seasoning. The seeds contain 19-21% oil which can be used as raw material for the manufacture of softeners, emulsifiers, detergents, soaps, and a wide range of polymers, including high grade engineering plastics. Some varieties of coriander have short growing seasons (84 days from planting to harvest). This rapid growth and maturation make coriander suitable for a double crop rotation through much of the Midwestern U.S. where winter wheat is produced. Winter wheat is planted in the fall and harvested around the first week of July, providing nearly 100 days of frost-free days for coriander production. Integrating coriander as a second crop will provide oil for industrial use without displacing a crop for food production. A simple process of removing the hulls from whole coriander was developed. Removing the hulls reduced the weight by 50% and also reduced the volume by about 60%. The reduced weight and volume of coriander seeds will significantly increase the output of the oil extraction equipment.
Technical Abstract: Coriander (Coriandrum sativum L.) is a summer annual traditionally grown for use as fresh green herb, spice or for its essential oil. The essential oil is obtained by steam distillation of crushed fruit and the residue is utilized as feed or processed further to recover the triglyceride. The triglyceride is obtained from the whole fruit by mechanical pressing or by solvent extraction. The coriander fruit has low density due to the void space between the mericarps and the high proportion of hulls in the fruit’s weight. Dehulling oilseeds before oil extraction is commonly employed whenever it is practical to do so, but this technique has not been applied to coriander seeds. This study evaluated the feasibility of dehulling coriander fruits as part of the seed preparation before oil extraction and developed a simple process of dehulling coriander. Coriander fruit with 17.6% oil and 10% moisture was dehulled by first splitting the fruit using an impact huller or a roller mill. Seeds still encased in the split hulls were loosened further using the impact huller. The hulls were removed by screening, aspirating, or using a gravity separator. Dehulled seeds with purity >95% was attainable. Dehulling the coriander fruit reduced the weight by 50% and reduced the volume by 60%. Dehulling coriander also doubled the oil content, increased the crude protein by 70%, reduced the crude fiber by 28%, and reduced other carbohydrates by 65%. The coriander fruit and dehulled seeds with purity up to 95% were amenable to screw pressing. Prepressing and solvent extraction would be more appropriate for pure dehulled seeds due to their high oil content. Dehulled seeds must be oil extracted right away to minimize the increase in free fatty acid.