Effects of steam distillation and screw-pressing on extraction, composition and functional properties of protein in dehulled coriander (Coriandrum sativum L.)

Authors: Hojilla-Evangelista, Milagros - Mila; Evangelista, Roque

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/26/2016
Publication Date: 1/19/2017
Publication URL: https://handle.nal.usda.gov/10113/5642519
Citation: Hojilla-Evangelista, M.P., Evangelista, R.L. 2017. Effects of steam distillation and screw-pressing on extraction, composition and functional properties of protein in dehulled coriander (Coriandrum sativum L.). Journal of the American Oil Chemists' Society. 94(2):315-324.

Interpretive Summary: In this research, we evaluated a newly-developed integrated process for coriander seed that produces essential oil, edible oil, and protein isolates, thus adding value to the coriander crop. Coriander, a summer annual plant typically used as fresh green herb, spice, or for its essential oil, has other components (fatty oil, protein, fiber) that could be recovered for higher-value uses. We observed that the impact of the combined steam distillation and mechanical oil extraction on coriander protein extractability, composition, and functional properties (solubility, foaming, emulsification, stability to heating). We successfully produced coriander protein isolates by using the conventional acid precipitation technique. We observed that dehulled coriander samples (steamed and non-steamed) produced higher-purity protein isolates (84-90%) than did ground whole fruit (67%). We found that the nutritional quality of coriander protein isolates was superior to those of their starting meals and soybean protein. We also noted that the coriander protein isolates produced substantial and stable foams, showed remarkably high emulsifying capacity, and were very stable during steam heating. Our results demonstrated that a protein concentrate could be a co-product from a dual oil process for dehulled coriander seeds, with nutritional and functional properties that are suitable for both food and non-food uses (e.g., whipped products, emulsions, or as a nutritional supplement).

Technical Abstract: Coriander (Coriandrum sativum L.) is a summer annual plant commonly used as fresh green herb, spice, or for its essential oil. An integrated process combined steam distillation, dehulling, and screw pressing to recover the essential oil and edible oil from coriander fruit. The current work determined the impact of the dual oil extraction approach on coriander protein extractability, composition, and functional properties and compared the results with those of ground whole coriander. Coriander protein isolates were produced by the acid precipitation method. All the dehulled samples (steamed and non-steamed) produced protein isolates with markedly higher protein content (84-90% dry basis, db) than did ground whole fruit (67% db). Coriander protein isolates showed similar amino acid compositions and had amino acid scores that were greater than those of their starting meals and soybean protein. Steam distillation had detrimental effects on the protein, based on major changes in SDS-PAGE band patterns and reduced protein recovery [from 42% (control) to 26%]. However, protein solubilities in steam-distilled samples were enhanced from pH 7 to 10 (> 90% versus 80% in non-steam-distilled coriander). Steam-distillation did not negatively affect foaming, emulsification, and heat coagulability properties of the protein isolates, as the values were equal to those of the non-steamed samples.