Chapter 10 - Degumming and Lecithin Processing and Utilization

Abstract

Degumming is the process for removal of phosphatides from crude soybean and other vegetable oils. The phosphatides are also called gums and lecithin. The latter term is also the common name for phosphatidyl choline, but common usage refers to the array of phosphatides present in all crude vegetable oils. Although all crude vegetable oils contain gums, soybean oil is currently the major source of commercial lecithin because it contains the largest amount of gums and is also the world's leading vegetable oil. In conventional solvent extraction, only half of the phosphatides present in soybeans are extracted. Use of preparation processes such as the Alcon process or expanders will change the array of phosphatides in the crude oil by increasing the phosphatidyl choline content by about 30% to 40% and will increase the total extracted phosphatides. Some plants use steam condensates for degumming rather than deionized water; however, the absence of iron in the condensate should be ensured. Some plants also use excess stripping steam in the last stages of miscella desolventizing as a means for hydration of phosphatides, but this is more difficult to control than simple water addition. This chapter illustrates the flowsheet for degumming soybean oil and crude lecithin production. Lecithin has unique release properties and as such has been used in pan frying formulations and in pan greases for baking. In addition, it is also used industrially as a release agent for ready removal of both wooden and metal concrete casting forms.