3 - Aqueous Extraction of Corn Oil After Fermentation in the Dry Grind Ethanol Process

Abstract

This chapter explains that the most widely used method for corn oil recovery by dry grind ethanol producers today involves removal from the thin stillage stream after fermentation using processes developed by GreenShift Corporation. The processes are described in six patents (Cantrell and Winsness, 2009, 2011a, b, 2012; Winsness and Cantrell, 2009 and Winsness, 2012). The chapter describes the processes for obtaining corn oil after fermentation in a dry grind ethanol plant. The chemical composition and appearance of the various corn oils can be very different based on the feedstock (corn germ, ground corn, corn fiber, etc.) and extraction process (pressing, hexane extraction, aqueous enzymatic extraction, post-fermentation centrifugation, etc.) used to produce the oil. Also, the levels of various components in corn oils are usually altered when corn oils are processed, customarily using conventional refining, bleaching, and deodorization. Refining, bleaching, and deodorization are performed on most edible oils to improve the flavor and smell and to increase the shelf life. With further research and development, it is likely that post-fermentation corn oil will be used as a feedstock for other types of biofuels, such as “green diesel” and other “drop in” fuels by using hydrotreating and other catalytic processes that are currently being developed. Until other domestic sources of inexpensive oils are developed from algae, jatropha or other sources now in development, inedible post-fermentation corn oil will likely remain one of the most attractive feedstocks for bio-diesel and other bio-fuel producers.