Environmental impact assessment of soybean oil production: Extruding-expelling process, hexane extraction and aqueous extraction

Abstract Expelling and hexane extraction are two typical processes for soybean oil production used in industry. The main issues for these two processes are the low efficiency and hazardous chemical problems respectively. Enzyme assisted aqueous extraction process (EAEP) was proposed to increase the efficiency without using organic solvent, which is replaced by water. The environmental impact analysis of these three processes are based on their mass flows, energy consumption and global warming potential. For mass flows, the environmental impact indices were calculated based on material flow of input and output components. Energy consumption was used to evaluate the carbon dioxide, other greenhouse gas (GHG), and criteria pollutants emissions by GREET models. According to our results, hexane extraction has the highest environmental impact due to the application of organic solvent. Expelling has the highest GHG and criteria pollutants emissions because of the high energy requirement for heat pressing processes. EAEP has similar environmental impacts to the expelling process, but it also lowers GHG and criteria pollutants emissions. EAEP has the potential to be a green process adopted by industry although a high energy intense pretreatment to produce finer soybean flakes for increasing oil recovery is still a challenge.