Solvent solutions: comparing extraction methods for edible oils and proteins in a changing regulatory landscape. Part 5: Impacts on the oil quality

This article constitutes the fifth part of a series dedicated to the comparative analysis of extraction solvents for oilseeds. This section evaluates the impact of various solvents on oil quality, focusing on enzymatic activity, oil acidity, peroxide value, fatty acid profiles, phospholipids, polyphenols, tocopherols, and sterols. For alcohols, such as ethanol, isopropanol, and methanol, results indicate an interesting suppression of enzymatic activity due to protein denaturation. Alcohols also lead to higher tocopherol content and lower acidity when solvent recycling employs a non-distillation process. Ketones, particularly acetone and methyl ethyl ketone, show potential for enzyme denaturation and exhibit low miscibility with phospholipids, which may impact the extraction process. Ethyl acetate is recognized for potentially enhancing enzymatic activity and extracting higher levels of antioxidants. Dichloromethane is effective in extracting more phospholipids compared to hexane. The use of 2-methyloxolane (2-MeOx) presents a potential issue of peroxide formation, leading to higher peroxide values in extracted oils. Additionally, 2-MeOx extracts higher amounts of phospholipids, polyphenols, and tocopherols, but results in lower sterol content for reasons not fully understood. Regarding fatty acid profiles, no study has shown a significant effect of solvent choice. These results highlight the complex interactions between solvents and oil components, illustrated by surprising findings such as the higher extraction of free fatty acids by alcohols. Despite a substantial number of studies, the presented results should be interpreted cautiously, as they were obtained under conditions not fully representative of industrial operations.