Solvent solutions: comparing extraction methods for edible oils and proteins in a changing regulatory landscape. Part 6: Impacts on meal quality

This article constitutes the sixth part of a series dedicated to the comparative analysis of extraction solvents for oilseeds. This section examines the effects of various solvent extraction methods on the quality of oilseed meals, particularly focusing on antinutritional factors and protein value. The study discusses the impact of these solvents on glucosinolates (GLS) in rapeseed meal, trypsin inhibitors in soybean meal, phytic acid and phosphorus digestibility, gossypol in cottonseed, and phenolic compounds. Alternative solvents with higher water miscibility may lead to more effective reduction of GLS in rapeseed meal due to increased moisture in the desolventizer. They also could denature trypsin inhibitors in soybeans before desolventization, but this effect is negligible due to sufficient toasting conditions in the desolventizer. The intensity of heat treatment can affect phosphorus digestibility, but this intensification often comes with undesirable effects on protein digestibility. For cottonseed, ethanol with added acids has been shown to be able to extract gossypol, while isopropanol was less effective. Phenolic compound extraction with more polar solvents has the potential to improve meal taste and appearance, but without major effect on the feed value of the proteins. Desolventization conditions significantly impact protein value, with mild cooking potentially improving digestibility, while excessive heat treatment can lead to Maillard reactions, reducing protein and the digestibility of sensitive amino acids. Non-hexane solvents have water miscibility, latent heat of vapourisation and solvent hold-up in the marc that lead to increasing the temperature, moisture and residence time required for effective desolventization likely to promote stronger reduction in protein digestibility. Further experimental data would be necessary to better assess this issue.