The move towards more sustainable production and consumption patterns is a goal shared by a large part of society. In the oil-mill sector, whether it be animal feed or human food, this development should make it possible to improve the protein autonomy of the territories and to use proteins more efficiently. Current methods make some of the rapeseed proteins indigestible and leave most of the undesirable compounds from the seeds in resulting meals. Residual oil, fibrous envelopes, glucosinolates, phytic acid, phenolic compounds and oligosaccharides, as well as overcooking, however, have negative effects on the value of proteins. An important part of the article is devoted to reviewing these effects. Their extraction, combined with milder heat treatments, would provide excellent quality proteins to the market and generate value for the entire value chain. Efficient dehulling and mechanical extraction would be the prerequisites for this development. An ethanolic extraction revisited to exploit the secondary metabolites would then complete this process with, however, a limited effect on phytic acid. All these technologies have the advantage of not posing major acceptability problems. This development requires new investments in applied research to make this new approach to processing oilseeds possible and efficient.

In a context where the search for naturalness, the need to reduce the carbon footprint and the development of a decentralized crushing sector are intensifying, mechanical extraction is a technology that is regaining major importance for the industry. The performance of this technique remains far below what is desirable, while the understanding of the main phenomena involved in screw presses remains insufficient. This article, after a brief presentation of the state of the art of this discipline, presents a new model centered on the notions of pressure generation and plasticity. According to this approach, plasticity can account for parameters such as the water and oil content of oilseeds, their temperature, and their possible dehulling. Plasticity in turn would explain both the compressibility of the cake and its ability to resist the thrust of the screws, and consequently to generate pressure or to creep or flow backward depending on the geometry of the screw and the cage. The model must also incorporate the notions of compression velocity, friction, and the complexity of the interactions between these parameters and the impact of the succession of screw segments and cone rings. It has been built on observation and experience and gives an understanding of the need to work simultaneously on the conditioning and geometry of the presses to achieve improved performance in terms of energy, efficiency, and reduction of the temperatures experienced by the proteins and oils

In the context of potential regulatory changes, this study compares the properties of various solvents for the extraction of edible oils. The solvents considered are hexane isomers, alcohols, ketones, ethyl acetate, dichloromethane and 2-methyloxolane. The study presents a detailed table of physical properties for each solvent, including boiling point, density, vapour pressure, flash point and miscibility with water. It also addresses chemical stability, reactivity and potential interactions of these solvents with oilseeds. Particular attention is given to solvent-substrate interactions measured by Hansen solubility parameter. Normal hexane and its isomers show high affinity for neutral lipids, a lesser one for polar lipids and fair selectivity for non-lipids. Due to their hydroxyl group, alcohols (methanol, ethanol, isopropanol) exhibit only a modest affinity for non-polar lipids, though this affinity increases with the number of carbon atoms in the alcohol molecule. They demonstrate a higher efficacy in extracting polar lipids; however, this extraction process also extends to numerous non-lipidic molecules. Ketones (acetone, MEK) offer a balance, with theoretically good affinity for both polar and non-polar lipids, although in practice they do not dissolve phospholipids. Ethyl acetate shows good solvent power for various lipids, its ester group being found in most of lipid molecules. Dichloromethane is a good solvent for lipids in general but raises potential safety concerns. 2-Methyloxolane is noted for its ability to efficiently extract both polar and non-polar lipids, offering a potential compromise between hexane-like and more polar solvents however, it is potentially hindered by its price and its limited availability.

Safety is a critical consideration in the oil mill industry, particularly in the context of solvent extraction processes. This study focuses on the safety concerns associated with various solvents used in oil extraction, highlighting the potential risks to workers and end consumers, as well as environmental impacts. The analysis reveals that alcohols, such as ethanol and isopropanol, generally offer better safety profiles compared to hexane, despite presenting higher risks in terms of ATEX (explosive atmosphere) considerations at ambient temperature. These alcohols have higher electrical conductivity, which reduces the risk of electrostatic charge accumulation and subsequent ignition. However, methanol stands out as particularly hazardous due to its wide explosivity range and low minimum ignition energy. Ketones, including acetone and methyl ethyl ketone (MEK), and ethyl acetate also show relatively favourable safety characteristics. These solvents exhibit good electrical conductivity and lower toxicity levels, making them safer alternatives to hexane. Ethyl acetate and MEK are particularly noted for their compatibility with existing safety protocols and equipment. On the other hand, methanol, hexane, and dichloromethane (DCM) rank poorly in multi-criteria safety comparisons. Methanol, DCM and hexanes are presenting specific toxicities making these solvents less desirable from a safety perspective. 2-Methyloxolane (2-MeOx) occupies an intermediate position, with some improvements over hexane but challenges related to its low water miscibility and potential for peroxide formation. The study concludes that while no single solvent is superior across all safety criteria, alcohols and certain ketones could present promising alternatives to hexane if safety was the dominant criteria of selection. In an holistic approach, the possible improvements in safety brought by these solvent must be balanced by their impacts on other criteria like energy consumption, products quality, and economic affordability.

The current study assessed the effect of rapeseed variety and oil extraction process on the apparent and standardised ileal digestibility (AID, SID) of crude protein (CP) and amino acids (AA) in rapeseed co-products in broiler chickens. PR46W21 and DK Cabernet rapeseed varieties were de-oiled by soft and standard hexane extraction, producing soft rapeseed meal (SRSM) and rapeseed meal (RSM), respectively. The soft, non-standard hexane extraction method was designed to reduce heat treatment that occurs prior to hexane extraction in order to maximise potential genetic differences in digestibility values of rapeseed co-products. The test meals were incorporated into semi-synthetic diets at a level of 500 g/kg; diets were fed to 14-day old paired chickens (n = 6 pairs) for ten days, when ileal digesta was collected post-slaughter from Meckel’s diverticulum to the ileal-caecal junction. The AID and SID of CP and AA were determined using titanium dioxide as inert dietary marker. The variety PR46W21 showed a greater AID and SID of CP, arginine, leucine, methionine, cysteine, phenylalanine, valine and lysine in RSM compared to the DK Cabernet RSM (p < 0.05). The soft processing increased AID and SID of CP, histidine and lysine in SRSM of PR46W21 and DK Cabernet compared to their RSM counterparts (p < 0.05). An interaction between variety and processing was only observed for AID and SID of tryptophan (p < 0.001), as only in PR46W21 standard processing reduced the tryptophan SID compared to its soft processed counterpart. The data support the view that the selection of rapeseed variety and modification of thermal treatment during the oil extraction might improve nutritional value of rapeseed meals