Patrick Carré

Glucosinolates (GSLs) from Brassica carinata press cake are of interest both as antinutritional factors to be removed from feed and as precursors of bioactive compounds for biocontrol, but their selective recovery must contend with the dual constraints of myrosinase activity and protein preservation. This study investigates hydro-ethanolic extraction and miscella concentration at laboratory and pilot scales on industrial-type press cakes and finely milled powders. At laboratory scale, when press cake was ground, fully dispersed in solvent and extracted after thermal myrosinase inactivation, GSL yields above 90% were achieved with low residual levels in the final meal, showing that neither diffusion nor thermal degradation is an intrinsic barrier. In contrast, pilot-scale percolation on intact cakes plateaued at about 70% overall recovery, with roughly 30% of initial GSLs remaining in spent cakes despite extended extraction times and high solvent-to-solid ratios, highlighting strong mass-transfer and percolation limitations. Incomplete myrosinase inactivation further caused substantial and variable GSL losses, particularly during miscella concentration, where up to 60–70% of solubilized GSLs could no longer be accounted for under some evaporation conditions. Clarification of extracts by centrifugation prior to evaporation allowed miscella concentration without measurable additional losses in selected trials. Overall, a carinata-based GSL “biorefinery brick” appears technically feasible only within a very narrow operating window and at a processing cost that is difficult to justify for bulk feed applications, unless high-value outlets for GSL-rich fractions can be secured.

This study aims to identify the morphological and anatomical factors that influence the dehulling capacity of sunflower achenes, a critical issue for the oilseed industry. Four cultivars grown at two sites over two cultivation years were examined. The study is based on observations from transverse sections of achenes, enabling measurement of the area of the achenes, embryos, and pericarp, as well as the length of contact zones between the pericarp and the embryo. Calculations were used to evaluate pericarp thickness, filling rate, and contact rate. Dehulling capacity does not simply depend on achene size or oil content but rather results from a complex balance between pericarp rigidity (as determined by its thickness) and the presence of gaps or adhesion zones at the pericarp/embryo interface. Genetic factors influence pericarp thickness and the propensity for hull/kernel contact. Environmental conditions impact the supply of water at both the flowering and seed-filling stages. The flowering period is crucial for pericarp development, and water stress during this period results in thinner pericarps and smaller achenes that are more difficult to dehull. The filling rate increases when water needs during seed filling are met, whereas the contact zones depend on the interaction between water supplies during both stages. In summary, the findings validate the role of the hull/kernel interface in dehulling and provide fresh avenues for selecting varieties with superior technological quality in sunflower achenes.

This study investigated the cold pressing of dehulled oilseeds, specifically sunflower kernels, using an instrumented continuous press at two rotational speeds (3.5 and 7 rpm). The research combined physical measurements (pressure, temperature) with oil content analysis of the cake inside the press. At 3.5 rpm, the extraction yield reached 91% with oil flow throughout the entire cage. However, at 7 rpm, the yield drastically decreased to 43%, with oil flow limited to the first half of the press. These variations corresponded to distinct pressure profiles within the press. At high speed, cake filtration resistance became limiting, leading to oil blockage due to capillary network collapse. Unidirectional compression tests revealed that increased compression speed resulted in rapid pressure rise followed by solid expulsion, which is an indicator of resistance to filtration by the dehulled product. Contrary to the most widespread hypothesis in the literature, the poor performance of screw presses with dehulled seeds is not due to lack of friction, but to increased fragility of the oil-conducting capillary network. These findings explain the poor performance of presses operating on low-fibre matrices and suggest potential improvements through adapted compression profile designs. The study also provides new insights into solid matter evolution, proposing the concept of a dominant screw segment whose flow rate determines upstream matter reflux and restricts downstream segment feeding.

This study presents a comprehensive, real-time investigation of the mechanical and flow dynamics within screw press during oil extraction from sunflower kernels and non-dehulled rapeseed. Using an instrumented press equipped with high-frequency sensors for pressure, torque, and cage strain, the research reveals pronounced cyclic fluctuations in internal pressures and deformations of the cage, closely tied to screw rotation. These findings challenge the adequacy of conventional steady-state models and highlight the need for dynamic approaches to capture the true behaviour of oilseed matrices during pressing. Comparative analysis demonstrates that sunflower kernels, due to their higher deformability and filtration resistance, exhibit flatter pressure profiles and reduced energy consumption, but also limit maximum pressure and oil yield compared to rapeseed. Residence time distribution measurements further uncover complex material flow patterns, including significant backflow at higher screw speeds, necessitating hybrid modelling approaches. The observed correlation between cage deformation and torque variation suggests that structural rigidity is a key factor for optimizing press performance and energy efficiency. Overall, this work advances the mechanistic understanding of screw press operation and provides new insights for improving oilseed processing efficiency and equipment design.

Over a period of four years, we carried out a systematic literature review of processes for improving the value of oilseeds and oilseed meals for animal feed, based on articles published in peer-reviewed journals. As this review revealed a growing body of work on the fermentation of soybean meal (FSBM) and rapeseed meal (FRSM), it was decided to assess the value of oilseed meal fermentation for pig feed by studying its effects on the composition, nutritional value, animal performance, health and microbiota of the animals, as well as on product quality, the economy and the environment. A total of 46 articles published between 2020 and 2023 (28 FSBM and 18 on FRSM) were collected and analysed. Each observation was assigned a positive or negative value depending on its effect. The analysis revealed a positive effect of fermentation for 88% of the observations (223 observations) for FSBM and 86% for FRSM (145 observations) for highly variable incorporation levels (1–35% of the feed for FSBM and 4–14% for FRSM). Aggregate observations of composition, anti-nutritional factors and nutritional value were positive in 88% of cases for FSBM compared with 75% for FRSM. Observations of zootechnical performance/product quality showed that FSBM was superior (90% positive effects) to FRSM (68%). Conversely, for health and microbiota, FRSM generated 96% positive observations compared with 86% for FSBM. These disparities within a very positive picture argue in favour of continuing to monitor the literature, but also of carrying out experiments in France, since none of the 46 studies analysed is French. It would be useful to identify the micro-organism strains and fermentation processes best suited to our local conditions and our oilcakes. In addition, the process costs deserve particular attention, especially due to the necessary post-fermentation drying step.

OCL, Oilseeds and fats, Crops and Lipids

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.

Oilseeds extraction of oils requires the use of a processing aid : a solvent. This seventh article on the comparison of solvents potentially capable of replacing hexane presents a multi-criteria analysis, systematically revisiting aspects from previous investigations. The methodology addresses the problem’s complexity by aggregating different dimensions representative of each criterion, resulting in a nuanced ranking approach. The comprehensive study examined critical dimensions including solvent extractive efficacy, operational safety, explosion risk, toxicity to workers, environmental impact, process modifications, energy consumption, effects on products quality, residual toxicity, technology readiness level, and economic feasibility. From a technical standpoint, hexane today remains the most efficient solvent for oilseed crushers. Dichloromethane may be a viable alternative due to its non-explosive nature, though its toxicity concerns are significant. 2-methyloxolane is the subject of ongoing research and development investments, which may ultimately establish it as a credible alternative solution. Different stakeholders present varied perspectives on solvent replacement. For worker safety, isopropanol and ethanol are preferable options. Environmental advocates may favor ethyl acetate because of its lower energy requirements during processing. Regarding food safety, both ethanol and ethyl acetate are generally regarded as acceptable solvents. Public authorities, for their part, must balance what is desirable with what is feasible, in a multi-criteria framework of balancing safety, toxicity, environmental impact, availability, and cost on a global scale.

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.

OCL, Oilseeds and fats, Crops and Lipids