Experimental determination of pesticide processing factors during extraction of seed oils.

Processing Factors (PFs) reflect the concentration or dilution of pesticide residues resulting from food processing. PFs are key elements to demonstrate the compliance of processed foods with Maximum residue levels (MRLs) as set by Regulation 396/2005. While efforts have been made by the European Food Safety Authority (EFSA) and by national authorities to compile PFs from processing studies, such PFs are not available for all pesticides/processed product combinations. The EU vegetable oil and proteinmeal industry association (FEDIOL) has therefore developed a theoretical approach to approximate MRLs in crude vegetable oils and fats, based on the partition coefficient (log Pow) of the pesticides and on the oil content of the raw materials. To substantiate this approach, a pilot-scale processing study was initiated with rapeseeds spiked with selected pesticides and the experimental PFs for these pesticides determined. The aims of this study were (i) to study the reliability of pilot-scale conditions for PF determination and (ii) to assess the experimental PFs obtained in comparison to the theoretical PFs proposed by FEDIOL. This study demonstrated that production yields obtained for crude oil and meal in this processing study are similar to those in industrial processes even if differences were observed in the individual production steps (mechanical or solvent extraction steps). The experimental PFs obtained confirmed that the chosen fat-soluble pesticides did concentrate in the oil fraction. For metalaxyl-M having a log Pow lower than 3, a partitioning between the oil and the meal was observed, as expected. By comparing the experimental PFs and theoretical PFs, it can be concluded that the FEDIOL approach can be recommended as a suitable tool when PFs derived from specific processing studies are missing. Similar studies on pesticides with wider ranges of log Pow are required in order to complete our conclusions on default PFs for vegetable oils.

Effects of Toasting Time on Digestive Hydrolysis of Soluble and Insoluble 00-Rapeseed Meal Proteins.

Thermal damage to proteins can reduce their nutritional value. The effects of toasting time on the kinetics of hydrolysis, the resulting molecular weight distribution of 00-rapeseed meal (RSM) and the soluble and insoluble protein fractions separated from the RSM were studied. Hydrolysis was performed with pancreatic proteases to represent in vitro protein digestibility. Increasing the toasting time of RSM linearly decreased the rate of protein hydrolysis of RSM and the insoluble protein fractions. The extent of hydrolysis was, on average, 44% higher for the insoluble compared with the soluble protein fraction. In contrast, the rate of protein hydrolysis of the soluble protein fraction was 3-9-fold higher than that of the insoluble protein fraction. The rate of hydrolysis of the insoluble protein fraction linearly decreased by more than 60% when comparing the untoasted to the 120 min toasted RSM. Increasing the toasting time elicited the formation of Maillard reaction products (furosine, Nε-carboxymethyl-lysine and Nε-carboxyethyl-lysine) and disulfide bonds in the insoluble protein fraction, which is proposed to explain the reduction in the hydrolysis rate of this fraction. Overall, longer toasting times increased the size of the peptides resulting after hydrolysis of the RSM and the insoluble protein fraction. The hydrolysis kinetics of the soluble and insoluble protein fractions and the proportion of soluble:insoluble proteins in the RSM explain the reduction in the rate of protein hydrolysis observed in the RSM with increasing toasting time.

Physical and chemical changes of rapeseed meal proteins during toasting and their effects on in vitro digestibility.

BACKGROUND: Toasting during the production of rapeseed meal (RSM) decreases ileal crude protein (CP) and amino acid (AA) digestibility. The mechanisms that determine the decrease in digestibility have not been fully elucidated. A high protein quality, low-denatured, RSM was produced and toasted up to 120 min, with samples taken every 20 min. The aim of this study was to characterize secondary structure and chemical changes of proteins and glucosinolates occurring during toasting of RSM and the effects on its in vitro CP digestibility. RESULTS: The decrease in protein solubility and the increase of intermolecular ß-sheets with increasing toasting time were indications of protein aggregation. The contents of NDF and ADIN increased with increasing toasting time. Contents of arginine, lysine and O-methylisourea reactive lysine (OMIU-RL) linearly decreased with increasing toasting time, with a larger decrease of OMIU-RL than lysine. First-order reactions calculated from the measured parameters show that glucosinolates were degraded faster than lysine, OMIU-RL and arginine and that physical changes to proteins seem to occur before chemical changes during toasting. Despite the drastic physical and chemical changes noticed on the proteins, the coefficient of in vitro CP digestibility ranged from 0.776 to 0.750 and there were no effects on the extent of protein hydrolysis after 120 min. In contrast, the rate of protein hydrolysis linearly decreased with increasing toasting time, which was largely correlated to the decrease in protein solubility, lysine and OMIU-RL observed. Rate of protein hydrolysis was more than 2-fold higher for the untoasted RSM compared to the 120 min toasted material. CONCLUSIONS: Increasing the toasting time for the production of RSM causes physical and chemical changes to the proteins that decrease the rate of protein hydrolysis. The observed decrease in the rate of protein hydrolysis could impact protein digestion and utilization.

Effect of the desolventizing/toasting process on chemical composition and protein quality of rapeseed meal.

BACKGROUND: During processing in a desolventizer/toaster (DT), rapeseed meal (RSM) is heated to evaporate the hexane and to reduce the level of heat-labile anti-nutritional factors such as glucosinolates (GSL). However, excessive heat treatment may reduce amino acid (AA) content in addition to lower AA digestibility and availability in RSM. The objective of the present study was to produce from one batch of a 00-rapeseed variety (17 µmol GSL/g dry matter (DM), seed grade quality) five differently processed RSM under standardized and defined conditions in a pilot plant, and to determine the impact of these different treatments on protein solubility and chemical composition, in particular with regard to contents of AA including reactive Lys (rLys) and levels of total and individual GSL. METHODS: Four RSM were exposed to wet toasting conditions (WetTC) with increasing residence time in the DT of 48, 64, 76, and 93 min. A blend of these four RSM was further processed, starting with saturated steam processing (< 100 °C) and followed by exposure to dry toasting conditions (DryTC) to further reduce the GSL content in this RSM. RESULTS: The contents of neutral detergent fiber and neutral detergent fiber bound crude protein (CP) increased linearly (P < 0.05), as residence time of RSM in the DT increased from 48 to 93 min, whereas contents of total and most individual GSL and those of Lys, rLys, Cys, and the calculated ratio of Lys:CP and rLys:CP decreased linearly (P ≤ 0.05). The combination of wet heating and DryTC resulted in the lowest GSL content compared to RSM produced under WetTC, but was associated with lowest protein solubility. CONCLUSIONS: It can be concluded that by increasing residence time in the DT or using alternative processing conditions such as wet heating combined with DryTC, contents of total and individual GSL in RSM can be substantially reduced. Further in vivo studies are warranted to elucidate if and to which extent the observed differences in protein quality and GSL content between RSM may affect digestibility and bioavailability of AA in monogastric animals.

Ultrasound induced green solvent extraction of oil from oleaginous seeds.

Ultrasound-assisted extraction of rapeseed oil was investigated and compared with conventional extraction for energy efficiency, throughput time, extraction yield, cleanness, processing cost and product quality. A multivariate study enabled us to define optimal parameters (7.7 W/cm(2) for ultrasonic power intensity, 40 °C for processing temperature, and a solid/liquid ratio of 1/15) for ultrasound-assisted extraction of oil from oilseeds to maximize lipid yield while reducing solvent consumption and extraction time using response surface methodology (RSM) with a three-variable central composite design (CCD). A significant difference in oil quality was noted under the conditions of the initial ultrasound extraction, which was later avoided using ultrasound in the absence of oxygen. Three concepts of multistage cross-current extraction were investigated and compared: conventional multistage maceration, ultrasound-assisted maceration and a combination, to assess the positive impact of using ultrasound on the seed oil extraction process. The study concludes that ultrasound-assisted extraction of oil is likely to reduce both economic and ecological impacts of the process in the fat and oil industry.

Alternative bio-based solvents for extraction of fat and oils: solubility prediction, global yield, extraction kinetics, chemical composition and cost of manufacturing.

The present study was designed to evaluate the performance of alternative bio-based solvents, more especially 2-methyltetrahydrofuran, obtained from crop's byproducts for the substitution of petroleum solvents such as hexane in the extraction of fat and oils for food (edible oil) and non-food (bio fuel) applications. First a solvent selection as well as an evaluation of the performance was made with Hansen Solubility Parameters and the COnductor-like Screening MOdel for Realistic Solvation (COSMO-RS) simulations. Experiments were performed on rapeseed oil extraction at laboratory and pilot plant scale for the determination of lipid yields, extraction kinetics, diffusion modeling, and complete lipid composition in term of fatty acids and micronutrients (sterols, tocopherols and tocotrienols). Finally, economic and energetic evaluations of the process were conducted to estimate the cost of manufacturing using 2-methyltetrahydrofuran (MeTHF) as alternative solvent compared to hexane as petroleum solvent.