Canolol Content Research Articles

Effects of steam explosion pretreatment on the bioactive components and characteristics of rapeseed and rapeseed products

The objectives of this study were to obtain the optimal technical parameters of steam explosion for rapeseed and investigate the effects of pretreatment on the bioactive components and characteristics of three diverse samples of Brassica seed (Brassica napus, B. juncea and B. rapa) and their products. Under the optimal conditions, Brassica napus formed the largest amount of canolol, namely, 1210.10 mg/kg; B. rapa formed the smallest amount, namely, 82.70 mg/kg; and the canolol content was 2110.00 mg/kg in Brassica napus oil. Meanwhile, compared to the traditional cold-pressed rapeseed oil, the total tocopherol and phytosterol contents in Brassica napus, B. rapa and B. juncea oil increased by 5.3%, 4.8%, and 7.4% and 2.1%, 3.2%, and 5.1%, respectively. Steam explosion pretreatment also significantly affected the total phenolic contents and antioxidant capacities of the three types of rapeseeds and their processed products (P < 0.05). In addition, by steam explosion pretreatment, the EAA contents of B. rapa and B. juncea rapeseed cakes increased by 2.22% and 4.49%, respectively. These findings will provide data support and a reference basis for the application and development of steam explosion technology to rapeseeds of various types.

Preparation of rapeseed oil with superhigh canolol content and superior quality characteristics by steam explosion pretreatment technology.

In this study, rapeseed was pretreated by steam explosion pretreatment technology and subsequently pressed to prepare rapeseed oil. GC, UPLC, and HPLC techniques were employed to analyze the quality characteristics of the rapeseed oil, including the canolol content and other quality characteristics. Additionally, the effect of steam explosion pretreatment technology on the canolol content of rapeseed oil was studied and the formation mechanism of canolol elucidated. The results revealed that when the steam explosion pressure reached 1.0 MPa, the canolol content of the tested oil increased from 41.21 to 2,168.69 mg/kg (52.63‐fold increase) and that sinapic acid played a significant role in the conversion of canolol. Thus, the sinapine was converted into the intermediate (sinapic acid) by hydrolysis, which in turn was transformed into canolol through decarboxylation. The instantaneous high‐energy environment generated by steam explosion pretreatment could intensify the hydrolysis and decarboxylation reactions of sinapine and sinapinic acid, thereby significantly increasing the canolol content of the oil. To prove the superiority of steam explosion pretreatment, we compared it with other pretreatment technologies, including traditional high‐temperature roasting and popular microwave pretreatment. The results revealed that rapeseed oil prepared by steam explosion pretreatment displayed the best quality characteristics. This study can be a reference for the preparation process of rapeseed oil with superhigh canolol content and superior quality characteristics using steam explosion pretreatment.

Sinapic acid derivatives in microwave-pretreated rapeseeds and minor components in oils

Microwave pretreatment has been considered to improve the quality of rapeseed oil for canolol generation. Canolol is assumed to be formed by the decarboxylation of sinapic acid (SA). In this work, sinapic acid derivatives in 39 microwave-pretreated rapeseeds and their roles in the enhanced oxidative stability of rapeseed oils were investigated. The average contents of sinapic acid derivatives in rapeseeds, including (from high to low) sinapine, sinapoyl glucoside (SG), disinapoyl gentiobioside (DSG), quercetin-sinapoyl-di-hexosepentose (QSDG), sinapoyl malate (SM), disinapoyl glucoside (DDSG) and SA, were determined. After microwave pretreatment, the canolol content in rapeseed increased from nil to 6.16–76.1 mg/100 g, while sinapic acid derivatives contents decreased. The degradation rates of SG, DDSG, DSG, SM, SA and sinapine were 59.1%, 40.2%, 33.7%, 27.4%, 14.4% and 11.3%, respectively. There was no correlation relationship between sinapine and canolol. However, SG, DSG, SM and DDSG were regarded to be the precursor substances of canolol. Additionally, the tocopherols, sterols and canolol contents, along with the induction period (IP) of microwaved rapeseed oil increased by 3.79%, 10.0%, 76.8 times and 38.7%, respectively. There was a significant positive correlation between IP and canolol content. These findings clarify the precursor substances of canolol and provide a theoretical support for the development and utilization of canolol.

Quality evaluation of rapeseed oil in Chinese traditional stir-frying.

Canolol is a potential antioxidation ingredient in rapeseed oil. Rapeseed oil with two levels of canolol (528.9 vs. 250.5 mg/kg) was used for stir‐frying different foods (potatoes, tofu, and vegetables). Comprehensive evaluations indicated that the canolol content in high canolol rapeseed oil (HCR) and low canolol rapeseed oil (LCR) after stir‐frying were in the range of 187.8–237.7 and 45.6–96.4 mg/kg, respectively. The degradation rate of total phenol was 58.4% and 80.3% in HCR and LCR, respectively. The loss rates of α‐ and γ‐tocopherol were 24.5% and 47.6%, respectively. Phytosterol concentration decreased by 20% and trans‐fatty acid was not detected in either rapeseed oil. In addition, the peroxide value, anisidine value, and malondialdehyde content in HCR were lower than those in LCR. The oxidative stability index in HCR was longer, showing lower extent of deterioration. Rapeseed oil with high canolol content displayed good oxidation resistance due to significant positive correlation with oxidation induction time (p < .01).

Primary Metabolites and Polyphenols in Rapeseed (Brassica napus L.) Cultivars in China

AbstractDefatted meals of 10 rapeseed (Brassica napus L.) varieties were investigated for their total phenolic, phenolic acid (free, esterified, and insoluble‐bound forms), and tannin contents. The antioxidant capacities (AC) of methanol extracts from samples were assessed using the 2,2′‐diphenyl‐1‐picrylhydrazyl radical (DPPH•), Folin–Ciocalteu method and ferric reducing antioxidant power (FRAP), and β‐carotene–linoleic acid tests. In the fraction of free phenolic acids, sinapic, caffeic, ferulic, syringic, gallic, and p‐coumaric acids were identified. In the fraction of esterified phenolic acids, sinapine, sinapoyl glucoside, and disinapoyl gentiobiose were identified. After basic hydrolysis, sinapic, ferulic, cinnamic, and 4‐hydroxybenzoic acids were identified, and sinapic acid (SA) constituted 98.3% to 99.6% of the total esterified phenolic acids. Eleven components (sinapic, protocatechuic, p‐coumaric, syringic, vanillic, gallic, caffeic, ferulic, salicylic, cinnamic, and 4‐hydroxybenzoic acids) in the fraction of insoluble‐bound phenolic acids were identified. The AC of the samples correlated with the total phenolic content. Overall, the total phenolics showed a better correlation with AC than the individual phenolic compounds. Moreover, SA, sinapoyl glucoside, and disinapoyl gentiobiose showed a highly significant and strong positive correlation with the AC of rapeseed meals, and the derivatives of cinnamic acid showed a higher correlation with AC than the derivatives of benzoic acid. The change in the canolol content in rapeseeds under microwave irradiation is discussed. The correlation of the canolol formed with SA and its derivatives is discussed.

Hexane‐Free Green Solvent Extraction of Canola Oil From Microwave‐Pretreated Seeds and of Antioxidant‐Rich Byproducts

The ethanol extraction from microwave‐pretreated and untreated canola seeds is studied. Two process are used to obtain the oil: in a control process (P1), the solvent‐free total extract (E) is washed with hexane, obtaining an oil fraction (OF). The second process (P2) consists of the partial evaporation of the solvent of the total extract (E), cooling, centrifugation, and separation by decantation of the generated phases: oil‐rich phase (OF + Ethanol), solvent‐rich phase (EthF + Ethanol), and solid phase (SF); and then evaporating the solvent to obtain OF and an extract of soluble in the phase rich in ethanol (EthF). No significant differences due to microwaves are detected in the yields. P2 gave mean yields of 32.8%db of OF, lower than obtained with P1 (42.1%db), 4.2%db of precipitated solids, and 7.7%db of EthF, which present a mean content of hexane‐solubles of 5.1%db. However, the quality analysis shows a smaller oxidative damage and an increase in canolol content due to the microwaves. P2 also generates an antioxidant‐rich byproduct, allowing to recover the canolol prior to a refining stage of the oil.Practical Applications: The use of organic solvents for the extraction of vegetable oils have some disadvantages, such as health and safety problems. At the same time, ethanol has begun to be studied as an alternative solvent due to its lower production costs than other alternative solvents, and to the fact that it is recognized as a “bio‐renewable” solvent. Numerous studies have shown the extraction of oil and impurities obtained with ethanol. However, no method have been developed for obtaining an insoluble‐free canola oil from the extract obtained with ethanol without using hexane. In addition, a favorable effect of the canolol content pretreated with microwaves in the canola oil is reported, nevertheless, the canolol is eliminated during the refining stage of the crude oil. The hexane‐free development process allows to obtain canola oil and an antioxidant‐rich byproduct, allowing to recover the canolol prior to a refining stage of the oil.Green solvent (ethanol) extraction from microwave‐pretreated canola seeds and a hexane‐free separation process is developed. The results show a high yield of canola oil and the production of an antioxidant‐rich byproduct.

Influence of de-hulled rapeseed roasting on the physicochemical composition and oxidative state of oil

The effect of roasting time on the contents of bioactive compounds (tocopherols, phytosterols, phenolic compounds), antioxidant capacity and physicochemical properties of rapeseed oil pressed from de-hulled seeds was investigated. The de-hulled seeds were roasted at a temperature of 165 °C for 20, 40, 60, 80, and 100 min. The results of this study show that a roasting pre-treatment led to a gradual increase in canolol content (from 1.34 to 117.33 mg/100 g), total phytosterols (from 573.51 to 609.86 mg/100 g) and total carotenoids (0.82 to 2.41 mg/100 g), while only slight changes in the contents of tocopherols were noted. With the increase in roasting time a gradual increase in oxidative stability (from 4.27 to 6.85 h), and antioxidant capacity, seen mainly in the hydrophilic fraction of oil (from 0.32 to 2.30 mmol TEAC/l) was found. Although roasting resulted in the formation of primary and secondary oxidation products, the quality parameters of oils were within Codex Alimentarius limits.

Antioxidant (Tocopherol and Canolol) Content in Rapeseed Oil Obtained from Roasted Yellow-Seeded Brassica napus

In this study, the effect of temperature (140, 160, 180 °C) and roasting time (5, 10, 15 min) on the bioactive compound content (canolol, tocopherol and plastochromanol-8) of cold-pressed oil from yellow-seeded rapeseed lines of different colors was investigated. Roasting increased the peroxide value in the seed oils compared to the oils from the control samples. However, roasting did not affect the acid values of the oils, which were 1.15–1.47 and 1.30–1.40 mg KOH/g, for line PN1 03/1i/14 (yellow seeds) and line PN1 563/1i/14 (brown seeds), respectively. In this study, the seeds of line PN1 03/1i/14 were characterized by different changes in canolol content during roasting than the seeds of PN1 563/1i/14. There was a 90-fold increase in canolol for the line PN1 03/1i/14 (768.26 µg/g) and a 46-fold increase for the line PN1 563/1i/14 (576.43 µg/g). Changes in tocopherol and PC-8 contents were also observed. There was an increase in the contents of γ-T and PC-8 in the oils obtained from the seeds roasted at 180 °C for 10 and 15 min. γ-T content increased by 17–18% after 15 min of roasting, whereas the PC-8 content increased twofold.

Bidimensional modeling applied to oil extraction kinetics of microwave-pretreated canola seeds

The effect of microwaves on canola oil extraction kinetics and on tocopherol and canolol content in oil was studied. Oil was extracted with hexane at constant temperature (298–333 K) at different times (300–64800 s). In general, for each temperature and time, a significant yield increase was achieved by effect of the pretreatment. A modified Fick's diffusion model was proposed to explain the extraction process; the parameters were adjusted to obtain washing fractions and the effective diffusion coefficient, which presented an Arrhenius-type temperature-dependence. The analysis of the parameters allowed to develop a modified bidimensional diffusion model (temperature and time-dependent), appropriately correlating the data for pretreated and untreated samples. An increase in the pre-exponential parameter due to pretreatment was observed, evidencing the influence of microwave radiation on the sample structure. The pretreatment did not significantly affect the oil quality indices, but increased the content of canolol and β and δ-tocopherol isomers.

Canolol, tocopherols, plastochromanol‐8, and phytosterols content in residual oil extracted from rapeseed expeller cake obtained from roasted seed

Due to the high canolol content rapeseed oil is increasingly often pressed from seeds subjected to the roasting process. However, there is a lack of data on the contents of canolol in residual oil produced from cake, a by‐product of cold pressing. The aim of this study was to investigate the contents of bioactive substances contained in expeller cake generated in cold pressing of rapeseed oil from seeds roasted at a temperature of 140, 160, and 180°C for 5, 10, and 15 min. Contents of tocopherols, plastochromanol‐8, and canolol were analyzed using the NP‐HPLC‐FL method, while contents of phytosterols – by GC‐FID. Based on the recorded data it may be concluded that 180°C is the best temperature for seed roasting, since at that temperature the greatest amount of canolol is formed and most of it passes to oil in the course of cold pressing. Contents of tocopherols in the tested oils ranged from 88.48 to 90.51 mg/100 g. A lower tocopherol content was recorded in residual oil of the press cakes in comparison to cold‐pressed oil, particularly in the case of samples roasted at a temperature of 160 and 180°C. Content of PC‐8 was higher in residual oil by over 4 mg/100 g in comparison to cold‐pressed oil. Also the total content of phytosterols in oils produced by solvent extraction from cake was higher than in cold‐pressed oil. Contents of phytosterols ranged from 4141.9 to 4826.1 μg/g oil.Practical application: Rapeseeds increasingly often are subjected to roasting prior to the cold pressing process. During roasting canolol is formed, which as a product of decarboxylation of sinapic acid, more efficiently penetrates to oil in comparison to sinapic acid. However, there is no data concerning the amounts of canolol remained in press cake. This study investigated the effect of temperature of rapeseed roasting on the content of bioactive compounds (tocopherols, PC‐8, phytosterols, and canolol) in residual oil from press cake. Results recorded in this study facilitate selection of roasting parameters so that the lowest possible amounts of bioactive compounds are retained in cake and they rather pass to cold‐pressed oil, enriching it and indirectly contributing to an enhancement of its oxidative stability. On the other hand, these results show that the expeller cake (from roasted seeds) as a by‐product can be further treated as a good source of bioactive compounds including canolol. They can also be used as a practical supplement to animal feed.This study investigates the effect of rapeseed roasting at a temperature of 140, 160, and 180°C for 5, 10, and 15 min on the content of residual oil and its composition in terms of such bioactive substances as tocopherols, PC‐8, phytosterols, and canolol. It is seen that residual oil extracted from rapeseed cake subjected to roasting has lower contents of tocopherols (particularly in the case of samples roasted at 160 and 180°C). PC‐8 is more effectively extracted with an organic solvent, since its content in residual oil was by 4 mg/100 g higher than in cold‐pressed oil. Also the content of phytosterols is higher in residual oil than in cold‐pressed oil. Contents of phytosterols ranges from 4141.9 to 4826.1 mg/g oil. Based on the recorded data it may be concluded that 180°C is the best temperature for seed roasting, since at that temperature the greatest amount of canolol is formed and most of it passes to oil in the course of cold pressing.

The long‐term storage of cold‐pressed oil from roasted rapeseed: Effects on antioxidant activity and levels of canolol and tocopherols

The aim of this study was to determine the oxidative stability of rapeseed oils cold pressed from seeds roasted at 140, 160, or 180°C for 5, 10, or 15 min versus the control (oil from unroasted seeds). The oils were stored for a period of 1 year. After 6 and 12 months of storage, the samples were analyzed to determine their peroxide and acid values, the levels of bioactive substances (tocopherols, plastochromanol‐8, and canolol), as well as antioxidant activity (DPPH test). It was shown that roasting the rapeseeds had a significant effect on the oxidative stability of the oils, which increased by almost 50%. In the case of oils pressed from seeds roasted at 140 and 160°C, it was shown that the longer the seeds were roasted, the smaller the reduction in canolol content. After 6 months of storage, the percentage decrease in the canolol content of oils from roasted seeds was recorded to be at a level comparable to that of the control. After 1 year of storage, the percentage loss of canolol was markedly lower (from 18 to 45%) than in the control (61%). The reduction in tocopherol levels was dependent on the duration of storage and on the type of sample. Principal component analysis (PCA) confirmed that the oxidative stability of oils produced from roasted seeds, particularly from those roasted at 180°C, was markedly higher than that of the other samples obtained from roasted seeds and the control.Practical applications: Studies concerning oxidative stability are most typically conducted by applying so‐called accelerated aging tests performed at high temperatures (Rancimat, Oxidograph test). In practice, this undermines the reliability of the results, since it is difficult to draw conclusions about the actual shelf life of a product, on account of the various mechanisms of the oxidation process. At high temperatures, the primary reactions are connected with polymerization and cyclization, which are not comparable to the reactions taking place under normal conditions. The analysis conducted here made it possible to follow the changes during the storage of the oil and the rate of degradation of bioactive substances reflecting cold‐storage conditions.Rapeseed oils cold pressed from seeds subjected to roasting (140–180°C for 5–15 min) were compared to rapeseed oil that was cold pressed from seeds not exposed to elevated temperatures through an analysis of their oxidative stability, antioxidant activity, and levels of bioactive substances (tocopherols, plastochromanol‐8, and canolol). The oils were stored for a period of 12 months at a temperature reflecting cold storage conditions (4°C). It was shown that the oils produced from seeds roasted at 180°C in particular exhibited greater oxidative stability and the best antioxidant properties. Antioxidant activity was shown to correlate with the levels of canolol (r = 0.9927; p &lt; 0.0001) and g‐T (r = 0.9765; p &lt; 0.0001), as well as with total tocopherols (r = 0.9796; p &lt; 0.0001).

Antioxidant activity and phytochemical content of cold‐pressed rapeseed oil obtained from roasted seeds

An analytic comparison was made of cold‐pressed rapeseed oil produced from unroasted seeds and cold‐pressed oil produced from seeds that had previously undergone roasting at temperatures of 140, 160, and 180°C for 5, 10, and 15 min. It was determined whether the duration and temperature of roasting have any qualitative and quantitative effects on the contents of the native antioxidants (tocopherol, PC‐8, phenolic compounds, canolol, and phytosterols) found in rapeseed oil. At the same time, changes in the antioxidant activity of oils produced from roasted seeds were determined. It was shown that roasting has no significant effect on the quality of cold‐pressed oils. The peroxide value of the oils ranged from 2.03 to 3.48 meq O2/kg, while the acid value did not exceed 0.68 mg KOH/g. Slight changes were observed in oils in terms of tocochromanol contents. A decrease was seen mostly in the level of the α‐T homologue, with an increase in the contents of γ‐T and PC‐8 (in oil from seeds roasted at 180°C). In the oil from the unroasted seeds, the canolol content was 11.54 μg/g oil. It was shown that increases both in temperature and in duration of seed roasting result in a statistically significant increase in the canolol content of cold‐pressed oils. For the seed roasted at 180°C for 15 min, this increase was fifty‐fold (609.94 μg canolol/g oil). The same roasting conditions also led to a twofold increase in the antioxidant activity of the oil.Practical applications: Cold‐pressed oils are increasingly frequently chosen by consumers due to their reputation as good source of bioactive components. An obvious example of such a food product is cold‐pressed rapeseed oil made from roasted seeds, in which the levels of canolol—a product of the decarboxylation of sinapic acid—is markedly increased. This compound is ascribed strong antioxidant properties, as well as antimutagenic and anticarcinogenic properties. Such oils truly deserve to be labeled bioactive products.An analytic comparison was made of cold‐pressed rapeseed oil produced from unroasted seeds and cold‐pressed oil produced from seeds that had previously undergone roasting at temperatures of 140, 160, and 180°C for 5, 10, and 15 min. It was determined whether the duration and temperature of roasting have any qualitative and quantitative effects on the contents of the native antioxidants (tocopherol, PC‐8, phenolic compounds, canolol, and phytosterols) found in rapeseed oil. In the oil from the unroasted seeds, the canolol content was 11.54 μg/g oil. It was shown that increases both in temperature and in duration of seed roasting result in a statistically significant increase in the canolol content of cold‐pressed oils. For the seed roasted at 180°C for 15 min, this increase was fiftyfold (609.94 μg canolol/g oil). The same roasting conditions also led to a twofold increase in the antioxidant activity of the oil.

Changes in the content of canolol and total phenolics, oxidative stability of rapeseed oil during accelerated storage

An oil sample was prepared by cold‐pressing from untreated (UTRO) and microwave‐treated (MWRO) rapeseed, and tertiary butyl‐hydroquinone (TBHQ) was added to another oil from untreated rapeseed. Microwave pretreatment significantly increased the total phenolics and canolol contents, as well as the initial acid value (AV), peroxide value (PV), and p‐anisidine value (pAV) of oil (p&lt;0.001). However, there was found to be a difference in the rate of increase of AV, PV, and pAV of oil during the autoxidation with the following order of all these values observed: UTRO &gt; UTRO + TBHQ &gt; MWRO. During storage, significant linear correlations (p&lt;0.001) were found between the PV, pAV, and canolol content (PV vs. Canolol = −0.960 to −0.890; pAV vs. Canolol = −0.889 to −0.968), and the DPPH activity was also linearly and significantly correlated with the content of total phenolics and canolol in oils. (DPPH vs. Tatal phenolics = 0.910–0.945; DPPH vs. Canolol = 0.941–0.962; p&lt;0.001). When the autoxidation test was completed (on the 10th wk), it was found that the contents of canolol and total phenolics in MWRO were the highest, followed by UTRO + TBHQ, and UTRO. These results indicate that the MWRO exhibited superior oxidative stability.Practical application: Canolol, also known as vinylsyringol, is a phenolic compound that has been identified as a decarboxylation product of sinapic acid, and this type of compounds is known for scavenging free radicals. In this study, we evaluated the changes occurring during storage in the contents of canolol and the total phenolics, oxidative stability, and antioxidant capacity of rapeseed oil and found good correlation among the canolol content, oxidative stability, and antioxidant capacity. Therefore, we can use canolol as a native antioxidant for rapeseed oil production in the future.Canolol in rapeseed and rapeseed oil that is formed by thermal decarboxylation of sinapic acid under microwave irradiation. Canolol formation has been shown to improve the oxidative stability of oil from microtreated rapeseed. The results showed a very good correlation between the level of primary oxidative products (peroxide values), secondary oxidative products (p‐anisidine values) and the contents of canolol in the rapeseed oil during storage. So, canolol has potential applications in oil storage.

Influence of Microwaves Treatment of Rapeseed on Phenolic Compounds and Canolol Content

Rapeseeds were treated with microwaves under 800 W for 0, 1, 2, 3, 4, 5, 6, 7, and 8 min at a frequency of 2450 MHz, and oil was extracted with a press to investigate the influence on phenolic compounds, including sinapine, the main free phenolic acids, and canolol content in the rapeseeds and oil from them. The results indicated that sinapine and sinapic acid was the main phenolic compound and free phenolic acid in the rapeseed, respectively, and canolol was the main phenolic compound in the oil from rapeseed by cold press. Microwave treatment significantly influenced phenolic compounds content in the rapeseeds and oil from them. The sinapine, sinapic acid, and canolol content in rapeseed first increased and then decreased depending on the period of microwave radiation (p < 0.05). The canolol content of 7 min microwave pretreatment rapeseed increased to the maximum and was approximately six times greater than that of the unroasted rapeseed. The amount of canolol formed was significantly correlated with the content of sinapic acid and sinapine (for sinapic acid, r = -0.950, p < 0.001, for sinapine, r = -0.828, p < 0.05) and also the loss of sinapic acid and sinapine (for sinapic acid, r = 0.997, p < 0.001, for sinapine, r = 0.952, p < 0.05) during roasting. There were differences in the transfer rate of difference phenolic compounds to the oil extracted by press. Almost all of the sinapine remained in the cold-pressed cake and only 1.4-2.7% of the sinapic acid, whereas approximately 56-83% of the canolol was transferred to the oil. The transfer ratio of canolol significantly increased with microwave radiation time (p < 0.001). Microwave pretreatment of rapeseed benefited improving the oxidative stability of oil.

Fluidized bed treatment of rapeseed meal and cake as possibility for the production of canolol

Canolol (2,6-dimethoxy-4-vinylphenol, 4-vinylsyringol), which is formed by thermally initiated CO2 splitting off from sinapic acid, possesses a high antioxidant potential. Furthermore different positive physiological properties are described. Due to rapeseed’s high content of phenolic acids, particularly sinapic acid, it is obvious to produce canolol as by-product of rapeseed processing. Roasting of rapeseed meal or cake in a fluidized bed followed by extraction with supercritical carbon dioxide of the formed canolol represents a production procedure which not impairs the commercial oil mill process. This article summarizes results from the roasting process with rapeseed meal and cake in fluidized bed equipments of different design and size showing that it is a suitable technique to transform sinapic acid into canolol. The achieved canolol contents are at 500 mg/kg in minimum, if the material is rapidly cooled-down after reaching the optimal temperature of 165 °C. Further roasting leads to a fast reduction of the canolol content. In addition it could be observed, that the sinapic acid content is not decreasing in the same amount as the canolol content increases. Sinapic acid seems to be “reproduced” during roasting. The reaction mechanisms of the described phenomena are not known.

Effect of Conventional and Microwave Toasting on Sinapic Acid Derivatives and Canolol Content of Canola

Canola seeds were subjected to conventional and microwave heat treatments to investigate changes in the phenolic profile of defatted meal and oil obtained from the toasted seeds. Different temperature (120–200 °C) and time (5–20 min) combinations were applied for toasting the seeds in a conventional oven. The seeds were also toasted using a microwave oven at 300 Watt power level with and without steaming. Phenolics were extracted from the defatted meal and oil of raw and toasted seeds. The main phenolic compounds namely sinapine (SP), sinapoyl glucose (SG), sinapic acid (SA) and canolol were identified and quantified by HPLC-DAD. Total phenolics and SA derivatives in the meal were found to decrease in both toasting treatments. Canolol was formed in the oil and subsequently increased with increasing toasting temperature up to 200 °C. The optimum toasting conditions under which the canolol content of the oil showed the highest increment rate (more than 2200 folds) were found to be 200 °C for 15 min in the conventional oven. However, the optimum microwave toasting conditions were 20 min with steam which increased canolol content by more than 1700 folds. Keywords: Canola, canolol, sinapic acid derivatives, toasting.

A novel insight on the high oxidative stability of roasted mustard seed oil in relation to phospholipid, Maillard type reaction products, tocopherol and canolol contents

The oxidative stability of the roasted and unroasted crude mustard seed oil samples collected from the Nepalese market was evaluated by monitoring the peroxide value (PV) and conjugated diene (CD) during storage in the dark at 50°C. These samples showed a wide variability in the oxidative stability as measured by PV ranging from 5.22 to 42.11meq oxygen/kg oil after 69days of storage. The PV after 40days of storage (PV40) as an index of oxidative stability of the different samples was not significantly correlated (p>0.05) both with the total radical scavenger concentration (sum of tocopherol, plastochromanol-8 and canolol) and the total radical scavenging capacity of the oil using the di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (DPPH) assay. Hence, those antioxidants were not solely responsible for the differences in the oxidative stability among the oil samples. On the other hand, the PV40 showed significant negative correlation with the canolol content (p<0.01), the phospholipid content (p<0.001) and the different browning reaction markers such as absorbance at 350nm (p<0.001), fluorescence (excitation at 350nm and emission at 440nm) (p<0.001), and the pyrrolized phospholipid content (p<0.01). Moreover, all the browning reaction markers and phospholipid content were also highly positively correlated (p<0.001) with each other. The phospholipid and its Maillard type browning reaction products together with canolol formed during seed roasting were primarily responsible for the high oxidative stability of the roasted mustard seed oil samples.

Effect of Microwave Treatment on Sinapic Acid Derivatives in Rapeseed and Rapeseed Meal

AbstractMicrowave treatment is a new method for rapeseed processing. To better understand the benefits of microwave pretreatment on rapeseed processing, qualitative and quantitative analysis of sinapic acid derivatives is needed. In this study, the effect of microwave treatment on the content of sinapic acid derivatives in rapeseed and the effect of cold‐press and solvent extraction on the content of sinapic acid derivatives in rapeseed meal were evaluated using ultrahigh pressure liquid chromatography. It was found that during the microwave treatment, the content of sinapine and sinapic acid in the rapeseed increased slightly at the outset of treatment and significantly decreased thereafter. Following 7 min of microwave treatment, the content of sinapine in rapeseed exhibited its largest decrease of 16.7 %. By contrast, microwave heating of the rapeseed increased the canolol content significantly. We employed two sample paired t tests as a means to analyze the difference between meal and defatted cold‐pressed cake. The results indicated that the content of sinapine and sinapic acid in defatted cake was significantly higher than that in meal, while the different extraction methods (solvent extraction and cold‐press) did not appear to have a significant influence on the content of canolol in meal (p ≤ 0.05).

Influence of thermal treatment of rapeseed on the canolol content

4-Vinylsyringol, also referred to as canolol, is a highly active antioxidant and potent lipidperoxyl radical scavenger found in rapeseed. The canolol content of rapeseed can be increased through the decarboxylation of sinapic acid via roasting treatments. Different roasting conditions were tested and compared and an optimum for the canolol formation was found at 160 °C. The canolol content of the rapeseed samples with optimal roasting increased by a factor of 120 in relation to the unroasted sample. The rapeseed was ground, extracted and analysed by normal-phase HPLC/UV. The structure of canolol was confirmed by NMR and MS techniques. Several rapeseed oils were purchased in German food stores and analysed. No differences in canolol content were observed in both cold-pressed and rape kernel oil samples tested. Dehulled rapeseed samples demonstrated no significant difference in canolol content when compared to unpeeled rapeseed samples.

Isolation, Identification, and Structure of a Potent Alkyl-Peroxyl Radical Scavenger in Crude Canola Oil, Canolol

Alkylhydroperoxides in oxidized oil are undesirable components because they become alkylperoxyl radicals (ROO*) in the presence of heme, hemoglobin, or myoglobin in red meat. ROO* are biochemically reactive and damage nucleic acids and proteins, thereby harming living cells. We isolated a component, a highly potent ROO* scavenger, from crude canola oil (rapeseed), which we designated canolol, and identified its chemical structure, 4-vinyl-2,6-dimethoxyphenol. The canolol content of crude canola oil greatly increased after the seed was roasted as compared with that from unroasted seed, but it decreased in highly purified oil. This anti-ROO* activity was highest in crude oil, deceased after each refining step, and was lowest in highly purified refined oil. Canolol was thus generated during roasting. As shown previously, canolol is one of the most potent anti-ROO* components in crude canola oil and its potency is much greater than that of well-known antioxidants, including alpha-tocopherol, vitamin C, beta-carotene, rutin, and quercetin.