1.De-oiled rapeseed and a protein isolate: characterization of sinapic acid derivatives by HPLC–DAD and LC–MS
Usha Thiyam, Pickardt Claudia, Ungewiss Jan, Baumert Alfred. Eur Food Res Technol (2009) 229:825–831
Rapeseed press cake and proteins contain significant amounts of phenolic compounds, namely sinapic acid, in the free and esterified form. HPLC–DAD and LC–MS demonstrates that the main phenolic compounds in de-oiled rapeseed, its corresponding press cake and the protein isolate are similar, that is SAD. Both, syringeldehyde and canolol was not found in the investigated protein isolate. Furthermore, the study also indicates that sinapine could be possibly degraded to produce another phenolic compound. This information can be useful to apply to commercial production of rapeseed proteins to relate to specific processing parameters of protein production and storage conditions of phenolic extracts. Further studies to understand the mechanism of degradation or structural changes involved for sinapine and sinapic acid is needed. In continuance of this study, the mass spectra of the unidentified compounds are currently under investigation.
2.Effect of Microwave Treatment on Sinapic Acid Derivatives in Rapeseed and Rapeseed Meal
Yanxing Niu • Mulan Jiang • Chuyun Wan • Mei Yang • Shuangxi Hu. J Am Oil Chem Soc (2013) 90:307–313
We also found that the concentration of canolol in the samples increased when the sample was exposed to microwave treatment for more than 3 min. After 7 min of microwave pretreatment, the concentration of canolol increased nearly sixfold. However, this result was still lower than that reported by Spielmeyer et al. This discrepancy may be due to the difference in the heating time and the absence of intervals during the heating. These results suggest that sinapine and sinapic acid are chemically degraded by microwave heating. Our results are consistent with those of Cerretani et al who reported decreasing concentrations of phenolic compounds in olive oil that was exposed to extended microwave heating. Liazid also reported that in microwave-assisted extraction, most of phenolic compounds including benzoic acids, cinnamic acids appear to be chemically stable up to 100 C, but at 125 C they are significantly degraded. We believe that the concentration of sinapine and sinapic acid in the samples increased slightly after 2 min of microwave heating, because these compounds may have been separated from the phenolics in the sample which are difficult to extract and analyze.
3.Production of Canolol from Canola Meal Phenolics via Hydrolysis and Microwave-Induced Decarboxylation
Rabie Y. Khattab • Michael N. A. Eskin • Usha Thiyam-Hollander.J Am Oil Chem Soc (2014) 91:89–97
2,6-Dimethoxy-4-vinylphenol (known as canolol or 4-vinylsyringol) is a well-known lipid-soluble potent antioxidant and antimutagenic compound formed in canola oil via sinapic acid decarboxylation during oil pressing at high temperature and pressure. The antiradical scavenging activity of canolol is much greater than that of well-known antioxidants, including vitamin C, bcarotene, a-tocopherol, rutin and quercetin. Unluckily, canolol is almost completely lost during oil refining which advocates its isolation from meal and adding it back to the oil. The lipophilic characteristics of canolol might account for its high affinity to the cell membranes and other biological membranes and hence its reactivity inside the body where water-soluble antioxidants are hard to react, thus establishing its outstanding role. The industrial demand of vinyl phenols and canolol is relatively satisfied by chemical synthesis and not from natural sources. Investigations have explored large scale synthesis of 4-vinylphenols through microbial or chemical decarboxylation of cinnamic acids such as p-coumaric acid, ferulic acid, sinapic acid and caffeic acid from plant sources including barley, wheat bran and sunflower seeds.
4.Influence of Microwave Treatment of Rapeseed on Minor Components Content and Oxidative Stability of Oil
Mei Yang & Fenghong Huang & Changsheng Liu & Chang Zheng & Qi Zhou & Hui Wang. Food Bioprocess Technol (2013) 6:3206–3216
Canolol is a compound in rapeseed that can be formed by thermal decarboxylation of the sinapic acid naturally occurring in canola seeds (Spielmeyer et al. 2009; Wijesundera et al. 2008) and directly correlated with oxidative stability of rapeseed oil (Koski et al. 2003). The temperature influences the amount of canolol formed in the rapeseed, and microwave time directly relates to the temperature of rapeseeds. Canolol is a phenolic compound, which is known for scavenging free radicals, and its lipid protective activity is similar to that of γ-tocopherol (Galano et al. 2011). Therefore, canolol has antioxidative effects and positive health benefits, and its presence in rapeseed oil is desirable. Moreover, the greater oil stability may also be due to the inactivation of oxidative enzymes, such as lipase, peroxidase, and lipoxigenase (Uquiche et al. 2008). Inactivation of these enzymes, potentially by heating, has been demonstrated to increase the shelf life of oilseeds (Ponne et al. 1996; Vetrimani et al. 1992).