Rapeseed phenolics

Satu V (2005) Analysis, isolation, and bioactivities of rapeseed phenolics. Dissertation, University of Helsinki... 

Amarowicz et al. (2000) and Matthaus (2002) investigated the effect of rapeseed phenolics on radical scavenging. The antioxidant activity of ethanolic (95%) extract of rapeseed meal towards the oxidation of rapeseed oil was better than that of some widely used synthetic antioxidants (Wanasundara and Shahidi, 1994). Phenolic compounds present in crude rapeseed oil have also shown antioxidant properties (Koski et al., 2003) in bulk and emulsified methyl linoleate and lecithin-liposome systems. Amarowics et al. (2003) investigated the antioxidant activity of phenolic fractions of rapeseed (total three fractions) using a P-carotene-linoleate model system and enhanced chemiluminescence and photochemiluminescence methods. A measure... 

Rapeseed phenolics isolated by Vuorela et al. (2004) were tested for radical scavenging and for liposome and low-density lipoprotein (LDL) model systems. The inhibition of hexanal and conjugated diene hydroperoxides formation was reported (>90% and >80%, respectively). All isolates also exhibited inhibition of LDL particles oxidation by >90%. The antioxidant activity of methanol and acetone extracts of canola hulls in a P-carotene-linoleate model system was comparable to that displayed by butylated hydroxyanisole (Naczk et al., 2005). These extracts showed more than 95% scavenging effects (at 40 p/assay on DPPH radical). Vuorela et al. (2005a,b) indicated that rapeseed phenolics were excellent antioxidants towards oxidation of phosphatidylcholine membrane (liposomes) and rapeseed oil (crude) phenolics were effective radical scavengers (DPPH test). The authors suggested that these phenolic isolates from rapeseed are safe and bioactive for possible food applications including functional foods intended for health benefit. 

Thiyam, U., Stockmann, H. and Schwarz, K. 2006h. Antioxidant activity of rapeseed phenolics and their interaction with tocopherols in rapeseed oil triglycerides during lipid oxidation. J. Am. Oil Chem. Soc. 83 523-528. 

Some phenolic acids such as ellagic acid can be used as floral markers of heather honey (Cherchi et al., 1994 Ferreres et al., 1996a,b), and the hydroxyciimamates (caffeic, p-coumaric, and ferulic acids) as floral markers of chestnut honey (Cherchi et al., 1994). Pinocembrin, pinobanksin, and chrysin are the characteristic flavonoids of propolis, and these flavo-noid compounds have been found in most European honey samples (Tomas-Barberan et al., 2001). However, for lavender and acacia honeys, no specific phenolic compoimds could be used as suitable floral markers (Tomas-Barberan et al., 2001). Other potential phytochemical markers like abscisic acid may become floral markers in heather honey (Cherchi et al., 1994). Abscisic acid was also detected in rapeseed, lime, and acacia honey samples (Tomas-Barberan et al., 2001). Snow and Manley-Harris (2004) studied antimicrobial activity of phenolics. 

Tannins are present in some varieties of canola but only at very low levels (Blair and Reichert, 1984). Canola, rapeseed and soybean hull tannins are not capable of inhibiting a-amylase (Mitaru et al, 1982), in contrast to those in other feedstuffs such as sorghum. Sinapine is the major phenolic constituent of canola and although bitter-tasting (Blair and Reichert, 1984) is not regarded as presenting any practical problems in poultry feeding except possibly for that noted above with brown-shelled layers. 

Blair, R. and Reichert, R.D. (1984) Carbohydrate and phenolic constituents in a comprehensive range of rapeseed and canola fractions nutritional significance for animals. Journal of the Science of Food and Agriculture 35, 29-35. 

Ferulic acid, a phenolic acid that can be found in rapeseed cake, has been used in the synthesis of monomers for ADMET homo- and copolymerization with fatty acid-based a,co-dienes [139]. Homopolymerizations were performed in the presence of several ruthenium-based olefin metathesis catalysts (1 mol% and 80°C), although only C5, the Zhan catalyst, and catalyst M5i of the company Umicore were able to produce oligomers with Tgs around 7°C. The comonomers were prepared by epoxidation of methyl oleate and erucate followed by simultaneous ring opening and transesterification with allyl alcohol. Best results for the copolymerizations were obtained with the erucic acid-derived monomer, reaching a crystalline polymer (Tm — 24.9°C) with molecular weight over 13 kDa. 

BCrygier, K. Sosulski, F. Hogge, L. 1982. Free, esterified, and insoluble-bound phenolic acids. 2. Composition of phenolic acids in rapeseed flour and hulls. J. Agric. Food Chem. 30 330-334. 

The example given in Table 4.10 illustrates the outstanding oxidation resistance of a rapeseed oil-based environmentally acceptable hydraulic fluid, containing a non-water-extractable phenolic antioxidant [83]. A similar type of non-water-extractable phenolic antioxidant provided excellent oxidation stability, TOST life >10,000 h, in a food-grade hydraulic fluid based on white oil [84]. All additives and the white oil are cleared by the (US)FDA. 

There are lots of research applications published regarding PLE and analysis of various compoimds in food and agricultural materials, for example pesticides in rapeseed (38), babyfood (39) and strawberries (40), lipids in com and oats (41) and in egg-containing foods (42), acrylamide in food samples (43), carotenoids in processed food (44), xanthones and flavanones in root bark (45), tocopherols in seeds and nuts (46), antioxidants in microalgae (47) and anthocyanins and total phenolics in dried red grape skin (48). More discussions... 

Amarowicz et al. (1994) studied the phenolic compounds of flaxseed meal extracted into 80% ethanol (v/v) by chromatographic techniques. Both hydrophilic and hydrophobic phenolic compounds were present. The separated hydrophilic fractions had a UV maximum absorption between 270 and 290 nm which was different from that observed for phenolic acids. Meanwhile, the tannin content of flaxseed meal was very low (125 to 137 mg/100 g of defatted meal) when compared to that of high glucosinolate rapeseed and canola (Shahidi and Naczk 1988 Shahidi et al., 1988 Wanasundara and Shahidi, 1994a). 

Oils with high maximum SIPA (mg 100 g" FW) included maize Iran oil (557.0), rapeseed oil (0.8-5.8), and virgin olive oil (0.1-2.6). The maximum SIPA was less than 2.0 in other oils. The major phenolic acids were identified as stigmastanol feralate (360.0), 24-methylcholestanol ferulate (100.0), 24-methylcholesterol ferulate (50.0), and sitosterol ferulate (30.0) in maize bran oil sinapine (0-2.6) and sinapic acid (0-2.3) in rapeseed oil and vanillic (0-1.0) and syringic (0-0.4) acids in virgin olive oil. 

Antioxidative compounds from oilseeds such as canola/rapeseed, mustard, flax, borage and evening primrose, soybean, cottonseed, peanut and sesame have been investigated. The antioxidative conq)onents present are diverse and may end up in the extracted oil or in their resultant meal after oil extraction. The antioxidative compounds present include tocopherols, sterols, phospholipids, phenolic acids and phenylpropanoids, flavonoids and isoflavonoids, hydrolyzable and condensed tannins, lignans, coumarins, amino acids, peptides and proteins as well as carotenoids (7). 

Sinapoyl esters are considered antinutritional compounds because they have a bitter and astringent taste, thus contributing to the bitter taste of rapeseed meal. The intensity of the bitter taste is comparable to the intensity of the bitter taste of caffeine. In the refining of rapeseed oil, sinapines form complexes with proteins. They show lower antioxidant activity than the corresponding phenolic acids and do not have antimicrobial effects. Sinapines present in the feed of some breeds of laying hens cause an off-flavour and fish-like odour of yolks. 

Sinapic acid, an important hydroxydnnamic acid is the most significant phenolic compound in rapeseed and forms 70.2-85.4% of free phenolic adds in defatted canola meals. Esterified forms of these phenolic acids constitnte abont 99% of total phenolics in rapeseed flour of which the sinapine, the choline ester of sinapic acid, is the main ester. A phenolic glucoside namely glucopyranosyl sinapate is also reported in canola (Amarowicz and Shahidi, 1994). Figure 2.1 shows the structures of sinapic acid, sinapine and glucopyranosyl sinapate. 

Recently, Harbaum-Piayda et al. (2010) demonstrated the possibility of new compounds such as cis- and tratis-diastereomers of 4-vinylsyringol dimer [cis-4,6-dimethoxy-5-hydroxy-l-methyl-3-(30,50-dimethoxy-40-hydroxyphenyl) indane and trani-4,6-dimethoxy-5-hydroxy-l-methyl-3-(30,50-dimethoxy-40-hydroxyphenyl) indane] and the vinylsyringol trimer in commercial rapeseed oils, as well as in a commercial by-product of oil refining, the deodistillate. The newly identified canolol dimer was present in the deodistillate of processed rapeseed oil in significant amounts (-3.50 g/kg). Trace amounts of phenylindane was also detected in commercial rapeseed oils. According to Harbaum-Piayda et al. (2010), this newly identified phenylindane compound had a high antioxidative potential and stressed its potential as an important phenolic compound to add value to the commercial deodistillate and rapeseed oils. 

There is only a single reference on the effects of rapeseed/canola phenolics on cell permeability. Satu et al. (2005) indicated that the crude rapeseed oil phenolic extract had no significant effect on the permeability of the model drugs. However, rapeseed meal phenolics enhanced the permeability of verapamil and ketoprofen indicating that they may have an impact on drugs and other components being actively transported across the cell membrane. 

Amarowics R, Raab B, Shahidi F. 2003. Antioxidant activity of phenolic fractions of rapeseed. Journal of Food Lipids, 10(l) 51-62. 

Kozlowska H, Naczk M, Shahidi F, Zademowski R 1990. Phenolic acids and tannins in rapeseed and canola. In Canola and Rapeseed. Production, Chemistry, Nutrition and Processing Technology. Shahidi F (Ed.). Van Nostrand Reinhold, United States of America, pp. 193-210. 

Naczk M, Amarowicz R, Sullivan A, Shahidi F. 1998. Current research developments on poly-phenolics of rapeseed/canola A review. Food Chemistry, 62(4) 489-502. 

Vermorel M, Hocquemiller R, Evrard J. 1987. Valorization of rapeseed meal. 5. Effects of sinapine and other phenolic compounds on food intake and nutrient uttiization in growing rats. Reproduction Nutrition Development, 27(4) 781-790. 

The background and detailed mechanisms of decarboxylation are very extensive, and therefore this chapter will discuss some specihc pathways of decarboxylation. In addition, we have highlighted recent cases of decarboxylation relevant to hydroxy-cinnamic acids in wine, beer and camelina and attempted to reason if such strategies can be transferred for value addition to processing of rapeseed and canola. An update on the recent thermal decarboxylation to form canolol, a phenol of interest in rapeseed and canola processing, is discussed in the last part of this chapter. 

Vuorela, S., Meyer, A.S. and Heinonen, M. 2004. Impact of isolation method on the antioxidant activity of rapeseed meal phenolics. J. Agric. Food Chem. 52 8202-8207. 

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