Glucosinolates and other anti-nutritive compounds in canola meals from varieties cultivated in Egypt and Japan
Canola meals from six varieties cultivated in Egypt (Seru4 and Pactol) and Japan (Kirariboshi, Tohoku95, Oominantane and Kizakinonatane) were investigated regarding anti-nutritive compounds, namely glucosinolates, phytic acid, sinapine and total phenols. All varieties except Kirariboshi contained a high level of total glucosinolates. A profile of 12 glucosinolates in all varieties was identified; aliphatic glucosinolates, progoitrin, epiprogoitrin, gluconapin, glucobrassicanapin and glucoberin were the most abundant. Other aliphatic glucosinolates, including sinigrin and gluconapoliferin, were of low level. Indolic and aromatic glucosinolates (4-Hydroxybrassicin, Glucotropeolin, Glucobrassicin, Gluconasturtin and
4-Methoxybrassicin) were low and showed few differences among varieties. The anti-nutritional effects are associated, to a large degree, with the content of aliphatic glucosinolates rather than indole glucosinolates, and the total aliphatic glucosinolates are present at a higher level in all varieties than total aromatic glucosinolate (including indole glucosinolate). Therefore, canola meal from all varieties could cause many anti-nutritive effects. Also it was found that Seru4, Pactol, Tohoku95, Oominantane and Kizakinonatane are high glucosinolates varieties because they contained more than 30 μmol g-1 however, only Kirariboshi was a low glucosinolate variety. The differences in the content of individual and total glucosinolates among the varieties may be attributed to genetic and environmental factors. Phytic acid was at a high level in all varieties with few differences. Oominatane contained the lowest level and Pactol contained the highest one. No remarkable differences were observed among Kirariboshi, Kizakinonatane and Tohoku. For total phenols, Tohoku contained the lowest level of total phenols while Pactol and Seru4 contained the highest level. Also, insignificant differences were observed among Kirariboshi,
Oominatane and Kizakinonatane in total phenols. Sinapine was found in all varieties with significant differences among varieties. Tohoku and Oominatane contained the lowest levels of sinapine, while Seru4 contained the highest one. Insignificant differences were observed among Kirariboshi, Kizakinonatane and Pactol. Thus canola meals from all varieties must be treated to remove or reduce the aliphatic glucosinolates and other anti-nutritive compounds.
Key words: Canola, glucosinolates, phytate, sinapine, phenols