Anti‐Nutritional Components, Fibre, Sinapine and Glucosinolate Content, in Australian Canola (Brassica napus L.) Meal

Abstract

Canola meal is highly regarded as a component of animal feed with a high protein content and a desirable amino acid profile. The presence of some components, in particular glucosinolates, sinapine and fibre, affects the value of the meal and reduces the amount that can be used in animal feed formulations. Glucosinolates in traditional cultivars (rapeseed) had very high amounts and this severely limited the usefulness of the meal. Canola breeding programs have successfully reduced glucosinolate content to trace amounts. However sinapine remains at levels sufficiently high to cause problems, particularly in poultry feed. The relatively high fibre level in canola also reduces the value of the product for animal feed. This study has determined the level of sinapine, glucosinolates and fibre in current cultivars of canola in Australia to illustrate advances made by breeding programs and limitations which still remain to raise the usefulness of a potentially valuable feedstock. Although glucosinolate levels in meal were shown to have been reduced to 11 lmol/g in some cases, sinapine remained at traditional levels of about 12-15 g/kg and neutral detergent fibre levels were about 30-40%. These issues are important priorities for canola breeders.

Extraction and characterization of protein fractions from Australian canola meals

“…Significantly higher lipid contents of the non-industrial Brassica meals in our study suggest that the defatting process carried out in the lab was less effective in comparison to the industrial oil extraction protocol which involved a more rigorous process with high temperature treatment. The significant differences in total phenolic and sinapine contents between different meal samples were in agreement with a previous study on antinutritional components in Australian canola meal (Mailer et al, 2008). The reduced sinapine content in industrial toasted meal in comparison to the pre-toast meal is possibly a consequence of the formation of oligomeric sinapine derivatives from monomeric sinapine in high temperature conditions during the desolventising process as suggested by Larsen et al (1983).…”

“…The total phenolic content was standardised against sinapic acid and expressed as sinapic acid equivalents (SAE) per gramme sample. Sinapine content was determined by high performance liquid chromatography (HPLC) according to the procedure described by Mailer et al (2008). Glucosinolate content was determined as glucose from the hydrolysis of the glucosinolates according to the official Australian Oilseeds Federation method 4-1.22 and reported as μmol/g oil-free meal at 10% moisture (Mailer & Pratley, 1990).…”

Canola/rapeseed protein-functionality and nutrition

“…The level of extractable phenolics of defatted canola meal ranges from 1.59-1.84 g/100 g of defatted canola meal and 0.62-1.28 g/100 g of the seed flour (Dabrowski and Sosulski, 1984;Naczk et al, 1998). Sinapine, the choline ester of sinapic acid is the most prominent phenolic compound of canola and the contents range from 6.8-10 mg/g of seed for European cultivars (Matthäus, 1998), 6-18 mg/g of defatted meal for Canadian canola (CCC, 2016), and 13-15 mg/g of defatted meal for Australian canola (Mailer et al, 2008). Reported total phenolic acid content in Puratein was 0.40% and Supertein TM was 0.26%, in which 93-96% was sinapic acid.…”

Profile and distribution of soluble and insoluble phenolics in Chinese rapeseed (Brassica napus)

“…Nowadays, plant breeding programmes have succeeded in reducing or almost eliminating the glucosinolate content. However, the phenolics content still remains high in those improved rapeseed varieties such as canola (Mailer, McFadden, Ayton, & Redden, 2008). Phenolics can cause protein digestion and absorption problems (Gilani, Cockell, & Sepehr, 2005) when rapeseed meal is used as animal feed.…”