Traditional and Emerging Feedstocks for Food and Industrial Bioproduct Manufacturing - Food and Industrial Bioproducts and Bioprocessing - page 14

1.3.1 Rapeseed/Canola
1.3.1.1 Production

Rapeseed is the major oilseed crop produced worldwide. Total world rapeseed production
was 58.1 million tonnes in 2008 (FAO, 2010). Canada, China, India, Germany are the top
rapeseed growing counties (Table 1.1 ).
Rapeseed belongs to Cruciferae family and Brassica genus. The original rapeseed
cultivars had high levels of erucic acid in the oil and glucosinolates in the meal. Rapeseed
oil feeding trials carried out with rodents indicated that high levels of erucic acid in oil led
to fatty deposits in heart and skeletal muscles and impaired growth of the animals (Przybylski
et al ., 2005). The presence of glucosinolate in rapeseed meal was damaging to poultry,
swine and ruminants. Isothiocyanates and other sulfur-containing compounds formed during
hydrolysis of glucosinolates interfere with iodine uptake by the thyroid gland, contribute to
liver disease and reduce animal growth and weight gain. Utilization of oilseed meal (seed
residue after oil extraction) as animal feed is critical for the economic viability of oilseed
processing operations. The erucic acid and glucosinolate content of the seeds had to be
reduced for the rapeseed meal to be acceptable as animal feed. In the 1970s the world's first
low erucic acid and low glucosinolate cultivar of Brasicca napus , often called double-zero
rapeseed, was developed through breeding. The term “canola” was registered by the Western
Canadian Oilseed Crushers in 1978 and then transferred to the Canola Council of Canada in
1980. Canola referred to those cultivars containing less than 5% erucic acid in the oil and
3 mg/g aliphatic glucosinolates in the meal. In 1986, the definition of canola was amended
to Brasicca napus and Brasicca rapa lines with less than 2% erucic acid in the oil and less
than 30 μmol/g glucosinolates in the oil-free meal. Today the name “Canola” is mainly used
in the American continent and Australia. In Europe “rapeseed” is the term commonly used
for both original high and low erucic acid rapeseed cultivars.
There have been very important developments in breeding and genetic modifications of
oilseeds, resulting in increased crop yields and oil content, incorporation of fatty acids
of nutritional importance that are usually obtained from other sources and expression of
industrial fatty acids that are currently sourced from petrochemicals or from low-yielding
plants. Recently, plant breeders have been paying more attention to increasing contents of
minor seed components, such as carotenoids, vitamin A (Shewmaker et al ., 1999 ),
tocopherols, vitamin E (Marwede et al ., 2004 ), sinapate esters (Hüsken et al ., 2005 ; Zum
Felde et al ., 2006 ) and phytosterols (Amar et al ., 2008 ) in rapeseed. Traditional rape
( Brassica napus L.) has a black seed coat. Yellow seeded rape types, which have thinner
seed coat and higher oil and protein content, are available today (Rahman, 2001).

1.3.1.2 Chemical composition

Chemical compositions of oilseeds vary extensively with variety, climate, soil, agricultural
inputs (i.e. seed quality, fertilizer and other agrochemicals) and agronomic practices. Hence,
the seed compositional data given in this chapter should be used as a point of reference. Oil
content of rapeseed, which is a heritable characteristic, may vary between 36 and 50% (dry
matter basis). Protein content of rapeseed is negatively correlated with its oil content (Zhao
et al ., 2006). Canola varieties contain 17-26% protein (Aider and Barbana, 2011). Ash and
fiber contents of rapeseed are around 4 and 23% based on dry matter, respectively (Yoshie-
Stark and Wäsche, 2004 ).