Harmonisation of Regulatory Oversight in Biotechnology Safety Assessment of Transgenic Organisms in the Environment, Volume 5..

II.3. BRASSICA CROPS (BRASSICA SPP.) – 235

Figure 3.41. Canola oil compared to other edible vegetable oils as to total saturated fat content

and other fatty acids

Source: Analyses conducted by POS Pilot Plant Corporation, Saskatoon, Canada, data courtesy of Canola
Council of Canada.

More recently plant breeders have combined the low linolenic trait with a reduced

level of linoleic acid to provide an oil with over 70% oleic acid (Table 3.15; Downey,

1996). The high oleic acid level further increases the oil’s stability so that little or no

hydrogenation of the oil is required, which would otherwise result in undesirable trans

fatty acids. Canola varieties that produce this latter fatty acid composition now occupy

about 10% of Canada’s oilseed rape growing area.

Canada Table 3.15. Fatty acid composition of canola and specialty B. napus varieties grown in

Oil type

Fatty acid composition (%)

C16:0 C16:1 C18:0 C18:1 C18:2 C18:3 C20:1 C22:1

Canola 4.7 <1.0 1.8 61.5 21.0 11.0 <1.0 <1.0

High erucic 2.0 <1.0 2.0 13.0 12.0 9.0 7.0 54.0

Low linolenic 4.0 <1.0 2.0 64.0 27.0 2.0 1.0 <1.0

High oleic 4.0 <1.0 2.0 75.0 9.0 8.0 <1.0 <1.0

Oil extraction of Brassica oilseeds yields about 40% oil and some 60% high protein

meal. The meal is used as a high-quality protein supplement in diets for animals, poultry

and fish. Unfortunately, the plant translocates and concentrates the glucosinolates in the

seed. As a result, rapeseed and mustard can contain over 120 mg/g of glucosinolates per

whole seed. This high concentration of glucosinolates, and their breakdown products,

greatly limited the amount of traditional rapeseed meal that could be fed to non-ruminant

animals, such as swine and poultry. Glucosinolates and their breakdown products reduced

the palatability of the meal but, more importantly, they interfered with the iodine uptake

by the thyroid gland and are active goitrogens. Feeding rapeseed meal to non-ruminant

animals frequently resulted in poor feed efficiency and weight gains as well as

reproductive difficulties (Bell, 1993). Thus, the amount of seed that could be processed

was determined by the limited size of the meal market.

A partial solution was the inactivation of the myrosinase enzyme as the first step in

the oil extraction process but enzymes in the animal gut, although less efficient, were also

able to hydrolyse the glucosinolates. The answer to this problem was to breed plants with

little or no glucosinolates in their seed.

0 102030405060708090100

Canola oil

Safflower oil

Flaxseed oil

Sunflower oil

Corn oil

Olive oil

Soybean oil

Peanut oil

Cottonseed oil

Lard

Palm oil

Butterfat

Coconut oil

Saturated fat Monounsaturated fat

Polyunsaturated fat Alpha-linolenic acid (an Omega-3 fatty acid) Polyunsaturated fat Linleic acid (an Omega-6 fatty acid)