Genetically modified seed oils

Genetically modified seed oils Recent years have witnessed great strides in the understanding and application of genetic engineering. This has been applied to... 

Genetically modified seeds with bespoke input and or output traits (eg, herbicide tolerance or high oleic oil composition)... 

The food technologist may be especially interested in the fate of the carotenoids in the seed oil. Like red palm oil, the resulting carotenoid-pigmented canola oil may be more stable due to the antioxidant properties of carotenoids and may be more attractive to consumers. Alternatively, for food security concerns, transgenic soybean or canola oils and seed meals that are genetically modified for more efficient bio-diesel production may be bio-safety marked with lipid-soluble carotenoids and water-soluble anthocyanins, respectively. Potatoes are excellent potential sources of dietary carotenoids, and over-expression of CrtB in tubers led to the accumulation of P-carotene. Potatoes normally have low levels of leaf-type carotenoids, like canola cotyledons. 

The advantage for the farmer is that he needs only one product, instead of several different selective (and more expensive) herbicides. Roundup ready soybeans were launched in 1996 and today 50 percent of the soybean crop in the United States is derived from roundup ready seeds. Other glyphosate-resistant transgenic crops introduced by Monsanto are maize and oil seed rape. Competing companies also developed herbicide-resistant plants or plants genetically modified to be protected against certain pests, but none has achieved a commercial breakthrough, mainly because of political reasons. 

Table 6.7. Soybean Seed Composition in Percentage at 13.0% Moisture Content as Measured by Near-Infrared Spectroscopy for Oil from Commodity and Six Types of Genetically Modified Soybeans...

Dobarganes, M.C., Marquez-Ruiz, G., and Perez-Camino, M.C. 1993. Thermal stability and frying performance of genetically modified sunflower seed oil, J. Agric. Food. Chem., 41, 678-681. 

The characteristic fatty acid patterns of plant triacylglycerols are to some extent under genetic control (see Section VI). In addition, environmental factors may modify the basic patterns, the extent of modification depending on the species. Thus the seed oils of plants grown in cool climates tend to be more unsaturated than those grown in warm climates (Hitchcock and Nichols, 1971). The chief influence seems to be on the characteristic fatty acid of the seed, so that for example in flaxseed oil there is a marked decline in the proportion of linolenic acid between 10° and 30°C and a corresponding increase in the proportion of its precursor, oleic acid (Canvin, 1965). Similarly, the proportion of linoleic acid in sunflower seed oil steadily declines between 10° and 30°C, to be replaced by oleic acid. Yet the linoleic content of safflower and the ricinoleic acid of castor are unaffected by the same variation in temperature (Canvin, 1965). All rules have exceptions, and the experiments of Appelqvist (1975) showed that different lines of zero-erucic acid rape could respond differently to the same climatic variations. 

Genetic modification of rapeseed to produce a high-stearate oil using antisense technology to reduce expression of stearoyl-ACP desaturase was reported in 1992 by Knutzon et al. When tested in the field, lines from the first modified plants showed stearate contents between 20 and 30% with total saturates slightly above 30%. Seed yield and germination under standard conditions were normal. 

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