Over
80 percent of the vegetable oil used in cooking and food manufacturing in the US
is soybean oil. In fact soybean oil is the largest single source of fat in
American diet. Its low price and ready availability often makes it the oil of
choice for making baked goods such as cookies, crackers, and pastries; as well
as salad dressings and margarine. But soybean oil is predominantly a
polyunsaturated fat, rich in linolenic acid. Therefore, soybean oil degrades
easily and causes "off' or rancid flavours, especially after prolonged
heating.
To increase its stability and to harden it for baking and margarine preparation,
oil manufacturers hydrogenate soybean oil. However, hydrogenation increases the
amount of trans-fatty acids in soybean oil. This makes soybean oil potentially
undesirable because trans-fatty acids raise blood LDL cholesterol levels, just
like saturated fats. As consumers become more aware of the health risks of
trans-fatty acids, and the health benefits from using monounsaturated fats,
soybean oil may lose its market share.
The Agriculture Department in Raleigh, North Carolina, US has developed a new
type of soybean called Soyola, using conventional breeding methods. Soyola
contains half as much linolenic acid as conventional soybean oil. Therefore, it
has been claimed that it need not be hydrogenated to increase its shelf life.
Seed for Soyola is available from N.C. Foundation Seeds, 8220 Riley Hill Road,
Zebulon, NC 27597, U.S.A. Researchers are also trying to reduce the already low
saturated fatty acid content of soybeans and at the same time increase their
concentration of oleic acid, the heart healthy monounsaturated fat.