Food Lipids: Chemistry, Nutrition, and Biotechnology

activity in the oil palm mesocarp so that more fatty acids can be elongated and
desaturated to oleic acid.
5. Other Lipid Targets
For the most part we have discussed modification of the kinds of fatty acid found
in triacylglycerols. However, vegetable oils can also contain other important lipid
components. These include the antioxidants of tocopherols (e.g., vitamin E) and of
mixed carotenoids (including �-carotene and lutein), plant sterols such as sitosterol
(which may have cholesterol-lowering properties in the human diet), and economically
important by-products of vegetable oil processing such as lecithin. As the enzymatic
bases for the synthesis of these compounds and the genetic bases for regulation
of amounts of these compounds become better understood, there should be
growing prospects for the genetic engineering of levels of these compounds as well
as flavor components in vegetable oils.
E. The Nature of Incremental Progress
When low erucic acid lines of rapeseed were first commercialized in Canada, the oil
content levels were typically less than 38% by weight. However, over years of breeding
progress, oil content steadily increased to a current average of 42–44%. The
primary determinant of value, oil quality, was first selected for and developed; then
further incremental improvements in yield, meal quality, and other traits were layered
onto the original trait.
Genetically engineered plant oils well each likely follow a similar path. That
is, after the synthesis and accumulation of lauric acid have been established in a
transgenic canola oil, it may become important to select (or genetically engineer) for
lower levels of linoleic and linolenic fatty acids. Or as discussed above, a coconut
LPAT enzyme may be engineered into the lauric canola to enable higher levels of
laurate to be achieved. Such higher levels of lauric acid made possible by the presence
of the medium chain LPAT enzyme may actually be achieved by field selections
(breeding) over a number of years of incremental improvements.
And finally, of course, once a valuable oil has been achieved in composition,
one would like to keep selecting for varieties with better and better yields. Thus, it
is clear that genetic engineering of oil composition, just like conventional breeding
of oil composition, comprises one or a few big steps—transgenes in the case of
genetic engineering—supplemented by a continuous process of fine-tuning the oil
and the crop variety producing the oil.
V. IDENTIFICATION OF UTILITY AND VALUE
A. Market-Driven Product Development
1. Fatty Acid Strategies
Fats and oils are ubiquitous components of most compounded formulations, whether
they are foods or industrial products. These applications may not involve the whole
triglyceride, or the pure derivative fatty acids that comprise triglycerides, but may
entail the splitting of the triglyceride into its component fatty acids (see Fig. 3) and
subsequent derivatization of those fatty acids into industrially important products
that move into the oleochemical markets.
Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.