Biotechnology to Improve Shelf Life and Quality Traits of Foods - Food Shelf Life Stability: Chemical, Biochemical, and Microbiological Changes - page 332

TABLE 10.6
Transgenic Oilseeds That Have Been Modified in Order to Improve
Quality Traits or Shelf Life

Target Year for
Commercialization Crop Altered Trait Organization

Canola Laurate 1996 Calgene

High-stearate Latter part of 1990s Calgene

Medium-chain fatty acids Latter part of 1990s Calgene

Cocoa butter alternative Latter part of 1990s Calgene

High-oleic 1996-1997 Inter Mountain Canola a

High-oleic, low-saturate 1998 Inter Mountain Canola a

High-stearate, low-polystearate 1997-1998 Inter Mountain Canola a

Soybean High-oleic, low saturate 1998-1999 Du Pont

High-lysine 1999-2000 Du Pont

High-stearate, low-polystearate 1999-2000 Du Pont

Corn High-oil, high-oleic 1999-2000 Du Pont

a

Inter Mountain Canola is commercially developing transgenic canola produced by Du Pont.

Adapted from Slabas et al. 54

70 and 80% oleic acid. They are trying to reduce the linolenic acid levels as well
as increase saturates to produce feedstocks for spreads and margarines. The changes
in fatty acid composition are seed-specific and do not have any effect on the rest of
the plant. 54 Bacteria and fungi are also able to produce a wide array of fatty acids,
some of which are commercially attractive. Their genes could be inserted in some
oilseed crops to fulfill present and future industrial needs.

Use of Biotechnology to Reduce Unwanted Traits

Acyltransferases in plants are responsible for decorating the glycerol backbone with
specific acyl groups. It seems that the 1- and 3-acyltransferases are fairly nonspecific
in a wide variety of plants. 55 In rapeseed the 2-acyltransferase positively discrimi-
nates against the incorporation of erucic acid (C 22 :1) and lauric acid (C 12 :0). This
barrier limits the maximal level of either lauric acid or erucic acid that can be
incorporated into oilseed rape manipulated to produce more of these fatty acids. 54
However, erucic acid is an unwanted trait because it has been characterized as
responsible for some intestinal disorders. 4,57 The Plant Biotechnology Institute in
Saskatchewan, Canada is attempting to use molecular biology to produce seed
without erucic acid.
A textured, plastic fat that enables shortening to be creamed and margarine to
be spread requires a certain hardness from the fat, which includes considerable
amounts of high-melting saturated fatty acids. Until recently, the only industrially
and economically viable way to make oils hard, without blending them, was through
hydrogenation. To produce a textured fat, hydrogenation is commonly used to convert
some of the unsaturated oleic, linoleic, and linolenic fatty acids to stearic acid. Plastic