Environmental Engineering Reference
In-Depth Information
the nutritionally undesirable fatty acid (C22:1, erucic acid) has been reduced to a very low level by
breeding, thus making the oil suitable for edible uses.
Canola oil typically has a nutritionally desirable FA profile with only traces of erucic acid, low
saturated FA (5-8%), and a good balance of MUFA (60-65%) and PUFA (30-35%). However,
there are several other profiles of FA in Brassica oil, which are of interest for food, non-food,
industrial, and novel uses. From a nutritional point of view the desirable Brassica oils are considered
to have reduced or very low levels (<7%) of saturated FA (C16:0, C18:0, C20:0, C22:0), low or less
than 3.5% of C18:3 (linolenic acid), mid to high levels (67 to over 75%) oleic acid (C18:1), zero or
negligible levels of erucic acid (C22:1), and a C18:3/C18:2 ratio of 1:2 (Shahidi 1990). The detailed
nutritional and functional benefits of these FA profiles in Brassica oils have been discussed and
reviewed elsewhere (Fitzpatrick and Scarth 1998; McVetty and Scarth 2002).
Brassica oil with high (>50%) or super high (>66%) erucic acid levels are termed as HEAR and
SHEAR (McVetty et al. 2008), respectively, and are suitable for industrial oil applications such as the
manufacturing of lubricants, slip agents, polymers, paints, inks, cosmetics, and pharmaceuticals. The
opportunity to develop a wide range of novel oil profiles in Brassica tailored to end use is increasing.
This may be particularly appropriate for Brassica oil used for the production of biodiesel. Although
the FA profile for an oil most suitable for making biodiesel is still being debated, it is generally
known that FA profiles of oils will have to be modified toward higher carbon chain lengths and
reduced branching/degree of unsaturation to improve the ignition quality and cold flow properties
of diesel engines run on biodiesel produced from Brassica oil.
Other FA profiles which are being created in Brassica oils using conventional and transgenic
breeding approaches (Voelker et al. 1996; Knothe et al. 1997.; Murphy 1999; Scarth and Tang 2006)
include oils with high levels of short and medium chain FA such as lauric acid (C12:0), caprylic acid
(C8:0), capric acid (C10:0), palmitic acid (C16:0) and stearic acid (C18:0).
In addition, several unusual FA of interest to industry are found in the seed oils of nonagronomic
species (Jaworski and Cahoon 2003). The unique functional properties of these oils are due to
varied carbon chain length, number and position of double bonds (0-5), and presence of uncommon
functional groups, such as hydroxyl, epoxy, or acetylinic groups (Thelen and Ohlrogge 2002).
Incorporation of these unusual FA into Brassica oils have been examined as a way to create new
industrial oils with novel properties. Profiles of such Brassica oils might include enrichment or
additions of monoenoic acid, gamma-linolenic acid, very long-chain (20-22 carbons) polyunsaturated
(4-6 double bonds) FA, conjugated FA, and FA with epoxy and hydroxy functional groups (Safford
et al. 1993; Liu et al. 2001; Huang 2004; Scarth and Tang 2006).
18.2.3 r
Egional
a
daptationS
Brassica
species exhibit adaptation to a wide range of agroclimatic conditions. Due to the
plastic nature of their phenotypes they can adapt themselves equally well to low or high input
cultivation techniques.
B. juncea
is more drought tolerant compared to other
Brassica
species
and is predominantly grown in the Indian subcontinent but is also widely grown throughout Asia.
This species, along with
B. napus,
is being developed for Australian climatic conditions and is
becoming increasingly popular for cultivation there. Another
Brassica
species, which is quite
tolerant to drought and also has resistance to diseases, pests and pathogens, is
B. carinata
that is a
major oilseed crop in Ethiopia. Because of its ability to adapt to difficult climatic conditions, this
species is of interest for cultivation in arid regions such as southern Europe.
Brassica rapa
is more
cold tolerant and early maturing varieties of this species are well adapted to the climatic conditions
of western Canada. However, various other ecotypes of this species (brown and yellow sarson
and toria) are well adapted for cultivation in the Indian subcontinent. Within Canada, the canola-
quality varieties of
B. napus
and
B. rapa
are mainly adapted to the Prairie Provinces (Manitoba,
Saskatchewan, and Alberta) with limited cultivation in Ontario and Quebec. Generally,
B. napus
varieties grown in western Canada require more frost-free days and mature in approximately
