ARTICLE
Auteur(s) : Terry A Isbell
New Crops and Processing Research, National Center for
Agricultural Utilization Research, Agriculture Research Service,
United States Department of Agriculture, 1815 N. University St.
Peoria, IL 61604, USA
Introduction
Agriculture production in the US is focused on a few commodity
crops, wheat cotton and the two largest crops, corn and soybean. In
2008, there was 35.2 M Ha corn in production with an
average yield of 9,745 kg/ha [1]. Soybean production in
2008 was 30.2 M ha with an average yield of
2,722 kg/ha [1]. Any effort in the development of a new crop
must consider the consequence on the existing commodity crop that
it will displace. As such, efforts from our group are directed
toward crops that can grow off-season with a commodity crop or on
land not currently growing a commodity crop. Secondly, the crop
must produce compounds that are unique or not readily available
from domestic sources. Lastly, the compounds may also serve as
replacement for petroleum derived products. Utilizing these
guidelines our group has been conducting research on mainly four
potential crops coriander, cuphea lesquerella and pennycress. These
four crops provide unique chemicals not readily available and have
the potential to be produced with little to no impact on food
producing commodity agriculture.
Coriander
Coriander is a plant from the Umbelliferae family that is commonly
grown as a condiment in food dishes as the herb cilantro. Coriander
is a summer annual that has upright branching steams that produces
an umbrella flora pattern and when mature the seed pod contains two
seeds. The seeds have been widely harvested for their essential oil
(~ 1%) linalool, ~ 65% of the composition of the
essential oil [2-4]. Of lesser known value is the high composition
of petroselinic acid contained within the seed oil. A recent
survey of the chemical composition of the known coriander germplasm
by Lopez et al. [5] reported that the triacylglyceride oil
fraction of the seed contains (12.8-30.2%) as shown in table 1. The petroselinic acid content within the
germplasm ranged from 57.9-74.8% relative to the other fatty acids
contained within the oil with and average value of 67.9%.
Interestingly, some of the higher oil and petroselinic acid types
also have shorter growing seasons with only 84 days from
planting to harvest for the highest petroselinate accession (Ames
26819). This rapid growth and maturation make coriander suitable
for a double crop rotation through much of the Midwestern US where
winter wheat is produced. Winter wheat is fall planted and
harvested around July 4th providing nearly 100 days
of frost free days for crop development. The challenges for this
type of rotation is limited mid-summer precipitation which is often
very localized coupled with declining day-lengths and eventually in
late season when pods are maturing the potential for early season
frost. In many parts of the world, coriander development has been
directed toward herb or essential oil production. A fair
amount of agronomic information has been published for its
agriculture production and the Canadians have demonstrated annual
production and developed grower guidelines including cost of
production [4]. The Canadians have reported average seed yields for
full season spring planted coriander between
900-1 120 kg/ha with yields up to 2,800 kg/ha.
Production costs were reported at $403/ha. We are currently
evaluating several coriander accessions for mid-summer planting
with intent to harvest in the fall.
Petroselenic acid, cis 6-octadecenoic acid, a unique
monounsaturated fatty acid that has the potential to be converted
into two useful commercial chemicals, lauric acid and adipic acid
according to figure
1. Oxidative cleavage of petroselinic acid by ozone has
been previously demonstrated [6, 7] and directly produces lauryl
aldehyde and 5-oxo-pentanoic acid. Both of these compounds can be
further oxidized to their corresponding fatty acids or in the case
of lauryl aldehyde reduced to lauric alcohol, a major ingredient in
many detergent applications. Adipic acid is a raw material for the
production of nylon-6.
Table 1 Variation in oil, petroselenic acid and days to
harvest in coriander germplasm.
|
PI Number
|
Oil Content (%)
|
Petroselenic (%)
|
Days to Harvest
|
|
Whole Collection
|
12.8-30.2 Avg. = 21.0
|
57.9-74.8 Avg. = 67.9
|
64-110 Avg. = 89
|
|
Ames 26819
|
26.4
|
74.8
|
84
|
|
Ames 23624
|
30.2
|
70.3
|
103
|
Cuphea
The genus cuphea represents a diverse group of species that have
high oil contents containing large amounts of medium chain
saturated fatty acids. Table 2 outlines
a number of diverse cuphea species where individual cuphea species
can produce large amounts of caprylic (8:0), capric (10:0), lauric
(12:0) or myrisitc (14:0) acids. Although cuphea produces a small
seed it is rich in oil with select species yielding 40% oil.
Because of its unique saturated fatty acid profile and high oil
content, cuphea has attracted much interest from the detergent
industry for its development as a crop. Unfortunately, cuphea
suffers a number of problems that are typically associated with a
new crop [8-12]. Cuphea is an indeterminate plant and begins
flowering in mid-summer and continues flowering until frost kills
the plant in the fall. Associated with the continuous flowering is
seed shattering, where mature seed is thrown from seed pods onto
the ground throughout the growing season. Because of these two
undesirable traits seed yields in cuphea have remained low
(220-675 kg/ha). A partial seed retention cross
(viscosissima × lanceolata) [10] labeled PSR-23 demonstrated
longer seed retention characteristics but fell well short of what
would be necessary to produce a commercially viable crop. The plant
also suffers from a sticky coating which protects the plant from
insect damage and this trait coupled with shattering and
indeterminacy make harvesting cuphea by mechanical methods very
challenging. Large quantities of wet green material processed
through the combine results in fouling of most of the feed aspects
into the combine and the deposition of a waxy material throughout
all parts of the combine. Cuphea does however, provide some
positive benefits to first year corn rotations where reduction in
corn rootworm infestations were observed with a corresponding
increase in seed yield [12-14]. Table 3
outlines a rotation scheme where cuphea, soybeans and corn were
grown the previous year and the resulting year’s corn production
evaluated against damage by corn rootworm. Corn on corn rotations
provided large infestations of rootworm. Soybean followed by corn
provided some reduction in rootworm populations but the western
corn rootworm beetle still produced damage and reduced corn yield.
Minimal damage was observed when corn followed cuphea in an annual
rotation which provided the highest yields of corn in this
study.
Novel chemistry that has led to improved lubricants from cuphea
utilizes the short chain saturated fatty acids to make highly
functionalized molecules. Cuphea fatty acids when reacted with
oleic acid to form estolides (figure 2) have been shown
to posses superior lubricating properties than many other vegetable
oils and petroleum derived products [15, 16]. The cuphea estolides
have very good cold temperature and oxidative performance yet
retain the good lubricating properties that vegetable oil based
materials posses (table 4). Increased
branching and reduction in the degree of unsaturation within the
estolide molecule provided a proportionate balance between
inhibition of crystal formation and saturation.
Table 2 Fatty acid profiles of various cuphea
species.
|
Species
|
8:0
|
10:0
|
12:0
|
14:0
|
16:0
|
18:1
|
18:2
|
Other
|
|
PSR-23
|
0.8
|
74.3
|
2.9
|
4.0
|
5.3
|
0.6
|
8.0
|
3.5
|
|
C. wrightii
|
0.0
|
36.1
|
53.6
|
3.2
|
1.3
|
1.6
|
4.0
|
0.2
|
|
C. tolucana
|
0.0
|
23.1
|
65.8
|
4.2
|
1.3
|
1.0
|
3.5
|
1.1
|
|
C. Viscosissima
|
16.0
|
62.3
|
3.5
|
0.8
|
1.5
|
1.7
|
3.5
|
10.7
|
|
C. pulcherrina
|
94.4
|
3.3
|
0.0
|
0.0
|
0.6
|
0.7
|
1.0
|
0.0
|
|
C. leptopoda
|
0.0
|
90.9
|
2.2
|
0.4
|
1.2
|
1.5
|
2.2
|
1.6
|
|
C. salvodorensis
|
25.3
|
0.9
|
2.8
|
64.5
|
5.2
|
0.5
|
0.5
|
0.3
|
|
Coconut
|
5.1
|
4.9
|
48.3
|
21.7
|
10.6
|
2.4
|
0.0
|
7.0
|
Table 3 Corn yields per calendar year in rotation with
corn, cuphea or soybean.
|
2001
|
2002
|
2003
|
|
Crop
|
lbs/acre
|
Crop
|
lbs/acre
|
Crop
|
lbs/acre
|
|
Soybean
|
|
Cuphea
|
|
Corn
|
1,716
|
|
Soybean
|
|
Corn
|
1,371
|
Soybean
|
|
|
Corn
|
1,444
|
Corn
|
1,227
|
Corn
|
824
|
|
Cuphea
|
|
Corn
|
1,493
|
Cuphea
|
|
|
Cuphea
|
|
Cuphea
|
|
Cuphea
|
|
|
Corn
|
1,354
|
Cuphea
|
|
Corn
|
1,634
|
|
Corn
|
1,410
|
Soybean
|
|
Corn
|
1,470
|
Table 4 Comparison of cuphea-oleic estolide to
commercially available oils.
|
Lubricant
|
Pour Point (oC)
|
Cloud Point (oC)
|
Viscosity Index
|
RBOT (min)
|
|
Commercial Soybean-based Hydraulic oil
|
– 18
|
1
|
220
|
83
|
|
Commercial Synthetic Oil
|
– 21
|
– 10
|
174
|
246
|
|
Commercial Petroleum Oil
|
– 27
|
2
|
152
|
223
|
|
Oleic Estolide
|
– 30
|
– 18
|
200
|
274
|
|
Commercial Hydraulic Oil
|
– 33
|
1
|
146
|
247
|
|
Coconut-Oleic Estolide
|
– 33
|
– 33
|
170
|
418
|
|
Cuphea-Oleic Estolide
|
– 42
|
– 41
|
170
|
420
|
Lesquerella
Lesquerella is a winter annual from the mustard family that is
grown in the desert Southwestern region of the US. Currently field
plots of lesquerella are producing 2,016 kg/ha of seed which
contains 30% oil that is rich in lesquerolic acid (57%) a hydroxy
fatty acid homologue of ricinoleic acid found in castor oil. Table 5 compares the complete fatty acid
profiles of both lesquerella and castor oils. Lesquerella contains
approximately 60% hydroxy fatty acids compared to castor which has
nearly 90% ricinoleic acid. Lesquerella has a substantial amount of
linolenic acid at 12% where castor has none. This higher level of
linolenic acid imparts reduced oxidative stability on many
lesquerella derivatives and products but generally provides better
cold temperature properties [17, 18]. The increased chain length of
lesquerella, 20 carbons versus 18 for castor tends to
provide better lubricity for some lesquerella derivatives. Of
particular note is the methyl ester derivative in lesquerella which
has better performance in lubricating low sulfur diesel blends than
the corresponding castor and soybean methyl ester blends [19].
Methyl lesquerolate at 0.2 wt% in ultra low sulfur diesel
provided sufficient lubricity to pass the High Frequency
Recipocating Rig (HFRR) test ISO limit of 0.45 mm wear scar
where both soybean and castor methyl esters failed. Castor methyl
ester blends passed at 0.5 wt% and soybean required 3% for the
blend to meet the ISO specification.
Hydroxy fatty acids are used in a wide range of products;
lithium greases, gelling agents, industrial lubricants, paints,
coatings and polymers. Lesquerella oil can engage in a number of
rich organic chemistry reactions (figure 3) do to its
homologues relationship to ricinoleic acid. This chemistry can lead
to production of detergents and monomers for the synthesis of long
chain nylons. In addition, several esterification routes can lead
to estolides (figure
4) which can provide molecules with good low temperature
properties. Furthermore, some varieties of lesquerella (auriculata)
contain large amounts of natural estolides (90%) within their seed
oil [20].
Table 5 Fatty acid composition of lesquerella and
castor oils.
|
Fatty Acid
|
Lesquerella
|
Castor
|
|
16:0
|
1.1
|
1.0
|
|
16:1
|
0.7
|
|
|
18:0
|
1.8
|
|
|
18:1
|
15.4
|
3.7
|
|
18:2
|
6.9
|
4.4
|
|
18:3
|
12.2
|
|
|
20:1
|
1.0
|
|
|
18:1 Hydroxy
|
0.6
|
89.0
|
|
20:1 Hydroxy
|
55.4
|
1.1
|
|
20:2 Hydroxy
|
3.8
|
|
Pennycress
Pennycress (thlaspi arvense) is a mustard family member that grows
as a winter annual across much of the Midwestern US and the world
[21]. Pennycress is planted and emerges in the fall then
over-winters as a small rosette. During the winter months small
amounts of growth occur during the few widely scattered mild days
within winter. In the spring the plant ramps into prolific growth
and bolts in early April. After two/three weeks of flowering the
seed has been fully set by early May and the crop desiccates over
the remainder of the month with harvest of mature dry seed by the
first week of June. The early harvest of pennycress allows growers
to establish a full season soybean crop immediately following
pennycress. Field harvest by combine is currently yielding
1,420 kg/ha seed. Hand harvest of 1 m2 block
within these bulk fields indicated yield potential up to
1,534 kg/ha.
Currently there are 17 known accessions of thlaspi in the
National Plant Germplasm system [22] and these accessions offer a
diverse range of chemical and agronomic traits. Table 6 outlines the fatty acid profile of the
Illinois pennycress currently under development. Erucic acid is the
largest fatty acid observed at 36.9% with linoleic and linolenic
acids as the other two major components of the oil. The high
linolenic acid content reduces the oxidative stability of the oil
(table 7). Fortunately, the low degree
of saturates within the oil helps impart improved cold temperature
properties making this oil superior to a number of other biodiesels
derived from vegetable oils. Table 7
presents the initial physical properties of both pennycress oil and
its methyl ester with respect to the ASTM requirement for a
biodiesel. As a crude oil pennycress meets all of the ASTM
requirements with the exception of acid value which may be
addressed when fully cultivated seed is crushed and converted to
methyl esters. Of particular note is the decent cold temperature
performance represented by both cloud and pour points. As expected,
the oxidative stability (OSI) just exceeds the requirement.
Pennycress seed and its defatted seed meal contain a
glucosinolate, sinigrin, when released can serve as a volatile
biofumigant [23]. Both, hexane extracted and expelled pennycress
meals when placed in contact with water released allyisothiocyanate
the aglycone of sinigrin found in pennycress seeds by action of the
active myrosinase enzyme. Pennycress meal was shown to be effective
at inhibiting the germination and growth of weed seeds in
laboratory test experiments as well as test plots. Seedmeal when
incorporated at 1.0 wt% into soil, particularly when the plots
were covered to prevent volatiles from escaping, completely
inhibited the appearance of weeds. This practice may be useful for
organic growers who may be looking for green practices for weed
control within field plots.
Table 6 Fatty acid composition of thlaspi (pennycress)
collected from Illinois.
|
Fatty Acid
|
Percent
|
|
16:0
|
2.4
|
|
18:1 D9
|
9.7
|
|
18:1 D11
|
1.3
|
|
18:2
|
20.8
|
|
18:3
|
13.8
|
|
20:1
|
9.1
|
|
20:2
|
1.9
|
|
22:1 D13
|
36.9
|
|
22:2
|
0.8
|
|
24:1
|
3.2
|
Table 7 Physical properties of pennycress oil and
methyl esters.
|
Oil
|
Methyl esters
|
ASTM requirements
|
|
Viscosity Index
|
222
|
277.0
|
NA
|
|
40 °C
|
39.1
|
5.0
|
1.9-6.0
|
|
100 °C
|
9
|
2.0
|
NA
|
|
Pour Point (°C)
|
– 18
|
– 15.0
|
NA
|
|
Cloud Point (°C)
|
– 10
|
– 10.0
|
Report
|
|
Acid Value (mg KOH/g Oil)
|
1.084
|
0.7
|
< 0.5
|
|
Flash Point (°C)
|
234
|
136
|
> 93
|
|
RBOT (avg min)
|
17.5
|
12.5
|
NA
|
|
RBOT w/antiox. (avg min)
|
39
|
54.0
|
NA
|
|
Copper Corrosion
|
1B at 51 °C
|
1a
|
< 3
|
|
OSI (avg hours at 110 °C)
|
4.09
|
5.6
|
> 3
|
Conclusion
New Crops development effort in the US is focused on the
advancement of crops that can be grown offseason or on
underutilized land. This manuscript outlined four crops that
address these concerns plus provide novel materials not currently
available domestically. Cuphea still has many agronomic issues and
will require the most technological breakthroughs before a
sustainable crop can be grown. However, successful cuphea
production would fill a much needed demand by the detergent
industry. Coriander has already been grown commercially in other
parts of the world for herb and condiment uses but production as an
oilseed has not been commercially demonstrated. Successful
production after winter wheat may make this crop economical for
both detergents and monomers in nylon production. Lesquerella will
provide a much needed crop to the desert regions of the US and fill
a need for domestic production of hydroxy fatty acids. The
agronomics of lesquerella look favorable and commercial production
in the fall of 2009 is anticipated. The chemistry of
lesquerella oil has been well demonstrated and will be able to
readily supplement many applications currently using castor oil and
provide a new raw material for additional applications. Pennycress
has great promise as a winter-spring production of fuel that will
not displace a food crop, soybean, for its production. Many
agronomic parameters for pennycress still need to be addressed but
limited commercial production is expected for the fall of 2009.
Acknowledgements
The author thanks scientists, technicians and students who have
performed many parts of this research and have shared co-authorship
on numerous peer reviewed manuscripts and abstracts. Those peers
who have contributed most directly to this effort are: Dr. Steve
Cermak, Dr. Robert Behle, Dr. Steve Vaughn, Dr. Roque Evangelista,
Dr. Laura Marek, Dr. David Dierig, Dr. Candy Gardner, Dr. Russ
Gesch, Dr. Winn Phippen, Dr. Stephanie Cape, Dr. Pedro Lopez, Dr.
Mark Widrlechner, Ben Lowery, Amber John, Melissa Winchell, Linda
Manthey, Molly Gass, Chelsey Rolando, Melissa Mund, Jeff Forrester
and Billy Deadmond. Special thanks to the local farmers who allowed
us access to their farms and expert advice on local farming
practices: Donnie Meehan, Roger Beecher, Chip Unsicker, Fred
Basehoar, George Geier and John Ackerman.
References
1 National Agriculture Statistics Service.
http://www.nass.usda.gov/QuickStats/index2.jsp, 2009.
2 Arganosa GC, Sosulski FW, Slikard AE. Seed
yields and essential oil of northern-grown coriander (Coriandrum
sativum L.). J Herbs Spices Med Plants 1998 ; 6 :
23-32.
3 Msaada K, Hosni K, Taarit MB, Hammami M.
Marzouk. Effects of growing region and maturity stages on oil yield
and fatty acid composition of coriander (Coriandrum sativum L.)
fruit. Scientia Horticulturae 2009 ; 120 : 525-31.
4 Blade S. Coriander.
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex121.
1998.
5 Lopez P, Widrlechner M, Simon P, et al.
Assessing phenotypic, biochemical, and molecular diversity in
coriander (Coriandrum sativum L.). Germplasm, 2007.
6 Murphy DJ. Designer oilseed crops: genetic engineering of
new oilseed crops for edible and non-edible applications.
Agro-Industry Hi-Tech 1991 ; 2 : 5-9.
7 Goebel CG. Chemical intermediates and derivatives from
unsaturated oils and acids. J Am Oil Chem Soc 1959 ; 36 :
600-4.
8 Isbell TA, Behle RW. Progress in the development of
cuphea as a crop for Midwest growers. Inform 2003 ; 14 :
513-5.
9 Forcella F, Gesch RW, Isbell TA. Seed yield,
oil and fatty acids of cuphea in the northwestern corn belt. Crop
Science 2005 ; 45 : 2195-202.
10 Knapp SJ. Breakthroughs towards the domestication of p.
372-379. In: J. Janick J, Simon JE (eds), New Crops. John Wiley
& Sons, New York, 1993.
11 Knapp SJ, Crane JM. Registration of reduced
shattering Cuphea germplasm PSR23. Crop Sci 2000 ; 40 :
299-300.
12 Knapp SJ, Crane JM. Registration of high oil Cuphea
germplasm VL186. Crop Sci 2000 ; 40 : 301.
13 Behle RW, Hibbard BE, Cermak SC,
Isbell TA. Examining cuphea as a potential host for western
corn rootworm (coleoptera: chrysomelidae): larval development. J
Econom Entomol 2008 ; 101 : 797-800.
14 Behle RW, Isbell TA. Evaluation of cuphea as a
rotation crop for control of western corn rootworm (coleoptera:
chrysomelidae). J Economic Entomol 2005 ; 98 :
1984-91.
15 Cermak SC, Isbell TA. Synthesis and physical
properties of cuphea-oleic estolides and esters. J Am Oil Chem Soc
2004 ; 81 : 297-303.
16 Cermak SC, Isbell TA. Estolides-the next biobased
functional fluid. Inform 2004 ; 15 : 515-7.
17 Isbell TA, Lowery BA, Dekeyser SS,
Winchell ML, Cermak SC. Physical properties of
triglyceride estolides from lesquerella and castor oils. Industrial
Crops and Products 2006 ; 23 : 256-63.
18 Moser BR, Cermak SC, Isbell TA. Evaluation of
castor and lesquerella oil derivatives as additives in biodiesel
and ultralow sulfur diesel fuels. Energy and Fuels 2008 ;
22 : 1349-52.
19 Goodrum JW, Geller DP. Influence of fatty acid
methyl esters from hydroxylated vegetable oils on diesel fuel
lubricity. Bioresource Technology 2004 ; 96 : 851-5.
20 Kleiman R, Spencer GF, Earle FR,
Nieschlang HJ. Tetra-acid triglycerides containing a new
hydroxy eicosadienoyl moiety in lesquerella auriculata seed oil.
Lipids 1972 ; 7 : 660-5.
21 Carr P. Potential of fanweed and other weeds as novel
industrial oilseed crops. In : Janick J, Simon J,
eds. New Crops Exploration, Research and Commercialization.
NY : John Wiley and Sons, Inc., 1991 : 384-8.
22 Marek LF, Bingaman B, Gardner CA, Isbell TA. Thlaspi arvense
(2008). A potential biodiesel crop: preliminary evaluation of the
USDA germplasm collection. Abstracts of the AAIC annual meeting.
http://www.aaic.org/08progrm.htm#POSTER_PRESENTATIONS_(Oilseeds)
23 Vaughn SF, Isbell TA, Weisleder D,
Berhow MA. Biofumigant compounds released by field pennycress
(thlaspi arvense) seedmeal. J Chemical Ecology 2005 ;
31 : 167-77.
|
Version imprimable
Version PDF
