 A
monthly series of articles by specialists at the University of Nebraska
Panhandle Research and Extension Center about issues of importance
April 2006 Topics:
Trans Fatty Acids -
New Listing on Nutrition Facts Labels
Karen Schledewitz
MA, PHREC Nutrition Extension Assistant
and Linda Boeckner PhD, PHREC Extension Nutrition Specialist
 Trans
fatty acids (TFAs) are a type of fat that occurs naturally in small amounts
in meat and dairy products, but are added in larger amounts to several
processed foods. TFAs have been produced by adding hydrogen to vegetable
oil making the fat more solid and less likely to turn rancid.
Food companies began adding
TFAs to many of their products because they help stabilize product flavor
and give products a significantly longer shelf life. TFAs were also considered
a healthier fat than saturated fat when they were introduced as a processed
food ingredient.
However, recent research has
linked TFA intake to increased LDL cholesterol (commonly called “bad
cholesterol”), and therefore increased risks of coronary heart disease,
including heart attack.
As of January 1, 2006, food products containing more than .5 grams of
trans fatty acids per serving are required to report that information
on their Nutrition Facts Label. This regulation is a response of the Food
and Drug Administration (FDA) to consumer concerns over research results
linking TFAs intake to increases in LDL cholesterol. This Nutrition Facts
Label regulation is intended to provide information on the trans fatty
acid content of food, which in turn will assist consumers in maintaining
heart-healthy dietary practices.
The new trans fatty acid listing
on the Nutrition Facts Label will appear on its own line directly under
the line reporting the amount of saturated fat per serving (as shown in
the sample label insert). The label will not report a % Daily Value (%
of total daily recommendation based on 2000 calorie diet) for trans fatty
acids alone because the FDA has not yet set that guideline.
The Institute of Medicine
of the National Academy of Sciences has stated that the link between higher
TFA intake and increased cardiovascular heart disease risk suggests “an
upper limit of zero” for TFAs intake. However, they further stated
that, because TFAs are “unavoidable in ordinary diets”, they
recommend that “trans fatty acid consumption be as low as possible
while maintaining a nutritionally adequate diet.” The average American
consumes 5 to 6 grams of TFAs a day, and eating less than that would be
nutritionally reasonable in light of recent research (unless otherwise
directed by a dietician).
Many foods, including dairy
products and meat, have some TFAs, but they are found in the greatest
amount in such foods as stick margarine, solid vegetable shortening, commercially
prepared baked foods and fried fast foods. TFAs are found in somewhat
smaller amounts in processed food products such as cake mixes, chips,
salad dressing and microwave popcorn.
If you are concerned about
lowering your trans fatty acid intake, some simple tips include:
• Use tub or liquid
margarine labeled “trans fat free”
• Use olive or canola
oils for cooking or salads and avoid animal fats such as lard and butter
• Replace chips, crackers
and cookies with low-fat or unprocessed foods such as low-fat cheeses,
fruit and vegetables
• Avoid commercially
fried foods such as french fries and breaded meat patties and pieces
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Biodiesel increases
market for oilseed crops
David Baltensperger
Plant Breeder
University of Nebraska Panhandle Research & Extension Center
Biodiesel production has rapidly increased the market for several minor
oilseeds that have potential to be grown in the Nebraska Panhandle.
Brown mustard (Brassica juncea)
and rapeseed and canola (Brassica napus) are two closely related species
that have potential for use as biodiesel, as well as the more distantly
related species camelina sativa (False flax). Canola, the best known of
these, has been grown widely in the northern U.S. and Canada as a food
oil. It originated from the hybridization of Brassica rapa with Brassica
oleracea. Its progenitor rapeseed was grown industrial uses for many years
prior to the development of genotypes with low euricic acid and low glucosinalate
that was valuable as a human food.
Brown mustard, Brassica juncea,
originated from the hybridization of Brassica nigra with Brassica rapa.
This probably happened in southwestern Asia and India, where the natural
distribution of the two species overlaps. Brown mustard has been grown
for oilseed, greens, and as a spice. In the 1940s, a yellow-seeded variety
of brown mustard was imported into the United States from China and became
widely cultivated because, unlike some other mustards, it could be mechanically
harvested. Currently, efforts are underway to develop canola-quality brown
mustards.
False flax is an annual or winter annual originating in the Mediterranean
to Central Asia and very adaptable, especially to cooler climates, where
higher temperatures are not experienced until after flowering. Camelina
was cultivated as an important crop in the Iron and Bronze ages. Its oil
was the main one used in oil lamps for centuries. Currently it is primarily
used as an oil in cosmetics.
More information about these
crops is available at the Panhandle Research and Extension Center’s
web page on biodiesel crops, at www.panhandle.unl.edu/biodiesel.
These crops are very flexible, responding well to a wide range of rainfall
or to supplemental irrigation. Plants can branch and put on more flowers
as moisture becomes less limiting; however, they will produce some yield
even with very limited water. Camelina is least responsive to improved
production conditions of the three, but most tolerant of poorer conditions.
Dryland cropping systems have
moved from winter wheat-fallow to more intensive systems that include
warm-season crops such as proso millet, sunflower, and corn. The availability
of a spring-planted, cool-season broadleaf crop with an extensive market
opportunity would have significant rotational benefits to High Plains
producers. These crops could emerge as such a crop. While there are both
winter and spring types of these crops, this article will focus on spring
types.
Preliminary work shows that
these crops may be best adapted to limited irrigation in the Panhandle.
Due to the small seedling size, they are difficult to consistently establish
under dryland conditions that involve tillage. A little irrigation at
the establishment stage can make a large difference in potential productivity.
These crops use less water than irrigated wheat, and therefore in areas
where wells dry up in August or total pumping is limited, these crops
have real potential. Depending on price on a given year, spring canola
may even be adapted to fully irrigated situations.
There is potential that they
may be used instead of summer fallow to transition from a full-season
summer crop to winter wheat. Harvest normally occurs in early August,
which allows four to six weeks to replenish surface soil water before
planting winter wheat. Because they do not leave much residue after harvest,
it is best not to follow them with summer fallow. They fit into rotations
well between cool- or warm-season grass crops in a crop rotation.
It is important that winter annual weeds are prevented from producing
seed in other phases of the crop rotation, because it is difficult to
control these weeds in these crops with currently labeled herbicides.
Some spring canola now has herbicide tolerance and can be sprayed with
roundup, but this trait is not available in brown mustard or camelina.
Due to plant diseases, these crops should not be included in a rotation
more than once in four years.
Some possible dryland crop
rotations involving these oil crops include:
1) Winter wheat-corn or proso millet- spring oil
2) Winter wheat-spring oil -proso millet-fallow
3) Winter wheat-corn-spring oil -proso millet
A winter wheat-proso millet-spring
oil rotation may work well on shallow or coarse-textured soils with limited
soil water holding capacity, where continuous cropping may make more sense
than on deep silt or silt loam soils. Both non-wheat crops have a reasonable
chance of producing an acceptable yield with average to above-average
rainfall during the growing season, especially on coarser soils where
water infiltration rates are good.
Irrigated rotations also will
work well when the following crop is expected to be wheat. Most summer
crops should be acceptable preceding the spring oil crop; however, herbicide
carryover issues should be monitored carefully (see Weed Management Section).
All three crops use small grain equipment, limiting the need for large
investments in machinery. However, due to small seed size with low seeding
rates it is necessary to have drills with seed distribution units small
enough to adjust to proper seeding rates. Planting costs are similar to
those for wheat. The low investment costs and increasing consumer demand
for biodiesel potentially make it a good alternative crop for Nebraska
growers.
General Agronomics
Brown mustard and canola seed is small (96,000 seed/lb), but camelina
is even smaller (600,000 seeds/lb). A field with good internal drainage
is essential for stand establishment and yield because they do not tolerate
standing water.
Seedbed Preparation
Proper seedbed preparation is essential for the successful establishment.
They need a seedbed that is firm and well-packed to allow for proper seeding
depth and seed-to-soil contact. After disking, a final harrowing or packing
should create a firm, packed planting surface. Excessive tillage can cause
soil moisture loss and surface crusting. The final tillage operation should
occur less than a week before planting to kill weed seedlings, incorporate
the herbicide, and move soil moisture into the seeding depth zone. A well
prepared seedbed is essential for promoting emergence, achieving desired
stands, and decreasing weed pressure. No-till systems optimize planting
without depleting stored winter moisture; however, weed control programs
for no-till systems have not yet been developed for brown mustard or camelina
(see Weed Management Section).
Planting Methods and
Rates
Begin planting in April when soil temperatures at planting depth are 40°F
or warmer, but seeding up through May 15 has been effective in this region.
Planting too early can reduce stand establishment due to cold soil temperatures.
Yields can decline with delayed seeding if crop flowering and seed fill
occur under hot summer temperatures. In this region, it is generally best
to plant early rather than late as that leaves more recrop options if
stands fail.
Seeding rates range from three to six pounds pure live seed per acre for
dryland. Use seeding rates of five to eight pounds if the crop is to be
planted and irrigated. The lower rates in the range are more appropriate
for the smaller seeded camelina. The size seed limits planting depths
to 1/8 to 3/4 inches. Seeding depths of 1/4 to 1/2 inch are optimal when
moisture is adequate. A grain drill is desirable for seeding. Drills with
6- to 12-inch row spacings are adequate. The narrow row spacings will
enable the stand to cover the soil surface more quickly and reduce weed
competition. Disk openers are better than hoe-type openers because of
their improved precision in seed placement and the fact that the seedlings
endure a three- to four-week period of susceptibility to soil covering.
While final plant populations
of 10-12 plants per square foot (dryland) and 14-16 plants (irrigated)
are ideal, weed-free stands of two to four plants per square foot are
salvageable because the crops compensate by branching in thin stands.
Soil Fertility
Soil testing is the most effective monitoring device a grower can have
to manage soil fertility. These oil seed crops will benefit from proper
fertilization. Adequate levels of nitrogen, sulfur, phosphorus, and potassium
are essential for rapid stand establishment and optimum yields. They are
heavy nitrogen and sulfur users, showing greater response to high nitrogen
(wheat recommendation x 1.25) and especially sulfur (wheat recommendation
x 2) than wheat and barley. They need a total availability of 150 pounds
of nitrogen to produce 3,500 pounds of grain per acre. An early spring
application is as effective as split applications. They are sensitive
to fertilizer salt burning with furrow applications of both nitrogen and
sulfur. Where soil moisture might be limiting during germination, in-furrow
nitrogen and sulfur applications are discouraged.
Phosphorus and potassium requirements are similar to those of high yielding
wheat crops. Regional soils typically have high residual potassium levels
and a response from potassium fertilizer would not be expected. Apply
both nutrients as a preplant treatment according to soil test results.
Optimum soil pH is 5.8 to 7.8. Apply sulfur preplant in forms that are
more readily available, such as ammonium sulfate or ammonium thiosulfate
rather than elemental sulfur. It should be applied to achieve a soil test
plus applied ratio of 1 pound sulfur to 6 pounds nitrogen.
Weed Management
Growers should be aware of the sensitivity of these oil crops to several
broadleaf herbicides. Avoid fields with residual levels of triazines,
imadazolinones, some sulfonylureas, picloram, and dicamba (for example:
Ally, Amber, AAtrex/Atrazine, Banvel, Beyond, Finesse, Peak, Pursuit,
Raptor, Rave, and Tordon). Refer to herbicide labels and herbicide consultants
for potential problems with residual herbicides. Weeds and volunteer crops
should be destroyed before planting as even the roundup tolerant material
will only allow low rates of roundup to be applied over the top. Preplant
tillage can control weeds and volunteer wheat, but a tillage-herbicide
program will control problem infestations better than tillage alone. Treflan/Trifluralin
is registered for use, but it will not control many weedy mustards. Growers
should be sure to prevent these weeds from going to seed in previous crops
in the rotation. If Treflan is to be applied, note that it requires soil
incorporation within 24 hours of application. Postemergence control of
grass weeds may be achieved with Select or Prism herbicides. These grassy
weeds are more economically controlled with tillage and Treflan/Trifluralin
herbicide, but the use of Select or Prism may be warranted if extreme
grass weed infestations occur. Until other weed control options are developed
for use in no-till brown mustard and camelina production, no-till producers
may want to consider substituting herbicide-resistant (Clearfield, Liberty-resistant,
or glyphosate-resistant) spring canola for brown mustard.
Disease Management
Several diseases can reduce the yield potential of brown mustard, but
proper management practices can reduce the threat of disease. These practices
include a one-in-four-year crop rotation and the use of disease-free,
certified seed.
Insect Pest Management
Several insects are known to infest these crops; however, little is known
of the potential for these insects to significantly damage production
fields in western Nebraska. Flea beetles are the most likely insects to
severely damage the crops, and camelina appears to be the most tolerant
of flea beetle injury. Brown mustard and canola have been seriously damaged
by flea beetles in western Nebraska. Early season cutworm damage also
may threaten stands in some fields.
There is little information available about the economic thresholds of
most of Nebraska's brown mustard pests, but regular monitoring of fields
to guard against insect problems is essential. Flea beetles first become
active in the spring when temperatures exceed about 58°F, and are
most likely to feed on warm sunny days. The beetles will feed on the leaves
of the mustard and create small circular pits or shot hole damage. The
cotyledon stage is most susceptible to damage because the plants cannot
tolerate rapid defoliation and the associated water loss from this type
of feeding. Once the first true leaves have developed, damage potential
is reduced because plants can more easily tolerate defoliation. The insect
is of little concern after the two- to four-leaf stage unless there are
extreme populations.
Irrigation
Brown mustard has the potential to respond to various supplemental irrigation
levels because of its indeterminate type of branching. Optimum yields
will be achieved by irrigation levels similar to irrigated spring wheat
or oats. If adequate water is available for growth, these crops will use
17-19 inches of water during the growing season, with camelina using slightly
less than canola or brown mustard.
During bolting (late May), these crops will be using one inch of water
per week. During peak growth in early June (bud-flowering), crop water
use will be nearly two inches of water per week and will continue at this
level through flowering and initial pod fill. By early July (following
pod set), water use will begin to decrease at a rate of approximately
0.3 to 0.4 inches per week until harvest in early August. Irrigation timing
becomes critical in June (during flowering). If adequate precipitation
has occurred, irrigation can be delayed. Without adequate precipitation,
soil water should be monitored at least twice a week.
In some cases it may be difficult to keep up with water needs during the
peak water use period because plant use can exceed the amount of water
the irrigation system can apply. If this is the case, it is important
to maintain a relatively full soil profile starting in early June so the
plant can use both stored soil water and irrigation water to avoid plant
water stress. Like most crops, water stress causes yield reduction, but
because of the ability to add or drop flowers, they are more flexible
crops than most.
Harvesting and Storage
Direct combine harvest is the most popular method in North America and
Europe. Swathing is also possible when weed or humidity problems make
direct harvest difficult. Harvest should not begin until seed moisture
is below 10 percent. Delivering a crop above 10 percent moisture will
result in dockage and the chance of heating damage during storage. Growers
usually use a combine with a reel head. Seed moisture levels should be
30 percent or lower before swathing. When the seeds in the pods are 75
percent brown colored, the seed moisture should be about 30 percent. Threshing
should start when the seed is at 10 percent moisture and no green seed
is present. Swathing too early will result in green seed, lower oil content,
and higher seed moisture. Swathing too late will result in excessive shattering.
Seed moisture should not exceed 8 percent for long-term storage.
Economics and Marketing
There are few biodiesel markets in Nebraska. Currently, the primary market
for these crops is with Blue Sun BioDiesel through Progressive Producers
in Sidney, Nebraska. They require an equity position in the company for
crop delivery. Further development of a commercial market will help make
these crops an excellent alternative cash crop for Nebraska growers.
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