| Richard estimates that combine
systems are able to harvest 90 to 95 percent of lodged sugarcane in a
field. This is much better than the 75 percent soldier harvesters deliver.
Unfortunately, the billeted cane brings more trash impurities (leaves
and tops) and mud into the factory, which makes it more difficult to clarify.
The traditional clarification process is called cold liming. Eggleston
explains how it works: "The cane juice is mixed in a tank, then
lime in the form of calcium oxide is added to the tank and mixed. The
solution stays at the same 'cold' temperature the entire timeabout
105 °F. The lime neutralizes unwanted organic acids and forms an
insoluble complex with phosphates. The complex precipitates out of solution,
bringing unwanted impurities with it, and is eventually filtered off."
In 1995, Eggleston began conducting factory studies comparing cold
liming with two other clarification processeshot liming and intermediate
liming. She had discussed the idea with Duane Legendre, chief engineer
with Lafourche Sugars Corp., in Thibodaux, Louisiana, who also sits
on the Dedicated Research Funding Committee of the ASCL. Says Legendre,
"My family's factory had always used hot liming, but the place
I was working at in 1995 used cold liming. I wanted to know which clarification
process was better."
In hot liming, the cane juice is preheated to 180 °F to 200 °F.
It is then heated quickly, under pressure, to 220-225 °F. When the
pressure is released, the juice begins to boil violently, or flash,
and the lime is added. In some factories, the lime can be added just
before the flashing stage. In intermediate liming, only 30-50 percent
of the juice is preheated. The lime is added when all the juice is about
150 °F, and then it's flash-heated to 220 °F.
Eggleston knew that other areas of the world had switched from cold
liming to mostly hot liming, but in 1995, cold liming was still the
preferred processing method in the United States. "The main advantages
were considered to be its simplicity of operation and the lower levels
of sucrose inversion, or sucrose losses, it generated," she says.
"But these conclusions were drawn mainly from laboratory studies,
which don't always take into account the complexities of factory processing."
Eggleston decided to take her research to the factories themselves and
was helped with grants from the ASCL.
Big Benefits From Hot Liming
From 1995 through 2000, Eggleston worked with factory operators and
engineers to gather data and compare the three clarification processes.
During the last few years, she cooperated with Adrian Monge, the production
manager for Cora-Texas Manufacturing Company in White Castle, Louisiana.
"Gillian came to the factory and talked to us about her research,"
Monge says. "We had already been investigating intermediate liming,
but not hot liming. We decided to put in a hand to help, and we collected
data with her. The research made a difference, and we ended up switching
to hot liming. The results we got proved that the change was worth it."
Eggleston explains some of the benefits of hot liming: "By switching
from cold to hot liming, a medium-size factory like Cora-Texas could
reduce its sucrose losses enough to save $283,000 per season. That's
a conservative estimate," she adds.
By making the switch, the same factory could also reduce its lime consumption
by at least 20 percent. And, it would need 90 percent fewer chemicals
to clean its heat exchangers.
Depending on the equipment they're using, factory managers might spend
anywhere from several hundred to several thousand dollars to change
from cold or intermediate to hot liming. "But," says Eggleston,
"the economic advantages of operating hot liming across a sugarcane
processing season more than make up for this investment in just 1 year."
Roddy Hulett, chairman of ASCL's Dedicated Research Funding Committee,
has seen factorys take Eggleston's research to heart. "Our organization
funds research like Gillian's," he says, "but we let the mills
decide how to use the results."
The response has been overwhelming. Hulett says, "In 1995, only
one factory in the state was using hot liming. As of late 2002, five
factories were using it, and another one had made the switch in Florida.
A sixth processor in Louisiana has committed to making the switch during
the 2003 grinding season, and I expect we'll see even more factories
go to hot liming next year.
"Gillian's work," he sums up, "shows the many economic
and processing advantages gained by changing to hot liming, particularly
now that growers harvest mostly billeted cane."
One of the manuscripts Eggleston wrote about her research won the American
Society of Sugarcane Technologists' Outstanding Paper Award (Manufacturing
Section) in June 2000.By Amy
Spillman, formerly with ARS.
This research is part of Quality and Utilization of Agricultural
Products, an ARS National Program (#306) described on the World Wide
Web at www.nps.ars.usda.gov.
is in the USDA-ARS Commodity
Utilization Research Unit, Southern Regional Research Center, 1100
Robert E. Lee Blvd., New Orleans, LA 70179-0687; phone (504) 286-4446,
fax (504) 286-4367.
Louisiana Sugarcane: Looking for
That "One in a Million"
Sugarcane was introduced into southern Louisiana by the Jesuits in
1751. But during the early years of the 20th century, root rot and mosaic
virus nearly destroyed the crop and the industry it supported.
In 1924, the U.S. Department of Agriculture established a research
station at Houma, Louisiana.
Two years later, it entered into a three-way memorandum of understanding
with the Louisiana State University (LSU) Agricultural Center at St.
Gabriel and the American Sugar Cane League (ASCL) to test new sugarcane
Over the next few years, the stationand its cooperatorshelped
save the state's sugarcane industry through introductions of disease-resistant
and disease-tolerant varieties from abroad. The three partners have
continued their varietal improvement work to this day.
Since southern Louisiana's winter temperatures are not conducive to
the flowering of cane and the production of true seed, or "fuzz,"
ARS' commercial sugarcane efforts take place at its Sugarcane Field
Station at Canal Point, Florida. The seed produced there is then shipped
to Houma for planting and evaluation. Cooperators at LSU's Agricultural
Center also produce seed, but in indoor facilities. At Houma, scientists
use indoor facilities to make crosses with wild species to create experimental
breeding lines for researchers at the two other locations, with hopes
of introducing useful new traits, such as pest resistance, for future
Ed Richard, who leads ARS' Sugarcane Research Unit at Houma, says,
"We plant 130,000 potential varieties annually, and LSU AgCenter
plants another 100,000. It'll take 12 to 14 years to identify and develop
a new superior variety from these.
"Right now," he continues, "we have two varieties that
are candidates for release in 2003Ho 95-988 and HoCP 96-540. They
rival the production capacity of LCP 85-384."
That's good news to Robert Judice, a farmer who's been growing sugarcane
in Louisiana since 1962. "This year, 95 percent of my fields are
planted with 384. Next year, it'll be closer to 100 percent because
it yields so well. But planting all one variety scares me. I'd like
a little more diversity, just in case a new disease or pest begins attacking
384," he says.
Thanks to the work being done at Houma, St. Gabriel, and Canal Point,
he should get that diversity soon.By Amy
Spillman, formerly with ARS.
This research is part of Plant, Microbial, and Insect Genetic Resources,
Genomics, and Genetic Improvement, an ARS National Program (#301) described
on the World Wide Web at www.nps.ars.usda.gov.
Edward P. Richard, Jr.,
is with the USDA-ARS Southern
Regional Research Center's Sugarcane Research Unit, 5883 USDA Rd.,
Houma, LA 70360; phone (985) 872-5042, fax (985) 868-8369.
"Raising Cane: ARS Research Benefits Sugarcane Growers and
Processors" was published in the September
2003 issue of Agricultural Research magazine.