Commercial Process For Low-Cholesterol
ITHACA, N.Y.— Cornell Uni
versity food scientists have
improved a process to remove
cholesterol from milk to the point
where they say it is commercially
viable. They have developed a
continuous process that can
remove 90 percent of the choles
terol in milk by forcing carbon
dioxide through the fat in milk at
pressures more than 1,300 times
that found in the average automo
bile tire.
The highly efficient technique
- similar to die one used to decaf
feinate coffee - opens the way for
producing low-cholesterol milk
and other dairy products such as
butter, ice cream, cheese and
yogurt. The Cornell researchers
plan discussions with dairy indus
try representatives to further deve
lop the technique.
The process, known as “super
critical fluid extraction,” could
have a worldwide impact on thw
dairy industry, according to food
scientist Syed S.H. Rizvi, who so
far has applied it only on a laborat
ory scale. He is a professor of food
engineering in the College of
Agriculture and Life Sciences at
UUiiK FEED BINS
We Will Assemble And
Deliver Bins To Tent hml
We Stock Truckloads Of Chore-Time Bins
& Miles Of Chore-Time FLEX-AUGER®
Get The Complete System - Feeding, Ventilation, Watering
From Your Authorized Master Distributor
Li'i.iL-rUi
agrl
systems
Cornell.
Rizvi said that the process
could be used to remove most of
the cholesterol from milk fat, so
that the decholesterolized butter
fat then could be added back to
skim milk to create low
cholesterol milk or used as a major
component for making other low
cholesterol milk products. These
might include butter, ice cream or
cheese.
“What makes our process parti
cularly exciting is that it not only
reduces cholesterol by 90 percent,
but also recovers up to 85 percent
of decholesterolized butterfat,”
Rizvi said.
“If we had gotten only a few
pounds of decholesterolized fat
from 100 pounds of butterfat pro
cessed, the yield would have been
too low to make any economic
sense,” he pointed out.
The Cornell research group is
not the only one developing super
critical extraction for cholesterol
removal, Rizvi pointed out. Sever
al companies also are experiment
ing with the method, but have
apparently not yet reported a high
yield, continuous process that
NORTHEAST AGRI
SYSTEMS, INC.
FLYWAY BUSINESS PARK
139 A West Airport Rd. \ 7
Lititz, PA 17543
(717) 569-2702
matches the Cornell technology.
These companies include Super
critical Processing Inc. of Allen
town, Pa., and Phasex Corp. of
Lawrence, Mass.
Perhaps more importantly, the
patent office of Japan recently dis
closed that the Food Research
Society of Higashimura City near
Tokyo has applied for a Japanese
patent on a similar technique for
cholesterol removal, Rizvi said.
The independently developed
Japanese method reportedly can
reduce the cholesterol level in but
terfat by nearly 84 percent, with
about 87 percent recovery of the
decholesterolized fat. The patent
application cites a 1986 paper
entitled “Modification of Butter
Oil by Extraction with Supercriti
cal Carbon Dioxide” published in
the journal Agricultural and Bio
logical Chemistry by scientists
from Tohoku University in Sen
dai, Japan.
Rizvi said the Japanese tech
nique is reported to use slightly
different materials and conditions
for the extraction process, but also
could be economical.
CHORE-TIME
The feed bin is the very
heart of any feeding system
if the bin lets you down, the
system quits.
That’s why we put so
many quality features into
our Complete line of feed
bins - which includes 6-foot
diameter steel or poly
ethylene (great for H.M.
com), 6-foot, 7-foot, and
9-foot models. All are avail
able in several capacities -
so you have a wide selection
of bins to fit your needs.
Here are just a few of the
quality features that make
our bins such an outstanding
buy:
• Sturdy Ladder
System
• All Bin Seams Are
Double Caulked
Choice of 16 or 25
Inch Hopper
Opening
• All Galvanized
Steel Parts
“We see the two independently
STORE HOURS;
Mon.-FH. 7:30-4:30
Sal 8:00-11:30
Milk Developed At Cornell
developed methods as confirma
tion that the supercritical fluid
extraction is viable, and it encour
ages us to proceed as quickly as
possible to develop the process for
commercialization,” he said. Riz
vi added that the Japanese patent
application does not interfere with
plans to commercialize the Cor
nell technique.
Rizvi explained that, in his pro
cess, cholesterol is removed by
injecting carbon dioxide into but
terfat under high pressure, up to
4,000 pounds per square inch, at
40 degrees Celsius (104 degrees
Fahrenheit). Under such a pres
sure, carbon dioxide becomes
“neither a gas nor a liquid, but a
supercritical fluid,” as he calls it
When the high-pressure carbon
dioxide is passed through a batch
of butterfat, it picks up cholesterol
along with some fat (triglycer
ides). The cholesterol-laden “gas”
moves into a second unit where
the pressure and temperature,
among other conditions, are mani
pulated in such a way that the car
bon dioxide releases the choles
terol.
‘This second stage of the opera
tion is critical because this is
where cholesterol is removed
selectively,” Rizvi said.
The supercritical carbon diox
ide, still carrying some choles
terol-reduced fat, flows into a
third vessel held at atmospheric
pressure, where it becomes gase
ous and dissipates, leaving behind
fat (triglycerides).
With most of its cholesterol
now gone, the decholesterolized
components of butterfat in the first
and third vessels are collected to
make low-fat milk, butter, cheese
and other milk products with little
cholesterol.
The process also separates but
terfat’s major constituents - tri
glycerides - into two parts: one
that stays solid at room tempera
ture and the other that is liquid.
These fats can be collected sepa
rately after the process.
“By using more low-melting
triglycerides than high-melting
ones, it may be possible to pro
duce a more spreadable butter,”
said Rizvi, who plans to use the
technique to reduce cholesterol
from other animal fats such as
beef tallow and lard. He is deve
loping such low-cholesterol and
more spreadable butter and other
dairy products.
Rizvi said that reducing the
cholesterol in butterfat should not
affect the flavor, taste and nutri
tive value of milk and dairy
products.
He also said that the continuous
nature of his supercritical extrac
tion process means that it is possi
ble to process butterfat in com
mercial quantities cost-effec
tively. The prototype laboratory
scale apparatus can handle only
small amounts of butterfat for
Farmers Paired According
To Manure Status
LANCASTER The Lancas
ter Conservation District is com
piling a list of people in Lancaster
County who have manure to sell
or give away and those who would
like manure for their land. Based
on data recently compiled by the
District, nearly all townships
within the county have some
farms with excess manure. How
ever, most farms could use more
manure on their cropland. A pair
ing of those farms with excess
with those who need more will
reduce pollution of streams and
groundwater and will also reduce
die need for chemical fertilizer
LancMfr Farming, Saturday, April 8,1988-A37
experimental purposes, but the
Cornell researchers are now plan
ning to scale up the system to pro
cess the materials in large
quantities.
Whole milk contains about 3.3
percent butterfat, which consists
of saturated and unsaturated fats
in the form of triglycerides, plus
phospholipids and cholesterol.
They account for about 130 grams
per gallon. In turn, about 0.4 per
cent of the butterfat in milk, or
about 532 milligrams per gallon,
is cholesterol. This white, odorless
fatty substance long has been
implicated as causing plaque in
arteries, which can produce heart
disease.
By adding decholesterolized
butterfat to skim milk, the Cornell
researchers already have made
decholesterolized 2 percent milk.
Two percent milk contains only 2
percent butterfat compared with
3.3 percent in whole milk. Also
popular is 1 percent milk.
David K. Handler, a professor
of food science and an expert on
milk quality, helped Rizvi evalu
ate the low-cholesterol 2 percent
milk. According to Handler, Riz
vi’s technique can be used to
tailor-make a variety of low
cholesterol dairy products.
He predicted that sales of milk
and other dairy products with low
cholesterol levels “could increase
greatly in competition with other
types of beverages.”
In 1987, the average American
drank 20.7 gallons of milk as a
beverage, 3.3 gallons less than in
1965. This compares with the per
capita consumption of soft drinks
at 43.4 gallons, coffee at 25.3 gal
lons and beer at 23.9 gallons.
Rizvi said that, although the
supercritical fluid extraction pro-
cess is not new, researchers only
recently have recognized the
importance of this technology.
The technique is now used to
decaffeinate coffee and to obtain
hops extracts that give beer its
characteristic bitter flavor;
researchers have long hoped to
discover other food-processing
applications.
The method now used to decaf
feinate coffee beans is basically
the same as the cholesterol
removal process devised at Cor
nell. Rizvi’s achievement was to
optimize the precise operating
conditions and develop other criti
cal steps required for the efficient
removal of cholesterol from but
terfat with high recovery of the
usable product.
He developed the cholesterol
removal system with a team of
other Cornell researchers, includ
ing postdoctoral fellows Hakim
Benkrid and Roy Chao and gradu
ate students Betsy Tse and Abigail
Honer. His research has been sup
ported in part by the National
Dairy Promotion and Research
Board. •
inputs. It is the goal of the District
to help farmers get together to
solve problems locally and
voluntarily.
If you have extra manure or
could use some more on your
farm, please call the Lancaster
Conservation District at
717/299-5361. Information
needed is farm location, type of
manure, quantity of manure, and
time of the year available. When
two people in the area can be
matched, the District will contact
both parties. Details such as con
ditions of sale can then be worked
out between the two parties.