Note: Descriptions are shown in the official language in which they were submitted.
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PARTICULATE PLANT STEROL COMPOSITIONS
TECHNICAL FIELD
This invention relates to plant sterols, and more particularly to particulate
plant
sterol compositions having defined particle size distribution (PSD)
characteristics,
methods for making the same, and food and beverage compositions incorporating
the
same.
BACKGROUND
Coronary heart disease (CHD) is a common and serious form of cardiovascular
disease that causes a significant number of deaths in the U.S. each year.
Research has
shown that plant sterols, including phytosterols, phytostanols, and esters of
the same, can
lower total and LDL cholesterol and reduce the risk of CHD. For example, the
FDA has
authorized the labeling of foods as useful for reducing the risk of CHD when
supplemented with plant sterols. Because plant.sterols are very hydrophobic
compounds,
they typically have been incorporated into fat-based foods such as margarines
or salad
~ 5 dressings. In other food applications, plant sterols have been mixed with
emulsifiers in
order to achieve water dispersibility, although often at emulsifier
concentrations that can
introduce off flavors and that can significantly dilute the concentration of
plant sterols.
SUMMARY
The invention provides particulate plant sterol compositions and methods for
2o making the same. Particulate plant sterol compositions of the invention are
useful for
dispersion in aqueous media, including aqueous food and beverage products.
When
dispersed in aqueous media, such as a juice, the compositions do not impart
gritty, chalky,
or otherundesirable sensory qualities (i.e. with respect to color, flavor, and
mouth feel) to
the aqueous media. Methods for preparing the compositions are also provided,
including
25 one-pass milling methods that avoid the need for size classification and
recycling of
undesirably sized particles.
In one aspect, the invention provides a composition comprising one or more
particulate plant sterols. The composition demonstrates a multi-peak volume-
weighted or
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mass-weighted particle size distribution (PSD) and a multi-peak surface-area-
weighted
PSD of the one or more particulate plant sterols. The composition, when
dispersed in a
test juice, has an acceptable mouthfeel in the test juice.
A multi-peak volume- or mass-weighted PSD can demonstrate a first peak of
particulate plant sterols having a diameter less than 2 microns, with a volume-
weighted
mean particle diameter of about 0.3 to about 0.5 microns; and a second peak of
particulate
plant sterols having a diameter in the range from 2 to about 35 microns, with
a volume-
weighted mean particle diameter of about 8 to about 12 microns. A second peak
can
represent from about 65% to about 85% of the volume- or mass-weighted PSD, and
the
first peak can represent from about 15% to about 35% of the volume- or mass-
weighted
PSD. In another aspect, the volume-percentage of all particulate plant sterols
having a
diameter greater than 35 microns in a volume- or mass-weighted PSD can be less
than
about 3%, or less than about 0.5%.
~ 5 A composition provided herein can demonstrate a multi-peak surface area-
weighted PSD of the one or more particulate plant sterols. A surface area-
weighted PSD
can demonstrate a first peak of particulate plant sterols having a diameter
less than 2
microns; and a second peak of particulate plant sterols having a diameter in
the range
from 2 to about 35 microns, where the second peak has a surface-area-weighted
mean
2o particle diameter of about 8 to 12 microns. The first peak of particulate
plant sterols can
represent from about 78% to about 92% of the surface-area weighted PSD. The
first peak
of particulate plant sterols having a diameter less than 2 microns can have a
surface-area
weighted mean particle diameter of about 0.5 microns or less. The first peak
of
particulate plant sterols having a diameter less than 2 microns can have a
surface-area
25 weighted mean particle diameter of from about 0.3 microns to about 0.5
microns, or about
0.4 microns.
In another aspect, a composition can have a total specific surface area of a
multi-
peak surface area-weighted PSD of greater than about 2 m2/g, from about 2.5 to
about 7
mz/g, or from about 2.8 to about 6.5 m2/g.
3o In another embodiment, the invention provides compositions including
particulate
plant sterols that are dispersible or have been dispersed in an aqueous
medium. For
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example, a composition can be an aqueous composition. In other cases, a
composition is
a powdered composition. A composition can be a food or beverage composition. A
beverage composition can be selected from the group consisting of a juice, a
juice
concentrate, coffee, tea, a smoothie, a shake, soy milk, rice milk, a frappe,
a milk fluid, a
meal replacement beverage, a diet beverage, and a nutritional supplement
beverage. A
food composition can be selected from the group consisting of a bread, a baked
good,
candy, ice cream, a confection, an egg, an egg replacement, ice cream, yogurt,
a health
supplement, a meal replacement food, and a nutritional supplement.
A composition that includes a dispersion of one or more particulate plant
sterols in
an aqueous material can demonstrate no or only a slight detectable chalky
mouthfeel. A
particulate plant sterol composition can be mixed or dispersed in an aqueous
material in
order to substantially avoid an undesirable sensory attribute in an aqueous
dispersion of
particulate plant sterols. An undesirable sensory attribute can be a chalky,
gritty, drying,
or powdery mouthfeel.
15 In another aspect, the invention provides a process for preparing a
particulate
plant sterol composition. The process includes cooling a plant sterol starting
material;
and subjecting the cooled plant sterol starting material to impact or
attrition milling. A
plant sterol starting material may not include an emulsifier. About 88%-100%
(e.g.,
about 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100% ) by weight of a
plant sterol
2o starting material can be 1 or more plant sterols. A plant sterol starting
material can
include vitamin E and/or tocopherol. A plant sterol starting material can be
in the form of
pastilles having a diameter of from about 1 mm to about 4 mm, e.g., about 2
mm.
A plant sterol starting material can be cooled in the range from about -100
°F to
about -275 °F, or from about - 175 to about -250 °F, or to about
-225 °F. A plant sterol
25 starting material can be cooled with liquid nitrogen. When cooled with
liquid nitrogen,
milling of a plant sterol starting material can be performed in an inert
(e.g., NZ gas)
atmosphere.
Impact or attrition milling can be performed with a gap mill. A gap mill can
have
a rotor-stator gap in the range of from about 0.025" to about 0.05", or about
0.03".
3o Impact or attrition milling can be performed in a single pass. A gap mill
can have an
average tip speed of from about 110 m/s to about 150 m/s, or from about 120 to
about 135
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m/s. A particulate plant sterol composition can be discharged from a gap mill
at a
temperature from about -25 to about -275 °F, or at a temperature from
about -40 to about
-75 °F, or at about -40 to about -50 °F. Impact or attrition
milling can be performed in an
inert atmosphere. A cooled plant sterol starting material can be subjected to
impact or
attrition milling in the presence of one or more of the following: a flow
agent, a colorant,
a flavorant, a vitamin, a mineral, a source of fiber, a protein, and a
nutritional additive.
In another embodiment, the invention provides a process for preparing a
particulate plant sterol composition that includes milling a plant sterol
starting material in
a vortex mill having an inlet air pressure of from about 5 to about 6 bar and
an outlet
temperature of less than about 100 °F. Milling can be performed at a
temperature from
about 60 to about 80 °F and can be performed in a single pass and/or in
an inert (e.g., N2
gas) atmosphere. A plant sterol starting material can be as described
previously. A plant
sterol starting material can be milled in the presence of one or more of the
following: a
flow agent, a colorant, a flavorant, a vitamin, a mineral, a source of fiber,
a protein, and a
~ 5 nutritional additive.
In another embodiment, the invention provides a method for preparing an
aqueous
dispersion of a particulate plant sterol composition. The method includes
mixing a
particulate plant sterol composition with an aqueous material, where the
particulate plant
sterol composition demonstrates a multi-peak surface area-weighted PSD, as
described
2o above.
Unless otherwise defined, all technical and scientific terms used herein have
the
same meaning as commonly understood by one of ordinary skill in the art to
which this
invention pertains. Although methods and materials similar or equivalent to
those
25 described herein can be used in the practice or testing of the present
invention, suitable
methods and materials are described below. All publications, patent
applications, patents,
and other references mentioned herein are incorporated by reference in their
entirety. In
case of conflict, the present specification, including definitions, will
control. In addition,
the materials, methods, and examples are illustrative only and not intended to
be limiting.
3o Other features and advantages of the invention will be apparent from the
following detailed description, and from the claims.
v
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DETAILED DESCRIPTION
The invention provides compositions having one or more plant sterols in the
form
of particles having particular PSD characteristics. The particulate plant
sterol
compositions can be dispersed in aqueous media, such as certain food and
beverage
products, without imparting a gritty or chalky mouthfeel to the product.
Methods for
preparing particulate plant sterol compositions, including one-pass methods,
are also
described.
Plant Sterol Compounds
Particulate compositions provided herein can contain one or more plant sterol
compounds. The term " plant sterol" includes, without limitation,
phytosterols,
phytosterol esters, phytostanols, and phytostanol esters. Phytosterols (and
phytosterol
esters) are typically naturally occurring substances present in the diet as
minor
components of vegetable oils, while phytostanols (and phytostanol esters) are
hydrogenation compounds of the phytosterols.
Plant sterols for use herein can include any of various positional isomer and
stereoisomeric forms, such as a-, (3-, or y- isomers. Typical phytosterol
compounds
2o include a-sitosterol, 'y-sitosterol, (3-sitosterol, campesterol,
stigmasterol, brassicasterol,
spinosterol, taraxasterol, desmosterol, chalinosterol, poriferasterol,
clionasterol,
ergosterol, O-5-avenosterol, 0-5-campesterol, clerosterol, 0-S-stigmasterol, D-
7,25-
stigmadienol, ~-7-avenosterol, 0-7-(3-sitosterol, and 0-7-brassicasterol.
Suitable examples of phytosterol esters include, without limitation, ~-
sitosterol
laurate ester, a-sitosterol laurate ester, ~y-sitosterol laurate ester,
campesterol myristearate
ester, stigmasterol oleate ester, campesterol stearate ester, (3-sitosterol
oleate ester, (3-
sitosterol palmitate ester, (3-sitosterol linoleate ester, a-sitosterol oleate
ester, y-sitosterol
oleate ester, (3-sitosterol myristearate ester, (3-sitosterol ricinoleate
ester, campesterol
laurate ester, campesterol ricinoleate ester, campesterol oleate ester,
campesterol linoleate
3o ester, stigmasterol linoleate ester, stigmasterol laurate ester,
stigmasterol caproate ester, a-
sitosterol stearate ester, y-sitosterol stearate ester, a-sitosterol
myristearate ester, y-
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sitosterol palmitate ester, campesterol ricinoleate ester, stigmasterol
ricinoleate ester,
campesterol ricinoleate ester, and stigmasterol stearate ester.
Useful phytostanol compounds include a-, (3-, and y- sitostanol, campestanol,
stigmastanol, spinostanol, taraxastanol, brassicastanol, desmostanol,
chalinostanol,
poriferastanol, clionastanol, and ergostanol.
Finally, phytostanol esters for inclusion in a composition provided herein
include,
without limitation, ~3-sitostanol laurate ester, campestanol myristearate
ester, stigmastanol
oleate ester, campestanol stearate ester, (3-sitostanol oleate ester, (3-
sitostanol palmitate
ester, (3-sitostanol linoleate ester, ~-sitostanol myristearate ester, (3-
sitostanol ricinoleate
ester, campestanol laurate ester, campestanol ricinoleate ester, campestanol
oleate ester,
campestanol linoleate ester, stigmastanol linoleate ester, stigmastanol
laurate ester,
stigmastanol caproate ester, stigmastanol stearate ester, a-sitostanol laurate
ester, y-
sitostanol laurate ester, a-sitostanol oleate ester, y-sitostanol oleate
ester, a-sitostanol
stearate ester, y-sitostanol stearate ester, a-sitostanol myristearate ester,
y-sitostanol
~5 palmitate ester, campestanol ricinoleate ester, stigmastanol ricinoleate
ester, campestanol
ricinoleate ester, (3-sitostanol, a-sitostanol, y-sitostanol, campestanol, and
stigmastanol.
Plant Sterol Starting Materials
Typically, a particulate plant sterol composition is prepared from a plant
sterol
2o starting material, e.g., as described in the methods below. Plant sterol
starting materials
can include one or more plant sterol compounds, as described above. For
example, a
plant sterol starting material can include multiple plant sterol compounds
(e.g., 2, 3, 4, 5,
6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20 or more) in any relative ratio (e.g.,
1:1, 2:1, 3:1, 4:1,
5:1, 6:1, 7:1, 8:1, 9:1, or 10:1).
25 Plant sterol starting materials can be derived from a variety of plant
sources, e.g.,
rice bran oil, corn fiber oil, corn germ oil, wheat germ oil, safflower oil,
oat oil, olive oil,
cotton seed oil, soybean oil, peanut oil, canola oil, tea, sesame seed oil,
grapeseed oil,
rapeseed oil, linseed oil, tall oil and other oils obtained from wood pulp,
and various other
brassica crops. Although plant sterols are typically derived from plants, a
plant sterol can
3o also be synthetically prepared, e.g., it need not be derived from a plant
source.
Additionally, plant sterol starting materials can be prepared as mixtures of
individual
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purified or synthesized plant sterol compounds or can be co-products resulting
from
purifications of other products (e.g., from plant sources). For example, a
plant sterol
starting material can be obtained as a co-product of the manufacture of
vitamin E and/or
tocopherols from vegetable oil deodorizer distillate.
Depending on the application, plant sterol starting materials may or may not
contain additional ingredients. For example, certain plant sterol starting
materials can
contain vitamin E and/or one or more tocopherols, e.g., when the starting
material is
obtained as a co-product of the manufacture of vitamin E. In some cases, about
88%-
100% (e.g.,88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99%) of a plant
sterol starting
material is made up of 1 or more plant sterol compounds. For example, in one
embodiment, a plant sterol starting material is made up of about 85-90% (e.g.,
about 85,
86, 87, 88, 89, or 90%) by weight a mixture of (3-sitosterol, campesterol, and
stigmasterol.
In other cases, a plant sterol starting material can be made up of about 88%-
100% (e.g.,
about 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100%) by weight a
mixture of [3-
~ 5 sitosterol, campesterol, stigmasterol, brassicasterol, campestanol, (3-
sitostanol, and ~-5-
avenosterol. In certain cases, a plant sterol starting material can be about
89%-91% by
weight a mixture of (3-sitosterol, campesterol, stigmasterol, brassicasterol,
campestanol, (3-
sitostanol, and O-5-avenosterol.
In certain applications, a phytosterol starting material does not include an
2o emulsifier (e.g., lecithin, mono- and/or di-glycerides, soribitan esters,
sucrose esters).
While not being bound by theory, it is believed that the addition of these
ingredients can
contribute to unwanted sensory attributes (e.g., with respect to color,
flavor, or mouthfeel)
of the compositions.
In yet other applications, one or more of the following is included in a plant
sterol
25 starting material: a flow agent (e.g., sodium aluminosilicate, potassium
ferrocyanide); a
colorant (e.g., beta-carotene); a vitamin or mineral (e.g., vitamins A, C, D,
E, and K, and
the B vitamins; and the minerals Ca, Fe, Mg, Zn, K, and Se); fiber (both
soluble and
insoluble; e.g., barley (3-fiber, oat (3-fiber, mannans, galactomannas, wheat,
oat, corn and
barley brans); a protein (e.g., amino acids, soy proteins, milk or egg
proteins); or a
3o nutritional additive (e.g., gingko biloba, ginseng, chondroitin,
glucosamine, echinacea,
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chromium picolinate, folic acid, soy isoflavones, citrus flavonoids, saw
palmetto, sterol
glycosides, and flavolignans).
Plant sterol starting materials can be in any form, e.g., pastilles, waxy
crude
solids, or powders. For example, plant sterol starting materials can be
obtained by
crystallization of an impure tocopherol-sterol mixture, which is dried,
melted, and formed
into pastilles about 1 to about 4 mm (e.g., 1, 2, 3, or 4 mm) in diameter.
Plant sterol
compounds and plant sterol starting materials (e.g., sterol pastilles) can be
obtained
commercially from, e.g., Cargill, Incorporated (Minneapolis, MN), Loders and
Croklaan
(Channahon, IL), Cognis Nutrition and Health (La Grange, IL), Forties Meditech
(Vancouver, B.C. Canada), and ADM (Decatur, IL). In addition, plant sterol
compounds
and starting materials can be synthesized and/or obtained from plant sources
(e.g., as
described in U.S. Pat. Nos. 6,411,206; 5,502,045; 6,087,353; and 4,897,224).
Particle Size Distribution Characteristics ofParticulate Plant Sterol
Compositions
15 Particulate plant sterol compositions provided herein can be described by
their
PSD characteristics. PSD characteristics can be measured with a particle-size
analyzer
that measures both Mie-scattered and Fraunhofer-diffracted light, e.g., the
Horiba Model
LA-910 Particle Size Analyzer. Typically, particulate plant sterol
compositions
demonstrate particular volume- or mass-weighted PSD characteristics and
particular
2o surface-area-weighted PSD characteristics. Without being bound by theory,
it is believed
that particulate plant sterol compositions that demonstrate the described PSD
characteristics do not impart chalky, gritty, powdery, oily, or other
undesirable sensory
attributes (i.e., with respect to mouthfeel, flavor, and color) to
compositions (e.g., food,
beverage, or aqueous compositions) in which they are dispersed.
25 For example, a plant sterol composition can demonstrate a mufti-peak volume-
or
mass-weighted particle size distribution (PSD) of the one or more particulate
plant
sterols. As used herein, the term "mufti-peak" means that a PSD demonstrates a
distribution possessing at least two distinct modes or peak maxima. In certain
cases, a
mufti-peak PSD can be bimodal.
so For example, a volume- or mass-weighted PSD can demonstrate a first peak of
particulate plant sterols having a diameter less than 2 microns, and a volume-
weighted
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mean particle diameter of about 5 microns or less (e.g., about 3 to about 5
microns, or
about 0.3, 0.35, 0.4, 0.45, or 0.5 microns). As used herein, use of the terms
"first,"
"second," "third," etc. to describe PSD peaks does not imply a time-dependence
of
appearance or measurement of such peaks nor does it reflect on the magnitude
of such
peaks. A PSD peak of particulate plant sterols having a diameter less than 2
microns can
be referred to herein as a "fines" peak. A first peak in the volume- or mass-
weighted PSD
can represent from about 15% to about 35% of the total volume- or mass-
weighted PSD,
or any value therebetween (e.g., about 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
26, 27, 28,
29, 30, 31, 32, 33, or 34%). A particulate plant sterol composition can
demonstrate a
volume-or mass-weighted mufti-peak PSD having a second peak of particulate
plant
sterols having a diameter in the range from 2 to about 35 microns. The second
peak can
have a volume-weighted mean particle diameter of about 8 to about 12 microns,
or any
value therebetween (e.g., about 8.5, 9, 9.5, 10, 10.5, 11, or 11.5 microns).
The second
peak can represent from about 65% to about 85% of the total volume- or mass-
weighted
PSD, or any value therebetween (e.g., about 66, 67, 68, 69, 70, 71, 72, 73,
74, 75, 76, 77,
78, 79, 80, 81, 82, 83, or 84%). In addition, the volume-percentage
contributed by all
particulate plant sterols having a diameter greater than 35 microns in the
volume- or
mass-weighted PSD is less than about 3% of the total volume- or mass-weighted
PSD,
e.g., less than about 2.5%, 2%, 1.5%, 1% or 0.5%.
2o Particulate plant sterol compositions described herein also demonstrate a
multi-
peak surface-area-weighted PSD. A mufti-peak surface-area-weighted PSD can be
bimodal. A surface-area-weighted PSD can demonstrate a first peak of
particulate plant
sterols having a diameter less than 2 microns, e.g., a "fines" peak. A first
peak of
particulate plant sterols having a diameter less than 2 microns (e.g., a
"fines" peak) can
have a surface-area weighted mean particle diameter of from about 0.3 to about
0.5
microns, e.g., about 0.3, 0.35, 0.4, 0.45, or 0.5 microns. A first peak of
particulate plant
sterols can represent from about 78% to about 92% of the surface-area weighted
PSD. A
mufti-peak surface-area-weighted PSD can demonstrate a second peak of
particulate plant
sterols having a diameter in the range from 2 to about 35 microns, with a
surface-area
3o weighted mean particle diameter of about 8 to 12 microns (e.g., about 8.5,
9, 9.5, 10,
10.5, 11, or 11.5 microns).
9
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The total specific surface area of a PSD can also be a useful parameter for
evaluating particulate plant sterol compositions. In the compositions of the
present
invention, the total specific surface area of a multi-peak surface area-
weighted PSD can
be greater than about 2 mz/g, e.g., ranging from about 2.5 to about 7 m2/g, or
from about
2.8 to about 6.5 m2/g.
Other Physical Characteristics of Particulate Plant Sterol Compositions
Particulate plant sterol compositions can be in a variety of forms, e.g.,
solid or
liquid. For example, a particulate plant sterol composition can be in powdered
form, e.g.,
immediately after preparation or for subsequent dispersion in an aqueous
medium.
Alternatively, a particulate plant sterol composition can be an aqueous
composition
having particulate plant sterols dispersed therein. An aqueous composition can
be a food
or beverage composition that contains water. For example, particulate plant
sterol
compositions can be dispersed in beverages such as a juice (e.g., a fruit
juice such as
~5 orange, grape, cranberry, apple, kiwi, mango, peach, pineapple, plum,
cherry, banana,
guava, papaya, grapefruit, natsudaidai, tangerine, clementine, mandarin
orange, currant,
watermelon, honeydew melon, cantaloupe, lemon, lime, pear, blueberry,
blackberry,
raspberry, or strawberry juice, or a vegetable juice such as tomato, carrot,
celery,
cucumber, spinach, lettuce, watercress, sprouts, beet, herbs, cabbage, or
wheat grass juice
20 , or mixtures of juices), a juice concentrate, coffee, tea, a smoothie, a
shake, soy milk, rice
milk, a frappe, a milk fluid (e.g., full fat milk, 1% milk, 2% milk, heavy
cream, half and
half, whipping cream, or light cream), a meal replacement beverage, a diet
beverage, or a
nutritional supplement beverage. A particulate plant sterol composition can be
incorporated in a food composition, e.g., a flour (e.g., a white, wheat, rye,
soy, or rice
2s flour), a baked good (e.g., a bread, a donut, a bagel, a muffin, a scone),
candy, ice cream,
a confection, an egg liquid, a liquid egg replacement, ice cream, yogurt, a
health
supplement, a meal replacement food, or a nutritional supplement. In certain
solid food
compositions, a particulate plant sterol composition can be first dispersed in
a liquid, such
as an aqueous composition, and then incorporated into the solid food
composition (e.g.,
3o breads). Alternatively, the plant sterol composition can be mixed with
other solid and/or
powdered food compositions (e.g., flours).
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Processes for Preparing Particulate Plant Sterol Compositions
Particulate plant sterol compositions described previously can be prepared
using
impact- and/or attrition-type milling techniques or jet- or vortex-milling
techniques. The
s described techniques can be performed in a single pass, i.e. without the
need for size
classification of the mill discharge and recycling of improperly sized
material to the mill.
In one process, a plant sterol starting material, as described above, is pre-
cooled
and then subjected to impact- or attrition-milling. For example, a plant
sterol starting
material can be cooled in the range from about -100 °F to about -275
°F, or from about -
175 to about -250 °F. In certain embodiments, the plant sterol starting
material is cooled
to about -225 °F. The plant sterol starting material can be cooled with
liquid nitrogen,
thereby resulting in an inert (N2 gas) atmosphere for milling. By pre-cooling
the plant
sterol starting material, it is believed that the plant sterols become friable
and pulverize
easily. A pre-cooled plant sterol starting material can be subjected to impact-
or attrition-
~ 5 milling in the presence of one or more of the following: a flow agent, a
colorant, a
flavorant, a vitamin, a mineral, a source of fiber, a protein, or a
nutritional additive, as
described previously. A pre-cooled plant sterol starting material can be
subjected to
impact- or attrition-milling in an inert atmosphere, e.g., NZ gas.
Impact- or attrition-milling can be performed with a gap mill. Gap mills
typically
2o include a plurality of flat blades arranged around a conical-shaped rotor
and a
corresponding conical ribbed stator. Size reduction is accomplished in part by
the impact
of particles with the rotor and stator, but predominantly by particle-particle
collisions.
Typically, a rotor-stator gap is in the range of from about 0.025" to about
0.05". For
example, in certain embodiments, the rotor-stator gap is about 0.03". The
rotor speed is
25 adjustable so that an average tip speed of from about 110 m/s to about 150
m/s is
achieved. In certain embodiments, an average tip speed is from about 120 to
about 135
m/s. Gap mills are available commercially from MicrotecMicrotec (e.g.,
Microtec-
Microtec Gap Mill), Bauermeister (e.g., Bauermeister ASIMA mill), Netzsch, and
Hosokawa-Bepex.
3o Impact- andlor attrition-type milling techniques do not require the product
to pass
through a sizing screen. In certain embodiments, the impact- or attrition-
milling, e.g., as
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WO 2005/087200 PCT/US2004/003937
performed with a gap mill, is performed in a single pass. After particle size
reduction, a
particulate plant sterol composition can be discharged, e.g., from a gap mill,
at a
temperature from about -25 to about -275 °F (e.g., at a temperature
from about -40 to
about -75 °F, or at a temperature from about -40 to about -50
°F). In some embodiments,
the composition is discharged at about -75 °F.
In another process for preparing a particulate plant sterol composition, a
plant
sterol starting material is milled in a jet- or vortex-mill. In these mills,
the driving force
for comminution is derived from the high volumetric flows of high pressure air
or other
gas, such as NZ, which will thereby produce an inert atmosphere for milling.
Comminution is mainly by particle-particle collisions, and the heat generated
in the
process is absorbed by the gas cooling upon expansion from, for example, 5 to
6 bar to
atmospheric pressure and dissipated by the high gas flow. Particle-particle
forces result
in fine comminution of the starting material, which does not exit until it has
achieved a
minimal particle size, according to the design of the chamber and the vortex.
Vortex
~5 mills are available from SuperFine Ltd., INOX Ltd., and Netzsch, or as
described in U.S.
Pat. No. 5,855,326.
In the present process, a vortex- or jet-mill can have an inlet air pressure
of from
about 5 to about 6 bar. Milling can be performed at ambient temperature, e.g.,
about 60
to about 80 °F. A vortex-mill or jet-mill can have an outlet
temperature of less than about
20 100 °F. As indicated previously, milling with a vortex- or jet-mill
can be performed in a
single pass, and in the presence of one or more of the following: a flow
agent, a colorant,
a flavorant, a vitamin, a mineral, a source of fiber, a protein, or a
nutritional additive, as
described previously. Vortex- or jet-milling can be performed in an inert
atmosphere.
While not being bound by theory, it is believed that the impact/attrition or
vortex
25 milling processes described herein do less oxidative degradation damage to
the plant
sterols in the plant sterol starting material than other methods that employ a
melt of the
plant sterol starting material and/or allow the starting material to contact
air at
temperatures from about 300 to 400 °F.
The invention also provides a method for preparing an aqueous dispersion of a
3o particulate plant sterol composition. In the method, a particulate plant
sterol composition
is mixed with an aqueous material. The particulate plant sterol composition
demonstrates
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WO 2005/087200 PCT/US2004/003937
defined multi-peak volume/mass-weighted and surface area-weighted PSDs, as
described
previously. In certain cases, the dispersion can be heated gently (e.g., to 90
to 212 °F) for
a brief period of time (e.g., 1 sec to 1 min), and/or homogenized. See, e.g.,
US patent
publication no. 2003/0232118A1.
In another embodiment, the invention provides a method for preparing a
dispersion of a particulate plant sterol composition. In the method, a
particulate plant
sterol composition is homogenized with a pulp. A pulp can be any type of pulp,
including, without limitation, fruit and vegetable pulps, such as citrus pulp
(e.g., orange,
lime, lemon, and grapefruit pulp); apple pulp; pear pulp; plum pulp, peach
pulp; cherry
pulp, mango pulp; guava pulp; papaya pulp; and assorted berry pulps. A pulp
can contain
about 2-8% pectin, or any value therebetween (e.g., about 2, 3, 4, 5, 6, 7, or
8%). In
certain cases, a pulp containing about 5% pectin can be used. Water may be
included in
the homogenization process to help fluidize the pulp. If water is used, the
ratio of water
to pulp can be about 1:1 to about 4:1, or any value therebetween (e.g., about
1.5:1, 2:1,
2.5:1, 3:1, or 3.5:1). In certain cases, a ratio of 3:1 of water to pulp is
used. Particulate
plant sterols can be included at about 1% to about 10% by total weight of a
water/pulp/particulate plant sterol mixture prior to homogenization, or any
value
therebetween (e.g., about 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8,
4, 4.2, 4.5, 4.8, 5,
5.2, 5.5, 5.8, 6, 6.2., 6.5, 6.8, 7, 7.2, 7.5, 7.8, 8, 8.2, 8.5, 8.8, 9, 9.2,
9.5, or 9.8% by
2o weight). In certain cases, particulate plant sterol compositions can be
included at about 2-
3% by weight.
In the method, a pulp, water, and a particulate plant sterol composition can
be
mixed prior to homogenization. For example, a pulp, water, and a particulate
plant sterol
composition can be pre-mixed with high shear (e.g., about 10,000 rpm) using a
bench top
mixer. Premixing can occur until the particulate plant sterol compositions are
well
dispersed in the pulp/water mixture, e.g., about 1 to 10 minutes, or about 5
minutes. The
pulp/water/particulate plant sterol mixture can then be homogenized. The
pulp/water/particulate plant sterol mixture can be homogenized in more than
one stage.
For example, the pulp/water/particulate plant sterol mixture can be
homogenized in two
3o stages. In certain cases, the pulp/water/particulate plant sterol mixture
is homogenized at
about 3000-5000 psi in a first stage, and then homogenized at about 300-800
psi in a
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WO 2005/087200 PCT/US2004/003937
second stage. In some cases, the pulp/water/particulate plant sterol mixture
is
homogenized at 4500 psi in a first stage and S00 psi in a second stage.
Multiple passes
can also be used. A homogenized pulp/water/particulate plant sterol mixture
can deliver
about 0.5 to about 1.5 g, or any value therebetween (e.g., about 0.6, 0.7,
0.8, 0.9, 1.0, 1.1,
1.2, 1.3, or 1.4 g) of particulate plant sterols per 10 g of pure pulp (e.g.,
without added
water, wet basis).
After homogenization, a homogenized pulp/water/particulate plant sterol
composition mixture can be incorporated in a food or beverage composition, as
described
previously. In other cases, a homogenized pulp/water/particulate plant sterol
mixture can
be added to an aqueous medium (as described previously), and mixed to result
in an
aqueous dispersion of particulate plant sterols. In certain cases, an aqueous
medium can
be a juice, such as a single strength juice such as orange juice or cranberry
juice. In other
cases, an aqueous medium can include water, a homogenized
pulp/water/particulate plant
sterol mixture, and a fruit or vegetable juice concentrate. An aqueous
dispersion can
~5 contain about 0.3 g to about 1.8 g (or any value therebetween, e.g., about
0.4, 0.5, 0.6,
0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, or 1.7) of particulate plant
sterols per serving
(typically, 6-12 oz.).
While not being bound by any theory, it is believed that pulp, or some
component
of pulp such as pectins or terpenes, effectively homogenizes particulate plant
sterol
2o compositions, resulting in good dispersion, viscosity, and stabilization of
the
homogenized particulate plant sterol compositions. In addition, when
incorporated in an
aqueous medium, the resulting compositions have favorable mouthfeel and
sensory
characteristics (e.g., they are not chalky, oily, gritty, or astringent; and
demonstrate no or
minimal ringing, separation, or appearance of white flecked particulates,
known as
25 "floaters").
EXAMPLES
Example 1 - Preparation of Spray-Prilled Particulate Plant Sterols (SP-1)
S kg of 2 mm diameter sterol pastilles (Cargill, Incorporated, 90% by weight a
3o mixture of (3-sitosterol, campesterol, stigmasterol, brassicasterol,
campestanol, (3-
sitostanol, and ~-5-avenosterol) were melted in a Parr reactor and forced
under a NZ~g~
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WO 2005/087200 PCT/US2004/003937
pressure of 35 psig into a Spraying Systems, Inc. SU-42 two-fluid nozzle at a
rate of 2.7
gph, with the second, atomizing fluid being 3.6 scfin of 90 psig air; the
fluid temperatures
were 375 °F. The product was collected in a conical chamber under
atmospheric pressure
and ambient temperature. Particle size analysis on a Horiba LA-910 Particle
Size
Analyzer [See Table I] showed the sterols to have 6 volume-% (as determined on
a
volume-weighted PSD) and 56 surface-area%- (as determined on a surface-area
weighted
PSD) in the "fines" region (particles less than 2 microns in diameter), with
the "fines"
peak mean diameter being 0.6 microns or greater. The calculated specific area
of the
overall material was 1.1 m2/g.
The product from Example 1 was incorporated at a level of 4.25 g/L into orange
juice (see Example 9). Sensory evaluation of the juice proved it to be
unacceptably
"powdery/chalky" in mouthfeel, giving a drying sensation in the mouth.
Example 2 - Preparation of Cryo-Milled Particulate Plant Sterols (CG-79)
Sterol pastilles (as described above) 2 mm in diameter were cooled in-line to
an
inlet temperature of about -175 °F before entering a Microtec Model 200
"Gap" Mill with
a 0.030" gap. The pre-cooled sterol pastilles were milled in a single pass at
a feed rate of
about 465 #/hr and a rotor speed of 12,000 rpm. The mill discharge temperature
was -45
to -50 °F. The product was analyzed on a Horiba LA-910 Particle Size
Analyzer. See
2o Table I.
CG-79 was evaluated in the orange juice test described in Examples 1 and 9.
The
product was evaluated as not acceptable.
Example 3 - Preparation of Cryo-Milled Particulate Plant Sterols (CG-56)
Sterol pastilles (as described above) 2 mm in diameter were cooled in-line to
an
inlet temperature of about -245 °F before entering a Microtec Model 200
"Gap" Mill with
a 0.030" gap. The pre-cooled sterol pastilles were milled in a single pass at
a feed rate of
about 630 #/hr and a rotor speed of 12,000 rpm. The mill discharge temperature
was -75
°F. The product was analyzed on a Horiba LA-910 Particle Size Analyzer
(see Example
8). See Table I.
CA 02554547 2006-07-25
WO 2005/087200 PCT/US2004/003937
Example 4 - Preparation of Cryo-Milled Particulate Plant Sterols (CG-522)
Sterol pastilles (as described above) 2 mm in diameter were cooled in-line to
an
inlet temperature of about -225 °F before entering a Microtec Model 200
"Gap" Mill with
a 0.030" gap. The pre-cooled sterol pastilles were milled in a single pass at
a feed rate of
about 500-550 #/hr and a rotor speed of 12,000 rpm. Single pass milling was
performed
for about 3.5 hr total (1700# of sterol pastilles). The product was analyzed
on a Horiba
LA-910 Particle Size Analyzer. The mill discharge temperature was -75
°F. See Table I.
Example 5 - Preparation of Votex-Milled Particulate Plant Sterols (SF-1)
Sterol pastilles (as described above) 2 mm in diameter were drawn at a rate of
about 4 kg/hr into a 6"D SuperFine, Ltd. Vortex Mill with no cooling of the
material.
The driving force for the mill was an inlet stream of air at a pressure of
about 5.5 bar.
The product was analyzed on a Horiba LA-910 Particle Size Analyzer. See Table
I.
The product from Example 5 was incorporated into orange juice, as described in
~5 Examples 1 and 9. The material was rated excellent in the test juice
application, with no
detectable "powdery/chalky" mouthfeel or mouth-drying effect.
Example 6 - Characterization of Spray-Prilled, Cryo-Milled, and Vortex-Milled
Particulate Plant Sterols
2o Samples SP-1, CG-79, CG-56, CG-522, and SF-1 were analyzed on a Horiba LA-
910 Particle Size Analyzer and the distribution of particles plotted as either
volume (or
mass)-weighted PSD vs. particle diameter or surface area-weighted PSD vs.
particle
diameter. Each composition's total specific surface area was also calculated
from the
particle size distribution. Results are set forth in Table I below.
Table I
SP-1 CG-79 CG-56 CG-522SF-1
"Fines" Peak only,6 13.1 18.3 19 30
Volume-Weighted
PSD -
of Total
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WO 2005/087200 PCT/US2004/003937
"Fines" Peak only,56 75 79 83 85
Surface Area-Weighted
PSD - % of Total
"Fines" Peak only,0.6 0.6 0.5 0.4 0.4
Surface Area-Weighted
PSD - Mean Diameter
[ul
Specific Surface 1.1 2.0 2.9 4.4 6.1
Area
Total Distribution
-
calculated from
PSD
f m2/gl
Volume-Weighted 3.7 9.4 0 0.3 0
PSD -
of Material >
35 ~ in
diameter
Example 7 - Sensory Evaluation of Particulate Plant Sterols in Orange Juice
The mouthfeel, flavor, and color/appearance of orange juice containing SP-1,
CG-
56, and SF-1 particulate plant sterol compositions at a concentration of 1 g/8
oz (240 mL)
(see Example 9) were evaluated as blind, coded samples by a panel of 9 sensory
judges in
a round table discussion. None of the panelists had been trained specifically
for this
evaluation. The panelists were asked to describe the sensory characteristics
of each
sample, with special emphasis on mouth feel. SF-1 was determined to be the
least chalky
and most acceptable in terms of mouthfeel. The results are summarized in Table
II.
Table II
Sample ColorlAppearanceFlavor Mouthfeel Acceptability
Rank
1. UntreatedOrange-yellow Typical of Typical, 1
OJ, no
Control color, typical slightly chalky feeling;
of
OJ astrin ent acce table
2. CG-56 Light yellow Slightly Faint chalky3
color, like watery, lessmouthfeel,
a
smoothie; slightcharacteristicacceptable
oil film on OJ flavor
to
3. SF-1 Light yellow, More OJ Smooth, 2
like
a smoothie, flavor than creamy
slight #2
oil film on mouthfeel,
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WO 2005/087200 PCT/US2004/003937
surface slightly
more
viscous than
others; no
chalky
mouthfeel;
acce table
4. SP-1 Orange-yellow Slightly Slightly 4
color, typical watery, chalky and
of
OJ; no oily slightly powdery,
film
on surface astrin ent unacce table
Example 8 - Particle Size Analysis
Particle size analysis of particulate plant sterol compositions was performed
on a
Horiba LA-910 Particle Size Analyzer as follows. Powdered particulate plant
sterol
samples were shaken in a bag to mix thoroughly. A balance was tared with a 15
mL
conical tube on it, and 0.05-0.1 grams of sample was added to the 1 S mL
conical tube.
Water was added to the S mL mark of the 15 mL conical tube. 6 drops of Triton
X-100
(EM Science, CAS 9002-93-1) was added to the 15 mL conical tube using a
disposable
transfer pipet, and the conical tube was placed in an ultrasonic bath. After 1
minute of
sonication, the mixture was stirred with a spatula, and resonicated for
another 4 minutes.
During the 4 minute sonication, the 1 S m 1 conical tube was shaken 3 times.
The contents
of the 15 mL conical tube were transferred to a 7 mL tissue grinder. The
sample was
plunged 3 times using the pestle. Using a disposable S 3/4" borosilicate glass
Pasteur
~ 5 pipet, inserted halfway into the liquid in the tissue grinder, '/2 of a
Pasteur pipet full of
liquid was removed. All of the liquid in the Pasteur pipet was then dispensed
into the
instrument sample chamber containing 300 mL of DI water. After adding the
sample
solution to the instrument sample chamber, the sample chamber was sonicated
for 1
minute, and the particle size distribution data acquired.
2o Analysis of Standard
A prepackaged standard solution (Duke Scientific Corp. 0.5 p,m Particle
Counter
Size Standards or Duke Scientific Corp. 5.0 ~.m Particle Counter Size
Standards) was
added to the instrument sample chamber containing 100 mL of DI water until the
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WO 2005/087200 PCT/US2004/003937
%Transmittance was below 95%. The sample chamber was sonicated for 1 minute.
The
particle size distribution data was then acquired.
Example 9 - Preparation of Homogenized Pulp and Particulate Plant Sterol
Compositions
and Dispersion into Test Juices
The following process was used to produce orange juice (from concentrate)
containing 1 g particulate plant sterols per 240 mL:
Pulp Preparation
% by weight
Orange pulp 24.30
Water 72.89
Particulate plant sterols (e.~., CG-522, SF-1) 2.81
Total 100.00
1. The pulp, water, and sterol mixture was premixed with high shear (10,000
rpm) for 5
minutes using a bench top high shear mixer (PowerGen 1800D, Fisher
Scientific).
2. The premixed pulp, water, and sterol mixture was then homogenized (bench
top
homogenizer
2o Model 15, APV Gaulin, Inc.) in two stages at 4500/500 psi.
Preparation of Single Strength Orange Juice
by weight
Water 65.41
Sterol Containing Pulp Preparation 16.46
Frozen Concentrated Orange Juice 18.13
Total 100.00
3o The ingredients listed above were blended with simple mixing.
This formula delivers about 1 g of particulate plant sterols via 10 g pulp
(pure
pulp (no added water) on a wet weight basis).
A number of embodiments of the invention have been described. Nevertheless, it
will be understood that various modifications may be made without departing
from the
spirit and scope of the invention. Accordingly, other embodiments are within
the scope of
the following claims.
19
