Note: Descriptions are shown in the official language in which they were submitted.
WO 92/20243 PCI'/US92/03887
1 2102~23
IMPROVED FLUID, REDUCED FAT PEANUT BUTTERS
AND IMPROVED WHIPPED PEANUT BUTTERS
Technical Field
This invention relates to improved peanut butters,
preferably to reduced fat peanut butters, and most
preferably to whipped (aerated) reduced fat peanut butters.
The invention provides a fluid, reduced fat peanut butter
with a bimodal particle size distribution (PSD). The
invention also provides a whipped peanut butter with
superior appearance and aeration stability.
Background of the Invention
Conventional peanut and other nut butters consist of a
mixture of solid nut particles, liquid oil, and flavorants,
e.g. a sweetener such as sugar, high fructose corn syrup or
honey, and salt. Peanut butter is made by roasting raw
peanut kernels and then blanching and grinding them. The
comminuted nut particles are suspended in the oil from the
nut (or added oil) to form a product having a pasty and
spreadable consistency. In time, however, part of the oil
separates from the product and forms a separate layer on the
top of the peanut butter and a rigid crumbly mass
underneath. This tendency of peanut butter to separate on
standing can be overcome to some extent by the use of
stabilizers. Stabilizers are generally partially
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2 1 0 2 5 2 3 -2-
hydrogenated or highly hydrogenated fats and oils or other
emulsifiers.
Peanut butters typically contain about 50% oil and
about 50% solids. The stabilizer is usually added at a
level of 0.5~/0 to 3% by weight. Flavorants such as salt,
sugar and molasses can be added to improve the flavor.
Emulsifiers are usually added to reduce stickiness.
The spreadability and perceived stickiness (tendency of
the peanut butter to adhere or stick to the roof of one's
mouth and its resistance to breakdown during chewing) are
highly sensitive to the fat content of peanut butter. The
lower the fat content, the harder the product is to spread
and the greater is the stickiness perception. Consequently,
reduction of the fat content by 25% or more (to about 37% of
the peanut butter) while maintaining acceptable texture has
not been achieved.
Analysis of current (full fat) peanut butter products
shows the particle size distribution of the peanut solids to
be primarily two different ranges. One distribution curve
is composed of particles in the range of from about 18 to
about 118 microns, with the central portion of the
distribution being between about 24 and 118 microns in size.
The second particle size distribution range is primarily
between about 3 microns and about 14 microns with the major
distribution being between 5 microns and 11 microns. This
distribution is bimodal, i.e., two distribution curves which
overlap.
~ork by ~ong et al. defined fluid low fat nut butters
with monodispersed PSD (see European patent app~ication no.
0381259, published August 8, 1990. Their process utilized a
roll milling operation to prepare the defatted peanut
solids. These monodispersed solids have a particle size in
which the major distribution (80% or more) of particles is a
single particle size range of 18 microns or less, and
preferably wherein 90% of the particles are less than 13
CA 02102~23 1997-12-23
microns. Combining these solids with oil and additional
ingredients (i.e., flavorants, stabilizers, emulsifiers)
produced a fluid low fat peanut butter.
In contrast to Wong et al., the present invention
defines a fluid low fat nut butter with a bimodal PSD.
The process utilizes novel defatted peanut solids which
are combined with conventionally ground (full fat)
peanuts under high shear mixing conditions. The novel
defatted peanut solids are processed using milling (e.g.
roll mill) and high shear mixing (e.g. ReadcoTM mixer)
operations. Exposing the milled defatted peanut solids
to high shear mixing results in a reduced fat peanut
butter with a significantly lower viscosity than obtained
via roll milling alone. The combination of these solids
with ground, full-fat peanut paste in a high shear fluid
mixing operation (i.e. colloid milling) results in the
novel reduced fat peanut paste which displays a bimodal
PSD. This is beneficial for several reasons, including
the economic benefit from only defatting a portion of the
total peanut stream required for the reduced fat product,
and the peanut flavor benefit derived from same.
Previous attempts at whipped or aerated peanut
butters have generally resulted in poor appearance
(large, visible bubbles) and poor stability of the
aerated system, where bubbles grow or coalesce over time
and/or the product will collapse or deaerate. We have now
discovered that removal of oil (fat) from the system
improves the stability of whipped peanut butters.
The present invention achieves a significant
improvement in aeration stability by adding increasing
levels of stabilizer to the product. The preferred
stabilizer is a fully hydrogenated fraction of palm oil
which is high in PSP and PSS triglycerides. A low peanut
paste viscosity is required to achieve proper product
penetration (firmness) at these higher hardstock levels.
We have further discovered that additional
CA 02102~23 1997-12-23
improvements in whipped appearance are possible by
improving the process by which the gas dispersion is
formed. This includes ensuring that all gas is dissolved
before dispersion, by providing sufficient residence time
at high pressure (usually the dispersion pressure) after
introducing the gas into the product stream. Additional-
ly, the quality of the dispersion initially formed is
improved by providing as sharp a pressure drop as
possible across the dispersion valve or orifice.
Specifically, increasing the dispersion pressure and
employing a slot-shaped dispersion orifice results in
smaller and more uniform bubble sizes, and less streaking
or discoloration resulting from bubble size variation in
the bulk product. Static in-line mixers after dispersion
have also been found to enhance bubble and color uniform-
ity.
It is an object of an aspect of the present
invention to:
a. Provide a fluid, reduced fat peanut butter product
with a bimodal particle size distribution (PSD). This
encompasses both whipped (aerated) and nonwhipped low fat
peanut butters.
b. Provide a process for producing (low viscosity)
reduced fat peanut butter by further processing (high
shear mixing) defatted and roll milled peanut solids
before combining with full fat peanut paste and/or oil.
High shear (colloid) mixing the low fat peanut solid/
paste/oil mixture results in additional viscosity
reduction.
c. Provide a reduced or regular fat whipped peanut
butter product with superior appearance and aeration
stability.
This product is formulated with the maximum level
of stabilizer possible while achieving target
penetration.
Preferably the stabilizer is the high PSP/PSS
palm oil fraction described herein. At least 90% of
the bubbles in the whipped peanut butter have a
5 2 ~523
diameter less than 300 microns, preferably less than 100 microns.
d. Provide a process for producing the superior whipped peanut butter. The
appearance is further improved by forming finely dispersed gas bubbles by
fully dissolving the nitrogen gas into the product stream under high pressure,
and sharply releasing the p~s~u~ across an orifice or valve. The valve or
orifice design has a ~ignifir~nt effect upon the fini~hrd product appearance.
At least 90% of the bubbles have d diameter less than 300 microns, preferably
less than 100 microns.
All ingredient composition percentages given are by weight unless otherwise
noted. All size distributions (particle and bubble) are by volume basis.
Summary of the Invention
The invention in one aspect thereof is a reduced fat nut or oilseed butter
composition which contains:
(a) from about 40% to about 67% nut solids, between 65% and 80% of
said solids having a particle size less than 18 microns and a SPAN of
greater than 2.5 and not more than 5.0 (preferably greater than 2.5 and
not more than 3.5);
(b) from about 33% to about 45% oil;
(c) from 0% to about 3% stabilizer;
(d) from 0% to about 40% bulking agent;
(e) from 0% to about 8% flavorant; and
(f) from 0% to about 3% emulsifier;
wherein the product has a Casson plastic viscosity of between 2 and 15 poise and a
yield value below 300 dynes per square centimeter (preferably less than 175
dynes/cm2). The invention also relates to a composition as described above which is
whipped to contain dispersed gas bubbles, where at least 90% of the bubbles have a
diameter less than 300
",~
a~ i~
CA 02102~23 1997-12-23
.
microns. Processes for making these compositions are
also described.
Other aspects of this invention are as follows:
A whipped nut or oilseed butter composition
comprlsing:
(a) from about 40% to about 67% nut solids,
(b) from about 33% to about 55% oil;
(c) from about 1% to about 3% stabilizer;
(d) from 0% to about 40% bulking agent;
(e) from 0% to about 8% flavorant;
(f) from 0% to about 3% emulsifier; and
(g) from about 5% to about 25% inert gas;
wherein the whipped product has a Casson plastic
viscosity of between 2 and 15 poise and a yield value
below 300 dynes per square centimeter; and wherein the
whipped product contains dispersed bubbles of the inert
gas, at least about 90% of said bubbles having a diameter
less than 300 microns.
A process for preparing a reduced fat, fluid peanut
paste comprislng:
(a) defatting roasted and ground nut solids to an
oil content between about 15% and about 33%; then
(b) reducing the particle size of the defatted nut
solids so that at least about 80% of said nut solids have
a particle size of less than 18 microns; then
(c) exposing said nut solids to high levels of work
input by use of a twin screw extruder or twin screw mixer
configured for high shear; then
(d) combining said nut solids with ground, undefat-
ted peanut paste containing between about 45% and about
55% oil and having a bimodal particle size distribution
wherein one distribution curve is composed of particles
in the range of 18 to 118 microns and the second particle
size distribution range is primarily between 3 to 14
micons; resulting in a reduced fat peanut paste contain-
ing between about 33% and about 45% oil and having a
CA 02102~23 1997-12-23
-6a-
particle size distribution such that 65% to 80% of the
solids in the paste have a particle size less than 18
microns; then
(e) exposing the reduced fat peanut paste to high shear
rates to minimize the Casson plastic viscosity of the
paste;
wherein the peanut paste product has a SPAN greater than
2.5 and not greater than 5Ø
A process for preparing a superior appearance
whipped peanut butter product comprising:
(a) preparing a peanut paste having a Casson plastic
viscosity between 2 and 15 poise; then
(b) making a peanut butter by combining from about 73%
to about 99% peanut pase of step (a), from about 1% to
about 3% stabilizer, from 0% to about 40% bulking agent,
from 0% to about 8% flavorant, from 0% to about 3%
emulsifier, and from 0% to about 35% peanut oil, wherein
these ingredients are selected so that the final whipped
peanut butter product has a penetration between 240 and
320 millimeters/10 at 21~C; then
(c) dearating the peanut butter, and then injecting
under pressure an inert gas into the peanut butter so
that the final whipped peanut butter product contains
between 5% and 25% by volume inert gas; then
(d) providing sufficient residence time at high pressure
after injecting the gas to ensure that the gas is
completely dissolved in the peanut butter, wherein the
residence time is between about 2 minutes and about 4
minutes and the pressure is between about 200 psig and
about 600 psig; and then
(e) providing a rapid pressure drop from a region of
high pressure between 300 psig and 800 psig, to a region
near ambient pressure between 50 psig and 0 psig, to
disperse the gas into the peanut butter and make a
whipped peanut butter product;
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-6b-
wherein the whipped product contains dispersed bubbles of
the inert gas, at least about 90% of said bubbles having
a diameter less than 300 microns.
5Detailed Description of the Invention
Products
The present invention relates to reduced fat nut or
oilseed butter compositions and reduced fat nut or oil-
seed butter pastes, preferably peanut butter and peanut
paste. While this invention will be generally described
in terms of peanuts and peanut butter, it should be
readily apparent that other materials such as almonds,
pecans, walnuts, sunflower seeds, sesame seeds, pumpkin
seeds and soybeans could be utilized in this invention.
The term "nut" as used herein encompasses these nuts and
oil seeds. Mixtures of these nuts and oil seeds can also
be used.
The term "nut butter" as used herein, means a
spreadable food product made from nut solids and oil, and
encompasses spreads and purees. Nut butters according to
the present invention will contain from about 40% to
about 60% nut solids. Reduced fat nut butters of this
invention will contain from about 33% to about 45% oil,
while regular fat (not reduced fat) nut butters will
contain from about 33% to about 55~ oil. The remainder
being additives, e.g., stabilizers, flavorants,
emulsifiers and bulking agents.
Nut butter includes, but is not limited to the terms
"peanut butter" and "peanut spread" as these are defined
by the standards of identify of the Food and Drug
A~m;n; stration.
The oil used in the composition can be the oil which
naturally comes from the nut or seed during the grinding
and defatting step. Oils such as soybean oil, palm oil,
cottonseed oil, coconut oil, walnut oil and other
suitable oils can also be used herein to make the nut
butter. Preferably, for peanut butter, peanut oil is
used. Up to about 35% peanut oil can be used in the
present invention. With other products, such as the
- 6c - ~ 5 2 3
The otl used in the composition can be the oil which
naturally comes from the nut or seed during the grinding and
defatting step. Oils such as soybean oil, palm oil,
cottonseed oil, coconut oil, walnut oil and other suitable
oils can also be used herein to make the nut butter.
Preferably, for peanut butter, peanut oil is used. Up to
ab~ut 35X peanut oil can be used in the present invention.
~ith other products, such as the sunflower seeds and other
.
. =~
CA 02102~23 1997-12-23
sunflower seeds and other nuts, mixtures of oils may be
preferred for flavor. During the milling process some
oil is released from nut solids.
Low calorie oils and zero calorie oils such as
sucrose polyesters of long chain fatty acids (olestra)
and other polyol polyesters of fatty acids can be used
(see for example U. S. 3,600,186 to Mattson, et al and
4,005,196 to Jandacek). Mixed triglycerides made from
medium and long chain saturated and/or unsaturated fatty
acids can also be used herein. An oil which contains at
least 10% medium chain triglycerides can also be used.
Medium chain triglycerides are saturated fatty acids
having from six to twelve carbon atoms. Reduced calorie
peanut butters containing medium chain triglycerides are
described in U. S. 4,863,753 (Hunter, et al., 1989).
The products of the present invention contain from
0% to about 3% stabilizer. The stabilizer can be any of
the known peanut butter stabilizers, for example, hydro-
genated rapeseed oil, or other hydrogenated triglycerideshaving a high proportion of C-20 and C-22 fatty acids.
(See for example, U. S. 3,597,230 and U. S. 3,192,102).
Stabilizers are usually triglycerides which are solid at
room temperature. They solidify in the nut butter in
specific crystalline states and keep the oil from
separating. These materials can be mixed with a second
hydrogenated oil having an iodine value of less than a 8,
for example hydrogenated palm oil, canola oil, soybean
oil, rapeseed oil, cottonseed oil, coconut oil, and
similar materials. This stabilizer can also be mixed
with lower melting fat fractions as, for example, the
peanut butter stabilizer composition disclosed in U. S.
4,341,814 (1982).
Stabilizer used in the nut butters of the
invention is preferably a tailored beta-prime stable
hardstock termed a "PSP/PSS" hardstock, as disclosed
in U. S. Patent 4,996,074 to Seiden & White, issued
February 26, 1991. This beta-prime stable hardstock
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co0prises: (a) from about 45% to about 98% of
2-Stearoyldipalmitin (PSP) triglycerides; (b) from about 2%
to about 55% of 1-Palmitolydistearin (PSS) triglycerides;
(c) less than about 7% of tripalmitin (PPP) triglycerides;
(d) less than about 7~/. of tristearin (SSS) triglycerides;
(e) less than about 3% of diglycerides; (f) less than about
10% of total PPP plus SSS triglycerides; and (g) less than
about 10% of the fatty acids of the total triglycerides and
diglycerides being unsaturated.
"P", as used herein, is palmitic acid. "U", as used
herein, is an unsaturated fatty acid having 18 carbon atoms.
"S", as used herein, is stearic acid. Processes for making
the hardstock are described fully at column 3, line 61 to
column 7, line 11 of the Seiden & White patent. The
hardstock preferably is a fully hydrogenated stearine
fraction of palm oil high in PSP and PSS triglyceride
components. The hardstock can also be derived from
cottonseed stearine and other source oils. The PSP/PSS
hardstock is preferably used in the nut butters of this
invention at a level of about 1.07. to about 2.5% by weight
of the nut butter, preferably from about 2.0% to about 2.5%.
Highly hydrogenated high erucic acid rapeseed oil which
is shown in Example VI of the Seiden & White patent is an
example of a beta-prime tending hardstock particularly
suitable for use in the present nut butters in combination
with the PSP/PSS hardstock. When the PSP/PSS hardstock is
used in combination with highly hydrogenated (Iodine Value
less than 20, preferably less than 10) high erucic acid
(preferably at least about 40%) rapeseed oil, it should be
used in ratios of PSP/PSS hardstock:high erucic acid
rapeseed oil of from about 30:1 to about 10:1, preferably
from about 27:1 to about 20:1. The high erucic acid
rapeseed oil is more fully discussed in the Seiden & White
patent at column 7, line S0 to column 8, line 14.
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Sufficient hardstock should be added to achieve a final
product penetration (firmness) in the range of about 240-320
millimeters/10 at 21-C, preferably about 280-320.
In addition to the stabilizer, or in lieu thereof, up
to about 3% emulsifier can be used in the nut butters to
achieve the proper texture. The emulsifier can be any food
compatible emulsifier such as mono-diglycerides (e.g.,
Myverol), lecithin, sucrose monoesters, polyglycerol esters,
sorbitan esters, polyethoxylated glycols and mixtures
thereof. Up to about 3% and preferably from 1% to 3%
stabilizer and/or emulsifier is used.
The nut butters of the invention can optionally contain
up to about 8% flavorants. "Flavorants," as the term is
used herein, are agents which contribute to or enhance the
flavor of the nut butter. These include sweeteners, flavor
enhancers, artificial sweeteners, natural and artificial
flavors, and other additives which contribute to the flavor
of the butter or spread. Sweeteners are selected from the
group consisting of sugars, sugar mixtures, artificial
sweeteners and other naturally sweet materials. Sugars
include, for example, sucrose, fructose, dextrose, honey,
molasses, high fructose corn syrup, lactose, maltose, and
maltose syrups. Preferably, the sweetener will be something
which has a sweetness intensity about that of sucrose or
fructose. Sweeteners are added at a level of 0% to about
8X, preferably from about 1% to about 6X.
Artificial sweeteners include compositions such as
aspartame, acesulfam, saccharine, cyclamate, glycyrrhizin
and other artificial sweeteners. The amount of artificial
sweetener used would be that effective to produce the
sweetness that is desired; and would be about the equivalent
of the addition of from about 1% to 7% of sucrose.
Flavor enhancers include salt or salt substitutes such
as potassium chloride, sodium chloride/potassium chloride
mixtures, and seasoned salts. The level of flavor enhancer
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210~23
used is a matter of the desired taste level, but usually is
from about 0.1% to about 2%. Other flavorants include
natural or artificial peanut flavors, roasted flavors, and
praline/caramel flavors, walnut flavors, almond flavors and
flavor compositions.
Nut chunks, flavored or candied bits and other
additives can be mixed with the nut butters of the invention
at the desired level. These additives include chocolate
chips or bits or other flavored bits, e.g. butterscot~ch and
peanuts, jellies, (either low calorie jellies or egular
jelly or preserves), and pralined nuts or other candies.
Proteins, such as sunflower seeds, albumin, whey protein, or
soy protein, can be added to fortify this low fat product
with protein materials. These additives are usually added
at a level of from about 1% to about 207. by weight. Nut
chunks and flavored bits can contain fats and oils.
Therefore, the addition of these materials can affect the
fat content and the calorie level of the nut butter.
Bulking agents can also be used in the nut butters of
the invention at levels up to about 40Y.. Bulking agents add
body or texture to the product and are usually non-nutritive
or low calorie materials. Polydextrose (from Pfizer
Chemicals) and maltodextrin are preferred bulking agents.
Fibers, such as cellulose, can also be added. Sugar
substitutes which function like sugars but which are
non-nutritive can also ~e used herein. Such sugar
substitutes include the S-C-hydroxymethyl-aldohexoses
described in copending application of Mazur, serial number
190,486 filed May 5, 1988. If bulking agents are used,
generally from about 5~ to 40X bulking agents are added,
preferably from about 12% to about 2~%.
Processing
To make a nut butter, a nut paste is formed. It is
prepared by roasting nuts which have been cleaned to remove
all the debris. In some cases the nuts are blanched. Any
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conventional roasting technique can be used to prepare the
nuts for processing.
The roasted nuts are first ground, in a conventional
grinder or mill to produce a nut paste of pumpable
consistency. The exact particle size and type of mill used
are within the skill of the art. A Bauer mill is one
conventional mill that can be used to make a nut paste.
The nut paste is then defatted, the particle size of
the solids reduced, and the solid particles are processed in
a high shear mixing device to redistribute the limited
amount of oil around the particles, and to liberate
additional oil from within the particles to the area between
the particles. These steps are defined as follows:
As used herein, the term "defatted" means that some oil
or fat is removed from the nut solids. This can be done by
a hydraulic press, expeller or other conventional means.
As used herein, the term "particle size reduction" or
"means for reducing the particle size" means that the nut
particles are further ground or milled to meet the particle
size distribution requirements of this invention.
As used herein, the terms "high shear solids mixing
device~ or ~high shear fluid paste mixing device" or
"...process" means that the nut particles are processed in a
manner which redistributes the limited fat and coats each
particle more effectively with the fat. Additionally, this
high shear mixing step forces oil trapped within the
intraparticle network into the interparticle area, where it
acts to reduce Casson plastic viscosity.
A. Defatting or Deoiling Step
To make the nut solids having the particle size
distribution required by this invention, the nut paste is
defatted to about 5% to about 33% total fat content. A
hydraulic press similar to that used to remove cocoa butter
from cocoa solids can be used. Any press or similar device
used to deoil or defat solids can be used. The term
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"defatted" does not mean that all the fat or oil has been
removed. It means that the oil or fat which is easily
pressed out of the ground nut paste is removed. The
defatted peanut solids will contain between about 15% and
about 33% oil, preferably about 23% to 27%, and most
preferably about 25%.
The cake or paste which is produced by this defatting
process is then made into a powder to feed to the roll mill.
Any conventional milling or delumping equipment can be used.
Usually the powder has the consistency of coarse flour.
Preferably, the deoiled nut cake will pass through a Tyler
28 mesh sieve, or be less than 550 microns in size.
B. Particle Size Reduction
The nuts are then fed to a roll mill such as the five
roll Buhler SFL mill manufactured by Buhler Manufacturing of
Uzwil, Switzerland. Other mills which can be used include a
four roll or five roll Lehman mill manufactured by Lehman
Maschinefabrik GMBH, Aalen/Wurtt, Germany. Preferably a
five roll mill is used. The more rolls, up to five, that
are used on the mill the more efficient the process becomes.
Roll diameters of from about 8 inches (20.3 cm) to about 20
inches (50.8 cm) are commonly used.
The granular, defatted nut solids are fed to the roll
mill. The feed rate to the mill is controlled by the
operating parameters of the mill. Usually the product is
~choke~ fed to the mill, i.e., the product is constantly fed
to the roll mill so that there is always a supply of product
in the trough formed by the intake sides of the first nip.
The mills are operated at a zero gap between the rolls.
The rolls are pressed together by a hydraulic system and are
moved apart by the product. A typical Buhler SFL five roll
mill with 900 mm roll length and 40 cm diameter requires a
gauge pressure setting of 70 kgm/cm2.
The speed of the rolls is such that the product passes
through the rolls and is sheared in an efficient manner.
W 0 92/20243 ~ 1 0 2 ~ 2 3 P ~ /US92/03887
Roll speeds of from about 4 to about 90 revolutions/min. or
about 15 to about 375 feet/min. (450 cm/min to 11,250
cm/min) can be used. (These values are based on a 15 3/4
inch, 39.4 cm, roll diameter). The temperature of the rolls
is usually near ambient temperature.
The peanut particles can be passed through the mill a
second or a third time to be sure that the particle size
distribution is achieved. Additional shearing of the solids
is accomplished by additional passes. More than five roll
mill passes provides no additional benefit for this
invention.
Other particle size reduction methods can also be used.
These would include very fine grinding and passing through
an extruder.
The particle size reduction process (roll milling) of
solids having a fat or oil content from about 15X to about
33% results in a monodispersed particle size distribution
wherein at least 80~, of the solids have a particle size less
than 18 microns in size. Usually at least 90% of the solids
are less than 13 microns, and most typically the particle
size is between 2 and 11 microns and the fat content is from
20% to 33%.
Particle size distribution or polydispersibility can be
measured by the SPAN.
SPAN is an abstract, dimensionless width factor defined
as:
SPAN - Dgo - Dlo
D50
Dgo is the diameter of the ninetieth (9Oth) percentile
particles, i.e. 90% of the sample would have a smaller
particle size. Dso and Dlo are defined in a similar manner
and represent the 50th and 10th percentiles respectively.
WO 92/20243 PCr/US92/03887
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Accordingly, a completely monodisperse particle size
distribution whereby Dgo = D1o woula have a span equal to
zero. A SPAN of less than 2.5 defines the ~onodispersed
particle size distribution.
Particle size is measured with an instrument which uses
a light scattering technique such as the Malvern particle
size analyzer. The method using this instrument is given
below. Any light scattering analysis can be used. Because
of the nature of these solids, and because of their fat
content, the particles cannot be analyzed by conventional
sieving or air classification techniques unless all of the
fat is removed and the particles are dried to a powder.
The rheology of peanut butter or nut butter in its
melted state (stabilizers are in the liquid state) can be
characterized by the Casson flow equation which relates rate
of shear and stress. This rheological equation may be
written as:
~ ~ . Ko + K1i ~
where ~r, stress, D - shear rate and Ko and Kl are
constants. It has been well established that this equation
is linear for many solid suspensions such as inks and
chocolates. Thus Ko2 and K12 can be regarded as measuring
yield value and plastic viscosity respectively. The Casson
plastic viscosity measures the viscosity of a solid
suspension at an infinite shear rate. A Casson plastic
v~scosity between 2 and 15 poise, preferably between 2 and S
poise, is preferred for the reduced fat nut butters prepared
in this invention.
C. Solids or Paste Shearing Processes
High shear mixing of the defatted, milled solids
result in reduced Casson plastic viscosities, but no further
reduction in particle size. These high shear solids mixers
include twin screw mixers and extruders. Twin screwmixers
made by Readco are preferred for this invention.
3~
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The purpose of shearing the solids is to force the
particles to grind against each other or against the
processor thereby better distributing the oil across the
surface of all the particles. Better distribution of the
oil across the particles results in an increased wettability
of the milled nut solids which facilitates the
reconstitution of a low fat paste from peanut solids and
peanut oil and/or paste. With a continuous oil film over
the nut solids, wettability is enhanced due to the absence
of air adsorbed on the solids' surface.
D. Addition of Regular Ground Peanut Paste or Peanut
Oil
The solids shearing process is followed by addition of
regular ground peanut paste (bimodal PSD) or peanut oil.
The former requires a high shear fluid paste mixing process
(e.g., Colloid mills). This achieves essentially the same
result for the solids and paste mixture as for the solids
mixing (Readco) process, i.e., redistribution of the
available fat among the solid particles and reducing Casson
plastic viscosities: The Casson plastic viscosity of the
paste is between 2 and 15 poise. Preferably the viscosity
is minimized, to a range between 2 and 10 poise. Adding the
monodispersed, high shear mlxed solids to peanut oil does
not require high shear fluid mixing to further reduce the
paste viscosity. The combination of the defatted peanut
solids with the regular peanut paste or peanut oil, results
ln a reduced fat peanut paste containing between about 33%
and about 45% oil and having a particle size distribution
such that 65% to 807. of t~e solids in the paste have a
particle size less than 18 microns.
E. Preparation of the Nut Butters
The compositions herein, after being processed in a
homogenizer, are then mixed with other optional ingredients
if all the ingredients are not already in the product. Then
the product can be subjected to conventional processing.
WO 92/20243 PCI'/US92/038~7
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S,~,~o2523
The product is usually deaerated in a conventional deaerator
to remove residual air from the product. This minimizes the
oxidative rancidity of the triglycerides present in the nut
butter.
The deaerated paste can then be conventionally
processed and packaged. This involves processing to
crystallize the stabilizer, for example by treatment in a
scraped wall heat exchanger and picker. From the picker,
the product is filled into packages and usually tempered in
the containers for about 2 days at 80~F (26.6~C) to 90~F
(32.2~C) to make sure that the stabilizer is in the proper
crystalline form.
Deaerating, cooling, picking and tempering are
conventional in peanut butter processing. One skilled in
the art can easily adapt these techniques to the nut butters
of this invention.
Whipped or stabilized forms of nut butters can also be
made with these milled solids or pastes. Whipped nut
butters have from about SX to about 25% by volume of
nitrogen or other inert gas dispersed throughout the nut
butter.
~ hile conventional processing for forming whipped
toppings can be used to make the whipped or stabilized form
of nut butters, it is preferred to treat the nut butter with
nitrogen under pressure. The paste is warmed to between
140~F and 160-F and then deaerated by passing through a
vacuum deaerator. The warmed deareated paste is pumped at
approximately 100 to 300 psig pressure, preferably 200 to
250 psig (pounds per square inch gauge). Then dry nitrogen
or other inert gas such as carbon dioxide, helium, etc., is
injected into the hot deaerated paste at a pressure of 280
to 340 psig. Preferably, the level of nitrogen or inert gas
is between about 10~. and about 25%, more preferably between
about 10% and about 20%, and most preferably about 15% by
volume.
WO 92/20243 PCr/US92/03887
-1721o2~23
The nut butter is then chilled by passing through
scraped wall heat exchanger to about 75~F to 95~F. The
product becomes whipped when it is allowed to expand through
a nozzle or valve to ambient pressure and filled into the
jar. The nut solids of this invention make a more stable
whipped nut butter than conventional nut solids.
Use of the nut solids of the invention provides a fluid
non-sticky nut butter at fat levels lower than can be
achieved by conventional nut butter processing.
F. Processing for Superior Whipped Appearance
A preferred whipped nut butter of this invention
contains well-dispersed, small-sized nitrogen bubbles. The
whipped or foam structure of the nut butter is stable and of
good consistency. Several factors enter into providing
these benefits. First, reduction in viscosity of the
defatted nut solids allows the use of more hardstock than
could otherwise be used. (Adding more hardstock without
reducing the viscosity of the nut solids would result in the
final nut butter product being too viscous.) The larger
amount and the type of hardstock used plays a major role in
obtaining a good dispersion of desirably small-sized
bubbles.
In addition to using the right type of hardstock in the
right amount, the preferred whipped nut butter is processed
in such a manner that the desired dispersion of small-sized
bubbles is obtained in a stable, well-dispersed foam. The
rtght processing conditions are critical. The first step is
to in~ect nitrogen from a high pressure source into the nut
butter such that the level of nitrogen is between 10Z and
2 m, preferably about 15%, as measured by density difference
between the product with and without whipping. Then it is
important to retain the nut butter under a pressure between
about 200 and about 300 psig, at a temperature between about
130-F and about 160-F, for a time between about 2 minutes
and about 4 minutes, in order to fully dissolve the gas into
WO 92/20243 PCI /US92/038~7
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the oil phase of the product. Preferably the temperature is
between about 140-F and about 150-F during this time. The
product is next cooled by passing it through two scraped
surface heat exchangers where the temperature is reduced to
about 85-F. A similar dispersion is obtained by holding the
product for about 2 minutes at about 600 psig after the
booster pump, described hereinbelow.
The product is then flowed through a booster pump where
the pressure is increased to between about 500 psig and
about 700 psig, preferably about 600 psig, and the product
is then pumped across a specially designed orifice opening
where the pressure is quickly relieved to atmospheric
pressure. The orifice opening is a slot-shaped dispersion
orifice which is used instead of a typical gate valve
because the slot-shaped orifice gives a more uniform
distribution of small bubbles in the product. Specifically,
the design of the slot-shaped orifice is such that the slot
is rectangular, with a width of about 0.05 inch. Dispersion
pressure is adjusted by varying slot length. Use of the
slot-shaped dispersion orifice also eliminates streaking of
the product (i.e., streaking with darker colored stripes or
swirls). The slot design offers a sharper, more uniform
pressure drop than a gate valve. The result is much greater
velocity for the same set of operating conditions, resulting
in reduced streaks. Static in-line mixers may also be used
to reduce streaking.
Lastly, the product is packed into jars and then sealed
with a nitrogen headspace.
Casson Viscositv Measurement
A Brookfield Viscometer (HAT series), 5C4-13R chamber
with a 8C4-27 spindle is used. This arrangement consists of
a spindle "bob" of 0.465 inches (1.12 cm). The inner
diameter of the sample cell is 0.750 inches (1.87 cm). The
instrument is calibrated at 65~C and all samples are
measured at 65~C.
.WO 92/20243 PCI/US92/03887
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A sample size of 13.5 grams of peanut butter is placed
in the sample cell. The sample cell is then inserted in the
jacketed cell holder. To compensate for heat losses through
the tubings, etc, the water temperature entering the
jacketed cell holder should be a few degrees higher than the
desired sample temperature of 65~C. After the temperature
of the sample has reached 65~C the sample is pre-sheared for
about three minutes at 50 rpm. The speed is then changed to
100 rpm and a measurement taken after the dial reading
settles to a constant value. A total of five scale readings
are recorded for 100, 50, 20, 10 and 5 rpm. In general, the
time before reading should be:
Table 1
RPM Time Before Reading
(Seconds)
100 3
The dial reading and rpm are converted into shear
stress and shear rate values by multiplying the rpm and dial
reading by 0.34 and 17 respectively. A plot of the square
root of shear stress vs the square root of shear rate
results in a straight line. Readings where the dial pointer
goes off scale are ignored. A least squares linear
regression is made over the data to calculate the slope and
intercept.
This data is used to calculate two values. The first
of these is the plastic viscosity which is equal to the
slope of the line squared. The plastic viscosity is a
measurement of the peanut butter's viscosity at an infinite
shear rate. It accurately predicts the resistance to flow
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in-pumping, moving or mixing situations. The Casson plastic
viscosity is measured in poise.
The second value is the yield value which is equal to
the value of the x intercept (abscissa) squared. The yield
value is a measure of amount of force or shear that is
necessary to get the peanut butter to start moving. The
relationship between the plastic viscosity and the yield
value determine how a peanut butter will react in additional
processing. The yield value is measured in dynes pe~ square
centimeter.
Particle Size Analysis
A Malvern 2600D particle size analyzer with a Commodore
computer was used to analyze the particle size of the
samples. A small amount (about 0.01 grams) of each sample
was placed in a 25ml test tube and about l5ml of its acetone
are added to it. The sample is dispersed in the acetone by
using a vortex mixer. A transfer pipette is then used to
add this diluted solution dropwise to the acetone filled
cell of the analyzer. The sample is added until the
obscuration is 0.2 to 0.3. The obscuration refers to the
amount of light which is obscured by the sample because of
diffraction and absorption. The instrument reads more
accurately when the obscuration is 0.05 to 0.5 and
preferably from 0.2 to 0.3 (20X to 30% of the light energy
is reduced).
The apparatus is fitted with a 63mm lens to determine
the particle size of the paste. A magnetic stirrer is used
to insure that the sample is being dispersed during the
readings. Each sample is swept 250 times by the laser for
each reading. Each sample was rèad a minimum of three times
with a five (5) minute wait between each reading.
Measurement of Penetration
_ "Penetration" is a measure of the firmness or
consistency of the nut butters of the present invention.
Penetration is determined by measuring the distance a given
CA 02l02~23 l997-l2-23
weight (47 grams) of defined shape will penetrate the nut
butter after falling from a height of 2 centimeters above
the surface of the nut butter. The penetration of the
nut butter is related to its composition and processing,
and to the temperature of the sample at the time of
measurement. The detailed method for measuring penetra-
tion is described in U. S. Patent 4,996,074 to Seiden &
White, issued February 26, 1991, at column 25, line 65 to
10 column 27, line 63. Penetration is measured in units of
millimeters/10 at 21~C.
Example I
This example produces a reduced fat, whipped peanut
butter product. The fluid, bimodal PSD product resulting
15 from this process is not dependent upon whipping. This
product is produced on a semi-continuous pilot-scale
process, with measures taken to ensure processing from
peanut roasting to finished product packaging does not
exceed 18 hours.
About 1000 lbs. of whole, medium runner type peanuts
are roasted in a fluidized-bed type roaster to a Hunter
L-color of about 42. This relatively dark color is
necessary to offset the increase in L-color associated
with whipping, especially finely dispersed whipped
25 products. The roasted nuts are then split and blanched,
sorted to remove remaining wholes and hearts, and color
sorted. The nuts are then ground into a paste using a 2-
stage grinding procedure, a Bauer mill followed by a
texturizer, to achieve a Hegman grind gauge of about 20.
30 The oil content of the roasted, ground paste is about
52%.
The roasted, ground peanut paste is then split
into two streams. About 700 lbs. of the peanut paste
is pressed in a Carver Model 12-22D hydraulic cocoa
35 butter press for 10 minutes at 5000 pSi, expelling
peanut oil from the paste. (A portion of this
expelled oil is later used without further process-
ing for formulation). After pressing, the
WO 92/20243 PCr/US92/038~7
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resulting peanut cake (about 350 lbs.) contains about 25~o
oil. These peanut solids are next Fitz milled to a
flour-like consistency. This product is passed three times
through a 5-roll Buhler mill fitted with 15.75 inch (39.3
cm) diameter rollers that are 900 mm wide. The rollers are
at 30-C temperature. The feed to the mill is at a rate that
the rolls always have nut solids on them. The rate is 2000
lbs/hour in the first pass and 3000 lbs/hour in subsequent
passes (this is a result of differences in solid bulk
density between the first and second pass). The
differential roll speeds are as in Table I. The rolls are
set at 0 gap, and a feed gap having a gauge pressure of 70
kg/cm2 and a top roll pressure of 33 and 27 kg/cm2. After
roll milling, at least 80% of the defatted peanut solids
have a particle size of less than 18 microns (i.e., they are
monodispersed).
Table I
Roll SDeed
Rev./Min. Ft./Min.
1 4 16
2 13 52
3 34 139
~ 58 239
82 338
The roll milled peanut solids are then processed
through a Readco type mixer configured for high shear, where
the solids flowrate through the mixer is about 400 lbs/hr
and the motor draws about 16 amps. Peanut paste, from the
stream which was not pressed to remove oil, is added at the
end of the Readco barrel at the ratio of 1.7:1
(paste:solids). The oil content of the exiting peanut paste
stream is about 42X, and the peanut paste has a particle
W O 92/20243 2 1 0 2 5 2 3 P~/US92/03887
-23-
size such that 65-80% of the solids have a particle size
less than 18 microns.
The paste and solids mixture is then processed through
a colloid mill to finish the viscosity reduction process.
This entails recirculating about 300 lbs. of the 42% fat
peanut paste through the colloid mill, a brine cooled heat
exchanger to remove the S0-70-F temperature rise, and back
into a stirred tank from which the colloid mill is fed. The
colloid mill gap is set such that the outlet temperature
does not exceed 155-F, and the motor load is kept at about
6.0 amps. The viscosity of the 42% oil paste is reduced
from a Casson plastic viscosity of about 8.0 to about 4.0 in
six passes through the colloid mill at a flow rate of
6.0-6.5 lbs/min. The paste has a SPAN of about 3-3.5.
lS The resulting low viscosity, 42X fat paste is used in
the following formulation. A 300 lb. batch of 42.5% fat
peanut butter is formulated in an 80 gal. Hamilton kettle
with the following composition:
(q2% fat) Peanut Paste 85.40%
Peanut Oil s.3s%
Sugar 6.00%
Salt 1.40%
Dry Molasses 0.50%
Stabilizer:
~PSP/PSS 0.80%
Hardstock
Emulsifier:
Lecithin 0.35%
Myverol 0.20%
~Prepared as in Example V of U.S. Patent 4,996,074.
The paste, salt, sugar, and dried molasses powder are
mixed and heated to about 140-F in the kettle before adding
the molten stabilizer/emulsifier/peanut oil mixture. The
mixture is then processed at about lS lbs/min through a
WO 92/20243 PCI /US92/038~7
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Gaulin dairy homogenizer at 3000 psig into a 100 gal.
Hamilton kettle. The product is then ready for processing
through the finishing system, where deaeration, hardstock
crystallization, and nitrogen incorporation and dispersion
take place before packaging.
The finishing system is continuously operated at a
flowrate of 7.8 lbs/min (468 lbs/hr). The product is first
deaerated through a versator under 20-25 inches (Hg) vacuum.
Nitrogen is injected following deaeration such that
15X/volume is measured by density difference. The nitrogen
line pressure is 250 psig, and the product line pressure is
140 psig. The product is then cooled from about 140-F to
about 85-F through three scraped surface heat exchangers
(freezers) in series, with -S-F brine countercurrent on the
shell side. Following the freezing step, the line pressure
is increased from 100 to 300 psig through a Northern pump.
The nitrogen gas is finally dispersed into the product by
relieving the pressure across a 3/4 in. gate valve, and
filled via a 2-stage filler into 18 oz. peanut butter jars.
The residence time between the pump and valve is less than
0.5 min. The product is capped and sealed under a nitrogen
headspace, and tempered at 80-F for 24 hours. The product
contains about 15% nitrogen by volume. The product has a
Casson plastic viscosity of about 4.0 and a yield value of
about 155. The nitrogen bubbles in the whipped product have
a size such that 90% are less than 300 microns.
ExamDle 2
The following example produces a low fat aerated peanut
butter product that is significantly improved in aerated
appearance relative to conventional aerated peanut butters,
especially relative to reduced fat aerated peanut butters
formulated without the given high PSS and PSP palm oil
fraction hardstock, and most especially relative to full fat
aerated peanut butters without the given hardstock.
~vo 92/20243 PCT/US92/03887
-25- ~1~2523
Specifically, peanuts are roasted, split, blanched, and
sorted in a similar fashion as in Example 1. Peanuts are
ground into a paste and pressed to remove oil as described
in Example 1. The resulting peanut solid flour has an oil
content of about 24~/..
In this example, we have improved whipped appearance by
increasing the hardstock stabilizer level in the product so
that the dispersed gas bubbles are more quickly and
effectively stabilized from coalescence (growth) after
dispersion. The PSP/PSS hardstock prepared as in Example V
of U.S. Patent 4,996,074 (Seiden ~ White) (I.V. <1.0) is
used. In addition, rapeseed hardstock (Iodine Value <10)
(prepared as described in Example VI of the above-mentioned
Seiden ~ White patent) is added to the palm hardstock at a
1~ ratio of 25:1 palm:rapeseed. Addition of the palm and
rapeseed hardstocks at the increased level greatly improves
the high temperature stability of the gas dispersion.
Without this addition, the dispersed gas bubbles will grow
in size as the product temperature is increased from ambient
to above 90-F. This high temperature stability is believed
to be enhanced by the relatively higher melt point of the
rapeseed hardstock.
Increasing the given hardstock level in the formula
must be in combination with a peanut paste viscosity
reduction if the finished product penetration is desired to
remain in the target range. Therefore, this example
presents the best case of minimizing the reduced fat peanut
butter viscosity and maximi ing the level of the given
hardstock such that the penetration remains in the target
range of 240-320 millimeters/10 at 21-C.
The viscosity of the defatted solids and oil paste is
reduced relative to that in Example 1 by three primary
process modifications. The first modification simply
eliminates the paste addition step at the exit of the Readco
mixer. The solids are combined with the extracted peanut
WO 92/20243 PCI'/US92/03~7
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2 3
oil to the desired fat level in the Hamilton kettle.
Colloid milling is not necessary for this product, as no
further reduction in viscosity is achieved beyond that
obtained by the roll mill and Readco mixing steps.
The viscosity of the peanut solids and oil-based peanut
butter is further reduced by increasing the number of five
roll mill passes from 3 to 5, and increasing the amperage
(related to work input) through the Readco mixer from 16 to
30 amps. The oil is not added at the Readco mixer exit,
helping increase the work imparted to the solids in this
step. The total flowrate of solids through the Readco mixer
is identical to Example 1. After these processing steps,
the peanut solids are mixed with oil to form a paste. The
paste has a Casson plastic viscosity of about 3.0 poise and
a yield value of about 50 dynes per square centimeter.
A further reduction in aerated appearance is achieved
by the following process improvements. Following nitrogen
injection and before dispersion, the incorporated gas phase
must be completely dissolved into the oil phase in the
peanut butter. This becomes increasingly difficult as
nitrogen level and product viscosity increase. Completely
dissolving the gas before dispersion ensures that bubble
formation occurs into the oil phase and not into another
bubble, which is the easier route. This is believed to be
partially responsible for uneven and relatively large bubble
sizes in previous products. In the present example, this
complete gas dissolution is achieved by providing enough
product residence time at elevated pressures before
dispersion. The exact conditions necessary to achieve this
must be determined for each product, as solubility kinetics
are largely determined by the product physical properties
and processing conditions.
For this example, no further benefit (as measured by
reductions in bubble size) is realized beyond increasing the
3~ residence time between the booster pump and dispersion valve
~VO 92/20243 2 1 0 2 5 2 3 PCI'/US92/03887
-27 -
(with pipe) from less than 0.5 minutes to about 2 minutes,
and increasing the pressure over this portion of the system
from 300 to 500 psig. A similar product is produced by
providing about 4 minutes of residence time after nitrogen
injection and before freezing instead of about 2 minutes
after the pressure boost and before dispersion.
We have discovered that dispersion valve design
improves the uniformity of gas bubble size in the bulk
product after dispersion. This is easily observed by an
improvement in color uniformity throughout the product. As
the mean dispersed bubble size is decreased in the product,
the product becomes noticeably light in color. Especially
for more finely dispersed products, any variation in bubble
size from one area of the product to another will result in
lS a streak or discoloration. Thus, it is advantageous to
optimize the uniformity of the dispersion throughout the
product.
Two means have been found to improve the uniformity of
dispersion, or reduce streaking or discoloration. The first
is to form a more uniform dispersion initially, and the
other is to average out these nonuniformities after
dispersion. Dispersion through a slotted orifice,
rectangular in design with an entrance width of about 0.05
inch, is found to provide the most uniform dispersion in
this example. The nitrogen is dispersed into the peanut
butter to make a whipped product, by providing a rapid
pressure drop through this slotted orifice from a pressure
of about 600 psig to a pressure of about 0 psig. Static
mixers, preferably 4 Koch type SMX elements placed in-line
after the dispersion valve, will effectively eliminate
streaking and discoloration in this example. The whipped
product contains about 15% by volume dispersed nitrogen,
dispersed as bubbles having a size such that 90% are less
than 100 microns in diameter.
W O 92/20243 PCT/USg2/03~Q7
-28-
21~2S2~
The peanut butter is formulated as described below in a
500 lb. total batch size, then .inished, packaged and
tempered as described in Example 1, while incorporating the
5 process and product modifications just described
hereinabove.
Formula:
Peanut solids 66.00%
Peanut oil 24.00%
Sugar 6.00X
Salt 1.40%
*PSP/PSS hardstock 2.50X
*Rapeseed hardstock 0.10~~.
* The PSP/PSS hardstock is prepared as in Example V
of U.S. Patent 4,996,074 (Seiden & ~hite) (I.V.
<1.0), and the rapeseed hardstock is fully
hydrogenated high behenic (45%) rapeseed oil
prepared as in Example VI (I.V. <10) of the same
patent.
The whipped peanut butter product has a penetration of about
300 millimeters/10 at 21-C. ~he product contains about 42%
oil .
3~
