Microfibrillated cellulose and method for preparing a microfibrillated cellulose

A microfibrillated cellulose containing at least around 80% of primary walls and loaded with carboxylic acids, and a method for preparing same, in particular from sugar beet pulp, wherein the pulp is hydrolysed at a moderate temperature of 60-100.degree. C.; at least one extraction of the cellulose material is performed using a base having a concentration of less than 9 wt. %; and the cellulose residue is homogenised by mixing, grinding or any high mechanical shear processing, whereafter the cell suspension is fed through a small-diameter aperture, and the suspension is subjected to a pressure drop of at least 20 MPa and high-speed sheer action followed by a high-speed deceleration impact. The cellulose is remarkable in that a suspension thereof can easily be recreated after it has been dehydrated.

BACKGROUND OF THE INVENTION 
The present invention concerns a novel parenchymal cellulose and a process 
for its production. More particularly, the present invention concerns a 
novel microfibrillated cellulose and a process for its production from 
primary wall plant pulp, particularly from sugar beet pulp after 
extraction of saccharose. 
Cellulose is a substance of great industrial importance which has numerous 
applications, including: 
alimentary applications as a thickener to stabilize dispersions, emulsions 
and suspensions, for low calorie food products, low fat or low cholesterol 
food products, etc; 
industrial applications, in paints, paper, textiles, agriculture, 
cosmetics, etc; 
pharmaceutical applications, such as an excipient for medication, a 
precipitation control agent, ointment or cream support, intestinal 
transport agent, etc. 
Until now, all known celluloses have had disadvantages. 
WO 93/11182 from Weyerhaeuser describes a bacterial cellulose with a 
reticulated structure. Apart from being very expensive, such a bacterial 
cellulose can cause contamination problems in alimentary applications. 
FR-A-2 472 628 from ITT INDUSTRIES describes a microfibrillated cellulose 
essentially constituted by secondary walls obtained from wood pulp. Such a 
cellulose cannot easily be taken up into suspension once dehydrated. this 
causes considerable storage and transport problems due to the fact that 
the suspensions have a maximum cellulose content of about 4%. 
In attempting to overcome that disadvantage, EP-A-0 120 471 from ITT 
INDUSTRIES describes a redispersable dried secondary wall (since it is 
obtained from wood pulp) microfibrillated cellulose which is characterized 
by the presence of an additive which prevents the formation of hydrogen 
bonds between the cellulose fibrils. The quantity of additive is 
considerable (at least 50% by weight with respect to the cellulose, and 
preferably at least the same quantity thereof). The additive is, for 
example, a polyhydroxylated compound such as a sugar containing 5 to 6 
carbon atoms or a glycol, a borate or an alkaline phosphate, an aprotic 
solvent, an amine or a quaternary ammonium compound. Apart from the fact 
that the designation "cellulose" is improperly assigned to a product which 
is at most half cellulose, this "cellulose" is costly and is not suitable 
for all applications. Further, without the addition of additives this 
cellulose can only recover from 2% to a maximum of 20% of its initial 
viscosity after drying. Maintaining the viscosity requires the presence of 
an additive in an amount by weight which is substantially the same as that 
of the cellulose. 
EP-A-0 102 829 from Weibel describes a process for simultaneously isolating 
the cellulosic and hemicellulosic constituents of sugar beet pulp. 
However, as with FR-A-2 472 628 cited above, once dehydrated, the 
parenchymal cellulose obtained cannot readily be taken up again into 
suspension, causing the same storage and transport problems. 
Further, the economic exploitation of plant residues, in particular sugar 
beet pulp, is of great industrial importance. 
One aim of the present invention is to provide a microfibrillated cellulose 
which can be taken up into suspension after dehydration without adding an 
additive. 
Another aim of the invention is to provide a microfibrillated cellulose 
which regains almost all of its initial viscosity after drying, without 
adding an additive. 
A further aim of the invention is to provide a process for the production 
of cellulose by economic exploitation of primary wall plant residues, in 
particular sugar beet pulp. 
The present invention achieves all these three aims. 
Further aims and advantages of the invention will become apparent from the 
description below. 
THE INVENTION 
In general, native cellulose is always in a microfibrillate form, these 
microfibrils being associated to a greater or lesser degree to form 
fibers, walls and membranes. Each cellulosic microfibril is constituted by 
a rigorous assembly of parallel cellulose chains resulting from the method 
by which the cellulose is biosynthesized. Cellulose microfibrils are 
generally considered to contain only a few faults along their axis. Their 
mechanical properties are close to the theoretical mechanical properties 
of cellulose: a tenacity in the order of 130 GPa and a fracture toughness 
in the order of 13 GPa. Cellulosic microfibrils are thus of interest if 
they can be dissociated and reformed. 
Cellulose microfibrils are usually associated to a high degree in walls or 
fibers. The microfibrils in secondary walls are organized into highly 
oriented layers which form a fiber which cannot be dissociated; the 
microfibrils in primary walls are deposited in a disorganized fashion. The 
parenchyma is a typical example of primary wall tissue. While it is 
difficult, if not impossible, to separate secondary wall cellulose 
microfibrils without damaging them, it is easy to dissociate primary wall 
microfibrils, not only because of their looser organization but also 
because interstitial polysaccharides, which are usually charged, 
constitute a large percentage of these walls. 
Examples of parenchyma are sugar beet pulp, citrus fruits (lemons, oranges, 
grapefruit) and the majority of fruits and vegetables. An example of 
secondary wall plant matter is wood. 
The microfibrils of primary walls can be unravelled using a mechanical 
shear operation which would break the fibers of secondary walls to produce 
microfibrils. In other words, microfibrils can only be obtained from 
secondary walls by breaking the original fibers. 
Primary wall cellulose is thus a material with great potential. 
The present invention will be illustrated with reference to sugar beet 
pulp. 
Sugar beet pulp is principally constituted by parenchyma and thus by 
primary wall cells. 
The composition by weight of solid sugar beet pulp can vary depending on 
the origin of the pulp and the cultivation conditions. In general, the 
pulp contains: 
15% to 30% cellulose; 
12% to 30% pectins; 
12% to 30% hemicelluloses; 
2% to 6% proteins; 
2% to 6% mineral materials; 
2% to 6% lignin, tannins, polyphenols and ferulic ester. 
The treatment of sugar beet pulp to isolate cellulose from parenchymatic 
cells has already been proposed. EP-A-0 102 829 cited above concerns such 
a process and describes: 
suspending the sugar beet pulp in an acidic (pH&lt;4.5) or basic (pH&gt;10.0) 
aqueous medium; 
heating the suspension to a temperature of more than 125.degree. C. (0.5 
MPa); 
keeping the suspension at a temperature of more than 125.degree. C. for a 
period of between 15 seconds and 360 seconds; 
subjecting the heated suspension to mechanical shearing in a tube reactor 
followed by rapid depressurization through small orifices into a zone 
which is at atmospheric pressure; 
filtering the suspension and recovering the insoluble fraction which 
contains the parenchyma cellulose and the soluble fraction (filtrate) 
which contains the hemicelluloses; 
treating the cellulose fraction by bleaching with sodium hypochlorite and 
mechanical defibrlllation to produce a parenchyma cellulose paste 
constituted by cell wall fragments. 
As mentioned above, once dehydrated, the cellulose obtained using the 
process of EP-A-0 102 829 cannot easily be taken up into suspension. 
The present invention provides a process for the production of 
microfibrillated cellulose from primary wall plant pulp, in particular 
sugar beet pulp after saccharose extraction, comprising the following 
steps: 
(a) acid or basic hydrolysis of the pulp partially to extract the pectins 
and hemicelluloses; 
(b) recovering a solid residue from the suspension from step (a); 
(c) carrying out, under alkaline conditions, a second extraction of the 
residue of cellulosic material from step (b), this step being obligatory 
if step (a) is acidic and optional if step (a) is basic; 
(d) if necessary, recovering the cellulosic material residue by separating 
the suspension from step (c); 
(e) washing the residue from step (b) or step (d); 
(f) optionally, bleaching the cellulosic material from step (e); 
(g) recovering the cellulosic material by separating the suspension from 
step (f); 
(h) diluting the cellulosic material from step (g) in water to obtain 
between 2% and 10% of dry matter; 
(i) homogenizing the cell suspension from step (h); characterized in that 
(j) step (a) is carried out at a temperature between about 60.degree. C. 
and 100.degree. C., preferably between about 70.degree. C. and 95.degree. 
C., more preferably at about 90.degree. C.; 
(jj) at least one alkaline extraction step (a) and/or (c) is carried out on 
the cellulosic material, salid alkaline extraction being carried out with 
a base, preferably selected from caustic soda and potash, the 
concentration thereof being less than about 9% by weight, preferably 
between about 1% and 6% by weight; 
(jjj) homogenizing step (i) is carried out by mixing or grinding or any 
high mechanical shear operation followed by passing the cell suspension 
through a small diameter orifice and subjecting the suspension to a 
pressure drop of at least 20 MPa and to a high velocity shearing action 
followed by a high velocity decelerating impact. 
Conditions (j), (jj) and (jjj) are novel. It will be shown below that they 
can produce a novel primary wall cellulose with unique structural, 
morphological, chemical and rheological properties. 
In step (a), the term "pulp" means moist, dehydrated, silo stored or 
partially depectinized pulp. 
Extraction step (a) can be carried out in an acidic medium or in a basic 
medium. 
For acidic extraction, the pulp is suspended in water for several minutes 
to homogenize the acidified suspension at a pH which is between 1 and 3, 
preferably between 1.5 and 2.5, with a concentrated solution of an acid 
such as hydrochloric acid or sulfuric acid. 
For basic extraction, the pulp is added to an alkaline solution of a base, 
for example caustic soda or potash, with a concentration of less than 9% 
by weight, preferably less than 6% by weight, more particularly between 1% 
and 2% by weight. A small amount of a water-soluble anti-oxidizing agent 
such as sodium sulfite Na.sub.2 SO.sub.3 can be added to limit cellulose 
oxidization reactions. 
In accordance with the invention, step (a) is carried out at a "moderate" 
temperature, between about 60.degree. C. and 100.degree. C., preferably 
between about 70.degree. C. and 95.degree. C., more preferably at about 
90.degree. C. This is in contrast to the very high temperatures 
(&gt;125.degree. C.) used in the prior art. The duration of step (a) is 
between about 1 hour and about 4 hours. During step (a) of the invention, 
partial hydrolysis occurs with liberation and solubilization of the 
pectins and hemicelluloses while conserving the molecular weight of the 
cellulose. 
In step (b), the solid residue is recovered from the suspension from step 
(a). 
When the first extraction (a) is acid hydrolysis, the second extraction 
step (c) is obligatory and is carried out under basic conditions. When the 
first extraction step (a) is basic hydrolysis, the second extraction step 
(c) is optional. 
Thus, if necessary, the cellulosic material residue from step (b) undergoes 
a second extraction step in step (c). This latter step is an alkaline 
extraction step. 
Thus the process of the present invention always includes at least one 
alkaline extraction step. 
In accordance with the present invention, each alkaline extraction 
step--namely the alkaline extraction step of optional step (c) and/or the 
extraction of step (a), if it is basic--must be carried out with a base, 
said base preferably being selected from caustic soda and potash, the 
concentration thereof being less than about 9% by weight, preferably 
between about 1% and about 6% by weight. 
The applicant has shown that carrying out each alkaline extraction step 
employing the conditions of the process of the invention avoids the 
irreversible transformation: 
cellulose I.fwdarw.cellulose II 
This transformation would destroy the microfibrillar structure necessary 
for the specific properties of the product of the invention. 
The duration of each alkaline extraction step is between about 1 hour and 
about 4 hours, preferably about 2 hours. 
In step (d), the solid residue is recovered from optional step (c). 
In step (e), the residue from step (b) or step (d) is washed with copious 
quantities of water to recover the cellulosic material residue. 
In accordance with the invention, a certain percentage of the non 
cellulosic acidic polysaccharides (pectins, hemicelluloses) is retained at 
the surface of the cellulose microfibrils, having the effect of preventing 
them from associating with each other. This percentage of acidic 
polysaccharides is in general less than about 30% by weight, preferably 
less than 5% by weight. Too high a quantity of acidic polysaccharides 
would necessitate homogenization periods which were too long, but in 
accordance with the invention, this percentage must be greater than 0%. 
The cellulosic material of step (e) is then optionally bleached in step 
(f), for example with sodium chlorite, sodium hypochlorite, 5-20% dry 
matter hydrogen peroxide, etc, in a manner that is known in itself. 
Different concentrations can be used at temperatures between about 
18.degree. C. and 80.degree. C., preferably between about 50.degree. C. 
and 70.degree. C. The duration of step (f) is between about 1 hour and 
about 4 hours, preferably between about 1 hour and about 2 hours. A 
cellulosic material containing between 85% and 95% by weight of cellulose 
is obtained in this way. 
In step (h), the suspension from step (e), optionally bleached in step (f), 
is diluted again in water to 2% to 10% dry matter, then sent to step (i) 
which, in accordance with the invention, is carried out by mixing or 
grinding using any high mechanical shear operation, followed by passing 
the cell suspension through a small diameter orifice, subjecting the 
suspension to a pressure drop of at least 20 MPa and to a high velocity 
shearing action followed by a high velocity decelerating impact. 
Mixing or grinding is, for example, carried out by passage through a mixer 
or grinder for a period of several minutes to about one hour, in an 
apparatus such as a WARING blender provided with a four blade screw, or a 
mixing mill or any other type of grinder such as a colloidal mill, under 
the following conditions: the concentration of dry cellulose material is 
in the range 2% to 10% by weight. During mixing or grinding, the 
suspension heats up. The receptacle is preferably provided with a system 
of deflecting ribs by means of which the liquid is moved back towards the 
blades of the screw at the center of the receptacle. 
Homogenization proper is advantageously carried out in a MANTON GAULIN type 
homogenizer in which the suspension is subjected to a high velocity and 
high pressure shearing action in a narrow passage and against an impact 
ring. The homogenization conditions are as follows: after mixing or 
grinding, the concentration of dry pulp in the suspension is in the range 
2% to 10% by weight. The suspension is preferably introduced into the 
homogenizer after preheating to a temperature between 40.degree. C. and 
120.degree. C., preferably between 85.degree. C. and 95.degree. C. The 
temperature of the homogenization operation is kept between 95.degree. C. 
and 120.degree. C., preferably above 100.degree. C. In the homogenizer, 
the suspension is subjected to pressures which are between 20 MPa and 100 
MPa, preferably more than 50 MPa. 
The cellulose suspension is homogenized in between 1 and 20, preferably 
between 2 and 5, passes until a stable suspension is obtained. 
It should be noted that homogenization in the context of the present 
invention has a function which is different to that in the ITT INDUSTRIES 
patents cited above, namely FR-A-2 472 628 and EP-A-0 120 471. In the 
process of the present invention, the function of the homogenization step 
is to unravel the microfibrils without breaking them, while in the ITT 
INDUSTRIES patents mentioned above, the function of the same step is to 
break the secondary wall fibers to obtain microfibrils. 
The homogenization operation of step (i) is advantageously followed by a 
high mechanical shear operation, for example in an ULTRA TURRAX apparatus 
from SYLVERSON. 
We have established that the treatment is more effective at higher dry 
matter concentrations in the suspension to be homogenized and at higher 
homogenization temperatures. This means that as the cellulose 
concentration increases, the number of passes required decreases. However, 
the viscosity of the suspension during treatment, which depends directly 
on the concentration of the treated suspension, is a limiting factor. In 
fact, the apparatus is not designed to operate with suspensions which are 
too viscous. 
The applicant has established that special valves exist for cell grinding 
with which the number of passes can be reduced. Further, the number of 
passes will be reduced if water-soluble dispersing agents, suspending 
agents or thickening agents such as carboxymethylcellulose, cellulosic 
ethers, gelling polysaccharides (guar, carouba, alginates, carrageenans, 
xanthane and derivatives thereof) are added to the suspension to be 
homogenized. 
Sugar beet pulp contains 4% to 6% of mineral compounds which are insoluble 
in water. 
Soil residues and fairly large (&gt;1 mm) pieces of grit are among the mineral 
compounds present in sugar beet pulp. The applicant has discovered calcium 
oxalate monohydrate and silica crystals in these insoluble mineral 
compounds. Calcium oxalate monohydrate is found inside the cells which are 
generally localized in the wood-and bast bundles near the vessels. The 
calcium oxalate crystals are contained in certain cells and constitute a 
form of calcium storage in the plant. The nature, quantities and 
proportions of these minerals can vary with the soil in which the plant is 
cultivated, the sugar beet variety, the climate during growth, etc. 
The presence of calcium oxalate crystals causes a problem during 
homogenization as they are highly abrasive and it is preferable to 
eliminate them or at least to reduce their quantities substantially. 
Elimination can be carried out by treatment in an acidic medium, for 
example hydrochloric acid, e.g. acid extraction as could be carried out in 
step (a) (if that step is carried out under acidic conditions, of course), 
which transforms the calcium oxalate monohydrate into oxalic acid and 
calcium chloride, which are soluble in water. 
Calcium oxalate can also be eliminated by mechanical blending and 
screening. The applicant has established that the concentration of 
residual minerals can be reduced by blending and screening the dehydrated 
pulp before step (a) and retaining only the fraction with a granulometry 
which is between about 20 .mu.m and 1,000 .mu.m, preferably between 75 
.mu.m and about 600 .mu.m. 
When the cellulosic residue contains a non-negligible quantity of free 
calcium oxalate crystals or calcium oxalate crystals which are inside the 
cells after basic extraction or after bleaching, moderate grinding can be 
carried out wet, for example in a WARING blender type mixer or any other 
grinder, to rupture the cells, followed by filtering or screening through 
a suitable screen. The screen mesh can readily be determined by the 
skilled person, for example between 20 .mu.m and 75 .mu.m, e.g. a 75, 60, 
40 or 20 .mu.m mesh, depending on the extent of mixing or grinding, i.e. 
depending on the size of the cell fragments obtained and industrial 
feasibility. 
A further means of eliminating the calcium oxalate problem is to carry out 
an oxidation treatment, for example with ozone or hydrogen peroxide, 
associated with a bleaching treatment in step (f). 
In order to eliminate the calcium oxalate crystals, bleaching step (f) can 
also be carried out using ozone or hydrogen peroxide. 
Any of the means of eliminating or at least reducing the quantity of 
calcium oxalate crystals can be combined with each other or used 
separately, as can readily be determined by the skilled person in each 
particular case. 
The microfibrillated cellulose obtained using the process of the present 
invention is cellulose I. 
It is characterized in that it contains at least about 80%, more generally 
at least about 85%, of primary walls, and in that it is charged with 
carboxylic acids. The term "carboxylic acids" means simple carboxylic 
acids, their polymers and their salts. These carboxylic acids are 
generally uronic acids, such as galacturonic acid and glucuronic acid. 
The microfibrillated cellulose of the present invention is remarkable in 
that it can be taken up into suspension after dehydration. 
The microfibrillated cellulose of the invention is 15% to 50% crystalline. 
It is constituted by microfibrils with a cross-section between about 2 nm 
and about 4 nm. 
The microfibrillated cellulose of the present invention forms stable 
suspensions, of the liquid crystal type, constituted by nematic domains. 
The microfibrillated cellulose of the present invention has a group of 
beneficial properties: 
unique Theological properties such that stable suspensions can be produced 
at pHs in the range 2 to 12 and in a temperature range of 0.degree. C. to 
100.degree. C. at a minimum concentration of 0.2% and with the appearance 
of a gel at concentrations of more than 1%. 
The cellulose of the present invention behaves as a weak gel at 1% DM (dry 
matter) in water. Upon studying the oscillation viscoelastic behavior of 
the product in oscillation, it was found that G' and G" were stable in the 
frequency range and that G'=5G", G' being the elastic component of the 
system and G" being the viscous component. It should be noted that 
xanthane, for example, does not behave as a gel. The viscosity of the 
cellulose of the present invention at 20.degree. C. is much higher than 
that of xanthane at 20.degree. C. and equivalent to that of xanthane at 
80-90.degree. C. 
Regarding viscosity, at 2% in water, the cellulose of the present invention 
has a shear rate of 1.8 s.sup.-1 at a viscosity equivalent to high 
viscosity CMC at an identical concentration (.apprxeq.20 000 mPa.s) . The 
cellulose of the present invention has a viscosity which is much higher 
than that of xanthane (.apprxeq.7,000 mPa.s). A mixture of 1.8% of the 
cellulose of the present invention and 0.2% of CMC in water has beneficial 
rheological properties as the solution reaches viscosities of more than 
25,000 mPa.s. 
The cellulose of the present invention is a rheofluidifying and thixotropic 
substance. 
unique physical and chemical properties in that the cellulose is mainly 
constituted by cellulose associated with a residual amount of pectins or 
hemicelluloses which procure particular physical and chemical properties. 
The cellulose of the invention is constituted by microfibrils of the 
native or cellulose I type which are separated out to a greater or lesser 
degree. 
very high chemical reactivity, very large accessible surface area; 
excellent water retentive capacity; 
high suspending capacity; 
thickening capacity. 
Produced by the above process, the cellulose of the invention can be 
concentrated, preferably to about 50% of dry matter, by precipitation, for 
example from an alcohol such as ethanol, isopropanol or any other similar 
alcohol, by a freeze-thaw process, by a pressing operation by passage 
through a filter press (which cannot be used with other hydrocolloids such 
as xanthane, CMC, etc), by filtering, by dehydration, by dialysis against 
a hygroscopic solution with a molecular size which is larger than the pore 
size of the membrane used or by using any other process known to the 
skilled person for concentrating such suspensions. 
The cellulose, either directly from the process of the invention or after a 
concentration step, can be high or low energy dried by evaporation, 
dehydration, low temperature drying under controlled humidity, spray 
drying, drum drying, freeze drying or critical point drying, or by any 
other process which can -obtain the product in its secondary state. Low 
temperature drying conditions under controlled humidity are particularly 
advantageous in this respect as they are gentle and energy costs are 
lower. 
In contrast to the ITT INDUSTRIES patent EP 120 471, where the 
microfibrillated structure, without addition of additives, can only 
recover 2% to a maximum of 20% of its initial viscosity after drying (page 
4, lines 38-42), the cellulose of the present invention recovers almost 
all of its initial viscosity after drying without adding any additives. 
The cellulose of the present invention also has beneficial film-forming and 
strengthening properties. 
When a suspension of microfibrils of the invention is applied to a surface, 
for example a metal, glass, ceramic, etc surface, and allowed to dry, the 
microfibrils form a film on the surface. 
The cellulose of the present invention, spread in a thin layer, forms a 
film on dehydrating. The properties of the film are determined by 
measuring the corrected Young's modulus (Ecor), which gives the stiffness 
of the system. For example, Ecor=2,500 to 3,000 MPa at 25% humidity. 
Wet paper sheets can also be treated during manufacture by a suspension of 
the cellulose of the invention, thus improving their physical properties, 
in particular their tensile strength. 
In the non-alimentary field, there are many potential applications of the 
cellulose of the present invention: 
for paints, it constituted a good thickening agent in the aqueous phase, 
and can replace hydroxy-propyl-celluloses, for example; 
its film-forming and strengthening properties can be used in latex for 
paints, paper, adhesive coatings, etc. 
Incorporating 1% to 15% of microfibrillated cellulose into latex (and other 
hydrosoluble products) or thermoplastic compounds or cellulose acetates 
after transforming the surface considerably improves the modulus of 
elasticity and tensile strength. 
as a thickening agent which can be used in drilling muds. 
In the cosmetics and paramedical fields, the microfibrillated cellulose of 
the present invention constitutes a thickening agent competitive with 
Carbopol or other thickening agents used in these fields. This product has 
the advantage of being less sticky than the others, considerably improving 
the rinse properties of the products and giving it a more agreeable feel. 
In the papermaking industry, the following can be cited: 
using the strengthening properties of microfibrillated cellulose by 
introducing it into the paper pulp; 
combined use of the thickening, strengthening and film-forming properties 
of microfibrillated cellulose to coat certain special papers. The 
cellulose also has beneficial barrier properties. 
The cellulose of the invention can also be deposited on the surface of 
paper to improve its opacity and uniformity. 
The cellulose of the invention can be applied alone or with other compounds 
such as pigments and fillers which are normally used in the papermaking 
industry. 
The strengthening properties of the cellulose would, for example, be 
employed by introducing it into the paper pulp. 
In the alimentary field: 
microfibrillated cellulose can stabilize emulsions, act as an aroma 
support, a gelling agent and especially as a thickening agent; 
it can replace or act in synergy with other thickening agents already used 
in this field, such as xanthane, CMCs, or microcrystalline celluloses. 
Synergistic use is particularly important from the economic point of view. 
It means that far less product can be used to achieve the same effect. 
Examples of applications for microfibrillated cellulose in the alimentary 
field are fat substitutes, stabilization of mayonnaise, salad dressings, 
and in general all emulsions, ice creams, whipped creams, thickening 
agents for all types of beverages spreadable pastes, batters or leavened 
dough, milk desserts, meat products, etc. 
For the same rheological effect, the cellulose of the present invention is 
much cheaper than xanthane and bacterial cellulose.

DESCRIPTION OF THE EMBODIMENTS 
EXAMPLE 1 
Purification of Sugar Beet Pulp 
Dehydrated pulp of sugar beet harvested from the Nassandres region of 
France was taken up into suspension in deionized water. For better 
hydration, a WARING blender type mixer provided with a four blade screw 
was used, and intermittent mixing was carried out for 45 minutes. The 
suspension was acidified to a pH of 2 by adding a solution of H.sub.2 
SO.sub.4. This suspension was kept at room temperature (25.degree. C.) for 
15 minutes then heated to 80.degree. C. for 2 hours with constant 
mechanical stirring. The suspension was filtered through a metal screen 
and washed with copious quantities of water. The solid residue after 
washing was extracted with an alkaline solution. It was taken up into 
suspension in a caustic soda solution with a concentration adapted to 
produce a final caustic soda concentration of 2% by weight and a dry 
matter percentage of 2.5% by weight, both with respect to the total 
liquid. About 0.1% by weight of sodium bisulfite (Na.sub.2 SO.sub.3) with 
respect to the total liquid was added. The suspension was heated to 
80.degree. C. for 2 hours with constant mechanical stirring. After this 
treatment, it was filtered through a 0.6 mm sieve. The solid residue was 
washed with water until a neutral filtrate was obtained. 
After washing, the solid residue was taken up into a 2.5% suspension in a 
3.4 g/l sodium chlorite solution (NaClO.sub.2), buffered to a pH of 4.9 
with a mixture of caustic soda and acetic acid. The suspension was heated 
to 70.degree. C. for 3 hours with constant mechanical stirring. It was 
then filtered through a stainless steel screen and then rinsed with water 
until a colorless filtrate was obtained. A pale gray cellulosic residue 
with 3% to 5% by weight dry matter was obtained by filtering under reduced 
pressure using a Buchner funnel. 
The neutral sugar composition of the solid residue was determined by 
chemical analysis based on gas chromatographic characterization of the 
alditzl acetates obtained after acid hydrolysis of the polysaccharides, 
reduction and acetylation of the sugar monomers. The alditol acetates were 
identified using GC and the sugars were measured using myoinositol as an 
internal reference, allowing for the specific response factors of each of 
the alditols. The chromatograph was a HEWLETT-KARD 5890 with a flame 
ionization detector connected to a HEWLETT-KARD 3395 integrator. An SP 
2380 (0.53 mm.times.25 m) column was used with U nitrogen as the carrier 
gas. 
The alditol acetates were eluted with retention times which were 
characteristic of the column. Studies were carried out to determine the 
response factor for each alditol acetate. Knowing the area and the 
quantity of starting inositol, then using the surface area of the peaks 
for each alditol acetate, the quantity of corresponding oses could be 
deduced and the percentages by weight of each neutral sugar monomer 
obtained with respect to the total mass of neutral sugars in the sample 
could be calculated. The glucose derived almost entirely from hydrolysis 
of the cellulose; the percentage of glucose thus gave an indication of the 
purity of the cellulose in the sample. The other neutral sugars were 
principally xylose, galactose, mannose, arabinose and rhamnose and 
provided an estimation of the quantities of residual pectins and 
hemicelluloses. 
Chemical analysis of the resulting cellulose residue indicated 85% glucose. 
EXAMPLE 2 
Purification of Sugar Beet Pulp 
The entire series of treatments of Example 1 was repeated, adding a second 
treatment with sodium chlorite identical to the first treatment after the 
sodium chlorite treatment and corresponding rinse steps. This produced a 
whitish cellulosic residue with a neutral sugar chemical composition which 
varied little during the second bleaching step. Chemical analysis 
indicated 86% glucose in the resulting cellulose residue. 
EXAMPLE 3 
Purification of Sugar Beet Pulp 
Dehydrated pulp was taken up into suspension in deionized water and then 
acid hydrolyzed using the method described in Example 1. It was filtered 
and washed with water to eliminate the dissolved pectins and 
hemicelluloses. The solid residue was then extracted with an alkaline 
solution using the method described in Example 1. This alkaline treatment 
was carried out a second time. The solid residue was washed with water 
until a neutral filtrate was obtained before carrying out two successive 
bleaching steps using sodium chlorite and the method described in Example 
1. Chemical analysis indicated 89% glucose. 
Examples 1, 2 and 3 show that the larger the number of extraction steps, 
the purer the cellulose in the residue. 
EXAMPLE 4 
Purification of Sugar Beet Pulp 
The entire series of treatments of Example 1 was repeated, substituting the 
sulfuric acid solution with a hydrochloric acid solution to bring the pH 
of the suspension to 2. 
The cellulosic residue contained 90% glucose, similar to that obtained in 
Example 3. 
EXAMPLE 5 
Purification of Sugar Beet Pulp 
Dehydrated pulp was taken up into suspension in deionized water. For better 
hydration, a WARING blender type mixer provided with a four blade screw 
was used, and intermittent mixing was carried out for 45 minutes. The 
suspension was rendered alkaline by addition of a caustic soda solution 
with a concentration adapted to obtain a final concentration of 2% by 
weight of caustic soda and a dry matter percentage of 2.5% by weight, both 
with respect to the total liquid. About 0.1% by weight of sodium bisulfite 
(Na.sub.2 SO.sub.3) with respect to the total liquid was added. The 
suspension was heated to 80.degree. C. for 2 hours with constant 
mechanical stirring. After this treatment, it was filtered through a 0.6 
mm screen. The solid residue was washed with water until a neutral 
filtrate was obtained. This alkaline treatment was carried out a second 
time. The solid residue was washed with water until a neutral filtrate was 
obtained before carrying out two successive bleaching steps using sodium 
chlorite and the method described in Example 1. 
Chemical analysis indicated 87% glucose. 
EXAMPLE 6 
Purification of Sugar Beet Pulp 
The entire series of treatments of Example 5 was carried out, using three 
successive alkaline treatments with caustic soda with a concentration 
adapted to produce a final caustic soda concentration of 2% by weight in 
place of the two treatments of Example 5. The solid residue was washed 
with water until a neutral filtrate was obtained before carrying out two 
successive bleaching steps with sodium chlorite using the method described 
in Example 1. 
Chemical analysis indicated 92% glucose. 
EXAMPLE 7 
Purification of Sugar Beet Pulp 
The entire series of treatments of Example 5 was repeated, replacing the 
two alkaline treatments with caustic soda with two successive treatments 
with a potash solution with a concentration adapted to produce a final 
potash concentration of 2% by weight. The solid residue was washed with 
water until a neutral filtrate was obtained before carrying out two 
successive bleaching steps with sodium chlorite using the method described 
in Example 1. Using potash, cellulosic residues were obtained which had a 
purity similar to that obtained with caustic soda. 
EXAMPLE 8 
Influence of Caustic Soda Concentration 
Dehydrated pulp was taken up into suspension in deionized water by mixing 
in identical fashion to that described in Example 1. The suspension 
obtained was heated under reflux for 20 minutes then filtered through a 
0.6 mm screen. The solid residue was then taken up into suspension in a 
caustic soda solution with a concentration adapted to produce a final 
caustic soda concentration of 2% or 8% by weight and a dry matter content 
of 2.5% by weight, both with respect to the total liquid. This suspension 
was magnetically stirred for three hours at 20.degree. C. After this 
treatment, it was filtered through a 0.6 mm. screen and washed with water 
until a neutral filtrate was obtained. 
After extraction, the percentages of glucose obtained for treatment with 2% 
or 8% caustic soda were as shown in Table I: 
TABLE I 
______________________________________ 
Effect of caustic soda concentration on cellulose 
residue purity 
Caustic soda concentration 
% glucose 
by weight molar by weight 
______________________________________ 
2% 0.5M 48 
8% 2M 58 
______________________________________ 
It can thus be seen that during the first alkaline extraction step, the use 
of more concentrated caustic soda results in higher purity cellulose. 
EXAMPLE 9 
Influence of Caustic Soda Concentration 
Dehydrated pulp was treated as in Example 6. The purified cellulosic 
residue produced a 4% paste after filtering under reduced pressure using a 
Buchner funnel which was simultaneously treated in similar fashion in 
eight separate experiments. 50 ml of a 2%, 7%, 9%, 9.5%, 10%, 12%, 14% and 
17% by weight caustic soda solution was added to 0.6 grams of this sample. 
Treatment was carried out at a temperature T=20.degree. C. with constant 
magnetic stirring for 2 hours. After neutralizing with hydrochloric acid 
and dialysis of these suspensions against distilled water, the residue was 
oven dried at 50.degree. C. in small receptacles to obtain thin films of 
cellulosic residues for each experiment. 
In other experiments, a drop of suspension after dialysis was deposited on 
an electron microscope grid and then dried before examination. 
X-ray studies showed that films resulting from cellulose treated with 2% to 
9% by weight caustic soda diffracted in identical fashion to that of the 
starting cellulose. These were identified as cellulose I (interferences at 
0.54 nm, 0.4 nm and 0.258 nm) with a degree of crystallinity in the order 
of 35%. In contrast, for cellulose films treated with caustic soda at 
concentrations of 9.5% and above, a spectrum was obtained which was 
characteristic of cellulose II. It was characterized in particular by 
interferences at 0.7 nm, 0.44 nm, 0.4 nm and 0.258 nm. 
Electron microscopic examination established that the samples which had 
been treated with 2% to 9% caustic soda were in the form of entwined 
smooth cellulose microfibrils which could slide against each other (FIG. 
2). In contrast, after treatment with caustic soda at 9.5% and above, the 
sample had agglomerated into microgel grains constituted by elements which 
had become welded together (FIG. 3). This transformed cellulose no longer 
had the characteristic properties of the cellulose of the invention. 
In order to conserve the particular properties of the cellulose of the 
invention, the crystalline structure of the native cellulose must be 
preserved; thus if a caustic soda solution is used during the alkaline 
extraction step, a concentration of 9% must not be exceeded. 
EXAMPLE 10 
Elimination of Mineral Material 
Before rehydration, the dried pulp was ground for ten minutes in a mixing 
mill provided with a 1 mm screen. Screening through 600 .mu.m and 75 .mu.m 
sieves at the mill outlet recovered one particle fraction with a size of 
less then 75 .mu.m and a very large fraction between 75 .mu.m and 600 
.mu.m. After calcining for 8 hours at 560.degree. C., the ash mass was 
compared with the initial mass of the sample. This produced the amount of 
ash for each fraction: between 75 .mu.m and 600 .mu.m. a fraction 
comprising 5% of mineral material was isolated while below 75 .mu.m a 
fraction comprising 12% of mineral material was isolated. 
Thus grinding followed by screening produced a fraction which was depleted 
in mineral material. 
EXAMPLE 11 
Elimination of Mineral Material 
The residues from the purification steps described in Examples 1 to 7 were 
mixed in a WARING blender at very high speed for three minutes after the 
bleaching step and then filtered through a 25 .mu.m sieve. The 
effectiveness of such a treatment can be observed through an optical 
microscope as calcium oxalate crystals have the property of being 
birefringent when observed under polarized light. Before treatment, 
numerous crystals were observed between the cells on the bottom of the 
observation plate as well as crystals inside certain cells. After 
treatment, no more crystals could be seen between the cells on the bottom 
of the plates. 
This example shows that the crystals can be eliminated, depending on the 
amount of mixing and washing through a screen of suitable porosity. 
EXAMPLE 12 
Effect of Homogenization 
The suspensions from the treatments described in Examples 1 to 7 were 
suspensions of purified cells principally constituted by cellulose. 
Microscopic observation showed that cells were separated to a greater or 
lesser degree. These suspensions were passed through a GAULIN homogenizer 
at 40 MPa fifteen consecutive times at a concentration of 2% after 
preheating for one hour at 60.degree. C. The temperature increased rapidly 
to 80.degree. C. to 100.degree. C. 
In the homogenizer, the purified suspension was pushed into a pipe by a 
piston at high velocity then passed through a small diameter orifice in 
which the suspension was subjected to a large pressure drop and then 
thrown against an impact ring. Combining these two phenomena (pressure 
drop and decelerating impact) produced a shearing action and separation of 
the cellulose micrcfibrils. By passing the suspension through the orifice 
several times, a stable suspension of separated cellulose microfibrils was 
obtained. This was clear from optical or electron microscope observations. 
FIG. 4 clearly shows the entwined structure of the cellulose microfibrils 
constituting the primary wall of the parenchyma cells of the sugar beet. 
In FIG. 5, cellulose microfibrils which are separated from each other to a 
greater or lesser degree can be seen. This separating effect was a direct 
consequence of the homogenization treatment in the Gaulin homogenizer. 
The treated samples were suspensions of separate microfibrils and had the 
appearance of a gel. 
The cellulose obtained had at least 90% primary walls. 
Its crystallinity, observed by X-rays, was 33%. 
Electron microscope observation indicated that the average cross-section of 
the microfibrils was 2 to 4 nm; they were more than 7 .mu.m long and could 
be 15-20 .mu.m long. 
EXAMPLE 13 
Effect of Homogenization (Time) 
Sugar beet pulp was treated as described in Example 3, then mixed in a 
WARING blender for three minutes at high velocity, and then separated into 
three portions. The first portion was kept as it was, the second was 
passed 6 times through a GAULIN homogenizer at 50 MPa, and the third was 
subjected to 10 passes at 50 MPa. FIG. 6 shows the separate microfibrils 
after 10 passes through a GAULIN homogenizer. 
These suspensions were studied with a CARRI-MED CSL50 rheometer with a 
right cone geometry. The yield point corresponded to the minimum stress 
applied to obtain a viscosity value directly related to the gel strength. 
The suspension obtained was also characterized by the viscosity at a shear 
rate of 57.6 s.sup.-1. The results obtained for the three suspensions 
studied at a concentration of 1% are shown in Table II. 
TABLE II 
______________________________________ 
Rheological characteristics of suspensions 
at yield 
Number of .eta. (MPa .multidot. s) 
Sample passes .sigma..sub.0 (Pa) 
at 57.6 s.sup.-1 
______________________________________ 
1 0 1.4 16 
2 6 4.3 186 
3 10 7.6 328 
______________________________________ 
It is clear that the effect of homogenization, due to separation of the 
cellulose microfibrils, caused considerable improvement of the rheological 
characteristics. The characteristics of the microfibrils were similar to 
those of Example 12, apart from the percentage of primary walls being 90%. 
EXAMPLE 14 
Stability of Suspensions 
An important characteristic of the suspensions obtained in Example 12 was 
their ability to form stable suspensions. 
Such suspensions treated in accordance with Example 12 were stored for 
several months at concentrations of 0.1% to 7% without ever producing a 
settling volume less than 95%. 
EXAMPLE 15 
Stability of Suspensions 
A suspension of cellulose microfibrils treated in accordance with Example 
12 was treated with a solution of 0.1 M trifluoroacetic acid for 2 hours 
at 20.degree. C. 
Analysis of the neutral sugars using the corresponding alditol acetates 
gave a cellulose percentage of 95%. The suspension obtained was not 
stable. 
Trifluoroacetic acid causes preferential hydrolysis of pectins and 
hemicelluloses. A loss of stability was thus observed in correlation with 
hydrolysis of the pectins and hemicelluloses. 
This example clearly shows that the stability of these suspensions is due 
to the presence of pectins and hemicelluloses bonded to the cellulose 
microfibrils. 
EXAMPLE 16 
Take up into Suspension 
A sample prepared in accordance with Example 12 was oven dried in a flat 
bottomed polyethylene receptacle. After 12 hours at 100.degree. C., a film 
of dry cellulose was obtained. This film (0.2 g) was soaked in 10 ml of 
water at room temperature (25.degree. C.) and gently rubbed with a glass 
rod. After 30 minutes, a thick paste was obtained. Diluting this paste 
with water produced a suspension of cellulose microfibrils with identical 
properties to those of the starting suspension. 
EXAMPLE 17 
Take up into Suspension 
A sample prepared in accordance with Example 12 was oven dried in a flat 
bottomed polyethylene receptacle. After 12 hours at 100.degree. C., films 
of dry cellulose were obtained. These films were cut into strips and 
placed in a WARING blender with deionized water. After 15 minutes 
agitation, these strips had disintegrated to produce a suspension of 
cellulose microfibrils with analogous properties to those of the starting 
suspension. 
EXAMPLE 18 (comiparative) 
Take up into Suspension 
Samples prepared in accordance with Example 12 were oven dried at 
60.degree. C. for 12 hours. Films of cellulose were obtained which were 
treated with trifluoroacetic acid as in Example 15. The treated films were 
then taken into suspension in water. 
These samples were difficult to disperse and did not recover the initial 
properties of the cellulose. 
This example demonstrates that an uncharged cellulose (which is outside the 
scope of the present invention) cannot in practice be taken up into 
suspension after dehydration without significant deterioration of its 
rheological properties. 
EXAMPLE 19 
Reactivity 
The cellulose of the invention, prepared in accordance with Example 12, was 
incubated with an enzymatic mixture of Trichoderma reesei CL-847. 810 mg 
of the cellulose of the invention was taken up into suspension in 30 ml of 
distilled water in a conical flask. Stirring produced a homogeneous 
suspension of cellulose microfibrils which was equilibrated at 50.degree. 
C. for 15 minutes. The enzymatic solution was prepared by dissolving 31.10 
mg of enzyme (corresponding to 25 FPU/g of cellulose) in 15 ml of sodium 
citrate buffer with a pH of 4.8. The solution was added to the reaction 
medium which was incubated at 50.degree. C. with horizontal agitation at 
50 oscillations per minute. After 4 hours, 8 hours and 24 hours of 
reaction, 3 ml of the homogeneous reaction medium was removed (so as not 
to alter the concentration) and heated under reflux at 100.degree. C. for 
20 minutes in a conical flask to denature the enzymes and thus stop the 
enzymatic reactions. It was centrifuged for 10 minutes at 10,000 g and 
then filtered through a microporous cellulosic membrane with a 0.45 .mu.m 
pore size. Analysis was carried out using HPLC and glucose and cellobiose 
standards. It was seen that the cellulose of the invention was rapidly 
hydrolyzed by the enzymatic mixture to give 0.45 mg of reducing sugars 
(glucose and cellobiose) per mg of starting cellulose after 4 hours of 
hydrolysis, 0.58 mg per mg of starting cellulose after 8 hours of 
hydrolysis and 0.85 mg per mg of starting cellulose after 24 hours of 
hydrolysis. 
EXAMPLE 20 
Optimization of Process for Production of Microfibrillated Cecellulose from 
Sugar Beet Pulp on Industrial Pilot Plant 
Dehydrated sugar beet pulp was taken into suspension in a caustic soda 
solution with a concentration between 1.5% and 2% by weight with respect 
to the total liquid. 
The quantity of water required was such that the liquid/solid weight ratio 
was about 15 (1 kg of pulp in 15 kg of water). 
Taking into suspension was carried out in a tank with agitation. The 
resulting suspension was heated to 80.degree. C. for 2 hours. 
The solid fraction of the suspension was then separated from the liquid 
fraction by passage through a centrifugal dryer with a mesh size of less 
than 250 .mu.m. The cake was rinsed during centrifuging. 
The recovered cake was taken up into suspension in a new 1.5% caustic soda 
solution in a liquid/solid (DM) ratio which was identical to the above. 
Again, the resulting suspension was heated to 80.degree. C. for 2 hours, 
with agitation. 
Drying was carried out again, this time using a finer mesh (25-100 .mu.m), 
and the cake was rinsed with water. 
The cellulose cake was then taken up into suspension in a 3.5 g/l sodium 
chlorite solution with the pH adjusted to 4-5 using 33% HCl . The 
liquid/solid (DM) ratio of this suspension was again about 15. 
The bleached cellulose was then recovered by centrifuging with a 10-30 
.mu.m mesh. 
The cake was rinsed and centrifuged until a clear filtrate was obtained. 
The cellulose obtained was then diluted again in water to produce a dry 
matter content between 3% and 4%. The suspension was then passed into a 
FRYMA mixing mill to rupture the cell walls and "prehomogenize" the 
product. 
The ground cellulose was then homogenized in an APV GAULIN homogenizer at a 
pressure between 450 bars and 550 bars. The product was preheated to a 
temperature of more than 95.degree. C. so that the product was boiling as 
it passed through the orifice. The aim of this was to cause cavitation. 
The product underwent 3 to 10 passes depending on the desired degree of 
homogenization. 
The cellulose was then concentrated to a dry matter content of more than 
35% by passage through a LAROX or CHOQUENET type filter press. 
EXAMPLE 21 
Comparative Viscosity of Suspensions Before and After Drying 
Cellulose was prepared as in Example 20. 
Samples N.sup.o 1 and N.sup.o 2 were prepared as follows. 
The cellulose was pressed to 40% dry matter then dried to 60% (sample 
N.sup.o 1) and to 85% (sample N.sup.o 2). 
The two samples were then dried in a conditioning chamber at 20.degree. C. 
and 50% relative humidity and were then ground for 30 seconds in a coffee 
grinder before being taken up into suspension (2% dry matter) using the 
ULTRA TURRAX for 2 minutes. 
The control was 2% dry matter cellulose homogenized using the ULTRA TURRAX 
for 2 minutes. 
The viscosities of samples N.sup.o 1 and N.sup.o 2 and the control were 
measured after standing for 4 hours (due to the thixotropic nature of the 
cellulose) using a HAAKE VT 500 viscosimeter, an apparatus for measuring 
MV.sub.II, with a shear rate of 1.8 s.sup.-1. 
The following results were obtained: 
Viscosity of control: 25 Pa.s 
Viscosity of sample N.sup.o 1: 25 Pa.s 
Viscosity of sample N.sup.o 2: 22 Pa.s 
Thus the cellulose of the invention when dried to 60% dry matter recovered 
100% of its viscosity and when dried to 85% dry matter recovered 90% of 
its viscosity. 
The cellulose of the present invention is thus distinguished from the 
cellulose of ITT INDUSTRIES patent EP 120 471 which only recovers a 
maximum of 2% to 20% of its initial viscosity without additives and 
requires the addition of at least 100% by weight with respect to the 
cellulose of an additive to recover almost all of its initial viscosity. 
EXAMPLE 22 
Extraction of Potato Pulp Cellulose (after extraction of starch) 
Purification of potato pulp 
Potato pulp, from which starch had been extracted, was taken up into 
suspension in deionized water. For better hydration, a WARING blender type 
mixer provided with a four blade screw was used, and intermittent mixing 
was carried out for 45 minutes. The suspension was rendered alkaline by 
addition of a caustic soda solution with a concentration adapted to obtain 
a final concentration of 2% by weight caustic soda and 2.5% dry matter by 
weight, both with respect to the total liquid. The suspension was heated 
to 80.degree. C. for 2 hours with constant mechanical stirring. After this 
treatment, it was filtered through a 0.6 mm screen. The solid residue was 
washed with water until a neutral filtrate was obtained. This alkaline 
treatment was carried out a second time. The solid residue was washed with 
water until a neutral filtrate was obtained. 
After washing, the solid residue was taken up into a 2.5% suspension in a 
3.4 g/l sodium chlorite (NaClO.sub.2) solution, buffered to a pH of 4.9 by 
a mixture of caustic soda and acetic acid. This solution was heated to 
70.degree. C. for 3 hours with constant mechanical stirring. The 
suspension was then filtered through a stainless steel screen and then 
rinsed with water to produce a colorless filtrate. A cellulosic residue 
with 3% to 5% by weight dry matter was obtained by filtering under reduced 
pressure using a BUCHNER funnel. 
Chemical analysis of the resulting cellulosic residue indicated 93% of 
glucose. The average degree of viscosimetric polymerization was in the 
order of 1,000. 
Homogenization 
Homogenization was carried out as described in Example 12. 
Stability of suspensions 
Suspensions of microfibrils from potato pulp obtained using the above 
protocol were stable. 
Viscosity of suspensions 
For a 0.3% dry matter suspension: 
Brookfield: 250 MPa 
30 rpm, needle n.sup.o 2 
EXAMPLE 23 
Extraction of Carrot Cellulose 
1 kg of 10% DM carrots (i.e. 100 g of dry matter) was grated. The grated 
carrot was taken up into suspension in a caustic soda solution to obtain a 
mixture of 100 g of dry matter in 2 liters of 2% caustic soda solution. 
The suspension was heated to 90.degree. C. for 2 hours with mechanical 
stirring. After this treatment, liquid/solid separation was carried out by 
centrifuging. The solid residue was rinsed. It was then taken up into 
suspension in a 1.5% caustic soda solution with a liquid/solid ratio of 
15. 
The mixture was centrifuged again and the solid residue was recovered and 
rinsed. 
After homogenization as described in Example 12, a suspension was obtained 
which was stable in water and had the appearance of a gel. 
While the process of the present invention has been described and 
illustrated with reference to sugar beet, potato and carrot pulp, it can 
also be applied to the treatment of any parenchyma, for example any citrus 
fruits (lemons, grapefruit, oranges) and most other fruits and vegetables.