Title of Invention

A METHOD FOR PREPARING A NON-CRYSTALLISABLE POLYOL SYRUP.

Abstract TITLE : A METHOD OF PREPARING ANON-CRYSTALLISABLE POLYOL SYRUP. The invention concerns a method for preparing a heat-stable and alkali-resistant, non-crystallizable polyol syrup, comprising a step which consists in hydrogenating a sugar syrup and a step which consists in caramelizing the hydrogenated sugar syrup. The invention is characterised in that the hydrogenated and caramelized sugar syrup is purified on ion-exchanging resins, said purification comprising at least a process which consists in passing it at least once on strong cationic resin at a temperature less than 50 °C and selected according to the desired reducing sugar proportion in the non-crystallizable polyol syrup. The invention also concerns the use of the resulting polyol syrup for preparing toothpaste. (FIG. - nil)
Full Text A METHOD OF PREPARING A NON-CRYSTALLISABLE POLYOL SYRUP
The invention relates to a new method of preparing a
non-crystallisable polyol syrup that is resistant to heat
and to alkalis.
To be more specific, it relates to a new method of
preparing a polyol syrup that can be used in the
production of soap or detergent, in the formulation of
pharmaceutical syrups or toothpaste, i.e. in any
application that requires, in an alkaline and/or hot
environment, resistance to the formation of colorations
that are undesirable or compounds that are unsuitable
from the taste point of view.
By polyols are meant the products obtained by
catalytic hydrogenation of simple reducing sugars,
complex reducing sugars such as disaccharides, oligo-
saccharides and polysaccharides, and mixtures thereof,
which will be referred to hereinafter as "sugar syrup".
As a general rule, the simple reducing sugars
intended for catalytic hydrogenation in accordance with
the invention are glucose, xylose, fructose and mannose.
The polyols obtained are then sorbitol, xylitol and
mannitol.
The disaccharides are most often maltose,
isomaltulose, maltulose, isomaltose and lactose, which on
catalytic hydrogenation yield maltitol, isomalt,
isomaltitol and lactitol.
In the context of the present invention, non-
crystallisable composition means mixtures of polyols that
form non-crystallisable syrups at 20°C with a dry
materials proportion of 70% when stored in a hermetically
sealed container for one month. The non-crystallisable
sorbitol in the context of the invention is defined in
the European Pharmacopoeia, 1997, paragraph 0437.
Sorbitol syrups are widely used in the agriculture-

foodstuffs, pharmaceutical and chemical fields. In the
formulation of toothpaste, and in particular in the
production of sodium bicarbonate toothpaste, the use of
sorbitol syrups as humectants is possible only if they
are stable in the presence of sodium bicarbonate and do
not cause any brown coloration during storage. This
coloration is caused by reaction of the bicarbonate on
the reducing sugars: glucose, maltose, oligo-saccharides
and polysaccharides. The intensity of the coloration
increases with the number of units of the polysaccharide,
and a molecule of maltose therefore causes more
coloration than a molecule of dextrose. Coloration is
also strongly accelerated by the temperature to which the
syrup is exposed. It has been noted that the same
intensity of coloration is obtained after storage for 10
days at 45°C and after storage for 15 months at 20°C. It
is preferable for these syrups to be non-crystallisable
to facilitate handling and transporting them, regardless
of the climatic conditions, and to assure that finished
products prepared from such syrups are stable.
Maltitol syrups also represent a large class and are
mainly used in preparing non-cariogenic pharmaceutical
and food products.
Although more costly, xylitol syrups are being
widely used because of their high sweetening power, their
dental properties and their excellent humectant
characteristics.
It is known that the coloration of a polyol syrup in
the presence of alkalis is related to the presence of
reducing free sugars: glucose, maltose, oligo-saccharides
and polysaccharides.
Improving the stability of such syrups therefore
entails eliminating these free sugars.
Various approaches have already been investigated on
a laboratory scale.

Japanese patent JP 51.86406 offers the prospect of
improving the purity of crystallisable sorbitol syrups by
reducing crystallised glucose under alkaline conditions
maintained throughout the reduction reaction, in order to
obtain very pure sorbitol containing little non-reduced
sugar.
However, the above technique is of no practical
benefit on an industrial scale because it requires a
costly feed, monitoring and control system and the
constant addition of buffer and alkaline solution during
the reaction represents a penalty in terms of the
subsequent purification step. The method is also
relatively highly polluting because of the large
quantities of reactants used. Furthermore, there is no
reference to the stability of the sorbitol syrups
obtained by said method.
Japanese patent JP 41.12212 mentions a method of
preparing sorbitol of maximum purity resistant to heat
and to alkalis which entails reduction by adding hydrogen
at high pressure and either adjusting the pH of the
solution to a value from 8 to 10 just before the
reduction reaction is completed or heating the reduced
sorbitol solution, whose pH has previously been adjusted
to a value from 8 to 10 by means of an alkali, to a
temperature from 60°C to 90°C, followed, after
decomposition of the residual directly reducing sugars,
by separation by filtration, with or without
neutralisation by means of an acid and with or without
decoloration over charcoal, followed by purification over
ion-exchange resin.
The above method, which is applied to a
crystallisable sorbitol solution, gives rise to
considerable formation of impurities because the reducing
sugars are subjected to a relatively long processing
duration, of the order of five hours, and does not impart

sufficient stability.
Japanese patents JP 63.79844 and JP 71.45090
describe a method of preparing polyols resistant to heat
and to alkalis which entails treating for one to two
hours in a hot alkaline medium an aqueous solution of
polyols purified a first time by treatment with carbon
black and then over ion-exchange resin, and then
purifying again the solution obtained at 50°C, by passage
over ion-exchange resin. The above method is intended in
particular for crystallisable sorbitol syrups obtained
from very pure glucose syrups. Crystallisable syrups of
this kind are not suitable for use in particular in
toothpaste because of their many drawbacks. Also, the
above method is particularly complex because of the
multiple operations it involves, and is therefore
difficult to apply on an industrial scale.
Patent EP 0 711 743, of which the applicant is the
patentee, describes polyol compositions which are highly
chemically stable in an alkaline medium and have a very
low reactivity.
These compositions, which are particularly suitable
for use in a basic medium necessitating absence of
coloration, are obtained by catalytic hydrogenation of
simple or complex reducing sugars and then stabilising
the syrup and purifying the stabilised syrup.
The stabilisation step entails submitting the
sorbitol syrups obtained by hydrogenation to oxidation,
caramelisation or fermentation, so as to obtain syrups
exhibiting an optical density in an S test of less than
or equal to 0.100.
The applicant has shown that satisfactory stability
can be obtained only at low values in the above test,
which reflects the susceptibility of the compositions to
coloration in an alkaline medium.
Aiming to improve further the performance of a

method of the above kind, and with a view to limiting
mineral and organic waste, in order to protect the
environment, the applicant has, after lengthy research,
developed a new method which yields non-crystallisable
polyol syrups that are sufficiently stable in an alkaline
medium and, by limiting purification operations, offers a
high yield and reduced pollution, which prior art
techniques cannot provide.
Thus the applicant has found that, to obtain non-
crystallisable polyol syrups that are resistant to heat
and to alkalis, it is necessary to submit a sugar syrup
that has undergone a hydrogenation and caramelisation
step to a step of purification over at least one strong
cationic resin at a temperature below 50°C, said
temperature being chosen as a function of the desired
proportion of reducing sugars in the final composition.
The invention therefore provides a new method of
preparing a non-crystallisable polyol syrup, resistant to
heat and alkaline media, including a step of
hydrogenating a sugar syrup and a step of caramelising
the hydrogenated sugar syrup, characterised in that the
hydrogenated and caramelised sugar syrup undergoes
purification over ion exchange resins, said purification
including at least one passage over strong cationic resin
at a temperature less than 50°C, said temperature being
chosen as a function of the desired proportion of
reducing sugars in the non-crystallisable polyol syrup.
Considerable research by the applicant has shown the
importance of the working temperature on maintaining the
quality of the product during purification over a strong
cationic resin. The quality of the composition after
purification and in particular its final proportion of
reducing sugars is inversely proportional to the
temperature at which it is passed over the strong
cationic resin.

Purification over strong cationic resin in
accordance with the invention is therefore carried out at
a temperature below 50°C, chosen as a function of the
desired proportion of reducing sugars in the final
composition after purification. The applicant has found
that the temperature during passage over the resin can be
adjusted as a function of the proportion of reducing
sugars obtained after caramelisation and of the desired
final proportion of reducing sugars in the purified
polyol syrup. The required proportion varies as a
function of the intended applications of the syrup. For
preparing toothpaste, in addition to the nature of the
alkaline agent present in the paste, it is necessary in
particular to take into account the nature of the
colouring agents used to determine the acceptable limit
for resistance to coloration by the polyol syrup. Slight
yellow coloration is more readily acceptable for blue
pastes. The flavours used are also a factor to be taken
into account when determining the acceptable limit on the
proportion of reducing sugars. Thus for some bicarbonate
pastes, the acceptable limit is 3 50 parts per million of
reducing sugars (expressed as dextrose equivalents and
hereinafter abbreviated to ppm), and for others, such as
those containing pyrophosphates, proportions of up to
500 ppm may suit. This is equally applicable to other
pharmaceutical, cosmetic and food applications.
Under optimum conditions for hydrogenating and then
caramelising a non-crystallisable polyol syrup, minimum
reducing sugar proportions of the order of 50 ppm to 100
ppm are obtained. The applicant has found that under
these conditions the maximum temperature at which a syrup
of this kind can be purified over strong cationic resin
is 50°C if, allowing for the increased proportion of
reducing sugars in the resins, a final value less than or
equal to 500 ppm of reducing sugars is to be obtained,

regarded as being the acceptable maximum limit. Below
50°C, the temperature during passage over the resin can
therefore be adjusted as a function of the required
proportion of reducing sugars in the final composition
and of the proportion of reducing sugars initially
present after caramelisation, as explained more fully
later. Accordingly, passage over strong cationic resin
can advantageously be adjusted to a temperature of less
than or equal to 40°C, preferably less than or equal to
30°C and even more preferably from 20°C to 30°C if a very
low proportion of reducing sugars is desired in the
polyol composition according to the invention.
The purification as such is effected using standard
techniques, i.e. first passing over strong cationic
resin, then strong anionic resin, and then passage over a
mixed bed which is an equal parts mixture of the two
resins. It is also possible to modify the order in which
the resins are combined.
The aim of the strong cationic resin is to eliminate
cations, in particular sodium coining from the sodium
carbonate used in caramelisation, and the soluble nickel
coming from the hydrogenation catalyst.
The object of the strong anionic resin is to
eliminate organic anions such as gluconate in particular,
which is a degradation product from the caramelisation
step.
The use of a mixed bed in the final step optimises
purification by palliating any leaks of ions that might
have occurred in preceding steps.
The preferred cation exchange resin is a strong
cationic resin carrying a sulphonic type functional group
SO3H used in strong acid form, for example the IR 200 C
resin from ROHM and HAAS. The preferred anionic resin is
a strong anionic resin such as the IRA 910 resin from the
same manufacturer. The mixed bed consists of a mixture of

the two resins.
In one advantageous embodiment of the method
according to the invention, to prevent excessively long
residence times in the resin, with the attendant risk of
encouraging deterioration of the purified polyol syrup,
the purification over resins is effected at a flowrate
corresponding to 1.5 times the volume of the resin column
through which the syrup passes per hour.
In another advantageous embodiment of the method
according to the invention, caramelisation is conducted
in the hydrogenation reactor, under hydrogen and without
separating the catalyst, by introducing an alkaline agent
at the end of the hydrogenation reaction, at a time when
the pH is likely to be stable after adding the alkaline
agent, and without using a buffer.
Considerable research by the applicant has shown
that the hydrogenation step can advantageously be
combined with caramelisation in the same reactor, without
adding buffer, so as to obtain a polyol composition that
is stable in a hot alkaline medium from sugar syrup in a
manner which is economical and also not very polluting
after purification.
In the context of the present invention,
caramelisation means alkaline degradation of the reducing
sugars of the hydrogenate, leading to the formation of
corresponding enols. Alkaline agents suitable for
caramelisation include strong or weak bases. In a
preferred embodiment, the alkaline agent used for
caramelisation is sodium carbonate.
The sugar syrups subjected to the method according
to the invention can include in particular glucose
syrups, fructose syrups, glucose syrups rich in maltose
and xylose syrups.
The sugar syrup advantageously contains 60% to 95%
dextrose, 0.1% to 20% maltose, the remainder to 100%

consisting of polysaccharides and oligo-saccharides, the
above percentages being percentages by weight relative to
the dry weight of the saccharides contained in said
syrup.
The catalytic hydrogenation is carried out in a
manner known in the art, in a twin-jacket reactor, over
Raney nickel catalysts, although any other sugar
hydrogenation catalyst may be suitable.
It is preferably carried out at a hydrogen pressure
from 3 0 bars to 100 bars and at a temperature from 120°C
to 150°C, and even more preferably at a temperature from
130°C to 150°C, in order to optimise the rate of
hydrogenation whilst limiting secondary reactions.
Sodium carbonate is introduced into the reactor to
obtain a pH from 9 to 11, and preferably from 9.5 to 11,
at a time when the pH is sufficiently stable to require
no buffer solution nor addition of a massive quantity of
sodium carbonate to maintain the pH at that value. This
is generally achieved after 90 minutes of hydrogenation
under the conditions in accordance with the invention.
This criterion for introducing the sodium carbonate
results from studies of hydrogenation kinetics and
caramelisation conditions. If the reaction medium is
still rich in free reducing sugars, introducing the
alkaline agent destabilises the pH, which is
significantly reduced because of the conversion of the
free reducing sugars into corresponding acids.
Accordingly, beyond a reducing sugars proportion of
approximately 0.4%, too much acid is formed and the pH
therefore falls, rendering ineffective the stabilising
action of the caramelisation and entailing the addition
of too much sodium carbonate. It is therefore preferable
to introduce the alkaline agent when the proportion of
residual reducing sugars is less than 0.2%, and more
preferably less than or equal to 0.1%.

When the pH in the reactor is less than 9, the
caramelisation is insufficient. When it is greater than
11, the caramelisation is satisfactory but the ionic
charge of the hydrogenate becomes too high, which leads
to a consequential rejection of chlorides when
regenerating the cation exchange resins. The applicant
has found that, at a pH from 9.5 to 11, the excess sodium
carbonate in the reaction medium is sufficient to achieve
complete caramelisation of the sugars.
The method according to the invention produces
polyol syrups that are particularly suitable for use in
the preparation of basic pH products such as toothpastes
based on sodium bicarbonate or the family of sodium
phosphates, anti-acid compositions, shaving foams or
depilatory creams, or for the production of products at
high temperatures, whilst achieving a previously
unequalled return on investment, and a minimum level of
organic and mineral wastes.
In one advantageous embodiment of the method
according to the invention, the syrup obtained is a non-
crystallisable sorbitol syrup.
The non-crystallisable sorbitol syrup obtained
preferably contains at least 64 wt.% of sorbitol, at
least 6 wt.% of maltitol, the remainder to 100%
consisting of oligo-saccharides and polysaccharides, the
above percentages being expressed relative to the dry
weight of polyols present in the composition.
The syrup that can be obtained by the method
according to the invention can therefore be used with
advantage in preparing basic pH products containing
alkaline agents or treated or obtained at a high
temperature.
The invention also provides a toothpaste composition
containing the polyol syrup that can be obtained by the
method according to the invention.

The invention is illustrated by the following non-
limiting examples.
Example 1
A sugar syrup with the composition given below was
introduced with stirring into a 20-litre twin-jacket
reactor containing Raney nickel in suspension:
- dextrose: 75%/dry
- maltose: 8%/dry
- maltotriose: 3.6%/dry
- higher DP: 13.4%/dry
The dry material of the reaction medium was 40 wt.%
and the Raney nickel proportion was 5 wt.%, in both cases
relative to the dry weight.
Hydrogenation was carried out for 90 minutes at a
pressure of 50 bars and a temperature of 140°C.
A 3 wt.% solution of sodium carbonate was introduced
for 15 minutes so as to obtain a hydrogenate pH of 10.8.
The pH was found to be stable and the proportion of
reducing sugars was found to be less than 0.4 wt.%.
Hydrogenation was continued for 20 minutes.
Then the stirring of the reactor was stopped, the
contents allowed to settle for 15 minutes, and the
supernatant liquor drained into a settling tank to
recover the catalyst. The supernatant liquor from the
settling tank was then filtered to eliminate the final
traces of catalyst.
The syrup obtained in the above manner was cooled to
25°C and then purified over strong cationic resin, then
over anionic resin and finally over the mixed bed.
The syrup obtained was then subjected to a test for
its resistance to alkaline agents. The test, referred to
as the S test, is described in patent EP 0 711 743, of
which the applicant is the patentee. The lower the value
obtained in the S test (optical density less than 0.1),
the more stable the polyol composition.

500 mg of ultrapure sodium hydrogen carbonate and
250 mg of a 20% aqueous solution of ammonia were added to
5 ml of syrup.
The result was mixed and heated in a water bath
without stirring at 100°C for two hours.
The solution was cooled to 20°C and its optical
density measured at a wavelength of 42 0 nm using a
spectrophotometer such as the PERKIN-ELMER Lambda 5
UV/VIS spectrophotometer.
A calibration range was produced in the same manner
by substituting for the 5 ml of syrup, 3 ml of pure water
and 2 ml of anhydrous pure glucose solutions with
concentrations of 100, 200, 300, 400, 500, 600 and
1000 ppm.
The respective absorbencies of the above glucose
solutions were 0.04, 0.08, 0.120, 0.160, 0.205, 0.250,
0.413.
The syrup obtained in accordance with the present
invention had a relatively low optical density of 0.04.
This was equivalent to a glucose proportion of 100
ppm/dry, which indicates very high resistance to alkalis.
The method according to the invention therefore
produces a non-crystallisable polyol composition that is
highly resistant to alkaline and/or hot media in a more
economical and less polluting way than the prior art
techniques.
Example 2: Influence of temperature on purification
by means of ion exchange resins
The syrup obtained in example 1 before purification
was divided into seven fractions.
The fractions were purified over strong cationic
resin at respective temperatures of 20, 30, 35, 40, 45,
50, 52 and 60°C (fractions A to H), then over anionic
resin and finally over the mixed bed.
An S test was performed on each fraction after

purification and for each point the difference was
computed compared to the original test (delta S test).
The results are given in ppm dextrose equivalent.

The results show clearly the influence of the
working temperature on purification over strong cationic
resin. This shows that it is possible to adapt the
temperature of the composition during purification
according to the reducing sugar requirements necessitated
by the intended end use, which confers unheard of
flexibility on the method according to the invention.
Example 3: Formulation of a sodium bicarbonate
toothpaste
A sodium bicarbonate toothpaste with the following
formula was produced using products A and F from example
2 (purified over resins at 20°C and at 50°C):


The toothpastes A and B obtained had respective pH
of 8.4 and 8.7 in 10% solution.
After storage for six months at room temperature,
because of the satisfactory purity of product A, the
colour of paste A had not changed.
However, paste B was an unacceptable yellowish
colour after the same storage time.
Example 4: Formulation of anti-tartar toothpastes
with sodium pyrophosphate
An anti-tartar toothpaste with the following formula
was produced using sodium pyrophosphate as the anti-
tartar agent and product D from example 2 (purified on
strong cationic resin at 40°C):


The final pH of the toothpaste was 7.8 as such and
8.6 after dilution to 10%.
The colour of the toothpaste had not changed after
storage of six months at room temperature.
Syrup D from example 2 is therefore entirely
suitable for use in a toothpaste in the presence of anti-
tartar agent.

WE CLAIM:
1. Process for preparing a noncrystallizable polyol syrup stable to heat
and to alkaline medium, using a stop of hydrogonation of a sugar syrup
and a stop of caramelization of the hydrogenated sugar syrup,
characterized in that the hydrogenated and caramelized sugar syrup is
subjected to purification on ion-exchange resins, the said purification
comprising at least one passage over a strong cationic rosin at a
temperature of loss than 30oC, the said temperature boing chosen
according to the level of reducing sugars desired in the
noncrystalizable polyol syrup.
2. Process according to Claim 1, characterized in that the caramelization
treatment is performed in the hydrogenation reactor, under hydrogen
and without separation of the catalyst, by introducing sodium hydroxide
at the and of the hydrogenation reaction.
3. Process according to either of Claims 1 and 2, characterized in that the
caramelization step consists in bringing the pH of the hydrogenated
syrup to a value of between 9 and 11, preferably of between 9.5 and
11, whan this pH is likely to be stable.

4. Process according to any one of Claims 1 to 3, characterized in that
the purification stop is performed on a strong cationic resin at a
temperature of loss than 30oC, and than on an anionic resin and
finally on a mixed bed.
5. Process according to any one of Claims 1 to 4, characterized in that
the temperature for passing over a strong cationic resin is between 20
and less than 30oC.
6. Process according to any one of claims 1 to 5, characterized in that the
polyol syrup is a noncrystallizable sorbitol syrup.
7. Process according to Claim 6, characterized in that the
noncrystallizable sorbitol syrup has a sorbitol content of at least 64%
by weight, the oligo-and polysaccharide content constituting the
balance for 100%, these percentages being expressed relative to the
dry matter content of the polyois present in the composition.
The invention relates to a method of
preparing a non-crystallisable polyol syrup, resistant to
heat and alkaline media, including a step of
hydrogenating a sugar syrup and a step of caramelising
the hydrogenated sugar syrup, characterised in that the
hydrogenated and caramelised sugar syrup undergoes
purification over ion exchange resins, said purification
including at least one passage over strong cationic
resins at a temperature less than 50°C, said temperature
being chosen as a function of the desired proportion of
reducing sugars in the non-crystallisable polyol syrup.
It also relates to the use of the polyol syrup obtained
in the preparation of toothpaste.

Documents:

in-pct-2001-00651-kol-abstract.pdf

in-pct-2001-00651-kol-claims.pdf

in-pct-2001-00651-kol-correspondence.pdf

in-pct-2001-00651-kol-description (complete).pdf

in-pct-2001-00651-kol-form 1.pdf

in-pct-2001-00651-kol-form 18.pdf

in-pct-2001-00651-kol-form 2.pdf

in-pct-2001-00651-kol-form 3.pdf

in-pct-2001-00651-kol-form 5.pdf

in-pct-2001-00651-kol-letter patent.pdf

in-pct-2001-00651-kol-pa.pdf

in-pct-2001-00651-kol-reply f.e.r.pdf

in-pct-2001-00651-kol-translated copy of priority document.pdf

IN-PCT-2001-651-KOL-CORRESPONDENCE 1.1.pdf

IN-PCT-2001-651-KOL-FORM 27.pdf

IN-PCT-2001-651-KOL-FORM-27.pdf

IN-PCT-2001-651-KOL-PA.pdf


Patent Number 216902
Indian Patent Application Number IN/PCT/2001/651/KOL
PG Journal Number 12/2008
Publication Date 21-Mar-2008
Grant Date 19-Mar-2008
Date of Filing 21-Jun-2001
Name of Patentee ROQUETTE FRERES
Applicant Address 62136 LESTREM FRANCE, A FRENCH COMPANY.
Inventors:
# Inventor's Name Inventor's Address
1 SALOME JEAN-PAUL 70 ROUTE D'ESTAIRES 59232 VIEUX-SERQUIN, FRANCE.
2 FEREZ PATRICK 149 RUE DES MIOCHES 62136 LESTREM, FRANCE.
3 LEFEVRE PHILIPPE 3600, RUE DE MERVILLE 59660 HAVERSKERQUE, FRANCE.
PCT International Classification Number C07C 29/76,29/88,
PCT International Application Number PCT/FR00/02963
PCT International Filing date 2000-10-25
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 99/13492 1999-10-28 France