CA1339214C

CA1339214C - Crystalline lactitol monohydrate and a process for the preparation thereof, use thereof and sweetening agent

Info

Publication number: CA1339214C
Application number: CA000608902A
Authority: CA
Inventors: Heikki Olavi Heikkila; Juha Veikko Nurmi
Original assignee: Xyrofin Oy
Current assignee: Xyrofin Oy
Priority date: 1988-12-01
Filing date: 1989-08-21
Publication date: 1997-08-05
Anticipated expiration: 2014-08-05
Also published as: DK104191D0; WO1990006317A1; ATE135360T1; FI83965B; EP0456636A1; ES2018727A6; DE68925979T2; DK104191A; DE68925979D1; JP2733701B2; KR0141981B1; FI885588L; EP0456636B1; FI83965C; FI885588A0; NO174555C; NO912030D0; NO174555B; DK170378B1; NO912030L

Abstract

A crystalline lactitol monohydrate having lattice cell constants a = 7.815 ~ 0.008 .ANG., b = 12.682 ~ 0.008 .ANG., and c = 15.927 ~ 0.008 .ANG., and a melting range between 90 and 105°C, and a water content between 4.85 and 5.15 %, as well as a process of preparing said crystalline lactitol monohydrate by evaporating the aqueous solution of lactitol to a concentration between 75 and 88 % by weight, cooling the resultant mixture at a temperature ranging between 30 and 75°C, subsequently separating the lactitol monohydrate crystals from the mother liquor, and subsequently drying with air having a temperature between 120°C, and a relative humidity between 0 and 40 %, for a time period less than 24 hours. The invention also relates to the use of said crystalline lactitol monohydrate as a bulk sweetener for the total or partial replacement of sucrose, in dietetic products, confectionery, bakery products, cereals, desserts, jams, beverages, chocolate, chewing gum and ice-cream, and in pharmaceuticals and cosmetic products, such as tooth paste, as well as a special sweetening agent resembling sucrose, mainly composed of said crystalline lactitol monohydrate.

Description

133!~21 1 A crystalline lactitol monohydrate and a process for the preparation thereof, use thereof, and sweetening agent The invention relates to a new crystalline lac-titol monohydrate, and a process for the preparation thereof by crystallization from an aqueous solution, the use of the said new ~rys~ll;ne lactitol monohydrate in dietetic products, confectionery, bakery products, cereals, desserts, jams, beverages, chocolate, chewing gum and ice-cream, as well as in pharmaceutical and cosmetic products, such as tooth paste. The invention also relates to a new sweet~n;ng agent resembling sugar, mainly composed of the said new crystalline lactitol monohydrate.
Lactitol is a bulk sweetener which can be used as a total or partial repl~c~ment for sucrose, however, its energy content is only about half of that of suc-rose, and it does not cause increased blood glucose content; furthermore, it is tooth-friendly (see Develop-ments in Sweeteners, Ed. Grenby, T.H., Vol. 3, 1987, p. 65-81).
The preparation of lactitol from lactose has been known for a long time. Industrially, lactitol is prepared analogously with the preparation of sorbitol from glucose by hydrogenation in the presence of a Raney nickel catalyst. An aqueous solution of lactose, typi-cally having a concentration between 30 and 40~ by weight due to the poor solubility of lactose, is hyd-rogenated at 70 to 130~C at a pressure between 30 and 74 atm. The preparation is described in Wolfrom, M.L., Burke, W.J., Brown, K.R. and Rose, R.S., J. Am. Chem.
Soc. 60, (1938) p. 571-573.
Crystalline lactitol is reported to occur in anhydrous form (anhydride) as well as in the form of a monohydrate and dihydrate, which forms have been known for a long time with the exception of pure monohydrate.
Among the crystal forms of lactitol, lactitol monohyd-rate is of considerable commercial interest on account of its low hygroscopicity.
In the preparation process mentioned above, lactitol anhydride can be ~ly~allized by adding ethanol to a lactitol solution evaporated to a high concentra-tion. After a crystallization time of one month, the yield of lactitol was 80%, and the melting point of the resulting crystal, which was found to be an anhydride, was between 144 and 146~C.
The crystallization of lactitol dihydrate was presumably mentioned for the first time by Senderens, J.B., Compt. Rend. 170, (1920) p. 47-50. Lactitol sol-ution obtained by hydrogenation was evaporated slowly at room temperature so that crystallization was initi-ated. The melting point of the resulting product was 78~C, and Senderens mistakenly regarded it as a mono-hydrate. However, it appears from European Patent 0039981 and Wolfrom, M.L., Hann, R.M. and Hudson, C.S., J. Am. Chem. Soc. 74 (1952) p. 1105 that the product obtained by Senderens was a dihydrate having a moisture content of 9.5%, determined by a Karl Fisher method, and a melting point between 76 and 78~C.
The next attempt to prepare lactitol monohydrate by crystallization was made in 1979; the end product, however, was an impure dihydrate, see van Velthuijsen, J.A., J. Agric. Food Chem., 27, (1979) p. 680. The solubility of the "monohydrate" so obtained was reported to be 64% by weight at 25OC; however, it has been pro~ed that lactitol monohydrate cannot have such a solubility, see the above-mentioned European Patent 0039981. Taking into consideration that the alleged monohydrate was impure (4.5% of other sugars and dihydrate), the cor-- 13~21~

rected solubility is the right solubility of lactitol (about 59% by weight on dry substance basis). The reported melting range from 94 to 97~C also indicates the presence of a slightly overdried (impure) dihydrate.
5Another attempt to prepare lactitol monohydrate was made in 1981, see the above-mentioned European Patent 0039981. The low crystallization temperature, however, resulted in the formation of monohydrate and dihydrate either as mixed crystals or separately, the 10product being then dried into partially anhydrated monohydrate. The reported melting point 121-123~C is that of partially anhydrated monohydrate from which the lattice cell constants of monohydrate are obtained by means of a single-crystal X-ray diffractometer within 15the measuring accuracy. The surface layer of partially anhydrated monohydrate may be integral (double crystal) or fragmented or it may be composed of numerous separate anhydride crystals, which becomes apparent from the high scattering of the lattice cell constants when determined 20by the single-crystal method. Partially anhydrated mono-hydrate is at least as stable as a complete anhydride which does not bind water at room temperature at mode-rate relative humidities.
The surface layer of said partially anhydrated 25monohydrate is imperfect and under suitable conditions it will be restored partially or completely to the mono-hydrate form. Since the formation of a perfect lattice structure is irreversible, the restored crystal struc-ture will never be perfect, i.e. if the anhydride or 30partially anhydrated monohydrate takes (binds) crystal water, the product obtained does not have the crystal structure of lactitol monohydrate. Both the anhydrated and partially restored monohydrate easily get cloddy and have a rather poor flowability and rather a high 35hygroscopicity on account of the fragmented surface and 4 1~3~ 214 high dust content of the product.
Monohydrate loses all of its crystal water as rapidly as in two hours when it is dried at 105~C in a conventional laboratory oven. The melting point of the 5"monohydrate" disclosed in European Patent 0039981, that is, 121-123~C, corresponds to that of a mono-hydrate anhydrated to a degree of anhydration of 10 to 15%. In addition, the "monohydrate" disclosed in this patent, which lost 2% of its weight at 130~C during 103 days, is originally a monohydrate anhydrated to a degree of anhydration of 60%. The "monohydrates" dis-closed in the European patent are not monohydrates an-hydrated from pure monohydrate; instead, they are overdried products formed from the mixtures of dihyd-15rate and monohydrate due to the crystallization method.
Lactitol hydrate powders anhydrated to a moist-ure content of less than 3% have been prepared by drying both lactitol solution and crystalline hydrate. The hygroscopicity of these powders is utilized in drying 20moist mixtures (European Patent Application 0231643).
The preparation of pure lactitol monohydrate having lattice cell constants a = 7.815 + 0.008 A, b =
12.682 + 0.008 A, and c = 15.927 + 0.008 A; and a melt-ing range between 94 and 100~C, preferably between 94 25and 98~C, has now succeeded for the first time. The melting range was determined with a Buchi Tottol melting point apparatus. The lactitol content of the said pure lactitol monohydrate is more than 99.5% on a dry sub-stance basis, and its moisture content is between 4.85 30and 5.15%.
The new lactitol monohydrate has a good flow-ability and long shelf life, and it is stable at room temperatures, in relative humidities ranging from 25 to 75~. After having been stored under varying atmospheric 35conditions for about two years in an open paper sack, the lactitol monohydrate did not become cloddy and its flowability was 5.1 s/100 g measured by a funnel tech-nique, the inclination of the funnel being 60~, the pipe length 23 mm and the inner diameter 11 mm.
The infrared absorption of the lactitol mono-hydrate was measured by a Perkin-Elmer 398 spec~lu-~leter from a tablet having a composition of 1 g of lactitol monohydrate and 131 g of KBr. The infrared spectrum is shown in the drawing.
No more than 150 g of pure lactitol monohydrate on a dry substance basis dissolves in 100 ml of water at 25~C. Pure lactitol monohydrate crystals are colourless, odourless and transparent.
An accurate determination of the melting range of lactitol monohydrate can be most successfully carried out by introducing samples of milled lactitol into several capillary tubes and melting the open ends of the tubes before measuring. The measurements are car-ried out with a conventional melting point apparatus at different constant temperatures using one capillary tube per measurement until the extreme points of the melting range are found.
When determining the melting point, one must take into account that molten lactitol monohydrate has a high viscosity at its melting temperature, wherefore it takes time (even 2 minutes) before the sample is spread evenly on the walls of the capillary tube. Furthermore, the melt often contains bubbles caused by the liberation of crystal water, which remain in the melt for a long time.
In the process according to the above-mentioned European Patent 0039981, lactitol monohydrate anhydride is prepared by crystallizing lactitol within the temperature range from 10 to 50~C from a ~e~de~ lactitol solution obtained by hydrogenation and evaporated to a -concentration between 70 and 85~ or from a mother liquor obtained from the first crystallization step. This process can be used for the crystallization of lactitol only when the purity of lactitol in the feed solution is high, and since dihydrate may already be ~lys~ ed from pure lactitol solution, the ~ly~allization of pure monohydrate is difficult if not impossible.
In the crystallization process according to the invention, crystallization temperatures (in the range from 80 to 30~C) are considerably higher than in the prior art process (from 50 to 10~C), whereby it is possible to crystallize lactitol monohydrate in at least four successive crystallization steps. With the present new process the total yield of lactitol mono-hydrate (see the crystallization series of Example 1,wherein the total yield is 97.6% on lactitol) is con-siderably higher than can be achieved with the prior art process (no more than 85~ on lactitol).
The crystallization tests showed that if the crystallization is to occur in a controlled manner for obtaining a desired crystal size without a wide crys-tal size distribution, the crystallization should be effected in such a manner that the supersaturation of the mother liquor remains below 1.3 (preferably 1.2) with respect to lactitol throughout the crystalliza-tion. The supersaturation can be maintained within a desired range either by using a sufficiently long crystallization time or by measuring the dry substance content of the mother liquor with a refractometer. The supersaturation can be calculated from the dry sub-stance content of the mother liquor and from the sol-133921~
-ubility curve of lactitol. The supersaturation (s) is defined as follows:

s Cml ~ (100 - Cml') Cml'- (100 - Cml) Cml = measured dry substance content of mother liquor, % by weight Cml'= solubility of lactitol in the mother liquor Tests carried out and their results Monohydrate anhydride (Lacty-M, LCDE-31) partially restored during storage and having a melting range 97-103~C corresponding to 2% anhydration was cloddy and possessed a hygroscopity substantially greater than that of the monohydrate (from Test 2 in Example 1). Water absorptions at 20~C after storage for 3 days at various relative humidities are shown in the following Table I.

Table I. Hygroscopicity comparison f Monohydrate Lacty-M
(Example 1, LCDE-31 Test 2) 75% 0.05 wt % 0.2 wt %
85% 0.2 wt % 0.5 wt %
95% 2.5 wt % 3.3 wt %

f = relative humidity of ambient air, %.

Drying tests were carried out on lactitol monohydrate in a conventional laboratory oven at a pressure of 1 bar. The samples were weighed and the degree of anhydration was calculated as a function of the drying time. Table II shows the degree of anhydra-tion under varying drying conditions.

9 1~3~2:~4 ~ Table II Anhydration tests Drying Degree of anhydration (%) time 1 2 3 4 5 6 7 (h) 20OC 40~C 60~C 70~C 80~C 90~C 105~C
0% 25~ 15~ 10% 5% <5% <5%

O O O O O O O O

24 0.08 - - - 98 - 0.3 72 4.1 - 86 96 142 - 0.4 1) sample of 10 g at 20~C when f = about 0%, 2) sample of 10 g at 40~C when f = about 25%, 3) sample of 200 g at 60~C when f = about i5%, 4) sample of 200 g at 70~C when f = about 10%, 5) sample of 200 g at 80~C when f = about 5%, 6) sample of 200 g at 90~C when f < 5%, 7) sample of 200 g at 105~C when f < 5%, f = relative humidity of ambient air, %

133~214 The melting ranges of the partially anhydrated monohydrates formed in the test are 100-146~C (cf. Ex-ample 3).
On account of its excellent technical and physiological properties, the new lactitol monohydrate is particularly suitable as a substitute for sugar in diabetic, dietetic or tooth-friendly products. By com-bining lactitol monohydrate with other bulk or intense sweeteners, such as saccharin, Aspartame, Acesulfame K, Alitane, Sucralose, Stevioside or xylitol, a product highly resembling sugar and yet having a lower energy content and further being tooth-friendly can be prepar-ed. Also this product is novel, and can be used instead of sugar e.g. in sugar products, confectionery, jams, bakery products, table-top sweeteners, cereals, des-serts, chocolate, beverages, chewing gum and ice-creams, as well as in pharmaceutical and cosmetic pro-ducts, such as toothpaste.
Example 1 Cooling crystallization A four-step crystallization test sequence was carried out on lactitol monohydrate, starting from a filtered and de-ionised lactitol solution. The lactitol solution had been prepared from a lactose solution hyd-rogenated by the conventional technique.
All of the nine crystallization tests of this Example were carried out analogously with Test l which was performed in the following manner:
The crystallization was carried out according to the following steps: A lactitol solution having a purity of 98.3% lactitol in the dry matter was evapo-rated to 82.1% by weight at a temperature above 70OC, and 423 kg thereof was transferred into a crystallizer.
The crystallizer was a conventional horizontal cylindri-cal batch-operated cooling crystallizer having a vol-ume of 0.4 m3 and provided with a mixer and a recycling 133!~214 water jacket whose temperature was controlled by means of a microprocessor. In the crystallizer, the tempera-ture of the solution was adjusted to 70~C, whereafter the solution was seeded with ground lactitol monohydrate crystals. The seed crystal size was 0.02-0.05 mm, and the quantity thereof was 0.004% by weight on the lac-titol in the batch. After the seeding, the mass was cooled in 16 hours down to 40~C, first slowly and ul-timately more rapidly.
When the crystallization was complete the crys-tals were separated from the mother liquor with a con-ventional basket centrifuge wherein the crystals were also washed using 9.2% of water per obtained amount of crystal product. The centrifuged crystals were dried with a drum dryer using the conventional technique. The diameter of the cocurrent drum dryer used was 0.6 m, height 2.5 m and inclination about 1~; the speed of rotation was 3.5 rpm and the temperature of the drying air was 95~C. The feed rate of lactitol monohydrate was about 1.2 kg/min and the delay time about 30 minu-tes.
The performance conditions and results of the crystallization tests are presented in Tables III and IV hereinafter.
The total yield of lactitol monohydrate (four-step crystallization) was 97.6 %.

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13~9214 Crystallization Example 1 is intended to il-lustrate the practicability of the novel process, but the crystallization may also be carried out by modify-ing it in a manner as required by normal effective production operation. Thus the crystallization may also be performed without adding seed crystals, i.e. by al-lowing the solution to form seeds spontaneously as in crystallization test 5. Further, the crystallization may be effected entirely or partially by evaporative crystallization as demonstrated in Example 2. The crys-tallization may also be carried out in a continuous operation as long as the temperature is maintained in the range 80~C-30~C and the supersaturation of the mot-her liquor is maintained below 1.3.
Example 2 Evaporation crystallization Crystallization of lactitol monohydrate was performed starting from a lactitol solution prepared by hydrogenation (the same as in Example 1). The solu-tion was evaporatively crystallized for 5 hours at 60~C, whereafter the crystals were separated from a slightly cooled mass, washed, and dried, as explained in the following.
The lactitol solution was concentrated in a conventional 0.4 m3 evaporation crystallizer at 60~C
at a pressure of about 180 mbar until the dry matter content of the solution was 80.9% by weight and there was approximately 30% of solution on the volume of the crystallizer, at which point the solution was seeded with lactitol monohydrate seed crystals. The amount of seed crystals was 0.008% by weight of the lactitol monohydrate content of the final batch, and the average size of the seed crystals was about 0.03 mm. After the seeding, more feed solution was supplied to the ~y~al-lizer, and the evaporation was continued at 59-65~C so that the dry matter content of the mother liquor was in the range 78-82% by weight.
After evaporating for 5 hours, the crystallizer was replete with a mass which was transferred into a cooling crystallizer and cooled from 62~C to 55~C in 10 hours, whereafter the crystals were separated from the mother liquor by centrifuging and dried as in Example 1. The crystal yield was 49.7% on lactitol. The purity of the lactitol monohydrate product was 99.7%
on a dry matter basis, the dry matter content was 95.0%
and the melting range 94.5-98~C.
Example 3 Anhydration of monohydrate The lactitol monohydrate produced in Test 2 of Example 1 was dried at 20-105~C with drying air having a relative humidity of 0-25% for varying periods of time, whereby different partially anhydrated mono-hydrates were obtained. The melting range of the anhyd-rated monohydrates obtained is shown as a function of the degree of anhydration in Table V:

Table V Melting ranges Ds An Mp' Mp 95.00 0 94 98 monohydrate 95.15 3 100 105 95.25 5 103 118 96.10 22 113 128 98.40 68 129 140 99.10 82 138 143 100.00 100 144 146 anhydride Ds = dry matter content of product, % by weight An = degree of anhydration, i.e. amount of removed crystal water, %~5 Mp' = starting point for melting, ~C

Mp = melting point, ~C

Like Example 1, Examples 2 and 3 are intended to illustrate the invention, but the crystallization can be carried out also by modifying it in a manner as required by normal effective production operation, as explained hereinabove.
Example 4 Lactitol plain chocolate g Cocoa butter 165 Cocoa liquor 630 Lactitol monohydrate 719 Acesulfame K 2.3 Vanillin 0.3 Lecithin 6 Procedure: Conch. 17 hours at 50~ C and 3 hours at 60~ C.
Example 5 Lactitol milk chocolate g Cocoa butter 345 Cocoa liquor 195 Milk powder, fat 26 % 209 Lactitol monohydrate 789 Acesulfame K 1.4 Vanillin 0.3 Lecithin 6 Procedure: Conch. 20 hours at 50~ C.
Example 6 Lactitol chewy toffee g Lactitol monohydrate 306 Finmalt L (maltitol syrup) 306 Acesulfame K 0.2 Vegetable fat 39 Emulsifier 3 (Glycerylmonostearate) 1~3321 4 Gelatine 12 Water 25 Citric acid 8 Flavour, colour 1.5 Procedure:
1. Mix lactitol monohydrate, Finmalt L, vegetable fat and emulsifier.
2. Heat to 120~ C.
3. Add dissolved gelatine.
4. Add citric acid, flavour and colour.
5. Pull the mass 2-4 minutes.
6. Form the mass.
Example 7 Lactitol gelatine jelly g Lactitol monohydrate 200 Finmalt L (maltitol syrup) 267 Acesulfame K 0.63 Water 50 Gelatin 250 BL 35 Water 70 Citric acid (50 % solution) 5 Flavour, colour as required Procedure:
1. Mix lactitol monohydrate, Finmalt L, Acesulfame K
and water.
2. Heat to 116~ C.
3. Cool to 90~C and add dissolved gelatine.
4. Add citric acid, flavour and colour.
5. Deposit into starch moulds.
Example 8 Lactitol pectin jelly g Pectin (HM confectionery) 15 Lactitol monohydrate 50 Acesulfame K 0.7 Water 200 18 133921~
Sodium citrate 4 Citric acid 3.7 Lactitol monohydrate 265 Finmalt L (maltitol syrup) 630 Citric acid (50 % solution) 8.5 Flavours, colours 2.5 Procedure:
1. Homogenise pectin and lactitol monohydrate.
2. Add a solution of water, sodium citrate and citric acid.
3. Heat to 100~ C.
4. Add a homogenised mixture of lactitol monohydrate, Acesulfame K, Finmalt L, flavours and colours.
5. Heat to 106-108~C.
6. Add citric acid.
7. Deposit into starch or plastic moulds.
Example 9 Lactitol gum-arabic pastille g Gum arabic, 50 % solution 400 Lactitol monohydrate 220 Finmalt (maltitol syrup) 107 Acesulfame K 1.0 Water 100 Citric acid (50 ~ solution) 10 Flavour, colour 2 Procedure:
1. Mix lactitol and Finmalt to the water.
2. Heat to 120~C.
3. Add heated solution to gum arabic solution.
4. Add acid, flavour and colour.
5. Deposit into starch moulds.
6. Dry 48-60 hours at 60~C.

19 13~92l4 Example 10 Lactitol hard candy g Lactitol monohydrate 368 Finmalt L (maltitol syrup) 200 Acesulfame K 0.4 Water 100 Flavours, colour 2 Procedure:
1. Heat sweeteners and water to 160-162~C.
2. Keep the mass 10 minutes in vacuum (0.8-0.9 .... ).
3. Cool the mass and mix flavours and colours.
4. Form the mass.
Example 11 Lactitol strawberry jam g Strawberries 300 Water 300 Pectin (Obi Violettband B) 6 Lactitol monohydrate 500 Citric acid (50 ~ solution) 3 Calcium citrate 0.2 Calcium lactate 0.3 Potassium sorbate 1.7 Procedure:
1. Dry mix the pectin and 50 g of the lactitol.
2. Heat the fruit and water for few minutes.
3. Sprinkle the pectin/lactitol mixture into the fruit/-water mixture.
4. Bring to boil and keep boiling for a moment to dis-solve the pectin completely.
5. Add remainder of the lactitol and boil for a little while.
6. Add the preservative and the calcium salts soluted in a small amount of water.
7. Boil until the weight of the batch is 1000 g or until desired solid content is reached.

133921~

8. Stop boiling and add acid solution.

9. Cool to 70~C stirring from time to time and pack.
Example 12 Lactitol biscuits g Lactitol monohydrate 95 Fructose 95 Fat 10 Whole egg 50 Flour 175 Fibre (oat bran) 30 Sodium bicarbonate 7.5 Salt 1.5 Ginger Water 40 Procedure:
1. Cream fat with lactitol and fructose.
2. Mix eggs in one by one.
3. Shift together dry ingredients and add beating throughly.
4. Cool a few hours or overnight.
5. Bake in 170~C for about 11 minutes.
Example 13 Chocolate cake g Lactitol monohydrate 179.5 (milled) Butter 180.0 Whole egg 180.0 Flour 150.0 Cocoa powder 30.0 Saccharin 0.5 Procedure:
1. Dry mix the milled lactitol monohydrate with the saccharin.
2. Cream with the butter until light and fluffy.
3. Gradually beat in the eggs.

4. Fold in the flour and cocoa powder.
5. Deposit into a greased cake tin (16 cm diameter).
6. Bake for 60 minutes at 180~ C.
Example 14 Fatless sponge cake g Lactitol monohydrate (milled) 89.3 Eggs (separated) 180 Flour 90 Saccharin 0.2 Procedure:
1. Dry mix the milled lactitol with the saccharin.
2. Whisk egg yolks with lactitol mixture until thick and creamy.
3. Whisk egg whites until firm and dry.
4. Fold egg white into egg yolk mixture.
5. Fold in flour.
6. Deposit into a greased and floured cake tin (16 cm diameter).
7. Bake for 40 minutes at 180~ C.
Results:
Baked cake had golden colour and even crumb texture:
Weight 275 g Height 3.7 cm Volume 744 cm 25 Density 0.37 g/ml Example 15 Ice cream g Lactitol monohydrate 140 Butterfat 80 Skimmed milk powder 110 Water 660 Emulsified (stabiliser) (Grindstaad SE 33) 8.1 Aspartame 0.4 Colour (Bush Boake Allen Permucol egg yellow powder) 0.06 Vanilla flavour 0.4 Procedure:
1. Dissolve the lactitol and skimmed milk powder in the water (reserving about 5 ~ to dissolve the aspartame).
2. Add the butterfat and emulsifier (stabiliser).
3. Pasteurise at 72~ C for 10 minutes.
4. Homogenise.
5. Rapidly cool to 5~ C and age overnight at 2 - 4~ C.
6. Add colour, flavour and pre-dissolved aspartame.
7. Freeze to 100 % overrun.
Example 16 Frozen dessert g Lactitol monohydrate 100 Fructose 40 Butterfat 40 Skimmed milk powder 110 Water 700 Emulsifier (stabiliser) (Grindstaad SE 33) 9.3 Aspartame 0.24 Colour (Bush Boake Allan Permucol egg yellow powder) 0.06 Vanilla flavour 0.4 Procedure:
1. Dissolve the lactitol, fructose and skimmed milk powder in most of the water (reserving about 5 % to dissolve the aspartame).
2. Add the butterfat and emulsifier (stabiliser).
3. Pasteurise at 72~ C for 10 minutes.
4. Homogenise.
5. Rapidly cool to 5~ C and age overnight at 2 - 4 ~C.
6. Add the colour, flavour and pre-dissolved asparta-me.
7. Freeze to 100 ~ overrun.

Example 17 Sorbet g Lactitol monohydrate 250 Strawberry puree 150 Gelatin 125~ Bloom 10 Citric acid (50 %) 4.0 Aspartame 0.8 Colour (Hexacol Strawberry Red) 0.3 Strawberry flavour 1.1 Water 584 Procedure:
1. Dissolve the lactitol in the water.
2. Add the gelatin and mix.
3. Pasteurise at 72~ C for 10 minutes.
4. Rapidly cool to 5~ C and age overnight at 2 - 4 ~C.
5. Add strawberry puree, citric acid, colour and fla-vour.
6. Freeze to 65 ~ overrun.
Example 18 Table-top sweetener (Equivalent sweetness to sugar) g Lactitol monohydrate 100 Sodium saccharin 0.23 Procedure:
Dry mix using a ribbon blade (or other suitable dry powder mixer) until a uniform dispersion is obtained.
Application:
Suitable for direct replacement of succrose in all applications.
Example 19 Table-top sweetener ( 4 times as sweet as sugar ) g Lactitol monohydrate 100 Acesulfame K 1.85 Procedure:
Dry mix using a ribbon blade (or other suitable dry powder mixer) until a uniform dispersion is obtained.
Applications:
Suitable for use in reduced caloric formulations where some bulk is needed.
Example 20 Table-top sweetener (10 times as sweet as sugar) g Lactitol monohydrate 100 Aspartame 6.0 Procedure:
Dry mix using a ribbon blade (or other suitable dry powder mixer) until a uniform dispersion is obtained.
Applications:
Suitable for sprinkling or use in low caloric formula-tions where bulk is not required.
Example 21 Drinking chocolate g Lactitol monohydrate 200 Ski~ milk powder 70 Fat reduced cocoa powder 12 Procedure:
Reconstitute with 708 g hot water (total 1000 g).

Claims

1. A substantially pure crystalline lactitol monohydrate having lattice cell constants a = 7.815 ~ 0.008 .ANG. b = 12.682 ~ 0.008 .ANG., and c = 15.927 ~ 0.008 .ANG., a melting range between 90 and 105°C, and a water content between 4.85 and 5.15%.

2. A crystalline lactitol monohydrate according to claim 1, characterized in that it has a melting range between 94 and 98°C.

3. A crystalline lactitol monohydrate according to claim 1, characterized in that it has a flowability greater than 25 s/100 g, calculated by a funnel technique wherein the inclination of the funnel is 60°, the pipe length is 23 mm and the inner diameter is 11 mm.

4. A crystalline lactitol monohydrate according to claim 3, characterized in that it has a flowability greater than 10 s/100 g.

5. A crystalline lactitol monohydrate according to claim 1, characterized in that it has a hygroscopicity less than 0. 2% w/w humidity after 3 days at 20°C and 75% relative humidity.

6. A crystalline lactitol monohydrate according to claim 5, characterized in that it has a hygroscopicity less than 0.1% w/w.

7. A process for preparing a substantially pure crystalline lactitol monohydrate having lattice cell constants a = 7.815 ~ 0.008 .ANG., b = 12.682 ~

0.008 .ANG., and c = 15.927 ~ 0.008 .ANG., a melting range between 90 and 105°C, and a water content between 4.85 and 5.15%, characterized in that it comprises the steps of evaporating an aqueous solution of lactitol to a concentration between 75 and 88% by weight, seeding the evaporated solution at a temperature between 50 and 80°C, or allowing the solution to form seeds spontaneously at said temperature, cooling the resultant mixture to a temperature within a range between 30 and 60°C, subsequently separating the lactitol monohydrate crystals from the mother liquor, and subsequently drying with air having a temperature below 120°C and a relative humidity between 0 and 40%, for a period of time less than 24 hours.

8. A process according to claim 7, characterized in that the aqueous solution of lactitol contains no more than 30% of impurities, on dry substance basis.

9. A process according to claim 7, characterized in that the seeded solution is evaporated at a temperature ranging from 50 to 80°C
for increasing the crystal content of said solution.

10. A process according to claim 7, characterized in that the lactitol monohydrate crystals separated from the mother liquor are washed prior to drying.

11. A process according to claim 7, characterized in that the air used for drying has a temperature between 60 and 100°C.

12. A process according to claim 7 or 11, characterized in that the air used for drying has a relative humidity between 5 and 20%.

13. A process according to claim 7 or 11, characterized in that the drying step is carried out for a period of time ranging from 5 to 50 minutes.

14. A process according to claim 7, 8, 9, 10 or 11, characterized in that the crystalline lactitol monohydrate obtained has a melting range between 94 and 98°C.

15. A process for preparing a substantially pure crystalline lactitol monohydrate having lattice cell constants a = 7.815 ~ 0.008 .ANG. b = 12.682 ~
0.008 .ANG., and c = 15.927 ~ 0.008 .ANG., a melting range between 90 and 105°C, and a water content between 4.85 and 5.15%, characterized in that it comprises the steps of evaporating an aqueous solution of lactitol to a concentration between 80 and 88% by weight at a temperature between 70 and 80°C, cooling the solution to a temperature between 65 and 75°C, seeding the solution or allowing the solution to form seeds spontaneously at said temperature, subsequently cooling the resultant mixture slowly to a temperature within a range between 35 and 45°C, separating the lactitol monohydrate crystals from the mother liquor, and subsequently drying with air having a temperature below 120°C and a relative humidity between 0 and 40%, for a period of time less than 24 hours.

16. A process according to claim 15, characterized in that the aqueous solution of lactitol contains no more than 30% of impurities, on dry substance basis.

17. A process according to claim 15, characterized in that the lactitol monohydrate crystals separated from the mother liquor are washed prior to drying.

18. A process according to claim 15, characterized in that the air used for drying has a temperature between 60 and 100°C.

19. A process according to claim 15 or 18, characterized in that the air used for drying has a relative humidity between 5 and 20%.

20. A process according to claim 15 or 18, characterized in that the drying step is carried out for a period of time ranging from 5 to 50 minutes.

21. A process according to claim 15, 16, 17 or 18, characterized in that the crystalline lactitol monohydrate obtained has a melting range between 94 and 98°C.

22. A process for preparing a substantially pure crystalline lactitol monohydrate having lattice cell constants a = 7.815 ~ 0.008 .ANG. b = 12.682 ~
0.008 .ANG., and c = 15.927 ~ 0.008 .ANG., a melting range between 90 and 100°C, and a water content between 4.85 and 5.15%, characterized in that it comprises the steps of evaporating a mother liquor obtained from a previous crystallization step to a concentration between 80 and 88% by weight at a temperature between 70 and 80°C, cooling the solution to a temperature between 65 and 75°C, seeding the solution, or allowing the solution to form seeds spontaneously at said temperature subsequently cooling the resultant mixture slowly to a temperature within a range between 35 and 45°C, separating the lactitol monohydrate crystals from the mother liquor, and subsequently drying with air having a temperature below 120°C and a relative humidity between 5 and 20%, for a period of time less than 24 hours.

23. A process according to claim 22, characterized in that the mother liquor contains no more than 30% of impurities, on dry substance basis.

24. A process according to claim 22, characterized in that the lactitol monohydrate crystals separated from the mother liquor are washed prior to drying.

25. A process according to claim 22, characterized in that the air used for drying has a temperature between 60 and 100°C.

26. A process according to claim 22 or 25, characterized in that the drying step is carried out for a period of time ranging from 5 to 50 minutes.

27. A process according to claim 22, 23, 24 or 25, characterized in that the crystalline lactitol monohydrate obtained has a melting range between 94 and 98°C.

28. A process according to claim 7, 15 or 22, characterized in that the supersaturation of the mother liquor is maintained at a value below 1.3 relative to lactitol throughout the crystallization.

29. A process according to claim 7, 15 or 22, characterized in that the supersaturation of the mother liquor is maintained at a value below 1.2 relative to lactitol throughout the crystallization.

30. A process according to claim 22, characterized in that said mother liquor is obtained from the previous 2nd or 3rd crystallization step.

31. Use of a substantially pure crystalline lactitol monohydrate as defined in claim 1, 2, 3, 4, 5 or 6, as a bulk sweetener for the total or partial replacement of sucrose.

32. Use of a substantially pure crystalline lactitol monohydrate as defined in claim 1, 2, 3, 4, 5 or 6, in dietetic products, confectionery, bakery products, cereals, desserts, jams, beverages, chocolate chewing gum and ice-cream, as well as in pharmaceutical and cosmetic products.

33. A special sweetening agent resembling sucrose, characterized in that it is essentially composed of a substantially pure crystalline lactitol monohydrate having lattice cell constants a = 7.815 ~ 0.008 .ANG. b = 12.682 ~ 0.008 .ANG., and c = 15.927 ~ 0.008 .ANG., a melting range between 90 and 105°C, a water content between 4.85 and 5.15% and of a tooth-friendly sweetening agent.

34. A sweetening agent according to claim 33, characterized in that the crystalline lactitol monohydrate has a melting range between 94 and 98°C.

35. A sweetening agent according to claim 34 or 35, characterized in that the tooth-friendly sweetening agent is saccharin or xylitol.