SE452337B - PROCEDURE FOR THE PREPARATION OF A SWITCHING AGENT BY HYDROLYZE OF A LACTUS SOLUTION - Google Patents

Description

452 337 unfavorable and that the final product may be so diluted or of such composition that it must be further processed in order to be practically useful for many purposes.

A method for hydrolyzing lactose is also known from U.S. Patent 4,067,748. According to this method, lactose is hydrolyzed by means of a strongly acidic cation exchanger, preferably a strongly acidic polystyrene ion exchange plastic. The patented method states that hydrolysis can take place with a dry matter content of 20-40%, eg 30%, and that the hydrolysis takes place by means of an ion exchange plastic with a very low crosslinking number, preferably a crosslinking number of between 0.5 and 5%. . The method thus patented also works with lactose of a dry matter content which is so low that for many purposes it is not directly usable but must be subjected to further treatment such as evaporation, etc. Furthermore, an ion exchange plastic with a very low crosslinking number is used, which is possible. and may be suitable at the stated low dry matter contents, but which on the other hand would not be practically possible at higher dry matter contents due to the osmotic pressure at high dry matter content becoming so high that there is a risk that the ion exchange plastic balls will burst and thus be destroyed.

According to the patent, the lactose conversion also takes place while stirring lactose together with the ion exchange plastic, which causes cracking and wear of the ion exchange plastic balls. Alternatively, it is stated that the lactose conversion can take place by allowing the ion exchange resin to gradually descend in a column in countercurrent to an upward lactose-containing liquid and while the ion exchange resin is recycled to the top of the column.

The known methods are thus disadvantageous partly in that one is forced to work with relatively low dry matter contents in the lactose, partly also in that it is employed ae: necessary eiiar advantageous to ganunfara in the hydrolysis with the help of êñ Joñbytarplast with very low crosslinking number, something which at high to: Frk destroy the ion exchange plastic, and that the process is carried out while stirring lactose and ion exchange plastic, which measures in total lead to significantly longer conversion times of lactose to glucose and galactose.

It could be suspected that the use of an ion exchange plastic with a higher crosslinking number than mentioned in the previously known 452 337 publications or a conversion of lactose with a higher dry matter content or a lactose conversion by passing the lactose through a fixed bed of the ion exchange mass would lead to longer conversion times for lactose to glucose and galactose or alternatively to a lower degree of hydrolysis for maintained operating time, but it has surprisingly been found that this is not the case, but according to the invention it is possible to work with higher dry matter contents and ion exchange masses with higher crosslinking numbers. fixed bed of ion exchange mass and in spite of this get surprisingly short conversion times and a very high degree of hydrolysis.

The basis for the invention has therefore been the problem of proposing a new process for the production of lactose sweeteners, which process allows a practical and economical production of the desired sweetener.

The invention also relates to a sweetener prepared according to the process. Another object of the invention is to provide such a process in which the dry matter content of the lactose solution can be kept substantially higher than has hitherto been possible, and in which the dry matter content of the final product becomes correspondingly higher than what was previously considered possible without evaporation. or other further treatment of the hydrolysed product.

A further object of the invention is to provide a process for the preparation of sweeteners of lactose, according to which a substantially higher dry matter content is maintained than has previously been customary, in which a higher degree of hydrolysis is obtained than has previously been usual and in which in addition, the process can be run so that the rotational speed is significantly faster than what has previously occurred.

The process according to the invention is based on lactose in aqueous solution or permeate with a dry matter content of between 40 to 80%.

Preferably the lactose solution is given a dry matter content of between 50 to 600%. If the lactose is to be dissolved in water, the temperature is raised to between 80 and 150 ° C or preferably to between 90 and 120 ° C. At high temperature, lactose is dissolved more and more completely and thereby a higher TS content is obtained than at lower temperatures. The high TS content of the lactose solution gives the advantage of obtaining a concentrated solution, which does not need to be evaporated, and which allows a high capacity in the process. Depending on the starting point from which the lactose is produced, the pH value in the lactose solution may vary, but normally the pH value is below 7 and preferably at a pH of 5 - 6.

Optionally, the lactose solution can be filtered to polish the solution, but this is not absolutely necessary, but the lactose solution can be further processed immediately after the dissolution in water to break down the lactose into glucose and galactose.

This further treatment of the lactose solution takes place by an acidic heterogeneous catalyst, in this case hydrolysis, whereby the lactose solution is treated with a strongly acidic cation exchanger, e.g. polystyrene-sulfonic acid or with any other polymer-exchanged ion exchanger. In order to be able to work with the mentioned high dry matter contents and at the same time maintain fast turnover rates in the hydrolysis of lactose to glucose and galactose, a cation exchanger for this purpose should suitably have a moderately low degree of crosslinking, for example a degree of crosslinking of 5.5-10% or preferably 5.5-6%. In this context, the cation ion exchanger functions as a 'heterogeneous catalyst', in which the hydrogen ions break down lactose into glucose and galactose. The acidic heterogeneous catalyst is carried out at a temperature of 80-150 or preferably 90-120 ° C. Depending on how long the lactose solution is kept in contact with the cation exchanger, the process can be carried out to a degree of hydrolysis of between 40 and practically 100%. For commercial use to obtain maximum sweetness and best taste, the catalyst is suitably driven to a degree of hydrolysis of about 70-90%. At a degree of hydrolysis of less than 70 - 80%, there is a risk that lactose and / or galactose will crystallize out during long storage and under low temperature.

If it is desired to further increase the sweetness of the hydrolysed lactose solution, some extra lactose may be added, which enhances the sweetness of the glucose and galactose. Upon combining the lactose solution with the strongly acidic cation exchanger, the acidity of the lactose solution gradually increases, and the leaving glucose-galactose product can maintain a pH of 1.5 - 2.5. It can be considered an advantage that the glucose galactose solution maintains a relatively low pH value, as the microbial shelf life increases at a low pH value.

By starting from a lactose solution with as high a TS content as 40 - 80 452 337 or preferably 50 - 60%, the process has a high capacity, and a throughput of 0.2 - 2.0 bed volumes per hour is completely within the scope of the possibilities. with a maintained hydrolysis rate of over 80%. Such a throughput is significantly higher than what has previously been possible.

Despite the relatively high temperature throughout the process, the risk of caramelisation is small, due to the high flow rate and the rapid conversion, and the finished hydrolysed product contains very small and negligible amounts of caramelisation products.

To further improve the taste and remove any caramelizing substances in the finished hydrolysed glucose galactose product, the sugar product can be polished, e.g. by filtration through activated carbon. However, such polishing is necessary only for certain products, when a clear and uncoloured product is desired.

If necessary, the finished sugar product can also be evaporated, but since the TS content is as high as 40-80% or preferably 50-60%, evaporation is normally not necessary. The fully hydrolyzed product normally has a pH of 1.5 - 2.5. To adapt the sugar product to its future area of use, the pH value can be raised if necessary.

The sugar product produced is well suited for a variety of purposes; for example for use in foods such as pastries of various kinds, beverages such as beer, soft drinks and more, for all kinds of canned foods, where some sweetening is desired, for cheese products such as cheese dip, spreadable cheeses, cream cheese and more, for sweetening sweets and confectionery , for dairy products such as condensed milk, acidified cultured milk varieties, sour cream, yoghurt and more, for dry mixers such as baking mixes, pancake mixes, salad dressings, sausages, burgers, soups and more, or for sweetening ice cream. Many other uses are conceivable. The product produced thus has a very high TS content, and a high turnover rate, and it is possible to drive the process according to the invention to a very high degree of hydrolysis for the product.

It can be pointed out that it is very possible to control the degree of hydrolysis of a few percent when by varying the bed volumes, ie the conversion time for lactose to glucose and galactose. -w-uu-.W - u .... . . In the following, some examples of the method according to the invention will be described. In all examples an equipment has been used for treatment of 100 kg of lactose solution, and then in the following examples only the weight of the finished product is stated, it is thus assumed that in all cases 100 kg of lactose solution has been added to the equipment and treated.

EXAMPLE 1 40 kg of lactose powder made from whey was added to 65 kg of water at a temperature of 80 °. This temperature was maintained until the lactose was mostly dissolved, after which the lactose solution was treated with a strongly acidic cation exchanger consisting of polystyrene sulfonic acid with a degree of crosslinking of 8%. The hydrolysis was driven to a degree of hydrolysis of 40%, after which the finished hydrolyzed product was taken out and analyzed. The turnover rate corresponded to a bed volume of 0.50 per hour. The product showed a brownish-yellow color and had a faint caramel taste. After filtration of the product over activated carbon, the yellow-brown coloration disappeared and practically all the caramel taste and the final product showed a moderate sweetness. After storage in a refrigerated state at a temperature of below 10 °, the product gradually became cloudy by crystallizing out unconverted lactose and eventually sinking to the bottom.

EXAMPLE 2 65 kg of lactose made from whey was dissolved in 35 kg of water at a temperature of 97 °. When all the lactose was dissolved in the water, the pH was measured to be 5.51.

With a maintained temperature of 97 °, the lactose solution was treated with an ion exchange mass with a degree of crosslinking of 5.5%, which was a strongly acidic cation exchange. The hydrolysis was driven to a hydrolysis rate of 96%. Immediately after the hydrolysis, the pH was measured to 1.82. The product produced had a clean, sweet taste without noticeable off-taste. The color was faintly 452 337 yellowish. After polishing over activated carbon, the product appeared clear and completely without off-taste. The turnover rate according to this example 1 corresponded to 1 bed volume per hour. Due to the high degree of hydrolysis I, no crystallization of lactose could be detected even during long storage at low temperature.

EXAMPLE 3 80 kg of lactose made from whey were dissolved in 20 liters of water and at 40 ° under a pressure of 3; 10 bar. The pH of the lactose solution was measured to be 5.0. With a temperature maintained at 140 °, the lactose solution was treated with a strongly acidic cation exchanger based on polystyrene sulfonic acid, with a degree of crosslinking (DVB content) of 6%, and the hydrolysis was driven to a degree of hydrolysis of 92%. The turnover rate corresponded to a bed volume of 1.1 per hour. The finished product was brown and had a faint caramel taste. The product was considered without polishing well suited for bakery purposes. A certain tendency to crack formation in polystyrene- ß !!! the sulfonic acid plastic beads were observed, which is believed to be due to the high osmotic pressure that arose at the high dry matter content in this example.

EXAMPLE 4 50 kg of lactose made from cottage cheese whey was mixed with 100 kg of 100 ° water. The pH of the lactose solution was measured to be 4.5. At the maintained temperature, the lactose solution was treated with an acidic cation exchanger with a degree of crosslinking of 10% and the hydrolysis was driven to a degree of hydrolysis of 95%. The turnover corresponded to a flow rate of 0.7 2 bed volumes per hour. The finished product was pale yellow and had good sweetness without off-taste.

After polishing over activated carbon, a clear uncoloured product was obtained without any detectable off-taste. The product was considered well suited as a sweetener for beverages, for example beverages in the brewery area such as beer and soft drinks, etc. Despite the relatively high degree of crosslinking of the cation exchanger 452 337 "" "°" * '°.': \> - ma-, ~ ._ .. ~ .5 .. ~ 2L the hydrolysis could be driven to a degree of hydrolysis of 95% with a flow rate of 0.7 bed volumes per hour, which corresponds to a conversion rate of lactose to glucose and galactose of less than 1.5 hours.

EXAMPLE 5 71 kg of lactose powder made from whey was dissolved in 29 kg of water and mixed at a temperature of 119 ° at a pressure of 1.9 bar. The pH of the lactose solution was measured at 1.8. While maintaining the temperature, the lactose solution was treated with a cation exchanger with a degree of crosslinking of 5.5% and the hydrolysis was driven to a degree of hydrolysis of 93%. The turnover corresponded to a flow rate of 1.9 bed volumes per hour. The finished product was slightly yellow and had a pure sweet taste without noticeable off-taste. FH Despite the high dry matter content, the high degree of hydrolysis and the relatively low degree of crosslinking, the hydrolysis could be carried out at a flow rate of 1.9 bed volumes per hour corresponding to a conversion rate of the lactose of only about 1/2 hour. No significant cracking or other damage to the ion exchange plastic could be observed.

EXAMPLE 6 60 kg of lactose powder made from whey was dissolved in 40 liters of water at a temperature of 100 °. The lactose solution was treated with a strongly acidic cation exchanger, which was a mixture of 50% cation exchanger with a degree of crosslinking (DVB content) of 5.5% and the remainder with a cation exchanger with a degree of crosslinking of 8%. The hydrolysis was operated to a degree of hydrolysis of 98% at a turnover rate of 1.5 bed volumes per hour. The product produced was practically completely clear and colorless and had a strong sweet taste. 97 °.

EXAMPLE 7,452,337 For 50 kg of lactose powder was dissolved in 50 liters of water at a temperature if the lactose solution was hydrolyzed to 96% by means of a strongly acidic cation exchanger with a degree of crosslinking of 5.5%. The lactose hydrolyzate had a relatively strong sweet taste. To the lactose hydrolyzate was then added 15% pure lactose, with a taste panel judging the sweetness to be significantly greater than that of the just hydrolyzed lactose. the following tables: A further large number of experiments have been made, for which 1 Table 11 1 Ex Flow Temp Pressure Concrete result BV / h ° C bar TS degree of hydration% in 0.2 60 36 29 (34) 1 75 42 33 10 0.4 83 50 45 11 1 96 59 89 _ 12 0.7 97 65 95 13 1 120 2.0 72 96 14 1 141 3.8 81 96 15 1.5 60 35 30 16 1.5 74 41 36 17 1.5 86 50 45 18 1.5 95 60 82 19 2.0 97 66 97 20 1.9 119 1.9 71 93 'In the above example, a cation exchanger of the type with a degree of crosslinking is used. The benzene content of this cation exchanger is about 5.5%. Table 2 In the following example, a cation exchanger was used which had a DVB content of about 6%.

Ex F1öde _ Temp Tryck Konc Resu1 tat BV / h ° C bar TS hydrc fl ysgrad% 21 1 60 35 29 22 _1 74 42 33 23 1 85 50 47 24 1 95 2 59 93 25 1 99 65 98 § = f 26 1 119 2 , 0 _ 73 97 27 1 141 3,8 sz 96 '28 1, 5 61 0, 21 35 28 29 1, 5 73 41 40 ao 1, s_ ss 51 45' 31 1, 5 96 60 89 32 1, 5 98 65 96 33 1, 5 121 2, 0 73 97 34 1.5 141 3.8 82 96 452 337 ll Table 3 In the following example a cation exchanger with a DVB content of 8% was used.

Ex Flow Temp Pressure Concc Result BV / h “C bar TS degree of hydrolysis% 35 0.4 60 35 35 36 l, 2 74 4l 34 37 1,5 'ss so 46 38 l, 5 96 59 90 39 l, 5 99 66 97 40 l, 7 ll9 2.0 73 96 41 1.9 l4l 3.8 79 96 Table 4 Ex Flow Temp Pressure Concc Result BV / h ° C bar TS degree of hydrolysis%. 42 0.8 61 35 34 43 l, 2 73 42 35 44 1,5 85 50 42 45 1,5 97 60 98 46 1,5 99 65 98 47 l, 8 120 2,0 7l 97 48 2,0 l4l 3.8 81 97 In these examples, a cation exchanger was used in the form of a mixture of 50% of a cation exchanger with 8% degree of crosslinking and 50% of another cation exchanger with 5% degree of crosslinking with a combined degree of crosslinking (DVB content) of 6.75 %.

It should be noted that a cation exchanger with a low degree of crosslinking within the specified range facilitates the hydrolysis, so that a higher flow rate can be poured without thereby decreasing the degree of hydrolysis. At a degree of hydrolysis of more than 80%, the product becomes so stable that practically no crystallization occurs even during prolonged storage. However, cation exchangers with a low degree of crosslinking become quite pressure sensitive or brittle, and at high dry matter contents, as mentioned above, the osmotic pressure becomes so strong that it risks damaging the cation exchanger. Therefore, at high dry matter contents, it is often necessary to use cation exchangers with a higher degree of crosslinking within the specified range of 5.5-10% than would otherwise be desirable for operational reasons.

In the examples given above, equipment has been used throughout, which is shown in the attached figure 1, and the lactose and the permeate have been treated mainly at the temperatures in relation to the dry matter content shown in the attached curve, figure 2.

The plant in figure 1 consists of a closed container 1 with an upper judgment 2 and a lower judgment 3 and an intermediate bottom 4 next to the lower judgment 3.

A bed 5 of a cation exchanger has been applied to the intermediate bottom 4 and up to approximately half the height of the container, and at a level slightly above the upper surface 6 of the cation exchange bed there is an inlet 7 for lactose. The inlet 7 communicates with a spreader 8 provided with a number of nozzles (not shown) which spread the lactose evenly over the surface of the ion exchange bath. In the intermediate bottom 4, a number of grid-provided nozzles 9 have been arranged for discharging hydrolysed lactose to the volume 10 between the intermediate bottom 4 W? and the lower judgment 3, and the hydrolyzed lactose is taken out through an outlet pipe ll. At a level slightly above the inlet 7 for the lactose there is another inlet 12 for regeneration acid, which inlet 12 is also provided with a diffuser 13 to evenly distribute the regeneration acid over the surface of the ion exchange bed. At a level above the surface 6 of the ion exchange bed there is a further inlet 14 for compressed air or other gas.

In the hydrolysis of lactose, the oxygen inlet 12 and the air inlet 14 are closed, and lactose solution is pumped by a predetermined amount per unit time, preferably by a positive pump, into the container 1 and spread by means of the diffuser 8 evenly over the surface 6 to the ion exchange bed. The lactose gradually descends through the bed at a certain rate, but if lactose is pumped in at a higher rate than can pass through the ion exchange bed, a layer 15 of lactose solution arises on top of the surface of the ion exchange bed. A layer of 1ctose solution 15 about 5 cm high on top of the surface of the ion exchange bed is considered suitable, but if the level 16 of the actuation solution surface tends to rise, compressed air is continuously released into the formed pressure chamber 17, whereby the lactose solution under pressure can be passed through the ion exchange bed. in an automated manner is kept fairly constant by the sudden introduction of compressed air into the pressure chamber 17. The hydrolysed lactose can be batchwise or continuously withdrawn through the outlet pipe 11 in the bottom of the container. Due to the solid ion exchange bed, no wear of the ion exchange beads occurs, and the lactose solution pumped through the inlet 7 will, after consuming the acid in the ion exchange resin, always meet the strongest acid content at or when the outflow, which is high enough to be hydrophilic.

The acid content of the ion exchange resin decreases during the hydrogenation process, and at some point the ion exchange resin must be regenerated. This is done by flushing the inlet tube 7 for the lactose, the spreader 8 and the ion exchange bed 5 with water, after which water is pumped through the outlet tube 11 from below into the ion exchange bed, so that it is lifted and sucked up. Using air from the air inlet 14, the ion exchange bed 5 is pushed down to its original level, acid, preferably hydrochloric acid of about 5% concentration is pumped in through the oxygen inlet and diffuser 13 and passed from above through the ion exchange bed until the mass is acid saturated. Excess acid is displaced by purging with water, and then the plant is ready to be used again for the hydrogenation of lactose to glucose and galactose.

Figure 2 shows a diagram of suitable handling temperatures.

Along the vertical axis the percentage of dry matter has been indicated, and along the horizontal axis the solution temperature of 1 actose and permeate in water, respectively, has been indicated. It can be seen that the temperature for complete dissolution of lactose in water at, for example, 40% dry matter content is at about 92 ° C, and that the temperature rises with increasing dry matter content to about 140 ° C at 90% dry matter content. The corresponding temperatures for permeate are at about 55 ° C for 40% dry matter content and about 100 ° C for 90% dry matter content.

Claims (7)

452 337 14 P a t e n t k r a v Process for the preparation of a sweetener, characterized in that - lactose with a pH value of less than 7 is dissolved in water with a temperature of 60-150 ° C or preferably 90-120 ° C to a dry matter content of between 40 and 80% or preferably between 50 and 60%, or by heating a lactose permeate with the same dry matter content to the same temperature, after which the lactose solution formed is hydrolyzed by forcing the lactose solution through a solid bed during parallel flow. of a strongly acidic cation exchanger with a degree of crosslinking of 5.5-10%, whereby a conversion of lactose to glucose and galactose is obtained, and of the hydrolysis being driven to a degree of hydrolysis of 40-100% or preferably 70-90% at a flow rate of 2.0-0.5 bed volumes per hour corresponding to a conversion time for lactose to glucose and galactose of 0.5 to 2.0 hours, after which the obtained glucose-galactose product is cooled to a temperature of 10% 0 ° C and taken out for direct use, for intermediate storage or for further processing. Process according to Claim 1, characterized in that the hydrolysis is carried out without changing the temperature at which the lactose is dissolved in water or to which the lactose permeate is heated. Process according to Claim 1 or 2, characterized in that the lactose solution is polished before the hydrolysis. 452 337 15 Process according to one of the preceding claims, characterized in that the glucose galactose product obtained by the hydrolysis is filtered through activated carbon after the hydrolysis to polish the product and to remove any caramel taste. Process according to any one of the preceding claims, characterized in that the strongly acidic cation carrier is composed of polystyrene sulfonic acid or some other polymer-based acidic ion exchanger with a degree of crosslinking of preferably 5.5-6 l. Process according to one of Claims 1 to 3, characterized in that the finished hydrolysed product is subjected to one or more of the following treatments: filtration through activated carbon, evaporation to the desired dry matter content, adjustment of the pH value according to the product as the sweetener. is intended to be used for. Method according to one of the preceding claims. characterized in that the lactose solution before the catalytic treatment is given an arrow value of 1 ~ 7 or preferably 5-6, and that the finished hydrolysed product is kept at a pH value of 1.5-2.5.