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Field of the invention

The present description relates to methods for producing hydrolyzed gelatin solutions with a high degree of clarity and purity .

Background of the invention

The enzymatic hydrolysis of gelatin for producing hydrolyzed gelatin, commercially known as " collagen" , generally takes place using a method carried out in a discontinuous manner ( in batches ) . The method comprises a step wherein a hydrolytic enzyme and gelatin are placed in contact for an interval of time that allows hydrolysis of the gelatin macromolecules . This method involves the use of a tank, placed under agitation, fed by a solution comprising gelatin in variable concentrations , from a few percentage points up to values in the order of 50% . The enzyme is added to this solution and, after a period of time that may last a few hours , the hydrolysis reaction reaches a steady state and may be considered completed . The hydrolyzed gelatin present in the solution obtained has a signi ficantly lower molecular weight than the origin, and this is mani fested by a reduction in the viscosity of the solution . Once the enzymatic hydrolysis reaction is completed, the solution comprising hydrolyzed gelatin and the enzyme used for the hydrolytic reaction are sent to subsequent work steps envisaged in the production process . One of these steps includes the UHT sterili zation of the product , whose thermal treatment allows not only elimination o f the bacterial load, but also denaturation of the enzyme ( the enzyme loses its activity) .

Consequently, the tank in which the enzymatic hydrolysis was carried out is filled again with another solution of gelatin and another enzyme in order to start a new production batch .

Summary of the invention

The obj ect of the present description is to provide a simple and ef fective method for producing hydrolyzed gelatin with a high degree of purity .

According to the invention, the aforesaid obj ect is achieved thanks to the subj ect speci fically referred to in the following claims , which are intended as an integral part of the present description .

One embodiment of the present description provides a method for producing hydrolyzed gelatin comprising the steps of : i ) providing a starting solution comprising gelatin, ii ) filtering said solution comprising gelatin through an ultrafiltration membrane to obtain a retentate fraction and a permeate fraction comprising a solution of hydrolyzed gelatin, wherein said starting solution provided in step i ) comprises at least one of hydrolyzed gelatin and nonhydrolyzed gelatin, wherein when said solution provided in step i ) comprises non-hydrolyzed gelatin, the method further comprises a step of adding to said starting solution provided in step i ) at least one hydrolytic enzyme before step ii ) .

The hydrolyzed gelatin solution obtained in step ii ) with the described method has a turbidity equal to or less than 5 NTU (Nephelometric Turbidity Units ) . The hydrolyzed gelatin obtained with the described method has a molecular weight that can be between 50 Da and 50000 Da .

Brief description of the figures

The invention will now be described, by way of example , with reference to the attached figures , wherein :

- Figure 1 shows a diagram of a method known in the art for producing hydrolyzed gelatin;

- Figure 2 shows a diagram of an embodiment of the method subj ect of the present description wherein a starting solution comprising already hydrolyzed gelatin is fed continuously to feed batches ;

- Figure 3 shows a diagram of an embodiment of the method subj ect of the present description wherein a starting solution comprising hydrolyzed gelatin and nonhydrolyzed gelatin is fed continuously to feed batches ;

- Figure 4 shows a diagram of an embodiment of the method subj ect of the present description wherein a starting solution comprising non-hydrolyzed gelatin is fed continuously to feed batches ;

- Figure 5 shows two compared samples : on the left , a hydrolyzed gelatin solution obtained according to an embodiment of the method subj ect of the present description; on the right , a starting solution comprising gelatin not yet hydrolyzed and with high turbidity used in the method subj ect of the present description;

Figure 6 shows an additional diagram of an embodiment of the method subj ect of the present description wherein instruments and parts of a system are illustrated; FT : flow transmitter ; Brix T : refractometer ; TT : temperature transmitter ; LT : level transmitter ; HSL : very high level indicator ; PT : pressure transmitter ; CIP Tank : tank for washing the tank with chemical products ; UF : module containing the ultrafiltration membrane .

Detailed description of the invention

In the following description, numerous speci fic details are reported to allow a complete understanding of the embodiments . The embodiments may be implemented in practice without one or more of the speci fic details , or with other methods , components , materials , etc . In other cases , well-known structures , materials or operations are not shown or described in detail to avoid confusing certain aspects of the embodiments .

Reference throughout this description to " a single embodiment" or "one embodiment" indicates that a particular aspect , structure or characteristic described in relation to the embodiment is included in at least one single embodiment . Therefore , the forms of the expressions " in an embodiment" or " in one embodiment" that appear at various points throughout the present description do not all necessarily refer to the same embodiment . Moreover, particular aspects , structures or characteristics can be combined in any convenient way in one or more embodiments .

The titles shown here are for convenience only and do not interpret the field or meaning of the embodiments .

One embodiment of the present description provides a method for producing hydrolyzed gelatin comprising the steps of : i ) providing a starting solution comprising gelatin, ii ) filtering said starting solution through an ultrafiltration membrane to obtain a retentate fraction and a permeate fraction comprising a solution of hydrolyzed gelatin, wherein the starting solution provided in step i ) comprises at least one of hydrolyzed gelatin and nonhydrolyzed gelatin, wherein when said starting solution comprises non-hydrolyzed gelatin the method comprises a step of adding at least one hydrolytic enzyme to said starting solution .

In one or more embodiments , the method comprises a step of separating said permeate comprising, preferably consisting of , the hydrolyzed gelatin solution and said retentate .

In one or more embodiments , the method may comprise a step iii ) of concentrating the obtained hydrolyzed gelatin solution in the permeate and step iv) of drying the concentrated hydrolyzed gelatin solution in step iii ) . The hydrolyzed gelatin thus obtained is hydrolyzed gelatin, which may be in the form of a powder wherein, preferably, the water content is equal to 5% or less .

Gelatin is a natural polymer obtained by extraction in hot water, after a partial acid or alkaline hydrolysis , of the collagen contained in the connective tissues of animals , preferably cattle , pigs and fish . Collagen may also be obtained from fish bones , tendons and scales .

As anticipated in the previous sections , and as schematically illustrated in Figure 1 , known methods for producing hydrolyzed gelatin (hydrolyzed collagen, hereinafter simply "hydrolyzed gelatin" ) are discontinuous methods ( in batches ) , which envisage the use of tanks for conducting the hydrolytic reaction of gelatin, waiting for the period of time necessary for obtaining hydrolyzed gelatin, draining the tank and its restoration, and inactivating the enzyme .

The method subj ect of this present description is a continuous method that involves the use of ultrafiltration membranes . In recent years , separation techniques through the use of membranes have increased considerably . Today, membrane technology is used on a large scale , for example , for producing drinking water from sea water, for puri fying industrial ef fluents , and for the recovery of products in the food and pharmaceutical industries . Ultrafiltration membranes may have cut-of fs (molecular cuts ) such as to allow the separation of molecules with molecular weights even in the range between 500 Da and 100000 Da . These membranes , therefore , have the ability to retain, for example , colloidal particles , bacteria, proteins , polysaccharides and to allow the permeation of sugars , amino acids , salts and water . In the food sector, ( Food & Beverage ) , the practical applications of ultrafiltration membranes are linked to the concentration and puri fication of macromolecules present in complex solutions consisting of several substances , allowing the elimination of these salt solutions , sugars and any other low molecular weight compounds .

The method subj ect of the present description allows obtainment of hydrolyzed gelatin solutions with high clarity thanks to the use of ultrafiltration membranes .

The described method may be carried out on i ) starting solutions comprising already hydrolyzed gelatin, ii ) starting solutions comprising not yet hydrolyzed gelatin to which at least one hydrolytic enzyme is added, iii ) starting solutions comprising both already hydrolyzed gelatin and not yet hydrolyzed gelatin to which at least one hydrolytic enzyme is added .

The ultrafiltration membrane allows retaining - in addition to the hydrolytic enzyme possibly added to the starting solution - any suspended particles present in the starting solution . These particles , which may be protein and/or lipid in nature , have dimensions greater than 0 . 1 pm and, therefore , are not able to permeate the membrane , they may allow obtainment of a hydrolyzed gelatin solution with high clarity .

The method according to the embodiment illustrated in Figure 2 is a method that comprises a step o f providing a starting solution comprising hydrolyzed gelatin in a tank . This hydrolyzed gelatin may have a molecular weight between 50 Da and 50000 Da . The method according to the embodiment illustrated in Figure 3 is a method that comprises a step of providing a starting solution comprising hydrolyzed gelatin and non-hydrolyzed gelatin in a tank to which at least one hydrolytic enzyme is added.

The method according to the embodiment illustrated in Figure 4 is a method that comprises a step of providing a starting solution comprising only nonhydrolyzed gelatin in a tank to which at least one hydrolytic enzyme is added.

In one or more embodiments, the starting solution provided in step i) comprises gelatin in a concentration ranging from 2% to 50%.

This starting solution is a gelatin solution (not hydrolyzed or already hydrolyzed) in water.

The method may comprise a step wherein the solution provided in step i) , comprising non-hydrolyzed gelatin and/or hydrolyzed gelatin, is heated to a temperature between 10°C and 80°C, preferably between 40°C and 55°C.

This solution is sent to an ultrafiltration membrane to be filtered, obtaining a permeate and a retentate. For this object, a pump (for example illustrated in Figures 2-4, 6) may take the starting solution from the hydrolysis tank and feed it onto the ultrafiltration membrane.

The pressure difference (TMP, Trans-Membrane Pressure) , or rather, the pushing force applied upstream of the ultrafiltration membrane may be between 1 bar and 4 bar. This pressure difference between the two surfaces of the membrane allows the permeation of the hydrolyzed gelatin, which is sent to the subsequent envisaged work steps .

The pressure exerted by the solution to be filtered on the ultrafiltration membrane may be between 2 bar and 10 bar. The molecular weight of the gelatin macromolecules before hydrolysis may be in the range from 50000 Da and 500000 Da.

The molecular cut-off of the ultrafiltration membrane may be between 500 Da and 50000 Da. This parameter allows hydrolyzed gelatin to be obtained in the permeate, the molecular weight of which may be between 500 Da and 20000 Da.

The ultrafiltration membrane that can be used in the method may be selected from the group consisting of polymeric spiral membranes, steel membranes, ceramic membranes, and hollow fiber membranes.

The method may be carried out at a temperature between 10°C and 80°C, preferably between 45°C and 55°C.

In one or more embodiments, the starting solution comprising gelatin sent to the ultrafiltration membrane may have a concentration ranging from 2 degrees brix to 45 degrees brix.

The starting solution comprising gelatin to be subjected to step ii) of filtration through the ultrafiltration membrane may have NTU (Nephelometric Turbidity Unit) turbidity values even higher than 500 NTU.

The starting solution may comprise bovine, porcine and/or fish gelatin.

The hydrolyzed gelatin solution obtained with the described method (i.e. the permeate) may have a concentration between 1 degree brix and 30 degrees brix.

In one or more embodiments, the hydrolyzed gelatin solution obtained with the described method (or rather, the permeate) may have a turbidity value equal to or lower than 5 NTU.

The solution may be a solution of hydrolyzed gelatin in water. The hydrolyzed gelatin solution obtained with the described method may comprise hydrolyzed gelatin in a concentration ranging from 2 % to 60% .

The hydrolyzed gelatin obtained with the described method may comprise bovine , porcine and/or fish gelatin .

The hydrolyzed gelatin obtained with the described method may have a molecular weight ranging from 50 Da to 50000 Da .

The hydrolyzed gelatin solution obtained with the described method may be free of protein and/or lipid particles having dimensions greater than 0 . 1 pm .

In one or more embodiments , when the starting solution comprises non-hydrolyzed gelatin, the hydrolytic enzyme that can be used may consist of proteases .

The hydrolytic enzyme may be used in an amount equal to or greater than 0 . 1 % , preferably between 0 . 5% and 2 . 0% with respect to the weight of the non-hydrolyzed gelatin ( to be hydrolyzed) . In any case , the quantity of enzyme to be used depends on the activity of the commercial formulation .

In one or more embodiments , the permeate is a hydrolyzed gelatin solution while the retentate may comprise suspended particles , not yet hydrolyzed gelatin, enzyme .

The hydrolyzed gelatin obtained with the described method may be in the form of a powder . In this case , the method may comprise step iii ) of concentrating the obtained hydrolyzed gelatin solution in the permeate and step iv) of drying the concentrated hydrolyzed gelatin solution in step iii ) .

The hydrolyzed gelatin solution obtained in the permeate may be concentrated, for example , by thermal concentration or by means of a nanofiltration system . The concentrated gelatin solution may be dried, for example , by spray drying .

An important aspect of the method described here derives from obtaining a permeate fraction substantially consisting of a hydrolyzed gelatin solution . In other words , when the solution subj ected to the filtration step comprises non-hydrolyzed gelatin to which at least one hydrolytic enzyme is added, the method allows obtaining hydrolyzed gelatin devoid of hydrolytic enzyme in the permeate , as it is totally retained in the retentate .

This aspect plays an important role both on the ef fectiveness of the method, which does not require subsequent steps of inactivation, and allows separation of the enzyme from the hydrolyzed gelatin obtained, and on the quality of the gelatin obtained, as traces of hydrolytic enzyme in the final product could reduce its organoleptic qualities ( taste and smell ) . Furthermore , the presence of enzyme , even i f denatured, in the final product could induce intolerance or allergy phenomena in sensitive subj ects .

In a preferred embodiment , the retentate containing the enzyme , whose dimens ions are such as not to allow its permeation through the membrane , may be reused to feed the hydrolysis tank .

The enzyme is continuously recirculated in the reaction environment and, consequently, it is not necessary to integrate a new enzyme into the system for conducting the hydrolytic reaction . It is therefore evident that - compared to a method in batches as described in the previous sections - the consumption of hydrolytic enzyme for carrying out the method is signi ficantly reduced .

In the batch methods known in the art , the ratio between hydrolytic enzyme used and the quantity of hydrolyzed gelatin is in the order of 5- 10 kg of enzyme per 1000 kg of hydrolyzed gelatin produced .

In the case of the method subj ect of the present description, the ratio is in the order of 1-2 kg of enzyme per 1000 kg of hydrolyzed gelatin produced .

The method described here , compared to known methods , has the advantage of a lower consumption of hydrolytic enzyme .

Furthermore , the hydrolysis reaction is favored because , by removing the hydrolyzed gelatin produced from the reaction environment , the chemical balance of the hydrolysis reaction shi fts towards the reaction products .

An additional advantage provided by the method described is that once it has reached full capacity, the hourly quantity ( kg/h) of hydrolyzed gelatin removed from the system can be replaced with an equal quantity of fresh gelatin, in order to keep the volume constant inside the hydrolysis tank .

The ultrafiltration membrane usable in the described method also allows retaining the suspended particles present in the starting solution . These particles , of such si ze as not to permeate the membrane , may allow obtainment of a hydrolyzed gelatin solution with high clarity . This is evident from the image illustrated in Figure 5 where a hydrolyzed gelatin solution obtained according to an embodiment of the method subj ect of the present description ( left ) and a starting gelatin solution (not yet subj ected to the filtration step ) are compared . The hydrolyzed gelatin solution is decidedly clear and may have a turbidity even equal to 1 NTU, although the starting gelatin solution may have NTU values higher than 500 . Examples

The examples described below were carried out using an ultrafiltration system as shown in Figure 6. In the following description, the expression "feeding solution" means the solution comprising gelatin indicated with the expression "starting solution" in the terminology of the claims .

Example 1

The ultrafiltration membrane used has the following characteristics: manufacturer Koch; molecular cut 7500 Dalton; surface area 5.6 m ² .

In particular, 590 liters of a solution of porcine gelatin (15% concentration in water) at a temperature of 53.2 °C was introduced into the tank connected to the ultrafiltration system. The solution comprising gelatin was fed to the ultrafiltration system by recirculating both the retentate and the permeate inside the tank maintained in agitation.

At working time 00:25 (twenty-fifth minute) 1 liter of proteolytic enzyme (papain) was introduced, and the concentration of the protein present both in the retentate and in the permeate was periodically monitored .

At working time 00:35, a concentration of protein present in the permeate equal to 1.8% was detected.

The working conditions were kept constant until working time 03:00, reaching a viscosity of the feeding solution of 1.58 mPa*s (the viscosity was measured at the reference concentration of 10%) . The protein concentration in the permeate was equal to 7.2%. The permeate was then removed from the system and recovered in a dedicated tank for the subsequent 4 hours. The feed tank of the system is not replenished with additional gelatin solution or with water. At the end of the experiment, the volume in the feed tank was reduced to 220 liters, the concentration of protein in the feed solution was 21.6%, and in the permeate 14.4%.

During the experiment, the clarity of the feeding solution and the permeate was measured. The results collected during the experiment are reported in the following table, wherein in the "Note" column, the row with the number 1 indicates the operating condition that required the addition of 1 liter of enzyme, the row with the number 2 indicates the recovery of the permeate.

Example 2

The ultrafiltration membrane used has the following characteristics: manufacturer Koch; molecular cut 7500 Dalton; surface area 5.6 m ² .

In particular, 300 liters of a solution starting from porcine gelatin (22.1% concentration in water) at a temperature of 50.0°C was introduced into the tank connected to the ultrafiltration system. The solution of gelatin was fed to the ultrafiltration system by recirculating both the retentate and the permeate inside the tank maintained in agitation.

At working time 00:10, 1.5 liters of proteolytic enzyme (papain) was introduced and the concentration of the protein present both in the retentate and in the permeate was periodically monitored. At working time 00:40, a concentration of protein present in the permeate equal to 11% and a viscosity of the feeding solution of 1.79 mPa*s were found.

The working conditions were kept constant until the working time 01:10, reaching a viscosity of the feeding solution of 1.54 mPa*s (the viscosity was measured at the reference concentration of 10%) .

The protein concentration in the permeate was equal to 15.0%.

The permeate was then removed from the system and recovered in a dedicated tank. The feed tank of the system was not replenished with additional gelatin solution or with water until the working time of 04:40, allowing the concentration of the protein solution to increase. At time 05:00, water was introduced into the tank in order to reach a concentration of the feeding solution of the system of 21%. The feed tank of the system is not replenished with additional gelatin solution or with water up to time 7:40. From time 08:00 to 09:40, water was introduced into the tank in order to keep the protein solution present at a constant volume of 100 liters. The concentration of this solution decreased from 12.6% to 5.4%.

During the experiment, the clarity of the feeding solution and the permeate was measured.

The results collected during the experiment are shown in the table below, wherein the number 1 indicates the addition of the hydrolytic enzyme, the number 2 indicates the recovery of the permeate, the number 3 indicates the addition of water in the feed tank until a concentration of 21% is reached, the number 4 indicates the addition of water to reach a volume of 100 liters in the feed tank . Example 3

The ultrafiltration membrane used has the following characteristics: manufacturer Koch; molecular cut 7500 Dalton; surface area 5.6 m ² .

300 liters of a solution of bovine gelatin (23.4% concentration in water) at a temperature of 44.6°C was introduced into the tank connected to the ultrafiltration system. The gelatin was fed to the ultrafiltration system by recirculating both the retentate and the permeate inside the tank maintained in agitation .

At working time 00:05, 0.9 liters of proteolytic enzyme (papain) was introduced and the concentration of the protein present both in the retentate and in the permeate was periodically monitored.

At working time 00:30, a concentration of protein present in the permeate equal to 6.8% and a viscosity of the feeding solution of 1.82 mPa*s was revealed.

The permeate was then removed from the system and recovered in a dedicated tank. The feed tank of the system was not replenished with additional gelatin solution or with water until the working time of 07:35, allowing the concentration of the protein solution to increase. At time 07:35, water was introduced into the tank in order to reach a concentration of the feeding solution of the system of 29.7%. The feed tank of the system is not replenished with additional gelatin solution or with water up to time 09:05. At time 09:05, water was introduced into the tank in order to reach a concentration of the solution feeding the system equal to 19.8%. The feed tank of the system is not replenished with additional gelatin solution or with water up to time 10:50.

At the end of the experiment, the volume in the feed tank was reduced to 100 liters, the concentration of protein in the feed solution was 23.0%, and in the permeate 9.0%. The volume of permeate collected was 260 liters. During the experiment, the clarity of the feeding solution and the permeate was measured. The results registered during the experiment are reported in the table below, wherein the number 1 indicates the addition of the hydrolytic enzyme, the number 2 indicates the recovery of the permeate, the number 3 indicates the addition of water in the feed tank until a concentration equal to 29.7% is reached, the number 4 indicates the addition of water to reach a protein concentration equal to 19.8%.

Example 4

The ultrafiltration membrane used has the following characteristics: manufacturer Koch; molecular cut 3000 Dalton; surface area 5.6 m ² .

750 liters of a solution of porcine gelatin (14.0% concentration in water) at a temperature of 43.0°C was introduced into the tank connected to the ultrafiltration system. The gelatin was fed to the ultrafiltration system by recirculating both the retentate and the permeate inside the tank maintained in agitation .

At working time 00:20, 1 liter of proteolytic enzyme was introduced and the concentration of the protein present both in the retentate and in the permeate was periodically monitored.

At working time 04:05, a concentration of protein present in the permeate of 3.6% and a viscosity of the feeding solution of 1.80 mPa*s was found. The permeate was then removed from the system and recovered in a dedicated tank. The feed tank of the system was replenished with water in order to maintain the protein concentration in the range of 14%-16% up to working time 7:35, allowing the protein concentration of the solution to increase. At the working time 08:35, the volume in the feed tank was 600 liters, the concentration of protein in the feed solution was 15.3%, and in the permeate 3.6%.

During the experiment, the clarity of the feeding solution and the permeate was measured. The results collected during the experiment are shown in the table below, wherein the number 1 indicates the addition of 1 liter of proteolytic enzyme, the number 2 indicates the recovery of the permeate and the addition of water in the feed tank so to maintain the protein concentration at a value between 14% and 15%.

Example 5

The ultrafiltration membrane used has the following characteristics: manufacturer Koch; molecular cut 10000 Dalton; surface area 5.6 m ² .

400 liters of a solution of porcine gelatin (26.1% concentration in water) at a temperature of 46.9°C was introduced into the tank connected to the ultrafiltration system. The gelatin was fed to the ultrafiltration system by recirculating both the retentate and the permeate inside the tank maintained in agitation .

At working time 00:00, 2.2 liters of proteolytic enzyme (papain) was introduced and the concentration of the protein present both in the retentate and in the permeate was periodically monitored.

At working time 00:25, a concentration of protein present in the permeate equal to 8.1% was detected.

The permeate was then removed from the system and recovered in a dedicated tank. The feed tank of the system was not replenished with additional gelatin solution or with water until the working time of 05:00, allowing the concentration of the protein solution to increase. At time 05:00, water was introduced into the tank in order to reach a concentration of the solution feeding the system equal to 20%. The feed tank of the system is not replenished with additional gelatin solution or with water up to time 05:20.

At the end of the experiment, the volume in the feed tank was reduced to 90 liters, the concentration of protein in the feed solution was equal to 23.4%, and in the permeate 15.8%. The volume of permeate collected was 430 liters.

During the experiment, the clarity of the feeding solution and the permeate was measured. The results collected during the experiment are reported in the table below, wherein the number 1 indicates the addition of 2.2 liters of proteolytic enzyme, the number 2 indicates the recovery of the permeate, the number 3 indicates the addition of water to the feed tank to reach a protein concentration of 20%.

Example 6

The ultrafiltration membrane used has the following characteristics: manufacturer Koch; molecular cut 7500 Dalton; surface area 5.6 m ² .

A proteolytic enzyme (papain) was used, in an amount equal to 2 liters.

Below, the characteristics of the starting solution comprising gelatin subjected to ultrafiltration and of the gelatin solution obtained:

Starting solution

- Porcine origin gelatin in solution with a concentration in the range of 15-25% in water

- Processed quantity 1150 kg (expressed as dry)

- Turbidity value in the range of 20-410 NTU Gelatin solution obtained

- Quantity produced 1110 kg (expressed as dry product )

- Average turbidity value: 2.0 NTU

- Average viscosity 1.49 mPa*s

In particular, 950 liters of a solution of porcine gelatin (14.4% concentration in water) at a temperature of 43.2 °C was introduced into the tank connected to the ultrafiltration system. The gelatin was fed to the ultrafiltration system by recirculating both the retentate and the permeate inside the tank maintained in agitation .

At working time 00:00, 2 liters of proteolytic enzyme (papain) was introduced, and the concentration of the protein present both in the retentate and in the permeate was periodically monitored.

At working time 01:50, a concentration of protein present in the permeate equal to 6.8% was found, while the viscosity of the feeding solution was equal to 1.49 mPa* s .

At working time 03:10, the permeate was removed from the system and recovered in a dedicated tank.

From time 03:10 to time 100:45, the feed tank of the system was replenished with gelatin solution with a concentration varying in the range of 15-25% and with water, in order to keep the volume constant and the concentration of the protein solution contained.

At time 100:45, the replenishment of the gelatin solution was interrupted, and the replenishment of water was maintained in order to maintain a constant value of the concentration of the protein solution contained in the feed tank of the system.

At the end of the experiment, the volume in the feed tank was reduced to 150 liters, the concentration of protein in the feed solution was 14.4%, in the permeate 6.8%.

The volume of permeate collected was 11580 liters.

The quantity of processed gelatin (expressed as dry) was 1150 kg, obtaining 1100 kg (expressed as dry) of hydrolyzed gelatin and using 2 liters of proteolytic enzyme .

During the experiment, the clarity of the feeding solution and the permeate was measured. The results collected during the experiment are shown in the table below wherein the number 1 indicates the addition of 2 liters of proteolytic enzyme , the number 2 indicates the beginning of the recovery of the permeate , and the feeding of water and gelatin solution in the feed tank of the system, the number 3 indicates the CIP ( Clean In Place ) washing of the system, the number 4 indicates the interruption of the introduction of gelatin into the feed tank of the system, and the introduction of water to maintain the protein concentration in the range of 14 %- 17 % .

The description of the present application provides a method for producing hydrolyzed gelatin comprising the steps of : i ) providing a starting solution comprising gelatin, ii ) filtering said starting solution through an ultrafiltration membrane to obtain a retentate fraction and a permeate fraction comprising gelatin, wherein the starting solution comprising gelatin provided in step i ) comprises at least one of hydrolyzed gelatin and non-hydrolyzed gelatin, wherein when said solution provided in step i ) comprises non-hydrolyzed gelatin, the method further comprises a step of adding at least one hydrolytic enzyme to said solution .

The method may also comprise step iii) of concentrating the obtained hydrolyzed gelatin solution in the permeate and step iv) of drying the concentrated hydrolyzed gelatin solution in step iii) .

In one or more embodiments, the transmembrane pressure used in said step ii) of filtering may be between 1 bar and 4 bar. The molecular cut-off of the ultrafiltration membrane may be between 500 Da and 50,000 Da. The ultrafiltration membrane may be selected from the group consisting of polymeric spiral membranes, steel membranes, ceramic membranes, and hollow fiber membranes. When the first solution comprises nonhydrolyzed gelatin, the method comprises a step of adding at least one hydrolytic enzyme to said first solution. Furthermore, the method may be carried out at a temperature between 10°C and 80°C, preferably between 45°C and 55°C. Steps i) to supply and ii) to add the hydrolytic enzyme may be carried out in a reaction tank. The starting solution provided in step i) may comprise gelatin in a concentration ranging from 2% to 50%.

The description also provides a hydrolyzed gelatin solution obtained with the described method.

The hydrolyzed gelatin solution obtained with a described method may have a turbidity equal to or less than 5 NTU. The gelatin obtained with the described method may have a molecular weight ranging from 50 Da to 50000 Da.

Of course, while the principle of the invention remains the same, the details of formulation and the embodiments may vary widely with respect to what has been described and illustrated purely by way of example, without departing from the scope of the present invention .