Patent Application
20140308417
The present invention relates to a method for producing and a device for producing a skim milk starting material milk from milk by means of centrifugal separation and treatment with a microfilter membrane.
The elimination of bacteria from milk by treating the milk in a centrifugal separator or with a microfilter membrane is known from the prior art. (See patent documents 1 to 3)
A method for centrifugally disinfecting bacteria-containing milk involves sterilizing a liquid, in which the quantity of bacteria has been concentrated, by heating, and then re-blending this liquid with milk which has been subjected to centrifugal separation. Approximately 90% of bacteria are eliminated by carrying out this treatment.
When carrying out treatment with a microfilter membrane, which separates milk into two fractions by microfiltration by causing milk to flow along the surface of a filter (a disinfecting filter), a permeate that passes through fine pores (0.1 to 10 μm) in the filter is skim milk and a retentate that does not pass through the filter is cream. Due to the fact that fat globules and bacteria present in the milk are approximately the same size, the obtained skim milk contains substantially no bacteria.
A micro-filter for microfiltration has a structure in which a porous membrane (hereinafter referred to as a “membrane”) is formed on a support body. Cross flow type microfiltration involves causing a liquid supplied to a filter to flow along a membrane, which separates the liquid into a permeate that passes through the membrane and a concentrated retentate that does not pass through the membrane.
A skim milk is obtained when the milk fat component in raw milk, bovine milk or certified milk is removed, and the skim milk powder thereof is obtained by removing the water content in order to produce a powder form. A skim milk may be used for adjusting components in milk to be adjusted and for cooking in standard homes, or used as a starting material for food products and confectionery products.
A skim milk starting material milk is subjected to treatment in order to be used in skim milk and skim milk powder.
Conventionally, skim milk starting material milk production devices were provided with a heat exchanger for heating milk to a temperature sufficient for separation, a centrifugal separator for centrifugally separating milk into a cream fraction and a skim milk fraction, a microfilter, which subjected the skim milk fraction to treatment with a microfilter membrane and had an outlet for a permeate having a reduced bacteria content and an outlet for a retentate containing the residual bacteria that did not pass through the filter membrane, and a high temperature sterilization unit for sterilizing the retentate, and the sterilized retentate was combined with the permeate to obtain a skim milk starting material milk.
In addition, other conventional skim milk starting material milk production devices were provided with a heat exchanger for heating milk to a temperature sufficient for separation, a centrifugal separator for centrifugally separating milk into a cream fraction and a skim milk fraction, a microfilter, which subjected the skim milk fraction to treatment with a microfilter membrane and had an outlet for a permeate having a reduced bacteria content and an outlet for a retentate containing the residual bacteria that did not pass through the filter membrane, and a pipe for returning the retentate from the retentate outlet to the milk supply port of the centrifugal separator, and the permeate is provided as a skim milk starting material milk.
Patent Document 1: Japanese Patent No. 2879153
Patent Document 2: Japanese Examined Patent Application Publication No. H04-12933
Patent Document 3: Japanese Examined Patent Application Publication No. H06-97945
In the former conventional production device, highly concentrated proteins present in the retentate were treated by high temperature sterilization, which led to concerns regarding denaturing of the milk and effects on the flavor of the cheese ultimately obtained. In addition, high temperature sterilization treatment consumes large quantities of energy.
In addition, in the latter conventional production devices, the retentate, which did not pass through the filter membrane and which contained high concentrations of residual bacteria, was mixed with the starting material milk and returned to the centrifugal separator, which led to concerns regarding bacteria remaining inside the separator and contaminating both the cream fraction and the skim milk fraction. In addition, because high concentrations of bacteria were returned to the centrifugal separator, the bacteria removal rate in the centrifugal separator was reduced. Furthermore, because the retentate was returned to the centrifugal separator, a higher capacity centrifugal separator was required.
An objective of the present invention is to provide a method for producing and a device for producing a skim milk starting material milk which do not require high temperature sterilization treatment, do not cause denaturing, have no risk of affecting the flavor of the cheese, have low energy consumption, have no risk of contaminating a cream fraction or a skim milk fraction due to bacteria remaining in a centrifugal separator, increase the bacteria removal rate in the centrifugal separator, and do not require a large capacity centrifugal separator.
The device for producing a skim milk starting material milk of the present invention is characterized in that it comprises a starting material supply means that supplies a starting material milk; a first centrifugal separator, which has a supply port for the starting material milk, centrifugally separates the starting material milk into a cream fraction and a skim milk fraction, and has an outlet for the cream fraction, an outlet for the skim milk fraction and a sludge discharge port; a microfilter, which has a supply port for the skim milk fraction, subjects the skim milk fraction to treatment with a cross flow type microfilter membrane, and has an outlet for a permeate having a reduced bacteria content and an outlet for a retentate containing the residual bacteria that do not pass through the microfilter membrane; a second centrifugal separator, which has a supply port for the retentate, centrifugally separates the retentate into a clean fraction having a low bacteria content and a high bacteria content fraction, and has an outlet for the clean fraction and a discharge port for the high bacteria content fraction; and a means for returning the clean fraction from the clean fraction outlet to the skim milk fraction supply port in the microfilter and/or the starting material milk supply port in the first centrifugal separator; and the permeate is provided as a skim milk starting material milk.
The method for producing a skim milk starting material milk of the present invention is characterized in that a starting material milk is supplied from a starting material supply means, said starting material milk is supplied to a supply port in a first centrifugal separator, said starting material milk is centrifugally separated into a cream fraction and a skim milk fraction, said cream fraction is discharged from a cream fraction outlet, said skim milk fraction from a skim milk fraction outlet and a sludge from a sludge discharge port, said skim milk fraction is supplied to a supply port in a microfilter, said skim milk fraction is subjected to treatment with a cross flow type microfilter membrane so as to separate said skim milk fraction into a permeate having a reduced bacteria consent and a retentate containing the residual bacteria that do not pass through the microfilter membrane, said permeate and said retentate are discharged, said retentate is supplied to a supply port in a second centrifugal separator, said retentate is centrifugally separated into a clean fraction having a low bacteria content and a high bacteria content fraction, the high bacteria content fraction is discharged, said clean fraction is returned to said skim milk fraction supply port in said microfilter and/or said starting material milk supply port in said first centrifugal separator, and said permeate is provided as a skim milk starting material milk.
An explanation will now be given of the operation/execution and effect of the skim milk starting material milk production of the present invention.
In the skim milk starting material milk production of the present invention, a starting material milk is supplied from a starting material supply means. In the present specification, the starting material milk is milked from a cow, goat, sheep, and so on.
Next, the starting material milk is supplied to a supply port in a first centrifugal separator, the starting material milk is centrifugally separated into a cream fraction and a skim milk fraction, and the cream fraction, the skim milk fraction, and a sludge are discharged from a cream fraction outlet, a skim milk fraction outlet and a sludge discharge port respectively.
Before being supplied to the first centrifugal separator, the starting material milk may be subjected to temperature adjustment using a heat exchanger or the like, pressure adjustment using a pump or the like, or flow rate adjustment using a valve or the like.
The skim milk fraction from the first centrifugal separator is supplied to a supply port in a micro-filter, treated with a cross flow type microfilter membrane, and separated into a permeate having a reduced bacteria content and a retentate containing the residual bacteria that do not pass through the microfilter membrane, and the permeate and retentate are then discharged.
The microfilter has a supply port for the skim milk fraction, subjects the skim milk fraction to treatment with a cross flow type microfilter membrane, and has an outlet for a permeate having a reduced bacteria content and an outlet for a retentate containing the residual bacteria that do not pass through the microfilter membrane.
The skim milk from the centrifugal separator is used to produce powdered skim milk or is combined with cream to produce cheese. However, the skim milk contains bacteria. In addition, these bacteria include heat-resistant spore-forming bacteria. Spore-forming bacteria cannot be eliminated by conventional high-temperature short time sterilization (HTST methods in which sterilization is carried out for 15 seconds at a temperature of 72 to 78° C.) carried out downstream of a centrifugal separation system. In cases where bacteria remain alive in the final product, these bacteria emerge from spores and start to become active during storage or treatment at temperatures and humidities suitable for propagation. Bacteria have an effect on the texture of cheese products and on the storage stability of dairy products that contain skim milk powder.
A first characteristic of the skim milk starting material milk production of the present invention is the provision of a second centrifugal separator. The retentate is supplied to a supply port in the second centrifugal separator and is centrifugally separated into a clean fraction having a low bacteria content and a high bacteria content fraction.
The second centrifugal separator has a supply port for the retentate, centrifugally separates the retentate into a clean fraction having a low bacteria content and a high bacteria content fraction, and has an outlet for the clean fraction and a discharge port for the high bacteria content fraction. The first centrifugal separator is mainly used in order to separate into skim milk and cream, whereas the second centrifugal separator is used to remove bacteria.
For example, the second centrifugal separator, which is used to remove bacteria, eliminates 60 to 99% of spore-containing bacteria by means of gravity difference within the same temperature range as the microfilter without needing to carry out heat treatment.
A second characteristic of the skim milk starting material milk production of the present invention is discharging the high bacteria content fraction and returning the clean fraction to the skim milk fraction supply pore in the microfilter and/or the starting material milk supply port in the first centrifugal separator.
This return means returns the clean fraction from the clean fraction outlet to the skim milk fraction supply port in the microfilter and/or the starting material milk supply port in the first centrifugal separator.
As the clean fraction contains the skim milk fraction which has an extremely low bacteria content, it is possible to dilute the treatment liquid and reduce the load on the centrifugal separator and it is also possible to carry out the separation by the first centrifugal separator and/or the filtering by the microfilter membrane more efficiently.
In the skim milk starting material milk production of the present invention, since the clean fraction is returned, sterilization in a high temperature sterilization unit is not performed.
There is no damage caused by high temperature heat treatment.
In the skim milk starting material milk production of the present invention, the permeate serves as the skim milk starting material milk.
The water content in the skim milk starting material milk is eliminated and accordingly a dry powder form is obtained.
As for its use, the resulting product may be used for adjusting components in milk to be adjusted and for cooking in standard homes, or used as a starting material for food products and confectionery products, etc.
By carrying out the skim milk starting material milk production of the present invention as described above, it is possible to produce a skim milk starting material milk which does not require high temperature sterilization treatment of the skim milk fraction, and accordingly, does not cause denaturing to proteins or flavor components, has no risk of affecting the flavor of the cheese product, has low energy consumption due to the skim milk fraction not being heated to a high temperature, has no risk of contaminating the cream fraction or the skim milk fraction due to bacteria remaining in the first centrifugal separator, increases the bacteria removal rate in the first centrifugal separator, and does not require a large capacity first centrifugal separator.
A detailed explanation will now be given of a mode for implementing the present invention with reference to the drawings.
In the skim milk starting material milk production of the present embodiment, a starting material milk (2) is supplied from a starting material supply means (1); that is a storage tank. The starting material milk (2) is milked from dairy cattle.
First, the starting material milk (2) is supplied to a supply port (4) in the first centrifugal separator (3) and centrifugally separated into a cream fraction (5) and a skim milk fraction (6), and the cream fraction (5), the skim milk fraction (6) and a sludge (10) are discharged from a cream fraction outlet (7), a skim milk fraction outlet (8) and a sludge discharge port (9) respectively.
Before being supplied to the first centrifugal separator (3), the starting material milk may be subjected to temperature adjustment using a heat exchanger, pressure adjustment using a pump or the like, or flow rate adjustment using a valve or the like, which are not shown in the drawings.
The skim milk fraction (6) from the first centrifugal separator (3) is supplied to a supply port (12) in a microfilter (11), treated with a cross flow type microfilter membrane (13), and separated into a permeate (14) having a reduced bacteria content and a retentate (15) containing the residual bacteria that do not pass through the microfilter membrane, and the permeate (14) and retentate (15) are then discharged.
The microfilter (11) has the skim milk fraction supply port (12), subjects the skim milk fraction (6) to treatment using the cross flow type microfilter membrane (13), and has an outlet (16) for the permeate (14) having a reduced bacteria content and an outlet (17) for the retentate (15) containing the residual bacteria that do not pass through the microfilter membrane.
The skim milk fraction (6) from the centrifugal separator is ultimately used to produce skim milk. The skim milk (6) contains bacteria, and bacteria are separated into the retentate (15).
A first characteristic of this mode is the provision of a second centrifugal separator (18). The retentate (15) is supplied to a supply port (19) in the second centrifugal separator (18) and centrifugally separated into a clean fraction (20) having a low bacteria content and a high, bacteria content fraction (21).
The second centrifugal separator (18) has the supply port (19) for the retentate (15), centrifugally separates the retentate (15) into the clean fraction (20) having a low bacteria content and the high bacteria content fraction (21), and is provided with an outlet (22) for the clean fraction (20) and a discharge port (23) for the high bacteria content fraction (21). The first centrifugal, separator (3) is mainly used in order to separate into skim milk and cream, whereas the second centrifugal separator (18) is used to remove bacteria (21).
The second centrifugal separator (18) eliminates 60 to 99% of spore-containing bacteria by means of gravity difference within the same temperature range as the microfilter without needing to carry out heat treatment.
A second characteristic of this mode is discharging the high bacteria content fraction (21) from the system and returning the clean fraction (20) to the skim milk fraction supply port (12) in the microfilter and/or the starting material milk supply port (4) in the first centrifugal separator.
Which of these supply ports to return the clean fraction to is a matter that should be appropriately altered and selected according to the type of starting material milk, skim milk, cheese, and so on.
The return means, which consists of ducts, pipes, valves and so on, returns the clean fraction (20) from the outlet (22) for the clean fraction (20) to the skim milk fraction supply port (12) in the microfilter (11) and/or the starting material milk supply port (4) in the first centrifugal separator (3).
In this mode, because the clean fraction (20) contains the skim milk fraction, which has an extremely low bacteria content, it is possible to dilute the treatment liquid and reduce the load on the treatment device (the centrifugal separator or microfilter) to which the treatment liquid is returned. It is possible to carry out the separation by the first centrifugal separator and/or the filtering by the microfilter membrane more efficiently.
In this production mode, sterilization in a high temperature sterilization unit is not performed.
In this mode, there is no damage caused by high temperature heat treatment.
In this production mode, the permeate (14) is served as a skim milk starting material milk (26).
The water content in the skim milk starting material milk is eliminated and accordingly a dry powdery form is obtained.
As for its use, the resulting product may be used for adjusting components in milk to be adjusted and for cooking in standard homes, or used as a starting material for food products and confectionery products, etc.
In conventional skim milk starting material milk production, there are provided a centrifugal separator (3) that centrifugally separates milk (2) into a cream fraction (5) and a skim milk fraction (6); a microfilter (11) which subjects the skim milk fraction (6) to treatment using a microfilter membrane (13) and which has an outlet (16) for a permeate (14) having a reduced bacteria content and an outlet (17) for a retentate (15) containing the residual bacteria that do not pass through the microfilter membrane; and a high temperature sterilization unit (24) which sterilizes the retentate (15), and a sterilized retentate (25) is combined with the permeate (14) to form a skim milk starting material milk (26).
As can be seen from the comparison given above, the skim milk starting material milk production of the present invention does not require high temperature sterilization treatment of the retentate of the skim milk fraction, and accordingly, does not cause denaturing to proteins or flavor components, has no risk of affecting the flavor of the cheese product, and has low energy consumption due to the retentate of the skim milk fraction not being heated to a high temperature.
With this production, there is provided a centrifugal separator (7) that centrifugally separates milk (2) into a cream fraction (5) and a skim milk fraction (6); a microfilter (11) which subjects the skim milk fraction (6) to treatment using a microfilter membrane (13) and which has an outlet (16) for a permeate (14) having a reduced bacteria content and an outlet (17) for a retentate (15) containing the residual bacteria that do not pass through the microfilter membrane; and a pipe (27) for returning the retentate (15) from the retentate outlet (17) to a milk supply port (4) in the centrifugal separator (3), and the permeate (14) serves as a skim milk starting material milk (26).
As can be seen from the comparison given above, the skim milk starting material milk production of the present invention has no risk of contaminating the cream fraction or the skim milk fraction due to bacteria remaining in the centrifugal separator, increases the bacteria removal rate in the centrifugal separator and does not require a large capacity centrifugal separator.
The example given below shoos how a skim milk starting material can be produced according to the present invention.
Milk having a fat content of 4.05% and a protein content of 3.47% is supplied to a first centrifugal separator at a rate of 10,000 liters per hour.
A cream fraction having a fat content of 40.00% is removed from the first centrifugal separator at a rate of 1,000 liters per hour. Meanwhile, a skim milk fraction having a fat content of 0.05% and a protein content of 3.60% is removed from the first centrifugal separator at a rate of 9,000 liters per hour.
The skim milk fraction is supplied to a microfilter, and a permeate having a fat content of 0.04% and a protein content of 3.58% is removed at a rate of 8,550 liters per hour. Meanwhile, a retentate having a fat content of 0.24% and a protein content of 3.98% is removed at a rate of 450 liters per hour.
The 450 liters per hour of retentate is introduced into a second centrifugal separator. A clean fraction is removed from the second centrifugal separator, mixed with the skim milk fraction, and supplied to the microfilter.
Meanwhile, a high bacteria content fraction is discharged as a sludge from the second centrifugal separator to outside the system.
The permeate from the microfilter is used as a standardized milk for the cheese ultimately produced.
Moreover, the present invention is not limited to the aforementioned working example, a variety of alterations are possible under the gist of the present invention, and these alterations are not excluded from the scope of the present invention.
This invention can be used to produce a skim milk starting material milk.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-243066 | Nov 2011 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2012/078401 | 11/1/2012 | WO | 00 | 5/6/2014 |
