JP3279836B2 - Processing method of milk etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating milk or the like in which milk or a milk product liquid is concentrated using a heat-resistant reverse osmosis composite membrane spiral module.

[0002]

2. Description of the Related Art An evaporator is often used as a method for concentrating milk or milk product liquid. In recent years, flat membrane type reverse osmosis membrane modules are sometimes used as concentration separation means.
However, in the operation of the evaporator, a large amount of heat energy is required to evaporate a large amount of water from the dilute solution, which increases the operating cost. Further, the apparatus becomes large due to the evaporating operation, so that initial equipment costs and installation space are increased. In addition, denaturation of the protein may progress due to the concentration process at a liquid temperature exceeding 60 ° C., and the quality of the product may not be maintained.

[0003] The membrane separation method using the flat membrane type reverse osmosis membrane module does not require heat energy and can be continuously concentrated and separated. Therefore, it is widely used in various industrial fields such as foods. I have. Therefore, the problem of the operating cost in the conventional evaporator operation is solved, and further, since the concentration operation can be performed at room temperature, denaturation of the protein due to heat does not occur.

[0004]

However, in the above-mentioned flat membrane type reverse osmosis membrane module, since the liquid temperature is operated at normal temperature or low temperature, the permeation flux becomes small, and in order to manage a constant throughput, A large separation membrane area is required, and the size of the separation membrane device is increased. As a result, initial equipment costs and installation space may be larger than those of the evaporator.

In the membrane separation treatment, when the undiluted solution to be treated is concentrated for a long time, so-called fouling substances such as proteins, saccharides, and microorganisms are deposited on the membrane surface on the undiluted solution supply side, and the permeation of the membrane separation device is caused. There is a problem that flux and separation efficiency are reduced. In the membrane separation treatment of milk or milk product liquid concentration, proteins, fats and the like are accumulated, and the permeation flux and separation efficiency of the membrane separation device are remarkably reduced with time. In order to recover the membrane separation performance, it is necessary to remove fouling substances deposited on the membrane surface, and a cleaning chemical is often used for the removal. However, in order to completely remove the cleaning chemicals remaining in the flat membrane type reverse osmosis membrane module after chemical cleaning for use in a food line, a large amount of time is required for cleaning water and energy for circulating the cleaning water.

The present invention has been made in order to solve the above-mentioned problems, and is a method for membrane separation of a high permeation flux in a temperature range where protein denaturation is not caused. And a method for treating milk and the like that can be handled in a small installation space. Further, the present invention provides a method for treating milk or the like which can easily remove a fouling substance deposited on a membrane surface by using a small amount of a cleaning chemical without using or even using a cleaning chemical.

[0007]

Means for Solving the Problems The method of treating milk or the like according to the present invention is not limited to whole milk or skim milk, whey or milk.
Processed liquid (whey to soluble protein or lactose)
Is concentrated using a heat-resistant reverse osmosis composite membrane spiral module at a liquid temperature of 40 ° C. or higher, wherein the heat-resistant reverse osmosis composite membrane spiral module is subjected to a liquid temperature of 60 ° C. The above is the configuration including the washing step of sterilizing with hot water.

[0008] The main components of milk are water, protein, fat,
Carbohydrates and minerals, as well as vitamins, enzymes, pigments and other minor components are present. Most of the carbohydrates in milk are lactose, so lactose is often used instead of carbohydrates. When milk is processed and fat-rich parts are distinguished, this is called cream, and the rest is called skim milk. For skim milk, the original milk is called whole milk. Skim milk consists of insoluble protein and clear whey, and whey consists of soluble protein and lactose. The liquid processed from the above milk refers to a residual liquid obtained by separating soluble protein or lactose from whey.

[0009] The milk can be made into a commercially available milk without undergoing a concentration step after sterilization or the like. Concentration is performed as a technique for controlling the component concentration in the case of mixing the above-mentioned whey, concentrated whey, etc. with whole milk to produce milk rich in minerals. The present invention is also used as a method of using a liquid processed from the above milk, concentrated skim milk or concentrated whey to connect to the development of a new product. Furthermore, since the volume of milk or the like is reduced by concentrating it, there are great spatial and economic advantages in terms of distribution during transportation or storage.

The liquid temperature of the milk or dairy liquid used in the present invention is 40 ° C. or higher, and usually, treatment at 60 ° C. or lower can reduce protein denaturation and improve the quality of milk or dairy liquid. Can be guaranteed. However, even at a high liquid temperature exceeding 60 ° C., depending on the time of exposure to the high temperature and the heat resistance of the milk or milk product liquid used, the treatment can be carried out without increasing the denaturation of the protein. For example, in the concentration of a lactose-containing liquid from which a soluble protein has been separated, the liquid can be treated at a liquid temperature exceeding 80 ° C., so that the liquid temperature of the milk or dairy liquid to be used depends on the heat energy cost, heat resistance of the equipment material, milk or The liquid temperature of 40 ° C. or higher is appropriately determined in consideration of the heat resistance and viscosity of the dairy liquid and the relationship between the viscosity and the membrane permeation rate. Also, 4
By treating at 0 ° C. or higher, spoilage due to bacterial contamination during the treatment can be suppressed.

The heat-resistant reverse osmosis composite membrane spiral module used in the present invention can be processed at 40 ° C. or higher because the membrane and the module members have heat resistance. By including a washing step of sterilizing the membrane spiral module with hot water at a liquid temperature of 60 ° C. or higher, the membrane separation performance of the heat-resistant reverse osmosis composite membrane spiral module is quickly restored. The washing step used in the present invention usually includes a pure water washing (room temperature) step, a chemical washing step using an alkali or acidic aqueous solution, a hot water sterilization step, and a pure water washing (room temperature) step. In the hot water sterilization step, the dissolution of milk fat components and the like remaining after the chemical washing step is promoted. Even if the cleaning does not include the chemical cleaning step, the purpose of the chemical cleaning may be achieved by including the hot water sterilization step. For example, in the ten washing steps, the purpose of the chemical washing can be sufficiently achieved by including the hot water sterilization step even if the washing includes the chemical washing step once but does not include the chemical washing step. . Further, depending on the properties of the milk or dairy product liquid to be used, the purpose of chemical cleaning can be achieved by hot water cleaning without including a single chemical cleaning step.

The heat-resistant reverse osmosis composite membrane spiral module used in the present invention is, for example, a sulfonated polyethersulfone, polyvinyl alcohol or polyamide composite membrane. The module members other than the membrane material are made of a heat-resistant material such as polysulfone, epoxy, and polyphenylene sulfide. The salt rejection of the heat-resistant reverse osmosis composite membrane spiral module used in the present invention varies depending on the purpose of concentration and the physical properties of the target undiluted solution, that is, milk, etc., but generally the operating pressure is 10 kg / cm in a 0.15% NaCl aqueous solution. ² for rejection of 10-9
9.5% is preferably used.

[0013]

As described above, according to the present invention, milk or dairy product liquid is concentrated using a heat-resistant reverse osmosis composite membrane spiral module at a liquid temperature of 40 ° C. or higher, so that membrane separation can be performed at room temperature or low temperature. The permeation flux is increased as compared with the concentration, and the concentrated milk or dairy liquid can be obtained efficiently. Furthermore, since the concentration process proceeds at a temperature that suppresses protein denaturation, the quality of milk or dairy product liquid can be guaranteed, and a predetermined amount can be processed even with a small membrane area. Since the hold-up is smaller than that of the flat membrane module, the cleaning operation and the membrane replacement operation can be easily completed. Therefore, the operation cost is small. In addition, since hot water sterilization can be performed, sterilization and recovery of membrane separation performance can be easily achieved without using chemicals at the time of washing or by using only a small amount of chemicals. As a result, it is possible to produce economic advantages such as shortening of the time for the cleaning step and chemical costs. Furthermore, since the permeate of the heat-resistant reverse osmosis composite membrane spiral module obtained by the treatment method of the present invention is clear water containing a large amount of minerals such as calcium due to cell water derived from milk, it is used for beverages leading to new products. Can be served as

[0014]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples.

Example 1 A heat-resistant reverse osmosis composite membrane spiral module (manufactured by Nitto Denko, membrane material: polyamide, model: NTR-759HG-S)
4F, performance: operating pressure 15k in 0.15% NaCl aqueous solution
g / cm ² for 30 minutes after circulating operation.
ton / day, rejection 99.5%. ), 50 L of commercially available milk (3.5% milk fat undiluted solution) at a temperature of 40 ° C. and a circulation flow rate of 2
When the concentration treatment was performed twice at 0 L / min and operating pressure of 20 kg / cm ² , the permeation rate was 0.60 L / min at the start of treatment.
Met. For comparison, concentration was performed at a temperature of 10 ° C., and the permeation rate at the start of the treatment was 0.47 L / min.

Example 2 A concentration treatment was carried out in the same manner as in Example 1 except that the temperature of the milk to be treated was changed to 60 ° C. At the start of the treatment, the permeation rate was 1.28 L / min.

Example 3 Commercially available milk diluted with milk to be treated (3.5% milk fat undiluted solution 2)
The concentration was increased to 3 times in the same manner as in Example 1 except that the permeation rate was 1.33 L / mi at the start of the treatment.
n. For comparison, concentration was performed by lowering the solution temperature to 10 ° C. At the start of the treatment, the permeation rate was 1.10 L / min.
Met.

Example 4 In order to evaluate the effect of hot water sterilization, the number of viable bacteria in milk was measured. The measurement was performed according to the MF method (JIS Industrial Water K-0101, according to the Japanese Pharmacopoeia) at a culture temperature of 30 ° C. for 7 days. The viable cell count in the milk before the concentration treatment in Example 1 was 25 (CFU / mL) (CFU: COLONYFORM
ING UNIT), 30 (CFU / mL) after the concentration treatment, and 1 (CFU / mL) of viable bacteria in the washing water after hot water washing by circulation operation using pure water at 90 ° C. for 10 minutes. . As a comparative example,
When the operation at 10 ° C. was performed in the same manner as in Example 1, the viable cell count in the milk before the concentration treatment was 28 (CFU / mL), after the concentration treatment was 35 (CFU / mL), and pure water at 20 ° C. After 10 minutes of circulating operation, the number of viable bacteria in the wash water was 180 (CFU /
mL). It can be seen that the hot water sterilization of the present invention has a sufficient sterilization ability.

Example 5 In order to evaluate the cleaning effect by hot water sterilization, the permeation flux was measured. In the same manner as in Example 1, the same heat-resistant reverse osmosis composite membrane spiral module was used, and commercially available milk was concentrated up to 2 times, then washed with water at room temperature, washed with chemicals and water at room temperature, and sterilized with hot water. Three washings were performed. The results are shown in Table 1.

[Table 1] As is clear from Table 1, it can be seen that the membrane permeation performance has been recovered only by the hot water sterilization step without using a chemical.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-123426 (JP, A) Bulletin of the International Dairy Federation, No. 1, Belgium. 212, (1987), p. 38-48 Hiroshi Shimizu, Membrane Processing Technology, First Volume (Fundamentals and Products), Japan, Fuji Techno Systems Co., Ltd., March 15, 1991, p. 447-480 (58) Int.Cl. ⁷ , DB name) A23C 1/14 A01J 11/10 A23C 9/142 B01D 61/02

Claims (1)

(57) [Claims] (1) Whole milk, milk or skim milk, whey or
Liquid processed from milk (whether soluble protein or
Is a dairy product liquid which is a residual liquid obtained by separating lactose) at a liquid temperature of 40 ° C. or higher using a heat-resistant reverse osmosis composite membrane spiral module. A method for treating milk or the like, comprising a washing step of sterilizing with hot water at 60 ° C. or higher.