JP3149256B2 - How to concentrate food - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for concentrating food. More specifically, the present invention relates to a method for highly concentrating foods without using a specific pervaporation membrane, thereby impairing or losing the aroma and flavor contained in the foods.

[0002]

2. Description of the Related Art As a method of concentrating a liquid food, a reduced pressure heating concentration method and a freeze concentration method have been known for a long time. However, while the vacuum heating and concentration method is efficient, it has a problem that the unique flavor of each food is changed or lost due to the loss of volatile components that cause the flavor. In addition, the freeze-concentration method has low efficiency, and likewise, depending on the food, freezing often causes a change or loss of flavor. On the other hand, in recent years, functional membranes have been used for concentrating foods. For example, JP-A-56
Japanese Patent No. 29954 discloses a technique for preventing loss and deterioration of aroma components by combining an extract such as coffee with an ultrafiltration membrane and a reverse osmosis membrane. JP-A-3-195482 discloses a method for concentrating vegetable juice and fruit juice by combining reverse osmosis concentration and vacuum concentration. Japanese Patent Application Laid-Open No. Sho 62-241 discloses a method for producing an instant beverage, which comprises concentrating an extract of tea leaves and cereals by a reverse osmosis concentration method, and further spray-drying the concentrate. However, in the concentration method using a reverse osmosis membrane, there is a problem that the concentration cannot be increased to a certain concentration or more by itself because the osmotic pressure is used. On the other hand, pervaporation has been attracting attention as a method for separating a liquid mixture. Polymer Processing (1988, 37, 4 25
As described in page 2), in the separation method based on pervaporation, a liquid mixture is mainly used for separation, and is divided into a primary side and a secondary side across a membrane, and the separated liquid mixture is fed to the primary side. The secondary side contains the vaporized vapor of the permeate (permeate), which is in contact with the non-active porous layer of the membrane. In this state, if there is a difference in the chemical potential constituting each mixture on both sides of the membrane,
The driving force causes molecules on the feed side to move through the membrane. At this time, due to the difference in the resistance of each molecule in the membrane, the membrane permeability of each component is different, so that the component having a high membrane permeability is concentrated on the permeate side, and the component decreases on the feed side. In practice, in order to lower the vapor partial pressure of the osmotic component on the permeation side of the membrane, a method of evacuating with a pump or flowing an inert gas is used. According to this method, it is known that an azeotrope or the like, which was conventionally difficult to separate, can be efficiently separated.
It can also be continued from a mixture of components with good and poor permeability until the desired separation is achieved. The features of this method are energy saving, easy dehydration of multi-component mixture, no risk of product contamination and pollution, purification to high purity, small plant installation area It is mentioned that automation, labor saving and the like are easy. It is conceivable to apply the pervaporation method having the above-mentioned excellent characteristics to the concentration of food instead of the conventional method. For example, Japanese Patent Laid-Open No. 2-268813, a method of concentrating by pervaporation fruit juice or the like using a film containing a specific amount of carboxylic acid monomer units is disclosed. Similarly, JP-A-3-306
Care about 62 JP - in the membrane separation process of the liquid system, the alcoholic beverage is supplied to the primary side of the hydrophobic membrane, a secondary capturing the vapor which passes through the secondary side when the lower pressure than the primary side A method for producing an alcoholic beverage having a higher alcohol concentration than the stock solution is disclosed. An ultrafiltration level membrane is used as the separation membrane.

[0003]

However, even if a pervaporation method is used to concentrate food, it is not always easy to concentrate without losing the flavor of coffee, wine, fruit juice or the like, or losing the aromatic components. Was not. That is, the index for selecting the pervaporation membrane to be adopted was not clear.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies in applying the pervaporation method to the concentration of food, and found that if a pervaporation membrane having a specific separation performance represented by a specific index is used, With the knowledge that the desired concentrated food can be obtained without leaking the flavor component of the food,
The present invention has been completed.

That is, the first aspect of the present invention is that the content is 90 to 90%.
In addition to 97 mol% of acrylonitrile structural units,
Copolymer having 2-diethylaminoethyl structural unit
An asymmetric membrane consisting of a body, comprising 2-5% by weight of ethyl acetate
Separation factor for water when treating aqueous solution
And the water permeation rate is 3.0 kg / 70 ° C.
dewatering using a pervaporation membrane of m ² · hr or more
The second is a method for concentrating food, characterized in that, in the first invention, a food that has been concentrated in advance using a reverse osmosis membrane is used as a concentrated raw material.

[0006] The pervaporation membrane used in the present invention is 2
Against water when using an aqueous solution of -5% by weight of ethyl acetate
That the separation factor of 10 or more, and the permeation rate of water 70 ° C.
At least 3.0 kg / m ² · hr
However, the separation factor for water is 20 or more,
Particularly, the overspeed is 4.0 kg / m ² · hr or more.
preferable. Incidentally, the separation factor referred to herein (alpha) is, (Cw
/ Ce) Permeate / (Cw / Ce) feed. Here, Cw indicates the concentration of water, and Ce indicates the concentration of ethyl acetate.

[0007] In the present invention, water under the above conditions
The separation coefficient is 10 or more and the water permeation rate
Using a pervaporation membrane with a value of 3.0 kg / m ² · hr or more
In effect, the flavor side of the food is substantially on the permeate side of the membrane.
Almost no leakage and no loss of food flavor
Achieve the object of the present invention of efficiently concentrating foods
I can do it.

The above-mentioned separation factor and transmission used in the present invention.
A specific copolymer is used as a pervaporation membrane having a high speed.
The asymmetric membrane used is usually a non-porous membrane. The active membrane (skin layer) has a thickness of 1 to 2 μm and is formed as a homogeneous polymer membrane on a porous support layer such as a nonwoven fabric. It consists of a structure. Film forming method is not specific, it may be used as the known methods.

As the active membrane of the pervaporation membrane for separation, usually,
Cellulose esters, polyamides, polyimides, polysulfones, polyacrylonitrile-based polymers and the like are used, but those composed of acrylonitrile-based polymers are particularly preferred. Construct the pervaporation membrane used in the present invention
As the material of the active film, 90 to 97 mol% of acrylonitrile
2-diethylamino methacrylate in addition to the tolyl structural unit
Acrylonitrile copolymer having ethyl structural unit
used. 2-diethylaminoethyl methacrylate
In order to solve the problem of the present invention,
Therefore, the function as a useful active film is improved. The
Contains 2-diethylaminoethyl methacrylate structural unit
The amount is not particularly limited, and the acrylonitrile structure
It is used within the range of 100 mol% in total with the structural units.

[0010] acrylonitrile used in the present invention
Methacrylic acid constituting the Le copolymer 2- Jiechiruami
Other monomers other than vinyl ethyl include vinyl acetate, methacrylic acid, acrylic acid, methacrylic esters, acrylic esters, acrylamide, vinyl sulfonic acid, styrene sulfonic acid, vinyl pyrrolidone, vinyl pi
Lysine, maleic anhydride , 2-acrylamido-2-methyl-1-propanesulfonic acid and the like can be mentioned. In addition,
The preferred molecular weight of the acrylonitrile copolymer according to the present invention is 20,000 to 500,000.

[0011] Examples of the foods that can be applied to the present invention is coffee, Japanese tea, non-alcoholic beverages of tea, etc., sake, wine, alcoholic beverages such as beer, vinegar, soy sauce, source,
Examples include seasonings such as mirin and fruit juices such as orange, apple, grape, and pineapple. Taking coffee as an example, a coffee extract, instant powdered coffee and the like can be produced by concentrating the coffee extract by the method of the present invention or by combining another additional step. In addition, the food concentration method of the present invention is not limited to simple concentration, and may be combined with another step. For example, it is possible to increase the degree of concentration by using the method of the present invention for foods that have been concentrated using a reverse osmosis membrane in advance. Alternatively, it can be applied to the development of beverages with new flavors that have never been seen before. For example, in the production of whiskey, by combining the distillation step and the concentration method of the present invention, it is also possible to produce an alcoholic beverage having a new flavor that has never existed before.

[0012]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0013] (Reference Example 1) a known method polyacrylonitrile copolymer polymerized on the basis of (acrylonitrile / vinyl acetate / methacrylic acid 2-diethylaminoethyl = 94/5/1 (molar ratio),
(Viscosity average molecular weight 62,000) in dimethylformamide (DMF) to give a 20% by weight solution, which is applied to a polyester woven fabric at a thickness of 250 μm and subsequently coagulated in water at 15 ° C. An asymmetric film having a skin layer having a thickness of 1 μm was prepared. This membrane was further boiled in hot water for 1 hour to obtain a target pervaporation membrane. The performance of the obtained pervaporation membrane was 70 ° C., 4.4
The test was conducted using a weight% aqueous solution of ethyl acetate. as a result,
The separation coefficient (α) for water is 53, and the water permeation rate is 4.
It was ² kg / m ² · hr. Similarly, when a 9.8% by weight aqueous solution of ethyl acetate at 70 ° C. was used, the separation coefficient with respect to water was 60, and the permeability coefficient of water was 3.2 kg / m ² · hr.

[0014] with (Example 1) pervaporation membrane obtained in Reference Example 1, was assembled pervaporation apparatus shown in FIG. In FIG. 1, 1 is a heating jacket by a heat medium, 2 is a prepared food, 3 is a sealing nitrogen supply port and an outlet, 4 is a stirring rod, 5 is a pervaporation membrane, 6
Is a liquid nitrogen cooling bath, 7 is a trap, and 8 is a vacuum pump. Note that the effective membrane of the pervaporation membrane is a circle of 47 mmφ.
Was . Using a commercially available coffee maker, 20 g of coffee powder was extracted with 300 g of hot water. 200 g of the extract was pervaporated and dehydrated by the apparatus shown in FIG. The treatment is performed at a temperature of 70 ° C. for 3 hours, and 12.2 g of colorless,
A clear, tasteless, odorless permeate was obtained. The thus concentrated coffee was subjected to gas chromatography analysis using a PEG20M column, and as a result, peaks of many volatile components as shown in FIG. 2 were detected. In FIG. 2, the horizontal axis represents time, and the vertical axis represents peak intensity. The numbers in the figure indicate the retention time (minutes) of the peak component. Similarly, as a result of performing gas chromatography analysis of the permeate, no peak was detected.

[0015] (Example 2) using a commercially available coffee maker, coffee was extracted with hot water from the coffee beans 30g you powder 300g roasted 1
50 g was pervaporated and dehydrated using the same membrane and apparatus as in Example 1. The treatment was carried out at a temperature of 80 ° C. for 8.5 hours, and 56.85 g of a colorless, transparent, tasteless and odorless permeate was obtained in the trap. The average permeation rate of water for 8.5 hours is 3.85 Kg /
m ² · hr. Subsequently, pervaporation dehydration was performed for 30 minutes to obtain 3.4 g of a permeate. The water permeation rate at this time was 3.9 kg / m ² · hr. Even when concentrated to a high concentration, no decrease in the water permeation rate was observed.

[0016]

As described in detail above, by employing the method for concentrating food of the present invention, food can be efficiently concentrated without impairing or losing the aroma and flavor contained in the food. .

[Brief description of the drawings]

FIG. 1 shows a pervaporation separation apparatus used in Example 1 of the present invention.

FIG. 2 shows the results of analysis of coffee concentrated in Example 1 by gas chromatography.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating jacket 2 Food preparation 3 Seal nitrogen supply port and outlet 4 Stirrer bar 5 Pervaporation membrane 6 Liquid nitrogen cooling tank 7 Trap 8 Vacuum pump

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B01D 61/36 A23F 5/28 B01D 61/02 B01D 61/58

Claims (2)

(57) [Claims] An acrylonitrile having a content of 90 to 97 mol%.
2-diethylamino methacrylate in addition to the tolyl structural unit
An asymmetric membrane made of a copolymer having ethyl structural units
Thus, when a 2 to 5% by weight aqueous solution of ethyl acetate is treated
Has a separation coefficient of 10 or more for water, and has a water permeation rate
Is not less than 3.0 kg / m ² · hr at 70 ° C.
Concentration of foods characterized by dehydration using a gas permeable membrane
Method. 2. A food previously concentrated using a reverse osmosis membrane.
The method for concentrating food according to claim 1, wherein the product is a concentrated raw material.