WO2001076395A1 - Method and device for freezing food - Google Patents

Abstract

A freezing method and device, which provide frozen food having the same quality after unfreezing as before freezing. A food freezing device (1) comprising a freezing tank (2) containing an antifreeze solution (7), a motor-driven antifreeze solution driving section (3) installed in the freezing tank, a motor-driven freezing subject elevating section (4) supporting food to be frozen and immersed in the antifreeze solution in the freezing tank, and a motor-driven freezing machine (5) for cooling the antifreeze solution, wherein a high potential field generating means (6) is installed to impart an electric field to the antifreeze solution, the whole device is electric-insulation-wise supported on an installation floor (27), each motor is electric-insulation-wise supported on an attaching portion, and the motor output is delivered through electric insulation belts (15, 22, 30).

Description

 Specification

 Food freezing method and freezing device

Technical field

 The present invention relates to a food freezing method and a food freezing device used in the method.

Background art

 As a method of freezing food, it is generally well-known that cold air is brought into contact with the inside of a freezer.However, where cold air flow does not sufficiently come into contact, for example, the back, side, and bottom of appropriately arranged foods. The frozen food tends to have uneven freezing, and its low thermal conductivity increases the time it takes to pass through the maximum ice crystal formation zone (-1 to 15 ° C) of the food to be frozen. Water becomes ice crystals, grows, causes tissue destruction, and drips when thawing, leading to quality deterioration. Therefore, to prevent food deterioration due to freezing, it is important to pass through the maximum ice crystal formation zone in a short time.

 Therefore, a rapid air freezing method and a freezing method using liquid nitrogen and liquid carbon dioxide have been proposed. In addition, utilizing the low freezing temperature of salt water, calcium chloride aqueous solution, propylene glycol, alcohol solution, and the like, a pline freezing method has been put to practical use in which food to be frozen is directly immersed in these solvents. The biggest advantage of this method is that since the thermal conductivity of brine solution is one order of magnitude higher than that of air, the freezing speed is high and the maximum ice crystal formation zone, which is the main cause of quality deterioration of frozen foods (-1 to 1) (5 ° C).

However, freezing foods with a high moisture content, foods with weak tissues (cells), wasabi, chicken liver, milt of fish, etc., or those with a freezing temperature difference such as lean and fat, may lose their shape during thawing or destroy tissue. This causes a problem of deterioration in quality such as texture, texture, texture and the like. Recently, a special magnetic field has been created in the cold air (freezer) to generate a weak current inside the food, causing water molecules in the food to vibrate due to the magnetic field resonance phenomenon. By using a dielectric freezer that does not crystallize (Tetsuo Owada, “Building Equipment and Plumbing” No. 11, 1989), drip during thawing can be reduced by freezing water at the same time as starch and protein in food materials. Attempts have been made to produce fresh frozen foods.

 The dielectric freeze method, in which a magnetic field is applied to the air while freezing, does not become ice crystals even when the water content of the food is 0 to -5 ° C, and the water freezes at the same time as the starch and protein of the food material. There is an advantage that no dripping occurs because the water in the tissue does not become ice crystals at first. However, it is difficult to create a uniform and stable shape of the magnetic field in cold air in a large chamber, which is not suitable for mass production that requires a large volume. No refrigeration method using a magnetic field in brine has been attempted.

 As described above, despite the demand for frozen foods with good freshness, excellent texture, color tone and flavor, and few trips when thawing, the conventional freezing method has the advantages and disadvantages that are still satisfactory. Absent.

 Therefore, an object of the present invention is to provide a high-quality frozen food that is the same as before freezing even after thawing.

Disclosure of the invention

In general, the present invention provides a manufacturing method and a manufacturing apparatus capable of mass-producing high-quality frozen food by supplementing the disadvantages of the brine refrigeration method and the high-potential electric field refrigeration method by applying a high-potential electric field to antifreeze. It can be provided. That is, the method of the present invention is characterized in that, in the prine freezing method in which an object to be frozen is immersed in antifreeze and frozen, an electric field is applied to the antifreeze to perform freezing. The present invention provides the advantages of each of the above-described prine refrigeration and dielectric freezer refrigeration. This is because the high potential electric field in the solution can be applied more uniformly than in air, and the high potential electric field can be applied to the pipeline in a large solution pipeline. A potential electric field can be applied, and a large amount of frozen products can be processed. In addition, the time required for freezing to pass through the maximum ice crystal formation zone (11 to 15 ° C), which is important for food quality, can be reduced by about 20% compared to the conventional pline freezing method. As a result, it is possible to produce frozen foods with good freshness, excellent texture and color tone, and with little drip when thawed. Furthermore, it is applied to wasabi, wasabi, milt of fish, etc., which had weak tissue (cells), which was difficult with the conventional freezing method. After thawing, there was almost no decrease in freshness, and the flavor, texture, color tone, etc. were reduced. No food with little drip was obtained, making it possible to produce frozen food. Foods to be subjected to the freezing method of the present invention include marine products such as fish, shellfish, seaweed, crustaceans, fish eggs, livestock products such as cattle, pigs, chickens, eggs, agricultural products such as root vegetables and fruits, and These cooked products include food in general.

 An apparatus according to the present invention comprises: a freezer containing an antifreeze maintained at a low temperature; an antifreeze driving unit provided in the freezer and driven by an electric motor to stir or circulate the internal antifreeze; A frozen object lifting / lowering unit provided to support food and immersed in antifreeze in the freezer and driven by an electric motor; and a refrigerator driven by an electric motor for cooling the antifreeze. In the food freezing apparatus provided, a high-potential electric field generating means is provided to apply an electric field to the antifreeze, the whole apparatus is electrically insulated and supported on an installation floor, and each of the electric motors is mounted. It is characterized in that it is electrically insulated and supported by the section and outputs the output power through an electrically insulating belt.

Since the entire device is insulated and supported on the floor on which the device is installed, it is possible to apply an electric field from the high potential generating means to the antifreeze in the freezer without any trouble ₍ In addition, since the electric motor, which is the driving source of each unit that mechanically drives the device, is insulated from the mounting unit and the driving force is transmitted through the insulating belt, the electric motor is used. There is no influence of the high potential electric field generation means on the side, and each operation part operates reliably. Therefore, the method of the present invention can be performed. As a high-potential electric field generating means, a high-frequency electric potential generator (Japanese Patent Publication No. 38-610), which was invented by Mr. Kubo, is suitable. One of the secondary terminals of the transformer is insulated and sealed, and the other is connected to the pipeline. The point of the high potential electric field generating means is that one of the output terminals is insulated and sealed, and the current hardly flows. The brine solution to be used may be calcium chloride, ethylene glycol, propylene glycol, an alcohol solution, or a mixture thereof, and a 50-68% ethyl alcohol aqueous solution may be used. It is preferable to use it after cooling to ~ 57 ° C, and it is suitable for freezing food.

 The high potential generated by the high potential electric field generating means employed in the present invention may be AC or DC. In the case of alternating current, the frequency is not particularly limited, but may be higher than 50 or 60 Hz. In short, when the frozen object passes through the maximum ice crystal formation zone, Any high potential or magnetism may be used as long as the ion binding force of water molecules in the object is not weakened. BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 shows a schematic configuration of an embodiment of the device of the present invention, in which (a) is a partially longitudinal front view, (b) is a side view, and (c) is a plan view.

FIG. 2 is a graph showing the difference in the maximum ice crystal formation zone transit time between Example 1 and Comparative Example 1. BEST MODE FOR CARRYING OUT THE INVENTION

 An embodiment of the method of the present invention is to form an electric field applied with a high potential of 5 to 100 kv in antifreeze cooled to −20 to −50 ° C. and to form an electric field in a container made of polyethylene or the like. Frozen food is immersed for 10 to 60 minutes to obtain frozen food. The refrigeration system used in this method is as shown in Fig. 1.

 The food refrigerating apparatus 1 shown in FIG. 1 includes a freezer 2, an antifreeze driving unit 3, a frozen object elevating unit 4, a refrigerator 5, and a high-potential electric field generating unit 6. The freezer 2 has a heat insulating structure using a heat insulating material, and stores the antifreeze 7 therein, and the net shelf 9 supporting the article to be frozen 8 descends from the opening opening upward and is immersed in the antifreeze 2. It has become to be. This freezer 2 is supported on the floor 7 via insulators 34.

 The antifreeze driving unit 3 immerses the shaft 11 with the propeller 10 in the antifreeze 7 and rotates the propeller 10 to stir the antifreeze so that the whole becomes a uniform temperature or circulates. The antifreeze liquid 2 is in good contact with the heat absorbing portion 1 2 of the refrigerator 5 and is sufficiently cooled, and the low temperature antifreeze liquid is effectively contacted with the frozen product 8 in the net shelf 9 to be uniformly cooled. It is to make sure. The rotary drive of the propeller shaft 11 is an electric motor 13, and the electric motor 13 is mounted via an insulating insulator 14, and the rotation output is output via an insulating belt 15, for example, via a rubber belt. You. Thus, the motor 13 is completely electrically insulated from the rest of the food freezer 1.

The to-be-frozen material lifting / lowering unit 4 drives the net shelf 9 up and down, and supports the net shelf 9 on a net shelf supporting part 16. The net shelf supporting part 16 is set up on the edge of the freezer 2. It can be moved up and down by being guided by two guide posts 17, and a rotating screw shaft 18 provided between the posts 17, 17 in parallel with this and a screw It is designed to be driven up and down by a female screw portion 19 provided in the joining net shelf support portion 16. The rotation of the screw shaft 18 is performed by an electric motor 20. This motor 20 is also attached via the insulator 21 in the same manner as described above, and outputs via the insulating belt 22.

 In the refrigerator 5, the compressor part 23 is installed at an appropriate position beside the freezer 2, a heat absorbing part (freezing coil) 12 is installed at the bottom of the freezer 2, and the compressor part 23 and the heat absorbing part 1 2 Is connected by a refrigerant passage 25, and a compressor outside the freezer and a portion related to the compressor are supported on a floor surface 27 via an insulator 26. Further, a motor 28 for driving the compressor is also separately supported on the floor via an insulator 29, and is output via an insulating belt 30.

 The high-potential electric field generating means 6 uses the above-described high-frequency potential generating device, which is supported on the floor surface 27 via the insulating insulator 31, one of the secondary terminals is insulated and sealed, and the other is Is brought into contact with the antifreeze 7 in the freezer 2 via the electrode 33 connected to the conducting wire 32.

 In this refrigerating apparatus, the refrigerator 5 and the antifreeze driving unit 3 are operated in advance to lower the antifreeze 7 in the freezer 2 to a predetermined temperature or less, and the frozen product 8 is placed on the net shelf 9 to be frozen. The object to be frozen 8 can be frozen in a high-potential electric field by operating the object lifting / lowering section 4 to immerse the article in the antifreeze 7 and raising the net shelf after a predetermined time.

 Examples of the method of the present invention will be described below, but the present invention is not limited to these examples.

[Example 1]

Fatty raw beef cut to a thickness of 80 mm, length and width 80 mm, It was stored in a polyethylene bag, evacuated and sealed, and then frozen according to the method of the present invention. The antifreeze 7 was cooled to −35 to −38 ° C in advance using a 55% ethyl alcohol aqueous solution (150 liters), and the cooled antifreeze was added to the cooled antifreeze by a high-potential electric field generator 6 at 10 kV. An electric potential was applied to crush the beef. The temperature course of the beef during immersion was measured using a temperature sensor, and the results are shown by curve A in Fig. 2. Fig. 2 shows a curve obtained by freezing the same beef and measuring the elapsed temperature under the same conditions except that the high-potential electric field generating means 6 was not operated, that is, without applying the electric field, as Comparative Example 1. Shown by B.

 As shown in FIG. 2, the passage time in the maximum ice crystal formation zone (11 to 15 ° C.) is 7.5 minutes in Example 1 and 9.5 minutes in Comparative Example 1. Is about 20% shorter. The reason is that the application of a high-potential electric field causes the water in the beef to vibrate, reducing the size of the water and reducing the energy load.

The frozen beef of Example 1 and Comparative Example 1 was preserved at −30 ° C. for one month, spontaneously thawed and tasted. As a result, the beef of Example 1 had good freshness and flavor. Comparative Example 1 Was slightly inferior to that of Example 1. Although no significant difference was observed, the color after thawing was judged to be closer to the color before freezing in Example 1 than in Comparative Example 1 in the photographic judgment, and almost completely distinguished from Example 1 before freezing. It was not enough.

[Example 2]

The bamboo shoots excavated in the morning were peeled, and the body was stored in a polyethylene bag in the same manner as described above to obtain a sample. In the freezing, an ordinary freezer was used, which was frozen under the same conditions as in Example 1 with an electric field applied, and Example 2 and that frozen under the same conditions as in Comparative Example 1 without applying an electric field was Comparative Example 2. Compare frozen ones Example 3 was used. After freezing, they were stored in the same freezer at 130 ° C for 10 days, then thawed with cold water, and their taste was evaluated. The results are shown in Table 1. The values in the table are the sum of the evaluation scores from eight general panelists. The evaluation scores are 3 for good, 2 for normal, and 1 for bad. From the results in Table 1, it is clearly recognized that the example 2 is good. table 1

[Example 3]

2 cups of water, 1 cup of sake, 2 tablespoons of mirin, 6 tablespoons of sugar, 2 tablespoons of sugar, 1 1/2 tablespoon of soy sauce. Boil the cups, put about 600 g of fish milt, and boil about 1 2 Cook over medium heat until This boiled milt is placed in a polyethylene container, sealed and used as a sample for freezing. There were three types of freezing treatment using this sample: Example 3 according to the method of the present invention, Comparative Example 4 using the dielectric freeze method using cold air for comparison, and Comparative Example 5 using a general freezer freezing. The dielectric freeze method used an ABI Tomin rack-type freezer, and it took about 2 hours for the temperature of the frozen product to reach -25 ° C. Each of the obtained frozen products was stored at −30 ° C. for 7 days, thawed with running water, and subjected to a taste test. The results are shown in Table 2. The values in the table are the sum of the scores of the evaluations by the seven general panelists. The evaluation scores are 3 for good, 2 for normal, and 1 for bad. From the results in Table 2, it can be clearly seen that Example 3 is good. Table 2

 Separately, when each sample was thawed and placed on a filter paper and the amount of liquid falling was examined as a drip, it was hardly recognized in Example 3 and Comparative Example 4, but was reliably obtained in Comparative Example 5. Also, the tactile crispness was best in Example 3, followed by Comparative Example 4 which was slightly weaker, and Comparative Example 5 was insufficient.

[Example 4]

After boiling the crab, the meat of the legs was taken out, placed in a polyethylene bag and sealed to make a sample. There were three types of freezing treatment using this sample: Example 4 by the method of the present invention, Comparative Example 6 by the solution brine method without applying a high-voltage electric field for comparison, and Comparative Example 7 by freezer freezing. As the antifreeze in the freezing of Example 4 and Comparative Example 6, a 50% aqueous solution of ethyl alcohol was used. The obtained frozen product was stored at −30 ° C., subjected to natural thawing 60 days later, and subjected to a taste test. The results are shown in Table 3. The values in the table are the sum of the scores of the evaluations by the seven general panelists. The evaluation scores are 3 for good, 2 for normal, and 1 for bad. In addition, when the tactile sensation is expressed in words, if the crab is good, it has elasticity, crab flavor, juicyness, etc., but if it is bad, it has elasticity. Rather than paper, etc., and the figures in the table reflect these. Table 3 clearly shows that Example 4 is superior. Table 3

[Example 5]

Raw wasabi was placed in a polyethylene bag and sealed to form a sample.Frozen treatment using this sample was performed in the same manner as in Example 4 except that a high voltage electric field was applied for comparison with Example 5 according to the method of the present invention. There were three types, Comparative Example 8 using the solution plumbing method and Comparative Example 9 using the freezer. The frozen product was naturally thawed after storage at −30 ° C. for 60 days, and a taste-related test was performed. As a result, in Example 8 and Comparative Example 9, the raw wasabi was so soft that it could not be rubbed off with a grater, but in Example 5 it could be rubbed down with a grater in the same way as hard, unfrozen fresh raw wasabi. In Example 5, the scent of wasabi appears only after being rubbed down, but in Comparative Examples 8 and 9, the scent is strong when thawed. From these results, it is recognized that the tissue (cells) of Example 5 was not destroyed, and that of Comparative Examples 8 and 9 were clearly destroyed. Thus, in Examples 1 to 5, clearly better results were obtained even in comparison with the conventional brine refrigerating method. In Examples 2 to 5, the frozen food had weak tissue or a high moisture content, and the conditions were severe in that the tissue was likely to be destroyed by freezing, and favorable results were not obtained in the past. It is. The reason why such good results can be obtained is that the time required to pass through the maximum ice crystal formation band measured in Example 1 and Comparative Example 1 was shorter in Example 1 than in the high potential electric field. Examples 2 to 5 by giving Even so, the time required to pass through the maximum ice crystal formation zone is shortened. Industrial applicability

 The invention described in claim 1 can produce frozen food with good freshness, excellent touch and color tone, and with little drip, and good freezing of food with high moisture and weak tissue (cells). Processing can be performed, and an effect that a large amount of processing can be performed is achieved.

 The invention described in claim 2 has the effect of enabling the method invention described in claim 1.

Claims

The scope of the claims 1. In the spline refrigeration method for freezing crush saturated with the frozen food in the antifreeze, food method refrigeration and performing freezing by applying an electric field to the antifreeze ₍ 2. A freezer containing an antifreeze maintained at a low temperature, an antifreeze drive unit provided in the freezer and driven by an electric motor to stir or circulate the antifreeze inside, and supporting the frozen food. A food refrigerating apparatus comprising: an object-to-be-frozen elevating / lowering unit provided so as to be immersed in antifreeze in the freezer and driven by an electric motor; and a refrigerator driven by the electric motor for cooling the antifreeze. , A high-potential electric field generating means is provided so as to apply an electric field to the antifreeze, electrically insulating and supporting the entire apparatus with respect to an installation floor, and electrically insulatingly supporting each of the electric motors with a mounting portion. A food refrigeration apparatus characterized in that the output of the motor is output via an electrically insulating belt.