DE675161C - Method for the electrical thawing of frozen food, especially frozen meat - Google Patents

Description

Process for "electrical thawing of frozen food, In particular of frozen meat It is known to prepare food by freezing to preserve it from spoilage. In this way, for example, meat can be several Keep fresh for weeks. However, certain difficulties arise when the frozen food for use should be thawed.

Usually thawing is done by supplying heat from the outside, for example by placing the food in a warm atmosphere. The eligible ones Foods generally have a relatively low thermal conductivity. If, therefore, they are completely removed from the front and the outside by the supply of heat, i. H. to the inside, wants to thaw, so you need, since you only need relatively low temperatures can apply for a considerably long time for the thawing process. This has the consequence that the outer layers of the food to be thawed have long since thawed -and therefore no longer protected against rot while parts are inside the Food is still frozen. As a result, it is often superficial Food spoilage.

To defrost meat you also have the @electric current served. As a result of the resistance which the meat offers to the electric current, electricity heat is generated in the meat. To introduce the electrical currents into the In known methods, meat is at various points on the piece of meat Electrodes applied or pierced. This thawing process already offers the advantage that 'the thawing heat inside the meat itself has an effect and thereby a more even heating is achieved, but this method adheres on the other hand, it also has a number of rather sensitive disadvantages. First of all, it should be noted that when the electrodes are applied to the piece of meat inside the same as a result uneven conductivity form very specific, distinctive current paths that Legs cause uneven heating. Furthermore occurs particularly immediately the electrodes -a severe overheating. To prevent this overheating It has been suggested to artificially cool the electrodes, but it can. this should only be viewed as a stopgap because of the overheating and therefore the necessary Cooling are very different. The structure of the plant is also supported by the additional necessary cooling equipment more cumbersome. Furthermore, @es is during thawing of frozen meat by means of direct current passage has the disadvantage that the electrodes due to the different strength of individual parts of the piece of meat to the whole specific positions have to. You may have to even more of the electrode pairs or groups are used at the same time and throughout a certain way to attach the carcass. Disregard of the by the additional electrodes caused an increase in overheating points This makes the process cumbersome and time-consuming and required x =: large a practice. Incorrect placement tdeejw even by confusing the electrodes IML'G major disadvantages arise. For cinei ': mass operation is therefore also the procedure direct power transmission for thawing supercooled and frozen food not suitable.

All these disadvantages are avoided in the method according to the invention. Here, too, the food is thawed using electricity. According to the invention, however, the food to be thawed is exposed to the action of electrical fields which are excited by voltages of very high frequency. The following preferably come into consideration: a frequency range which corresponds to a wavelength of approximately 5 to 50 m. The thawing method according to the invention enables the heat to be generated directly, just like the known method of direct current transmission. inside the food itself to be thawed, but in the method according to the invention no electrodes whatsoever need to be placed on the food to be treated. The food, for example pieces of meat, in the method according to the invention are only in the effective range of the electrical; brought into the field, whereupon the thawing process starts immediately. The food is fully penetrated by the electric field. In this way, a very considerable amount of heat can be supplied to the goods to be thawed in a unit of time without inadmissibly high temperatures occurring at any point. This is particularly important when defrosting frozen meat. A more intensive treatment of individual pieces of meat will often not be necessary at all in the method according to the invention. If it is nevertheless desired, it can be further strengthened by reinforcing individual parts of the electric field, e.g. B. by increasing the electric field density can be achieved. It is also possible to regulate and monitor the thawing energy by changing the strength or density of the electrical field. In the method according to the invention, several pieces of meat or the like can also be exposed to the action of the electric field at the same time, an advantage which is felt to be particularly pleasant when treating smaller pieces. : - "&. The defrosting process can be remote-cr at the @ `, ren according to the invention in a very short time '#i; must be carried out. Furthermore, since the 44 tl'u'fvorgang inside the to be treated- de. -'`The body begins and towards the outer- areas, the parts in contact with the air are only exposed to the influence of putrefactive agents for a very short time.

To avoid any risk of spoilage, you can defrost it to be carried out in an atmosphere that is not rotten. For example, it can be thawing the food in an oxygen-free atmosphere, e.g. B. in nitrogen, or in an air-diluted room. The high-frequency ones used for heating electric fields call in the gases surrounding the food to be thawed, So for example in the air, practically no warming.

The invention is not only of importance for such foods, -which easily go into putrefaction, but also for thawing those that go through exposure to higher temperatures will affect their usability in some other way be, for example, for fats such as butter, etc., which are already proportionate melt at low temperatures.

It is already known to use food for the purpose of cooking or frying to be heated in high frequency fields.

To thaw frozen food you have high-frequency electric Fields not yet used, however.

Claims (2)

PATENT CLAIMS: i. Method for the electrical thawing of frozen food, in particular of frozen meat, characterized in that the food to be thawed is exposed to the action of electrical fields; which are excited by voltages of very high frequency, in particular corresponding to wavelengths of about 5 to 50 m. 2. The method according to claim i, characterized in that that thawing in an anti-putrefaction atmosphere, e.g. B. nitrogen, takes place.