GB2412563A - Tempering frozen foods - Google Patents

Abstract

An method for tempering or softening frozen foodstuffs comprises cooling the surface with non polar non ionic cooling media during microwave radiation. The temperature at the surface may be as low as -40{C to prevent surface thawing. The coolant may be carbon dioxide, nitrogen or argon.

Description

Processing frozen compositions s

FIELD OF INVENTION

The present invention is broadly concerned with an improved method of tempering comprising the use of microwaves and non-polar and non-ionic cooling composition such as a non-polar non-ionic snow, for instance a CO2 snow, to put a body of a frozen composition for instance a frozen aqueous compositions such as a frozen plant or animal tissue in the optimum condition for processing (e.g. subdividing, for instance by cutting or slicing). This improved tempering method is particularly useful for slicing frozen organic materials like foodstuffs, such as frozen meat.

BACKGROUND OF THE INVENTION

A range of important raw materials are deep-frozen in order to preserve their quality during transportation and storage. They can not be cut or sliced as such and have to be tempered first. Meat and fish are important examples and are widely used in the food processing. Factories have problems softening or tempering large bodies or blocks of frozen organic material, such as frozen aqueous compositions, prior to further processing. Various procedures are adopted, the most common being to place the blocks or bodies of the frozen organic in tempering rooms, where they may reside for several days while attaining the desired temperature. In order to accelerate the process, media such as warm air or water have been used. Unfortunately, steps that speed up thawing rates tend to degrade the product. And induce microbiological hazard. If the surface thaws too soon, then the outer layers may deteriorate before the bulk has thawed.

There currently is a need for fast methods, which does not induce deterioration, for homogenous tempering of blocks or bodies of frozen organic materials such as frozen foodstuff and other perishable goods to reach the optimum condition for e e e improved processing. The current techniques do not provide a technical solution for all these requirements Patent US 5816053, for instance, discloses an apparatus for cooling and tempering bacon slabs supported upon wheeled trucks, which can be rolled on the floor inside a cooler. The apparatus includes an evaporator having multiple fans for moving air through refrigerated coils and in the cooler. Moisture collecting on the refrigerated coils drops into a drain pan and is drained through pipes outside the cooler. The fans are alternately rotated in opposite directions for equal time segments and baffles are provided inside of the cooler to assure uniform air chilling. A controller operates the evaporator so that the air inside of the cooler is cooled to a temperature less than the internal product temperature which is greater than freezing and specifically in the preferred form at a desired temperature differential of 20 DEG F. (11 C.) until an intermediate internal product temperature is reached. Then the evaporator maintains the air temperature inside the cooler below the final internal product temperature until Is the final internal product temperature is reached when the air is then maintained in the cooler at the final internal product temperature. By this technique homogeneous tempering can be reached but the process is a very slow.

Patent US2003183623 discloses a technique of tempering which is fast but can't neutralise temperature differences leading to unequally tempered foodstuff due to the handling. It involves a microwave oven with conveyor incorporating a shielding system mounted within an oven cavity of the microwave oven. The shielding system is provided to prevent selected portions of a food travailing through the microwave oven - from overheating relative to the remainder other pieces of food items in the system. This document discloses an invention that is particularly adapted for use in connection with the tempering, cooking or thawing of parallel-piped or rectangular- shaped food items and includes a frame structure fixedly mounted within and traversing substantially the entire length of the oven cavity, with the frame structure having a generally rectangular cross-section defined by both microwave impermeable portions and microwave transmissive portions on each side.

Rapid tempering could dramatically reduce the amount off drip loss that occurs during subsequent processing. This makes that the costs of microwave tempering c c c c e c e c c e c c e c c c e c e c c c e cce cec c C ce c c a e c c e c c

C C C C C

are justified in terms of the yield savings made. This technique is fast but foodstuff have now to be in a conditioned room before entering the microwave oven.

In general the expected speed of a microwave approach is appreciated but leads to product quality decreases as the outer layer of the thick and irregular pieces of organic material - the reality in industrial processing - tends to warm up too fast.

An opportunity exists for microwaves, which have a considerable penetration depth into frozen organic material. In theory, by overcoming the heat transfer problem, operations taking 24 hours or more could be reduced to a few minutes. A major difficulty prevents the straightforward use of microwaves in this application. The problem is that water absorbs power much more rapidly than ice, on account of the relative dielectric properties. As soon as water is formed in any part of the product, then gross differential heating is initiated: the water absorbs energy rapidly and heats up to boiling point, while large parts of the block are still frozen.

In general, surface regions will thaw first, absorb an even increasing proportion of the available power and prevent effective power from reaching central regions.

So any operation involving complete thawing is yielding problems. On the other hand microwave tempering, i.e. increasing the products temperature form the deep frozen state (say -15 C to -30 C) to a 'cuttable' state (say -2 C to -8 C), is much more attractive. By taking care efficiently to avoid any water formation, the "thermal runaway" described above cannot occur and successful tempering should be possible.

The present invention solves these problems. It is an embodiment of present invention that the radiation side (figure 11) is cooled with nonpolar non-ionic cooling composition during the microwave radiation to keep the product penetration high.

The temperature at the surface goes down to -40 C to prevent not only local thawing, but reliance can be is placed on controlling the heating rate, allowing thermal conduction to play a part.

This non-polar non-ionic cooling composition preferable has a temperature below- 20 C, more preferably below-25 C, yet more preferably below-30 C and most preferably below-35 C. The non-polar non-ionic cooling composition can be in the . . . . e. .e ce . a form of a gas, a fluid or a solid. If the non-polar non-ionic cooling composition is a solid it can be for instance be in the form of a snow, small granules such as micro granules, or small particles such as micro particles to cover the frozen organic material to be micro waved. If the non-polar non-ionic cooling composition is a fluid it can be a mist or droplets to cover the frozen organic material to be micro waved. The non-polar non-ionic cooling composition can be supplied to the bodies or blocks of frozen organic composition to be tempered in such amount or during such time that the surface temperature of the frozen organic material to be temperated stays optimal (e.g. under-3 C) to obtain a optimal quality of the outer layer. A sensor may be used at the surface of the bodies or blocks of the frozen organic material to control the supply of the non-polar non-ionic cooling composition.

An embodiment of present is directly covering the bodies or blocks of frozen organic materials by the non-polar non-ionic cooling composition just before the microwave treatment or during the microwave treatment Another embodiment of present is covering the bodies or blocks of frozen organic materials packed in a packing material suitable for microwave treatment by the non polar non-ionic cooling composition just before the microwave treatment and/or during the just before the microwave treatment.

An advantage of present invention is that controlled tempering of thick (e.g.1 to 30 cm, preferably 1 to 20 cm and most preferably 10 to 15 cm) and non conditioned boxed meat is obtainable in a very short time for instance less than 20 min. or even less than 10 min. going from - 18 C to -3 C. Large scale equipment suitable for the method of present invention available (e.g. MEAC Oven TYPE MEACHEAT32) which produce microwave (MOO) with sixteen 1.8 kW units or 28.8 kW microwave power output at 2 450 MHz. Typical throughputs are 1200 kg/hour, or more, depending on the temperature range to be covered and the product type/sizes.

A general claim made for the rapid tempering regime remains the dramatic reduction off drip loss that occurs during subsequent processing. The costs of microwave tempering are often justified in terms of time and throughput compared to classical methods next to controlling better the sanitary conditions of these phases in the e e . . . . . . process. The method of present invention overcomes the problems described above and achieves this requirements of rapid tempering combined with dramatic reduction off drip loss.

ILLUSTRATIVE EMBODIMENTS OF THE INVENTION

The treatment process of present invention is applicable to many types of frozen organic materials. The present invention is in particular applicable to many types of foodstuffs, bodies of tissues or food mass or bodies comprising tissue pieces with or without a binder, in selected shapes. It may be applied to larger cuts of meat or cubed or sliced meats, but also comminute foodstuffs such as ground meats are suited for the method of present invention. Furthermore, the invention is applicable to vegetable and fruit material. These and other objects, advantages, and features of the invention will be apparent from the following description of the preferred lS embodiments, considered along with the accompanying drawings.

Theoretical background

Tempering or softening of foodstuff frozen foodstuff/tissues/meat is on the one hand based on propagation and penetration of microwave energy. On the other hand energy is transferred into heat according to thermodynamic laws.

However, for several products, the skin effect is limited by the thickness or irregularity of the products to be tempered. The present invention overcomes this problem by the use of none polar snow which allow the microwaves to pass and prevents the outer (skin) layer from heating up too fast.

Propagation factor and penetration depth Many problems in microwave engineering involve the use of Maxwell's equations through which one can derive the following wave equations of the electromagnetic field (E electric field and H magnetic field) in the z direction (von Hippel, 1954) : a a a a ece c's e ce a2E * * a2E aZ2 = eOe IloR at2 and a2H * a2n 2 = eOe* at2 where E iS the dielectric constant and 11 the permeability. The solution to be considered here is that of a plane wave, which for the electric field E attains the form E = Ema (equation 1) This is a periodic field travailing in the z direction with a complex propagating factor A, given by = j(eO e*ll*,uO),/2 = + Jo (equation 2) where Cal is the circle frequency a is the attenuation factor and,B is the phase factor.

Figure 1 shows the essential features of such propagation. The wave is attenuated as it traverses the medium and therefore the power dissipated, which is a function of E2, reduces to an even larger extent.

To derive an expression for the attenuation of the incident power, we equate the real and imaginary part of equation 2, yielding after solving for a and and assuming p* = hi, = ( 2) [(1 +(eefflci)2)1/2 - 1]2 Np/m (equation 3) and . . . . c.

. . a ( 2) [(I + (Ed /e')2)l/2 + 1]1/2 red/m The expression for the attenuation factor can be simplified as follows: (a) For a highly lossy medium, where (Jeff / ) > 1, equation 3 reduces to {2p' e" V/2 2 Np/m (equation 4) which is the case for conducting materials, since from equation \ 1/2 CY = 2) [(I + (eeffle) ) - 1] Np/m with = 0, cr = a'0èff Therefore equation 4 yields a = 1/as where Gs is the skin depth.

(b) For a low loss medium, where (Jeff / ) < i, equation 3 after substitution of m=2f=2c,/\,oreducesto = 2 ( e' ) 6eff = X, he'll" Np/m where To is the free space wavelength and the free space velocity c has been equated to (,iJo ò)/2 and At'= 1.

Substitution of equation 2 into equation 1 yields E-E eZ j(cot-z) - max e The first exponential term gives the attenuation of the electric field and therefore the dissipated power follows the form pace2Z r r# C . * r r The penetration depth is defined as the distance from the surface of the material at which the power drops to -] from its value at the surface, that is P 2 ct S (equation 5) Substitution of equation 3 into equation 5 yields the general expression for the penetration depth Dp = 2t,J(p' E 6') [(I +(eeffl6) ) - 1] (equation 6) In terms of the free space wavelength equation 6 reduces with,u'= 1 to Dp = 2 t2 ''72 [(I + (6e,f/6)2)/2 _ i]-./2 (equation 7) Is For low loss dielectrics (Jeff / ) < 1 and the penetration depth approximates to iO(6)1/2 D. P ', 2 77 Jeff (equation 8) Equations 7 and 8 shows that the power of the penetration depth increases with larger wavelengths or in other words with decreasing frequencies. In general the penetration depths at frequencies below 100 MHz are of the order of metros and presents little problem as far as power penetration unless the loss factors are exceedingly high. At frequencies near the microwave heating regime the penetration depths are correspondingly smaller and often the size of the material to be treated, particularly when it is very wet, is many times larger than Dp and microwave heating could result in unacceptable non-uniformities in the temperature distribution.

Ohisson et al. (1974) have calculated the variation of the penetration depths of r * . * foodstuffs with temperature near the three industrially allocated frequency bands.

Their results are shown in figure 2. The general trends, as could be expected, are that we see higher penetration depths at lower temperatures and frequencies, since we have seen the effective losses for ice are much less than those for liquid water.

For raw (frozen) beef, depths of penetration of about 150 mm at sub-zero temperatures reduce to about 20 mm at room temperature, whereas in gravy the penetration depths are correspondingly smaller since the effective losses are primarily conductive and larger.

Perhaps, surprisingly, gravy would be more uniformly heated to temperatures above C at 2,45 GHz than at the other two lower g-frequencies. In contrast, in pure water the penetration depths increase with increasing temperatures highlighting the differences in the dielectric properties of foodstuffs with large salt content. More depth of penetration data have been published by Bengtsson and Risman (1971) on a variety of foodstuffs at 2, 8 GHz and in cod various temperatures from -20 C to +60 C at 2.45 GHz, as shown in figure 3. It transpires that there could be limitations in the treatment of lossy dielectrics if the dimensions are comparable with, or exceed, the penetration depth. Web materials on the other hand do not usually suffer from such limitations, as their thickness is small.

Figure 4 shows the dielectric constant frequency dependency of various foodstuffs.

Specific heat The internal energy of a system U in terms of its pressure p, volume V and external heat supplied to it is given in differential form by (Tabor, 1969) dU = Qh-pV "equation 9) Moreover, the system enthalpy is given by //h = A+ pa e e e e t e e e I t t e t eve Id. 'te e e e e e c e e (equation 10) Differentiating equation 10 and using equation 9 yields Ash = d Oh + Vdp (equation 11) The specific heat of a material in Sl units, c, is the amount of heat required to raise a Kg by 1 C. We can observe two definitions of specific heat, which follow from the above equation. First, differentiating equation 9 with respect to temperature at constant volume gives c = a u) = aQh V t3T1V bT which defines the specific heat at constant volume. Also, differentiating equation 11 with respect t temperature T at constant pressure gives (aHhN arch P aTIp aT (equation 12) which defines the specific heat at constant pressure. In gases there is a significant difference between Cp and Cv which does not apply to liquids and solids.

In fact, in the latter, the difference is extremely small and can be neglected.

Furthermore, the specific heat of most materials can be taken as constant with temperature up to well below the freezing point and starts to decrease at significantly lower temperatures. Measurements of the specific heat in solids are normally made at constant pressure. Table 1 shows the values of Cp for some common industrial materials.

Table 1 Specific heat of some common industrial materials c c c Specific heat cp Material Cal/(g C) kJ/(kg C) Acetone 0 51 213 Alcoholethyl O S5 2 31 Asbestos 0 2 0 84 Asphalt 0 4 1 67 Bakelite 03- 04 1 26-1 67 Beeswax 082 3 43 Brick common 0 22 0 92 hard 0 24 1 0 Cellulose 032 1 34 Charcoal, wood 024 1 0 Clay 023 0 96 Coal anthracite 0 3 1 26 Coal bituminous 033 1 38 Coal tar oils 0 34 1 42 Coke 027 1 13 Concrete (stone) 0 17 0 71 Cork board 0 45 1 88 granulated rolled 049 2 05 Earth (dry) 0 3 1 26 Fibre board (light) 0 6 2 51 Fibre hard board 05 2 09 Glass crown 0 16-0 2 0 67-0 84 flint 012 0 5 Pyrex 0 2 0 84 silicate 0 19 0 79 Graphite powder 0 16 0 67 Gypsum board 026 1 09 Ice (0 C) 0 49 2 05 India rubber 0 48 2 0 Leather (dry) 0 36 1 5 Limestone 0 22 0 92 . . :: .. :e:: :: :e . . . e Specific heat cp Material Cal/(g C) kJ/(kg C) Marble 0 21 0 88 Mica 0 11 046 Mineral wool blanket 0 2 0 84 Oils caster 0 44 1 84 olive 047 1 97 Paper 033 1 38 Paraffin wax 0 7 2 89 Plasterlight 024 1 0 sand 0 22 0 92 Porcelain 0 22 0 92 Plastics foamed 0 3 1 25 solid 04 1 67 Sand 0 19 0 79 Sandstone 0 22 0 92 Sawdust 0 21 0 88 Silica aerogel 0 2 0 84 Sodium chloride brine + 10 part H2O 0 8 3 34 + 200 part H2O 0 98 4 00 Turpentine 0 411 1 72 Water I 00 4 18 Wood fir 0 65 2 12 oak 0 5 2 09 Pine 067 28 Woolfelt 0 33 1 38 loose 03 1 26 Rate of rise of temperature As the microwave energy is absorbed in the material its temperature increases at a rate depending upon a number of distinct parameters. The power required to raise the temperature of a mass Ma kg of material from To C to T C in t seconds is given by extending equation 12.

p = Qh = Macp(T-To)lt (equation 13) Substituting P using equation Pav = Ernst v equation 13 i Id e C . . . . . . (T-To)/t = 0-556 X 10 ceff fE2ms C -I pep where p is the density of the material in kg/m3 and the specific heat is given in J/kg C. For a given material heated by high frequency energy at a given f, the rate of rise of T depends on (Jeff e2ms)' which is usually a function of the temperature (due to the variation of Jeff with T).

Advantages of microwave tempering Microwave tempering ensures consistently controlled temperatures throughout the block of product. This improved temperature uniformity eliminates most drip loss and therefore will enhance flavour, aroma and juiciness of the finished product.

Because drip loss is virtually eliminated, an operation can expect up to a 4% increase in finished yield.

Precise temperature control will assure consistency of particle size in all ground meat products. This enables a high degree of quality control concerning visual uniformity and consistency of bite.

The MEAC tempering system requires relatively little floor space. This will afford a maximum level of throughput at a minimal allocation of valuable production space. In addition, the MEAC Heat 32 series is expandable. This will allow an immediate increase in throughput at a fraction of the cost for new construction. What's more, for overhead transmitter installations the expansion will require no more floor space.

Product handling is kept to a minimum. Each box is handled only once and in-line process design can be configured to reduce your tempering labour costs to the bare minimum.

Because microwave tempering takes only minutes, as compared to days for conventional air tempering, you will have operational flexibility to instantaneously change your production plans. In addition, the three day tempering requirement can -e: . . : # c c. e

be eliminated thereby reducing the in process inventory requirement to one day.

This reduction in inventory frees valuable funds for other uses.

Controlled tempering also retards bacterial growth. This improves product quality and taste, increases shelf life, and reduce risk.

The elimination of bloody drippings on the floor will enable your to upgrade the overall sanitation in your plant. This contaminant will not be tracked throughout your facility.

Finishing cooked yield of many prepared foods can be improved because controlled microwave tempering does not allow valuable protein to leach from raw product.

The most frequent reason for processing equipment breakdown is improperly tempered meat. If meat is too cold, blades will break, parts will wear, and gears will blind. If meat is too warm, product will bind on blades, squeeze into crevases, and create undue stain. The resulting downtime can be dramatically reduced through microwave tempering techniques.

Portion control of the finished product is simplified because controlled tempering precludes overstuffing too warm product or under-filling too cold product. This eliminates product give-away, and reduces the risk of fine due to short weighting.

Finally, the cleaned and controlled microwave tempering process will prevent the potential confrontation with Government Regulators over crowded and messy work areas, unsanitary handling procedures, blood on the floor, etc. This will save you money in cleanup costs, downtime, and non-productive labour expense.

Summary of the invention

An industrial method for tempering or softening bodies of frozen components such as bodies of frozen tissue/food/meat in such a way that the temperature difference in the . . * a * C product due to handling, size or/and skin effect is neutralized and controlled by combining microwave energy and the use of a none polar non ionic snow layer.

In order to keep the product penetration high for thick and bulky products; the surface is frozen/cooled with non-polar snow during the microwave radiation. The temperature at the surface goes down to -40 C to prevent not only local thawing or warming up, but also to control the heating up rate by using thermal conduction.

Microwave (MOO) heating reduces the process time and, energy consumption; additionally the use of MW and non polar snow leads to better quality control of the tempering process. The combination with non polar (e.g. CO2) snow with the microwave approach provides optimal control over the temperature profile of the products, leading to mastering of the end temperature that is needed to allow for good processing downstream. An embodiment of the present invention is an industrial tempering method that can be applied for different packing or containers

Examples

Example 1: Two boxed beef of 50 by 40 by 15 cm3 are processed in a CO2 dose measuring device combined MEACHEAT 32 (Figure 6, Patent PCT/BE03/00214) system.

On boxed beef is without snow and one boxed beef is with snow. The difference between both methods is extraordinary. Differences at the surface of 18 C are measured between both qualities leading to not processable meat in the one not treated with non-polar snow.

Surface quality of beef treated with non-polar snow and MW tempered is high. The microwave field can be 0 to 30W/cm2, preferably 0 to 20W/cm2 and most preferably 1 to 2 W/cm2 there is no cooking or overheating of the radiation side (Figure 11).

Legend to the graphics of this application . a e * . . . . Figure 1 shows the propagation of a plane wave in a lossy medium. It shows the essential features of such propagation. The wave is attenuated as it traverses the medium and therefore the power dissipated, which is a function of E2, reduces to an even larger extent. s

Figure 2 demonstrates the penetration as a function of the temperature for various frequencies Figure 3 demonstrates the dielectric properties data for various foodstuffs Figure 4 demonstrates the frequency dependency of the dielectric constant Figure 5 shows a standard C02 dose- measuring device Figure 6 shows a C02 dose-measuring device with a MEACHEAT32 Figure 7 shows the CO2 dose-measuring device under operation, Non polar non ionic snow on boxed beef with a surface temperature of _ - 40 Figure. 8 shows a non treated beef with a surface temperature of +/- 20 C and a core temperature of +/- -18 C Figure. 9 shows conditioned beef with a core temperature of +/- - 4 C Figure 10 shows a conditioned beef with a surface temperature of +/- - 4 - O C Figure 11 shows a schematic illustration of temperature behaviour throughout the beef during operation

Claims (1)

1. - e a .

   1) A method of tempering or softening bodies of a frozen organic material, characterized in that the bodies are covered by a layer of a non-polar non-ionic cooling material and subjected to a microwave radiation until an optimal temperature has been reached to further process the organic material.

   2) The method of claim 1, wherein the non-polar non-ionic cooling material is non polar non-ionic snow.

   3) The method of claim 1, wherein the non-polar non-ionic cooling material is non polar non-ionic snow comprising CO2.

   4) The method of claim 1, wherein the non-polar non-ionic cooling material is non polar non-ionic snow comprising N2.

   5) The method of claim 1, wherein the non-polar non-ionic cooling material is non polar non-ionic snow comprising Argon.

   6) The method of claim 1, wherein the non-polar non-ionic cooling material is a non- polar non-ionic granulate material.

   7) The method of claim 1, wherein the non-polar non-ionic cooling material is a non- polar non-ionic granulate material comprising CO2, 8) The method of claim 1, wherein the non-polar non-ionic cooling material is a nonpolar non-ionic granulate material comprising N2 9) The method of claim 1, wherein the non-polar non-ionic cooling material is a non- polar non-ionic granulate material comprising Argon 1 O)The method of claim 1, wherein the non-polar non-ionic cooling material is a non polar non-ionic particulate material.

   11)The method of claim 1, wherein the non-polar non-ionic cooling material is a non polar non-ionic particulate material comprising CO2, 12)The method of claim 1, wherein the non-polar non-ionic cooling material is a non polar non-ionic particulate material comprising N2 13)The method of claim 1, wherein the non-polar non-ionic cooling material is a non polar non-ionic particulate material comprising Argon 14)The method of claim 1, wherein the non-polar non-ionic cooling material is a mist of a non-polar non-ionic particulate liquid. lo . .

   15)The method of claim 1, wherein the non-polar non-ionic cooling material is a mist of a non-polar non-ionic particulate liquid comprising CO2 16)The method of claim 1, wherein the non-polar non-ionic cooling material is a mist of a non-polar non-ionic particulate liquid comprising N2 17)The method of claim 1, wherein the non-polar non-ionic cooling material is a mist of a non-polar non-ionic particulate liquid comprising Argon 18)The method of the claims 1 to 17, wherein the non-polar non-ionic cooling material has a temperature of less than -20 C 19) The method of the claims 1 to 17, wherein the non-polar non-ionic cooling material has a temperature of less than -25 C 20) The method of the claims 1 to 17, wherein the non-polar non-ionic cooling material has a temperature of less than -30 C 21) The method of the claims 1 to 17, wherein the non-polar non-ionic cooling material has a temperature of less than -40 C Is 22)The method of the claims 1 to 21, wherein the frozen organic material to be tempered is selected of the group consisting of aqueous organic material, foodstuff, tissue, bodies comprising tissue pieces with or without a binder, cuts of meat or cubed meats, comminuted foodstuffs, vegetable material and fruit material.

   23)The method of the claims 1 or 22, wherein the microwave radiation is submitted to one side 24)The method of the claims 1 or 22, wherein the microwave radiation is submitted to two sides 25)The method of the claims 1 or 22, wherein the microwave radiation is submitted to three sides 26)The method of the claims 1 or 22, wherein the microwave radiation is submitted to four sides 27)The method of the claims 1 or 22, wherein the microwave radiation is submitted to five sides 28)The method of the claims 1 or 22, wherein the microwave radiation is submitted to six sides 29)The method of the claims 1 to 22, wherein the microwave radiation and the non polar non-ionic cooling material to cover the frozen organic material to be . . as. se.

   . . . . tempered is combined in such way that the temperature difference in the product due to handling, size or/and skin effect is neutralised and controlled.

   30)The method of claims 2, wherein the non-polar non-ionic polar snow is a carbon dioxide snow.

   31) The method of claims 6, wherein the non-polar non-ionic polar granules are carbon dioxide granules.

   32) The method of claims 10, wherein the non-polar non-ionic polar particles are carbon dioxide particles.

   33)The product prepared by the methods 1 to 32.