NL193606C - A method of treating egg products or related compositions to extend the life of such products. - Google Patents

Description

1 193606

A method of treating egg products or related compositions to extend the life of such products

The invention relates to a method for the treatment of egg products such as egg yolk, egg white, egg yolk and egg white together, or a mixture of egg yolk and / or egg white with other ingredients, comprising the following steps: a. Pasteurizing in the usual manner, b. extracting air and other gases from the pasteurized product.

Such a method is known from Dutch patent application No. 6613437.

Methods for producing useful egg products, for example in the production of various types of food products (in the confectionery industry, etc.) are well known. Methods of this type include various operations starting from fresh eggs, such as, in particular, washing and sterilizing the shells, in some cases separating the egg yolks and proteins, and further operations to get the product pasteurized. It is particularly important to obtain good results from the standpoint of the hygienic properties of the product and the ability to preserve the organoleptic properties of such a product for as long as possible. In fact, it is known that numerous bacteria are present in eggs and that, especially under certain conditions, they have a high reproduction capacity.

The pasteurization of the product, even if (as a result of the temperatures involved) this results in the destruction of a significant number of bacteria, does not completely solve the problem. It is actually possible that after pasteurization, bacteria survive in the product and are reproduced freely and quickly. The product should therefore be consumed as soon as possible since its hygienic properties last only a relatively short time. This creates a serious problem, both from a human health point of view, as well as from various industrial and commercial aspects.

According to Dutch patent application 6613437 it is now proposed to subject the egg product, in addition to pasteurization, to a venting or degassing by exposing the product to sufficient negative pressure. The elimination of air or other gases from the product significantly reduces the proliferation of bacteria and harmful germs, as it prevents the presence of air from causing oxidation or growth of bacteria still present, which reduces the hygienic quality of the product. product, which is preserved by cooling, adversely affects, thereby significantly reducing the duration and quality of such a product.

However, even after such a degassing treatment, the shelf life of the product remains limited.

According to the invention it has now been found that the quality of such a product can still be considerably improved and a more durable shelf life can be obtained by irradiation with ultraviolet rays. To this end, the invention provides a method as described in the preamble, characterized in that the method further comprises: c. exposing the product treated according to a and b to irradiation by ultraviolet rays.

It is noted that treatment of egg products with ultraviolet radiation is known per se. French Patent Application No. 2,367,435 already mentions sterilization of egg products at an elevated temperature by means of ultraviolet radiation as an alternative to sterilization of egg products (see page 1, line 9). However, it is noted that such treatment does not provide reliable sterilization of the product and involves significant denaturing of egg liquids, glucides and proteins.

It has now surprisingly been found that the sterilizing effect of ultraviolet radiation on an egg product is particularly effective when this egg product has been pasteurized and degassed beforehand. By carrying out such an irradiation phase after the pasteurisation phase and degassing phase, it is achieved that residual bacteria and germs, left over from the pasteurisation and degassing, are optimally destroyed, so that a virtually bacteria and germ-free end product can be obtained, which can be obtained after treatment. packed without 50 requiring any special further processing.

Without being bound by any theory, it is believed that the strong sterilizing effect of the irradiation in the method according to the invention is only effective when the number of residual bacteria and germs in the product has already been brought to a sufficiently low level by the previous pasteurization, and have insufficient reproduction capacity after the irradiation. It is essential that the ultraviolet irradiation form the final treatment phase. If the irradiation were to be carried out as the first treatment phase, where a high level of bacteria and germs are present in the egg product, these would still have sufficient reproduction capacity after the irradiation, and even if pasteurized and degassed, it would not be 193606 2 optimum minimum level obtained by the method according to the invention.

The invention will now be further elucidated on the basis of an exemplary embodiment of the method and an apparatus to be used therewith with reference to the drawing. In the drawing: figure 1 shows in full schematic the entire establishment or factory; figure 2 is an enlarged cross-section of an essential part of the establishment or factory; figure 3 shows in plan view a detail of the part shown in figure 2; Figure 4 shows in vertical cross section a detail of the same part, shown in figure 2; figure 5 shows a detail in vertical section, which shows a possible variant; figure 6 shows a detail in vertical section, showing another possible variant; figure 7 shows in vertical section a detail of a further possible variant; figures 8, 9 and 10 a variant respectively.

15

The device, shown in a completely schematic form in Figure 1, comprises a set of devices or installations, also referred to herein as "stations", denoted by the numerals 1 to 14, which are connected together as indicated in Figure 1 .

In part (or station) 1, the cooling of the whole eggs, i.e. including the eggshells, is generally at a temperature of about 0 ° C. The eggs are then transferred to plant or station 2, where they are washed at temperatures normally between 30 ° C and 40 ° C. In this way the shells of the eggs are still washed whole. The eggs are transferred from station 2 to plant or station 3, where the shells are sterilized using chlorine-based products at temperatures, generally in the range of 40 to 50 ° C (here too the eggs are whole, ie by 25 bowls). The eggs are washed and disinfected to eliminate the bacteria from the shells. Downstream of station 3 is installation 4, in which the shells are mechanically broken using an apparatus that prevents any mixing of the shells and their contents. At station 4, the contents of the eggs (yolk or egg white) are taken off, while the shells are eliminated. Downstream of station 4, one or the other of the two components (egg yolk or protein) or egg yolk and protein 30 can be transferred together for further processing. If only one of the two components is to be processed (e.g. the egg yolk), the two components are separated downstream from station 4 by installation 5. Station 6 serves to receive the egg yolk, station 7 to receive egg yolk and protein together, and station 8 for recording the protein.

If egg yolk and egg whites are to be used together, the separator 5 is of course not used. Thus, the product, subject to successive treatment in the stations indicated in Figure 1, will be the egg yolk alone (from station 6), egg yolk protein mixture (from station 7) or the protein alone (from station 8). In the case of egg yolk, there is a provision for an ultrafiltration plant (9) immediately downstream of station 6, arranged to remove any excess water from the yolk. Such water is present when there has been a dilution of the yolk by some protein during the separation phase. The device also includes an installation or station 10 for homogenizing, stabilizing and cooling. The product is homogenized by mechanical means, simultaneously or otherwise, cooling at temperatures generally between 0 ° C and 4 ° C. Downstream of said installation is filtration apparatus 11; downstream of the latter 12 for pasteurizing the product. Particularly in the case of the egg yolk, pasteurization takes place in station 12 by heating the product generally at temperatures between 60 ° and 65 ° C for a period of time and then cooling it to temperatures between 0 and 4 ° C. Downstream of said installation 12 is an installation (13) for stabilizing the product (treated according to the invention) and downstream of installation 13 is station 14 for packaging the product.

50 Now follows the description of the construction and the functioning of said installation 13, the details of which are shown separately in figures 2, 3 and 4. Said installation 13 has two parts (respectively right and left for an observer looking at figure 2), which are perfectly similar and therefore various elements containing these parts are designated by the same reference numerals. Each of said parts includes a tank, essentially formed by a container 15, fitted on the top 55 with a sealing panel or "lid" 16, attached to the container 15 by means, for example, screw 17, which allows release if desired. Attached to cover 16 is a motor with a reducing unit, referred to as a group with 18, the shaft 19 of which extends through the 3 193606 holder 15 and has two blades 20 and 21 respectively, which are at right angles to each other and with opposite screw movement for reasons, which will be explained more fully in the following columns. The lid 16 is also equipped with an element 22, which in this description is referred to as the "condenser", which essentially consists of a tubular body, which communicates with the inside of container 15. In condenser 22 two filters 23 and 24 intended to capture foam. In the same container 15 there is a grid 25, which is also able to capture (partly) the foam. The product is fed from pasteurization station 12 through pipe M (see Figures 1 and 2) and is divided into two branches, both indicated by M1 (see Figure 2), which lead respectively to the two tanks or containers 15, which are provided with associated valves. From the bottom of the two tanks 15, two pipes N1 lead to a single pipe N (also shown in Figure 1), which leads to packaging station 14 (see Figure 1). Each of these pipes N1 is provided with a valve (or tap) 27. From the condensers 22, two pipes 28 lead respectively to a single pipe 28A, which is connected to a pump 29 (see figure 4), arranged to produce a high degree of vacuum. The pipes 28 are equipped with two filters 30 and two valves (or taps) 31, respectively. On pipe 28A there is a vacuum 15 meters 32 and a filter 33 (figure 4).

A basic description of the operation of the installation in question follows, in particular for the treatment of the yolk (but also, if required, for the egg white or egg yolk-protein mixture). The egg yolk, as described above, is provided by station 6 (after the different phases established in stations 1-5) and then goes to stations 9, 10, 11 and 12, where the above processes 20 take place. The pasteurized yolk is continuously supplied from station 12 to installation 13 through pipe M and then to the two sections M1.

It is assumed (for example) that the tank 15 on the left side is empty (when looking at Figure 2 also indicated by 15A and that the corresponding valve 26 is open; this will allow the passage of the product (egg yolk) from pipe M to the inside of said tank 15A Under such conditions, the other valve 26 will be in closed position, preventing the product from entering the right tank 15, also indicated by 15B.

During the first period of about 5 minutes, the product will enter tank 15A and reach a certain level (for example, that indicated in Figure 2). During this period, no air is drawn out from tank 15A (i.e., the corresponding valve 31 prevents the passage of air) and the corresponding motor 18 is turned off, with the result that the agitator blades 20 and 21 are inoperative. After this first period, valve 26, belonging to tank 15A, closes the passage and, at the same time, motor 18 starts and suction, i.e. valve 31, corresponding to tank 15A, begins to open. Pump 29 (figure 4) remains operating. This is the beginning of the second period, which also lasts about 5 minutes, during which the subsequent phases take place. During the first 4 minutes or so of the second period, the air is drawn out from the inside of tank 15A, causing the expulsion from the product mass P (egg yolk) of a gas mixture consisting of air and other gases already present in the egg yolk, while others may have entered it during previous stages of the process at the stations described above. A fraction of the free water, which is also present in the yolk, is also sucked out together with this gas mixture. Such extraction of gas mixture and free water, 40 generated by pump 29, is facilitated by the bottom agitator blade 20, immersed in the product, which rotates continuously during said period of about 4 minutes. The shape (helical) of blade 20 is such that it pushes the product upwards.

During this suction phase, there is the formation of an unwanted thaw foam (which additionally rises as a result of the suction), which would cause serious damage if it reached the pump 29.

45 Blade 21 above the product mass P has a helix opposite to that of sheet 20, in order to push said foam downwards, so that it returns (partly) to the mass P below.

The rest of the foam that rises meets grate 25 and thus a part falls back into mass P while the part that rises, instead of entering condenser 22, is trapped by filters 23 and 24, which are in instead allow passage of the gas mixture and water vapor. Any foam not captured by filters 23 and 24 falls into filter 30 downstream and condenser 22. Filter 30 has a transparent wall and thus allows the operator to monitor the phenomenon and intervene. After this period of about 4 minutes, the suction stops (still related to the tank 15A considered). For the next about 20 seconds, carbon dioxide (CO2) is introduced into tank 15A at high pressure through pipe 34 with the stirrer (motor 18 and blades 20 and 21) in 55 operation to restore atmospheric pressure in tank 15A. After this period of about 20 seconds, the stirrer stops, the high pressure CO2 is shut off, and carbon dioxide under low pressure is again introduced through pipe 34 for about 40 seconds. At the same time valve 27, which belongs to tank 15A, opens passage 193606 4 (until then said valve of course closed the passage) and thus, both as a result of the effect of gravity and of the CO2 pressure, the product P (ie the egg yolk) ejected from tank 15A and, through pipe N1, transported to pipe N to packaging station 14. During said second period of about 5 minutes in which, in tank 15A, suction (about 4 minutes) and then CO2 5 and product discharge (about 1 minute), tank 15B is filled.

In other words, the two tanks alternate and the processes are repeated. Returning to the operation of the device during suction, it should be noted that in condenser 22 the mass of foam cools and partially condenses so that it falls back into tank 15A by gravity. Condenser 22 is surrounded by jacket pipe 40, in order to keep the interior 10 of the condenser cold. The low temperature treatment (in the present example) is particularly useful to prevent any proliferation of bacteria. The high degree of vacuum obtained with the aid of pump 29 allows the extraction of said gas mixture or said free water, even at a low temperature. Said carbon dioxide, in addition to the above mentioned functions, further exerts a bacteriostatic function with respect to the product. It has been found that adding small amounts of LYSOZYME (product obtained from protein) to the product (eg egg yolk) before and after the pasteurization phase can increase the life of the product and prevent bacterial proliferation. For example, 70-100 g of LYSOZYME is dissolved in one liter of water and such a solution is added to about 1000 liters of product (egg yolk). If the above-described stabilization process (with device 13) is not carried out continuously, but after a certain time (20 hours) after the homogenization phase, it is particularly useful to add the above-described LYSOZYME solution to the product. As an alternative to the installation, shown in Figures 2, 3 and 4, other installations can be used to extract the fluid mixture from the product. One of these is shown in Figure 5, where a perforated basket 35 rotated by motor 36 ejects product P entering container 38 through pipe 37 through the openings of its cylindrical side wall. The product collides with the wall of said container to form a thin film thereon and collects on the bottom of the container. The extraction of the gaseous mixture, which is obtained with the aid of a pump, via pipe 39, works particularly efficiently on the said film. The product P is then pumped out using pump 41. Another alternative solution is to use device 42 (see figure 6), where the product is fed through pipe 43 and comes into contact with a 30 pairs of convex or concave plates 44- 45 (or even flat), which form a film thereon, which facilitates suction through a pump through pipe 46. The product P is then pumped out using pump 47. A further alternative solution consists of using a device 48 (shown in Figure 7), which has a perforated hollow sphere 49, to which the product is fed through pipe 50. Product P passes through the openings in said sphere 49 in the lower part of the device. Suction is accomplished by a pump and associated pipe 51, and is particularly effective on the individual sprays emerging from the bulb. The product is pumped out by pump 52. Probes S1 and S2 (Figures 5, 6, 7) check the level of the product. The treatment of the product as described above (using the equipment shown in Figures 2, 3 and 4 or other) can be carried out after the pasteurisation phase, or before or during this phase.

In order to achieve a greater bactericidal effect, it is possible to place an ultraviolet beam device between installation 13 and station 14. Such rays, at least in a certain wavelength range, have a bactericidal effect. Figure 8 is identical to Figure 1, but in addition to the various parts shown in Figure 1 (and therefore denoted by the same reference numerals) includes said ultraviolet radiation device, indicated by 53. This ultraviolet ray device is shown in detail in Figure 9 and Figure 45 10, the latter of which shows the cross-section XX of Figure 9.

Device 53 has two identical parts, indicated in Figure 9 with Z1 and Z2, respectively. Each of these parts includes a tubular body 55, preferably stainless steel, and a second tubular body 54 within said body 55 and co-axially therewith. Body 54 is made of a material that is transparent to ultraviolet rays, preferably quartz. Between the two pipes is a jacket, indicated with 57. In pipe 54, two lamps 56 are arranged, which emit ultraviolet steel. Reference numeral 59 designates the protective sleeves for the electrical connections and 60 is sealing elements to prevent leakage of the product. 58 denotes a pipe connecting the two jackets 57 of the two parts Z1 and Z2.

The egg products supplied from installation 13 (described above) arrive at device 53 (part Z1), 55 as indicated by the pipe in figure 9. The product passes through jacket 57 between pipes 54 and 55 and is thus subjected to sterilizing action of the ultraviolet rays generated by the lamps 56. The product is then transported through pipe 58 to part Z2 where it passes through jacket

Claims (2)

No. 5 193606 57, in order to be subjected once again to the sterilizing action of the ultraviolet rays generated by the lamps 56 and said part Z2. Finally, the product leaves the device 53 (as indicated by the arrow in Figure 9) and arrives at station 14 where the product is packaged. It is also possible to install a storage tank for the sterile end product. It is recommended to use a gear pump to transport the product to device 53 (for example, the pressure is two or three atmospheres). The wavelength of the ultraviolet rays is, for example, 2537 A. Device 53 is equipped with an electrical control panel, which signals any fault functioning (such as failure of lamps 56, etc.). It is recommended to add a small amount of carbon dioxide to the product before it is supplied to device 53 in order to neutralize the action of the ozone, which can generate ultraviolet rays (ozone has an oxidizing effect on the fats). The degree of sterility of the product depends on its density (maximum for the protein, excellent for the whole egg, average for the egg yolk). A very important factor for the correct functioning of device 53 is the thickness of the product in jacket 57, which must be as small as allowed by the flow requirements (flow rate in liters / hour). Practice has shown that the optimal thickness ranges from 1 to 1.5 mm. The action of the ultraviolet rays in practice consists of the destruction of the protoplasmic membrane of the bacteria and is almost instantaneous. It is therefore unnecessary to set a special time for treatment with such rays. The double passage through parts Z1 and Z2 is therefore not intended to increase the treatment time, but to ensure full exposure to the ultraviolet radiation through all the mass circulating through the equipment. It is known that the penetration of ultraviolet rays into opaque and fairly dense products is very limited. The treatment of the product with ultraviolet rays is very important, as this further increases the life of the egg product thanks to the further reduction of the residual bacterial number produced using such rays. In the above-mentioned example, two parts Z1 and Z2 are provided, but the number of these parts may be different (for example, only one may be present). Preferably said parts are connected in series (as in figure 9), but they can also be connected in parallel, for example to obtain a larger current. Elements such as those indicated by Z1 (or Z2) can also be added in other parts of the schematic (Figures 1 or 8) instead of in the position between installation 13 and station 14. For example, an element like Z1 can be inserted between device 11, which serves for filtration, and installation 12, where pasteurization takes place, while others can be inserted between installation 12 and installation 13. Parts such as Z1 and Z2 can also be placed in other positions depending on whether only yolk, only protein, or both types are treated. A method for treating egg products such as egg yolk, egg white, egg yolk and egg white together, or a mixture of egg yolk and / or egg white with other ingredients, comprising the following steps: a. Pasteurizing in the usual manner, b. extracting air and other gases from the pasteurized product, characterized in that the method further comprises: c. exposing the product treated according to a and b to irradiation by ultraviolet rays. Hereby 3 sheets drawing