NL8801883A - Packaging and preserving food - by contact with gas subjected to negative corona treatment - Google Patents

Abstract

In the packaging and preservation of foods, the foods are contacted with gas which has undergone negative corona treatment. At least 50% of the gas is CO2, and the gas has been treated for at least 0.1 secs. to a corona discharge of at least 1000 V. The food is contacted with the gas for at least 0.1 secs. Several portions of food in open packages may be contacted with the gas at the same time in a closed chamber; the open packages are then sealed inside the closed chamber.

Description

Method for packaging and preserving food.

This invention relates to a method for packaging and preserving foodstuffs, in which the foodstuffs are brought into contact with gas.

Such a method is generally known, inter alia from Dutch patent application 75.12818, according to which packaged foodstuffs are subjected to a strong evacuation before final sealing and then the packaging is filled up with a gas mixture consisting of oxygen and carbon dioxide. The use of carbon dioxide in food preservation is brief and stated in very general terms in Ullmann's Encyclopedia der Technischeen Chemie, 3 edition, part 9, page 774 (1957) and part 11, page 459 (1960) and in Kirk-Othmer's Encyclopedia of Chemical Technology, 3 Ed., Vol. 4, p. 725 (1978).

Such treatment does not provide sufficient protection for foodstuffs. Meat, for example, then quickly takes on a dark color on the outside and bacteria and fungi still develop on the surface. Meat that has not undergone any other treatment can be kept for only 3 to 5 days after packaging under such a mixture of oxygen and carbon dioxide (usually 50-85% and 15-50% Ci ^).

The other methods of preservation (drying, sterilization by heating, treatment with salt, acid or other chemicals, storage at low to very low temperature) all have their limitations, which does not need to be explained in more detail here.

It has now been found that the shelf life of foodstuffs, in particular of meat, can be considerably increased by contacting those foodstuffs with gas that has undergone a negative corona treatment. As far as we know, corona discharges have never been associated with food preservation. Corona discharges are, however, used to disinfect air for operating rooms, etc.

The gas with which the food to be preserved is brought into contact can be air, nitrogen, oxygen, carbon dioxide or a mixture thereof, but preferably it consists essentially of carbon dioxide, i.e. at least 50% carbon dioxide or carbon dioxide.

The corona discharges must be produced with voltages of at least 1000 V, but preferably of at least 10,000 V.

The equipment required for this is already available, intended for the disinfection of workspaces, operating rooms, etc., and requires only limited adaptations in order to be used in the method according to the invention. The corona equipment can be located inside the room with food to be treated, but also outside, where there is then a sufficiently large connecting pipe to quickly transport the treated gas to the room with food to be preserved.

The food to be preserved must be contacted with the gas treated with corona discharges for at least 0.1 seconds, preferably at least 0.5-20 seconds. In general, longer than 30 seconds will not further increase the shelf life and therefore makes no sense, but it can not pose any further danger.

In order to take advantage of the sterilizing effect of the gas treated with corona discharges, the foodstuffs thus treated must be closed immediately afterwards, for example by immediately closing a container in which such a portion of foodstuff was treated, for example by placing a piece of laminate film over it. and seal it at the edges with that tray. An advantageous embodiment of the invention therefore consists in that several portions of foodstuffs in open packages within a closed chamber come into contact together with the gas that has undergone corona discharge and that the open packages are subsequently sealed within that closed chamber, although positive effects of corona discharges are also possible without closed packaging.

The preservation process according to the invention can be carried out in portions as well as semi-continuously and continuously. In the first case, the foodstuffs to be treated are located in a chamber with a door with supply and discharge pipes for the gas. Preferably, a large number of food portions are placed in such a room, all in an open container. The trays to be used for this are already generally known ("food tainers") and are widely available. In semi-continuous operation, there are two or more chambers that are alternately fed with the corona discharge treated gas. As such gas flows through one chamber, the treated portions are removed from another and new, yet to be treated portions are introduced. In a continuous operation, portions of the food to be treated, each in an open container, run through a kind of tunnel, in which also continuous gas is passed which had just undergone a corona discharge. The running speed of the trays and the length of the tunnel are such that each portion of food is exposed for at least 0.1 seconds to the gas just treated with corona discharges.

The method according to the invention relates to a surface treatment and is applicable to all foodstuffs that are attacked from the outside by decay. It has less effect on foods that are already internally contaminated with bacteria and / or other organisms. However, it is especially advantageous for the preservation of meat, fish, vegetables (including potatoes), bread products, eggs in the shell or not and other perishable goods. The effect of the method will be apparent from the example below.

Example

A carbonated steel bottle was connected to a T-piece with a corona discharge device HVG 30/5-H from Eltex (Neudorfer Strasse 5 D-7858, Weil am Rhein, BRD) via a pressure reducing valve and a flow meter. whose pointed electrode just protruded into the current path. A piece of hose of about 1 meter was placed at the free opening. All gas lines and tee were made of non-conductive plastic.

While a moderate flow of carbonic acid flowed past it, the discharge device was set to 30 kV, which was accompanied by a current of 5 mA. The free end was placed in a plastic bag which was held tightly around the gas pipe, containing a piece of about 1 kg of meat. After 20 seconds, the conduit was withdrawn from the opening of the bag and the bag was sealed.

The same portion of meat was put in the same plastic bag but did not undergo any treatment; this was the blank.

Surface samples from both pieces of meat were examined bacteriologically; these determinations were made by the company Biochem (Koenendelseweg 11, 's-Hertogenbosch). The actual start of the analysis was about 20 hours after the test was performed. The following results were obtained:

Taste Germs per gram _blank meat_treated meat_ 1. beef 1.4-10 ^ 2.6.10 ^ 6 Δ 2. pork 1.3.10 4.5.10 6 fi 3. beef, with 15, .10 2.4.10 slightly more contamination

Claims (5)

Method for packaging and preserving foodstuffs, whereby the foodstuffs are brought into contact with gas, characterized in that the foodstuffs are brought into contact with gas which has undergone a negative corona treatment. Method according to claim 1, characterized in that the gas consists of at least 50% carbon dioxide. Method according to claim 1 or 2, characterized in that the gas was subjected to a corona discharge of at least 1000 V for at least 0.1 second. Method according to any one of the preceding claims, characterized in that the food comes into contact with the gas which has undergone a negative corona treatment for at least 0.1 second. Method according to any one of the preceding claims, characterized in that a plurality of portions of foodstuffs in open packages within a closed chamber come into contact together with the gas which has undergone corona discharge, and that the open packages are subsequently sealed within that closed chamber.