IL40594A

IL40594A - Method of cooking and sterilization

Info

Publication number: IL40594A
Application number: IL40594A
Authority: IL
Original assignee: Carnaud J Et Forges De Basse I
Priority date: 1971-10-29
Filing date: 1972-10-17
Publication date: 1975-08-31
Also published as: BE789876A; ZA727396B; CH540652A; DE2250764B2; ES408045A1; OA04200A; BR7207569D0; IT972382B; AU3809872A; JPS4861645A; NL7214382A; JPS561065B2; CA991472A; IL40594A0; FR2165701B1; GB1400038A; SU458963A3; FR2165701A1; DE2250764A1

Description

Method of cooking and sterilization BTABIISSBMEHTS J.J. CARMAUD ET FORGES LE BASSE INDUE and Max BBAUVAIS C. 38607 40594/2 The present invention relates to improvements in the sterilizatio and/or cooking of products, for example foods, in containers whic are preferably cylindrical.

In U.K. Patent No. 863,804, there is described and claimed a method of simultaneously heating and sterilising cylindrical or substantially cylindrical containers such as for example, cans, bottles or jars, including the step of subjecting said containers to a heating front having a high temperature gradient, whilst simultaneously rotating the containers abou their longitudinal axes.

The method described in O.K. Patent No. 863,804 is known world-wide as the STEMFLAM method, and gives excellent results particularly in respect of the hourly output of the plant as well as from the point of view of reducing the corresponding investment costs.

In working this method industrially we have naturally attempted to provide further improvements, especiall in the case of canning or tinning vegetables or other relatively fragile or delicate products. In the course p£ research and work carried out to this end, we have discovered that the mere addition of a small amount of water to the filled containers causes (ver advantageously) a very high vacuum after sterilisation.

According to the present invention there is provided a method of cooking or sterilising products being canned or tinned, which comprise (a) filling containers with the products and adding to each container small quantity of aqueous liquid, (b) fixing but not sealing covers to the open ends of the containers, (c) passing the containers past a heat source with the longitudinal axes of the containers inclined to the horizontal so as to boil liquid collected at the bottom of each container, .(d) sealing the covers to the containers to be fluid-tight, (Q) heating the sealed containers to sterilisation temperature and maintaining the containers at the sterilisation temperature for a desired period of time and (f) cooling the containers; the containers being rotated about their longitudinal axes at least during steps (c) to (f)i Preferably, the amount of aqueous liquid added to each container is from 5 to 20% of the volume of the empty container. The cooling of the containers may be effected by spraying cold water thereon, and the containers may be heated, for example, either from a heat source which directly heats the containers, or from a radiation hea source.

The following observations have been made under the conditions of the invention: 1) A very short period of time is needed to boil the added water or aqueous liquid to drive the air from the containers through the s aces between the covers and container bodies; 2) by carrying out subsequent to the sealing of the containers, the sterilising treatment, only one or two minutes are necessary in order to reach a temperature between 125° - 135°C, which is highly suitable for the sterilisation of food products such as vegetables; and finally, 3) spraying of the containers thus sterilized with cold water causes condensation of the steam and produces a very high vacuum in the containers, ensuring moreover a very rapid cooling of the container.

Th tilting of te containers during the preliminary treatment is such that the quantity of hot water or aqueous 40594/2 The degree of tilting (which is determined by laboratory trials) is generally between 10° and 30° to the horizontal for containers having the usual dimensions of the tins or cans. Similarly, simple preliminary testing enables the determination of the amount of hot water or aqueous liquid, and the length of heating time necessary for each product and type of container.

The preliminary heat treatment between the clinching (applying the cover to the container body at several points along the circumference thereof, or the first step of a seaming operation intended to loosely secure the cover to the body of the container) and the sterilization and/or cooking pe se, may be performed, for example, on a series of slide conveyors mounted on a table as follows: each slide is constituted by a pair of parallel bars extending in the direction of travel of the containers, i.e., a lower bar formed for instance with angle-iron for supporting the containers eornerwlse at their bottoms, and an upper bar in a horizontal plane above that of the lower bar such that the supported containers lean on the upper bar with their own longitudinal axe3 at the desired appropriate angle to the horizontal; on each side of the slide there are two endless belts mounted one above the other and driven b any suitable known means at the required speed, in order to displace along the slide and rotate abou their own axes horizontal rods extending between the belts from c one side of the slide to the other, the rods being spaced from one another to receive a container between consecutive rods and each carrying a friction roller whereby rotation of the containers about their own axes is ensured when the belts are driven; and finally heating sources such as gas burners are The containers which leave the heating or curing table are then completely sealed either by seaming in two steps or by finishing the seaming step previously started for loosely securing the covers; once the containers are sealed, they are sterilized. To this end they may be, for exaiinple, introduced one after another into a sterilizer advantageously of the type described in U.K. Patent No. 863,304 where the heating and/or sterilization is effected during a residence time in the sterilizer which is experimentally predetermined for each type of container and each product. The containers are then passed through a simple cold water spray.

An apparatus in which the containers move along a helical path therein may be employed in order to effect the preliminary treatment and then the final treatment, one after the other. Along the helical path the containers are in successive order pre-heated, sealed tight by seaming or other suitable means, sterilized arid finally cooled. An apparatus which is considered satisfactory for such a treatment is disclosed in French Patent No. 1,198,003, In which the helical paths that are" followed by the containers are such that the longitudinal axes of the containers are inclined at the angle required according to the present invention. Such an apparatus for carrying out the method according to the invention may therefore comprise at least one helical conveyor comprising a travelling grating with parallel bars displaceable along a closed curve thereby moving along a cylindrical path inside of which is at least one stationar helical channel, whereby each successive, air of bars in combination with the sides of the channel form a moving compartment adapted to receive an article to be conveyed. A number of identical conveyors may be it has been found that the combination of the preliminary treatment according to the invention with the cooking or sterilization according to the aforesaid patent enables the construction of very compact and economical plants in which the total length of the heating, cooking or sterilization and cooling operations is generally between about 5 and 15 minutes which enables the canning to be carried out perfectly in less than 20 minutes including the time for clinching and final seaming.

In other words, it appears clearly that the invention provides for a procedure which is particularly inexpensive and furthermore speed is wholly adaptable to high/operation.

Furthermore , the cans treated according to the invention before sterilizing may be seamed in conventional seamer , i. e. without using conventional vacuum seaming maahines.

The containers may be of metal or other substances, such as glass jars.

Claims

40594/2 _ 1 - 7 - CIAIMS 1... A method of cooking or sterilising products to be canned or tinned, which comprises (a) filling containers with the products and adding to each container a small quantity of aqueous liquid* <b) fixing but not sealing covers to the open ends of the containers/ (c) passing the containers past a heat source with the longitudinal axes of the containers inclined to the horizontal so as to boil liquid collected at the bottom of each container, (d) sealing the covers to the containers to b fluid-tight, (e) heating the sealed containers to sterilisation teinperature and maintaining the containers at the sterilisation temperature for a desired period of time and (f) cooling the containers; the containers being rotated about their longitudinal axes at least during steps (c) to (f).
2. A method according to Claim 1, wherein the amount of aqueous liquid added to each container is from 5 to 20% of the volume of the empty container.
3. A method according to Claim 1 or 2, wherein the cooling of the containers is effected by spraying cold water thereon.
4. A method according to any of the preceding claims , wherein the heat source directly heats the containers.
5. A method according to any of Claims 1 to 3, wherein the heat source is a radiation heat source.
6. method according to Claim 1, substantially as hereinbefore described.
7. A container of cooked or sterilized products prepared according to the method claimed in any one of the preceding claims. For the Applicants