This invention relates to a tubular elasticated net with an inextensible weft.

Tubular elasticated netting is used to encapsulate meat products such as joints of beef or pork. The net remains on the joint during cooking to retain the shape and integrity of the joint. An example of a knitting machine which produces such netting is to be found in our British Patent No. 2333301. An example of a machine which packages meat in such netting is to be found in our British Patent No. 2380179. Reference is made to the specifications of these Patents for a clearer understanding of the present invention.

In addition to its use on joints of meat elasticated netting is also used in the preparation and presentation of cooked meat products such as sausages, hams, salamis and frankfurters. Portions of these products are encased in plastics, or sometimes fibrous, enclosures which limit their expansion during cooking and result in the uniform, cylindrical cooked meat products which supermarkets require for presentation and sales purposes and which facilitate slicing. Emulsions are commonly contained in collagen film. However it is necessary for the meat to be squeezed during cooking to prevent distortions due to the formation of voids as fats are melted and to achieve this the imperforate caging has been enclosed in a tubular, elasticated net. However, unless the stretch of the elastic is limited the result is unlikely to be the desired, uniform cylinder.

U.S. Patent Specification 1679822 discloses a rubber thread covered with helically wound textile threads. The latter are said to limit the stretch of the rubber as they straighten, i.e. as the pitch of the spiral windings increases. European Patent No. 1154696 discloses the use of such a covered thread as the weft of a net used to encapsulate food products. The yarn windings on the rubber thread limit the stretch of the rubber. Nets of the kind described in European Patent No. 1154696 have been in extensive commercial use throughout the world for at least the past twenty years. Problems arising from the use of such nets to control the shape of cooked meat products include the following: As acknowledged in US 1679822, if inextensibie and rubber threads are simply laid side-by-side and covered by yarn windings the resulting thread is so deformed as to be unmanageable and unsightly except when under extreme tension If a fine cotton or nylon thread is wound helically around the rubber thread it is easily broken when tensioned. The use of a thicker, stronger inextensibie thread is not only expensive but greatly diminishes the stretchability of the rubber. In any event the limit of stretch of such an assembly is not precisely determinable. The extent to which the yarn will bite into the rubber as the latter is stretched will vary as will the ultimate pitch angle of the helically wound yarn.

A principal object of the present invention is to improve upon prior art proposals such as the above

In accordance with one aspect of the present invention there is provided a method of preparing a meat product for cooking characterised in that it comprises fprcing the product into a tubular net which has mutually independent (as herein defined) elastic and

substantially inextensibie weft threads until straightening of the inextensibie weft threads limits the diametral expansion of the net while tensioning of the elastic weft threads subjects the product to a compressive force.

In accordance with another aspect of the present invention there is provided a tubular net for use in carrying out the method of the immediatley preceding paragraph, the net comprising spaced apart warp threads and spaced apart pairings of elastic and substantially inextensibie weft threads, characterised in that the elastic and inextensibie weft threads are in an independent relationship (as herein defined) all of the said weft threads being connected to each of the warp threads, the arrangement being such that when the elastic weft threads are in a relaxed condition the inextensibie weft threads are in a slack, unstraightened condition and such that straightening and tensioning of the inextensibie weft threads as the elastic weft threads are stretched positively limits the diametral expansion of the net. By an "independent relationship" of the two threads is meant that they are not twisted or otherwise connected together throughout their lengths. However they are both

advantageously connected to the separated warp threads of the net, conveniently at the same points along the lengths of the warp threads, in the relaxed condition of the elastic thread the 5 non-elastic thread lying loose between the warp threads.

The use of an inextensible thread independent of the elastic thread enables†he use of an inextensible thread of whatever strength is desired without either impeding the stretchability of the elastic thread or unacceptably raising the cost of production of the ne†. The elastic J O thread, which might be of bare rubber but typically has a rubber or synthetic rubber core on which cotton , polyester or nylon yarn is helically wound to cover it and the inextensible thread, which may simply be string, are drawn from separate bobbins and knitted to, or laid into the stitches of, the warp threads as the tubular net is produced in the conventional way.

15 Having a definite limit to the diametral expansion of the net enables the acpurate production of tubular nets suited to stuffing machines with nozzles of different sizes.

The elastic weft thread component may be of bare rubber or may have a rubber or synthetic rubber core covered by helically wound textile or plastics yarn and the inextensible weft 0 thread component may be of string.

In accordance with yet another aspect of the present invention there is provided a method of manufacturing the net described in the five immediately preceding paragraphs which comprises drawing the elastic and the inextensible weft threads from separate bobbins and 25 knitting them both to the warp threads, or laying them both into the stitches of the warp threads of the net such that between the warp threads the elastic and substantially inextensible weft threads are unconnected. The elastic and inextensible weft threads may be joined to the warp threads at the same points along the lengths of the latter.

30 In accordance with yet another aspect of the present invention there is provided a method of preparing a cooked, meat product which comprises layering or rolling the rneat and forcing it through a nozzle into a net as described in the six immediately preceding paragraphs, separating chosen lengths of the extruded, netted product and cooking the same.

A preferred embodiment of the invention will now be described by way of non-limitative example with reference to the accompanying drawings, in which:

Figure 1 illustrates a tubular net in accordance with the present invention in a relaxed condition, and

Figure 2 illustrates the net of Figure 1 when expanded to its maximum diameter. The tubular net 10 illustrated comprises separated warp threads 11 and separated elastic weft threads 12, the threads 12 either being of bare rubber or having a rubber core covered with helical windings of a textile or plastics material. As so far described the net is conventional. In accordance with the invention, however, additional, inextensible weft threads 13 of string are provided. In the production of the net the elastic 12 and inextensible 13 weft threads are drawn from separate bobbins and both knitted to the warp threads 11 at the same points 14 along the lengths of the latter. Alternatively the weft threads 12 and 13 can be laid into the stitches of the warp threads 11 at the points 14. Because of the provision of the inextensible threads 13 the elastic threads 12 could be of bare rubber.

In the relaxed condition of the elastic weft threads 12 the net 10 is of relatively small diameter as shown in Figure 1 and the string weft threads 13 are unstraightened and form loops between the warp threads. When the net 10 is expanded by forcing a meat product into it through a nozzle (not shown) the elastic weft threads 12 are tensioned and the string weft threads 13 straightened until, as shown in Figure 2, the net 10 reaches a maximum diameter permitted by the string weft threads 13. The elastic weft threads J 2 continue to exert a squeezing force on the meat while it is being cooked but the inextensible weft threads 13 prevent distortion of the product and ensure a uniform, cylindrical shape. In one example of the use of the net 10 ham cut from the bone was layered pr rolled and then forced into the tubular net through a nozzle, the net expanding to receive the meat and thus exerting a squeezing pressure on the meat. Predetermined lengths of the netted meat were then separated and cooked, the maximum expansion of the net determining the final shape of the cooked product. As used herein and in the appended claims the description "inextensible" of the weft threads 13 is qualified by "substantially" to allow for the fact that even a thread material such as string has a limited ability to stretch. The essential feature is that the weft threads 13 are very much less stretchable that the elastic weft threads 12 so that the object of the invention can be achieved.