Sandwich product and method for making same

A sandwich product is made by sealing the peripheral portions or edges of two slices or layers of bread together to form a substantially sealed pocket between the layers with filling material in the pocket. The sealing takes place without heat, and prevents cheese, sauce, or other filling ingredients from running out of the product upon heating of the product. Markings may be pressed into the product which form subpockets and restrict the flow of filling ingredients between subpockets. Score lines may also be formed to divide the product into multiple pockets which may be easily separated into separate pieces of the product.

BACKGROUND OF THE INVENTION
 1. Field
 This invention relates to food products. The invention envisages a method
 for producing sandwiches, particularly sandwiches which are toasted or
 otherwise heated prior to being consumed.
 For the sake of avoiding repetition, the term "sandwich" will be used
 throughout this specification and the claims to include a food product
 comprising two or more layers of bread which are brought together with an
 edible filling of any suitable kind therebetween. The layers may take the
 form of separate slices of bread cut from a conventional loaf or a single
 such slice folded over on itself. However, the layers may also take any
 other suitable form. They may, for example, particularly but not
 necessarily exclusively in a commercial operation, be formed from pieces
 of bread dough which are made into a desired shape before they are baked
 so that, after baking, they do not need to be cut or further shaped (other
 than for the removal of crust) before being used to make the sandwich. One
 such desired shape may be that of a conventional slice of bread.
 Furthermore, the term "bread" is used in a broad sense in this
 specification and claims. It is used essentially to imply that the product
 is pre-baked or otherwise cooked before it is used for carrying out the
 method of the present invention. It is intended to include in particular
 any suitable bread-like product which incorporates baked dough as an
 essential ingredient and which is used to make a sandwich according to the
 methods of the present invention.
 2. State of the Art
 There is, of course, a well-known technique for making toasted sandwiches.
 Commercially available devices are provided for the purpose. These devices
 conventionally comprise a pair of plates which are joined together by
 hinges or the like so that they can be pivoted to an operational position
 in which the working face of the first plate faces the working face of the
 second plate. In use, a sandwich is placed between the plates, in contact
 with the working faces. The plates are then heated and the sandwich is
 toasted by the heat which is transmitted through the working faces to the
 sandwich.
 Conventional such devices work best when the thickness of the sandwich is
 somewhat greater than the gap between the working faces. The sandwich is
 thus squeezed between the working faces which improves the contact, and
 hence the efficiency of heat transfer, between the plates and the
 sandwich. However, there is clearly a practical limit as to how much the
 sandwich can be squeezed since excess squeezing will not only tend to
 eject the filling from the sandwich (especially if the filling comprises a
 substance such as cheese which melts when it is heated) but will also have
 a deleterious effect on the quality of the sandwich.
 The working faces of most conventional devices of this kind are flat.
 However, cavities or recesses are molded into the working faces of some
 such devices. The bulk of a sandwich is accommodated in a cavity of this
 kind, the edges of the sandwich overlapping the periphery of the cavity.
 The edges of the sandwich are thus squeezed between the portions of the
 working surfaces bordering the cavity and, when the toasted sandwich is
 removed from the edge, the edges are often found to be sealed together.
 This sealing is, however, achieved by the applied heat. This can be
 demonstrated by separating the plates before the heat is applied. It is
 then found that the squeezed edges are not fused together and easily
 become separated especially if an attempt is made to heat the sandwich
 without returning it to the aforementioned toasting device. Any liquid in
 the filling will run out if the sandwich is turned on its edge.
 Bread toasting appliances wherein a slice of bread is positioned vertically
 on an edge in the appliance for toasting are in common use but are not
 generally used for heating sandwiches because the sandwich filling
 generally falls out of the sandwich when placed in a vertical position.
 The applicant believes that there is a need for a sandwich product which
 can be supplied to users ready to be toasted or cooked in some manner,
 such as by microwave, a conventional oven, frying pan or grill, or common
 toasting appliance. However, if such a product is to be acceptable, it is
 essential that it must be capable of being handled during manufacture,
 packaging, transport, unpackaging, and cooking without falling apart. It
 must further be such that cheese, sauce, or any other substance in the
 filling should not be able to escape when it melts or becomes less viscous
 upon being heated. This is important to prevent the cheese, sauce, or
 other substances in the filling from running out of the sandwich product
 into an oven, pan, or toaster during heating of the product, particularly
 when heating is accomplished by positioning the sandwich product
 substantially vertically on an edge in a common toaster appliance. Most of
 such toasters are of the radiant heat type which reduces the time required
 to brown the outside and to heat the ingredients to about 1.5 to 3
 minutes.
 In an earlier attempt to provide an acceptable sandwich product, the
 inventor of the present invention has proposed to glue together the two
 slices of bread in a sandwich, using an edible glue. These proposals are
 set out in international patent application Serial No. PCT/NZ93/00104.
 One drawback of gluing the slices together is that, although the layers are
 bonded together at lower temperatures, any meltable ingredients of the
 filling are still able to escape when they melt or becomes less viscous
 upon being heated. This limits the choice of ingredients.
 SUMMARY OF THE INVENTION
 According to the invention, there is provided a method of producing a food
 product comprising the steps of bringing together two layers of baked
 bread and using pressing apparatus to cold press edge portions of the
 layers together so that interfacing portions of the layers adjacent the
 edge portions become bonded together and remain bonded when the product is
 removed from the pressing apparatus.
 The pressing operation can be carried out with pressing tools at ambient
 temperature. Although it might under some circumstances be beneficial (for
 example, to avoid the bread sticking to the pressing apparatus) to gently
 warm the pressing apparatus, or at least those parts which press the edge
 portions of the layers together to effect the bond, it is not in any case
 necessary either to heat the apparatus to the temperature at which the
 product will begin to be cooked, or to heat the product to the extend that
 cooking commences.
 One beneficial aspect of cold pressing the layers in order to bond them
 together is that no heat is wasted. The heat which would be applied in
 other processes for this purpose would be wasted as it must be removed
 during the subsequent chilling or freezing of the product.
 In one form of the invention, a filling is inserted between the layers
 before the interfacing portions are bonded together, the filling being
 sealed between the two layers by the bonded interfacing portions. The
 filling may be as simple as, for example, garlic butter. However, the
 invention allows for fillings of a wide variety of foodstuffs, or mixtures
 of foodstuffs. Moreover, as appears in greater detail herein, fillings
 which have been developed specially for use with the present invention may
 be used.
 According to one aspect of the invention the product is prepared by cutting
 a loaf of bread along its length to form a slice which is folded on itself
 to form the two layers. In an alternative form of the invention, the two
 layers are constituted by two slices cut from a loaf of bread. In most
 commercial operations the loaf would be passed through a machine which, in
 one pass would cut the loaf into a multiplicity of slices.
 In one optional form of the invention, crust is removed from the layers.
 The crust removal may take place at any convenient stage but is
 conveniently effected at substantially the same time as the edge portions
 are pressed together and by the same pressing apparatus.
 The layers may be of square, rectangular, triangular, round, curved,
 trapezoidal or any other suitable shape.
 According to one aspect of the invention, decorative markings such as
 simulated grill marks or heat marks are printed or otherwise applied to
 the outer face of at least one of the layers. It is advantageous in some
 instances where a filling runs easily when heated to press markings into
 the sandwich so that such markings cause restriction to filling flow
 between the opposed bread layers. This keeps the filling more evenly
 distributed between the bread layers during toasting of the sandwich
 product. Further, if desired, the product can be scored and perforated to
 enable it to be easily broken into smaller pieces.
 Advantageously, the invention includes the further step of chilling or
 freezing the product after it is produced.
 In one form of the invention the filling includes a layer comprised of at
 least one foodstuff which is or has been divided into pieces which are
 held together by a binding agent. The binding agent may advantageously be
 gelatin or a similar agent which is cohesive when it is chilled and which
 melts when the product is heated prior to consumption.
 The pressing apparatus advantageously comprises at least one roll which
 presses the edge portions together with a rolling action.
 The invention allows for a wide variety in the thickness of the fillings.
 When the filling is thick the bread must be stretched over the edges of
 the filling, requiring a stronger seal. The invention contributes
 materially to the strength and integrity of the seal.
 It is intended that the scope of the invention should cover a food product
 whenever it is prepared by a method as disclosed and claimed herein.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
 In FIGS. 1 and 2, the sandwich 10 shown comprises two layers of bread with
 an edible filling 16 therebetween. It is considered to be important for
 the commercial viability of the invention that the layers can be in the
 form of slices 12, 14 cut from a conventional loaf of bread and thus, as
 cut, each has crusted portions 38 around its periphery. However, this is
 by way of example only and the variable nature of the bread product and
 its filling are described below.
 In the present example, two pressing tools 18, 20 are mounted in alignment
 in a press, not shown. The press has a mechanism which can be actuated to
 advance the upper tool 18 towards the lower tool 20. Actuation of the
 mechanism can be manual or with power assistance.
 The upper tool 18 comprises a base 22 having a flat, lower face 24 with a
 substantially rectangular periphery defined by downwardly extending
 shoulders 26 extending along each edge of the face 24 and intersecting at
 the corners thereof. Each shoulder terminates in a lower face 36 which is
 approximately perpendicular to an inner face 34.
 The lower tool 20 is substantially identical to the upper tool 18. However,
 the lower tool is inverted in used. The lower tool 20 thus comprises a
 base 22' having a flat, rectangular upper face 24' with upwardly extending
 shoulders 26'. Each shoulder terminates in an upper face 36' which is
 approximately perpendicular to an inner face 34'.
 Cutting blades 46 are mounted about the periphery of the lower tool 20.
 In the present example, the length and width of the face 24 of the upper
 tool 18 are both 100 mm. The depth of the shoulder portion 26 as measured
 by the distance from the face 24 to each face 36 is 10 mm. The width of
 each face 36 is 5 mm. The lower tool 20 is substantially identical to the
 upper tool. As should be obvious, these dimensions are given by way of
 example only and may vary within wide limits.
 The press is operated to raise the upper tool 18 clear of the lower tool 20
 as shown in FIG. 1. The sandwich 10 is then inserted in the space between
 the tools, resting on the sharpened upper edges of the cutting blades 46.
 The cross-sectional size and shape of the loaf, and hence of the slices
 18, 20, is chosen so that the slices 18, 20 overlap the peripheries of the
 tools 18, 20 at least to the extent that the crusted portions 38 of the
 slices are located outwardly of the cutting blades 46. However, to
 minimize waste, the size of the slices should only be marginally greater
 than the size of the tools 18, 20. By way of example, for use with tools
 18, 20 of the size described above, the slices may be 125 mm long, 125 mm
 wide and 10 mm thick.
 The press is then operated so that the upper tool 18 is advanced towards
 the lower tool 20. In the course of this movement, the faces 36 come into
 contact with the upper slice 12 and further advancement of the upper tool
 18 causes the crusts to be cut off by the cutting blades 46 and the two
 slices 12, 14 to be squeezed together by the faces 36, 36' near the outer
 edges of the slices. Advantageously the size of the filling 16 should be
 chosen so that the filling lies within the peripheries of the tools 18, 20
 and preferably of the faces 34, 34'. The inner face of the upper slice 12
 thus has a peripheral portion 40 located outwardly of the filling which,
 when the slices are squeezed together, comes into direct contact with the
 similar portion 42 of the inner face of the lower slice 14.
 It has been found that, when the two slices of bread are squeezed together
 in this manner between tools which are properly designed and with
 sufficient pressure, a bond is formed between the two slices at their
 interfacing peripheral portions 40, 42 which are squeezed together between
 the faces 36, 36' of the tools. This squeezing seals the two layers
 together and forms a substantially sealed pocket or cavity between the
 layers of bread inwardly of the outer sealed edges which can hold filling
 therein. The shape of the sandwich is governed by the profile of the tools
 18, 20. In the present example, the tool 18 is advanced to a position in
 which the distance between the faces 36, 36' is 2 mm. This distance can of
 course be adjusted as required. The shape of the sandwich so produced is
 as shown in FIG. 2 and provides a secure bond as well as a pleasing
 appearance.
 There is no need to heat the tools substantially or for any gluing agent to
 be applied between the two slices. The bond is strong enough to hold the
 two slices together during subsequent handling and packaging. It is also
 sufficient to form a seal which prevents the leakage of a constituent of
 the filling 16 which may become liquid, particularly when the sandwich 10
 is heated prior to consumption. This is an advantage of the greatest
 importance since it is intended that the sandwich 10 should be factory
 produced and delivered to users in a ready to use form which requires no
 further preparation other than heating. Such users would include domestic
 users as well as snack bars and other businesses which offer food products
 of this kind to the public. Many, if not most of such users will heat the
 sandwich 10 in a conventional toaster appliance or machine which receives
 the toast in a vertical disposition. Leakage of liquid from the filling 16
 when the sandwich is being heated in such toasters will render the product
 unacceptable to the market and make the use of a loaf filling such as
 described below with reference to FIG. 8 impractical.
 The cutting blades 46 act as a barrier to prevent pieces of the filling
 from falling out or being ejected when the sandwich is pressed by the
 tools 18, 20.
 The requirements for ensuring an adequate bond will vary. Amongst the
 factors which will affect the quality of the bond are:
 a. The pressure or squeezing force per unit area applied to the bread and
 more especially to the peripheral portions 40, 42.
 b. The moisture content of the bread. This will be affected by, inter alia,
 the "bake level" and the freshness of the bread. A 0% bake level
 represents a fully unbaked product whereas a 100% bake level represents a
 fully baked product containing less moisture. The moisture content and the
 bake level affect the pressure required to form an adequate bond.
 c. The nature of the bread. As is well known, some breads are light and
 airy while others are heavy. The thickness of the slices, the solids
 content of the bread per unit volume and the percentage of such solids
 which comprise ingredients other than baked dough are all likely to affect
 the required pressure and also the area over which the two slices must be
 squeezed together.
 d. The presence, accidental or intentional, of matter between the portions
 40, 42 which are squeezed together. Matter from the filling 16 could, for
 example, migrate by dislodgement or squeezing from the center of the
 sandwich to the periphery.
 e. The nature of the filling including the liquid content thereof and any
 propensity of the filling to expand when heated and thereby apply pressure
 to the slices.
 f. The shape of the pressed together edge portions, which, as already
 noted, is determined by the shape of the pressing tool.
 Because of the wide variations in the above and possibly other factors, it
 will be necessary to determine by experiment the size and shape of the
 tools and the pressure to be applied in many cases. However, it has been
 found that tools of the size and configuration described above can be
 successfully used with a wide variety of bread types, from light, airy
 white bread to heavy brown breads. Typically, using slices which are 10 mm
 thick cut from fresh baked white bread with a moisture content of about
 58%, a density of about 0.2 g/cc, and using a filling (comprising a slice
 of cheese and a slice of ham) which is 3 mm thick the bread slices will
 bond adequately under a force of 13 kg applied to the upper tool.
 A force of 13 kg applied to the upper tool has been calculated to equate to
 700 g/cm.sup.2 applied to the bread over the area of the faces 36 of the
 upper tool.
 The above quantities are average quantities. Using the same pressing tools,
 adequate bonding has been found to occur, or may be expected, within a
 range of values around those quantities. For example, the thickness of the
 slices of both white and brown bread can vary between 8 mm and 15 mm. The
 moisture content of the white bread can vary between about 30% and 60% and
 the density of the white bread can vary between 0.2 and 0.4 g/cc. The
 quality of the bonding has been found to deteriorate as the bread loses
 its moisture--bread which is a day old still bonds adequately whereas if
 bread which is more than three days old is used without being kept fresh
 as by freezing or the like, the bond is too poor to be reliable. An
 important variable parameter is the applied pressure. Using the same
 pressing tools on the white bread mentioned in the example, a force as low
 as 10 kg applied to the tools was still found to effect an adequate bond
 between the slices.
 Similar results have been achieved when brown bread having the qualities
 mentioned in the above example was used.
 If the crusts are not removed during the pressing operation, the sandwich
 will have the appearance shown in FIG. 3 after it has been pressed. It
 will have necked portions 44 where the slices have been pinched and bonded
 together adjacent their edges by the pressing tools. Although the crusts
 may be left intact, it is thought that in most cases it will be
 preferable, from a marketing point of view, to remove the crusts. This can
 be achieved by one means as noted above. However, it is also possible to
 cut the crusts off by hand or to provide a cutting tool for removing the
 crusts. One example of a cutting tool is shown at 46 in FIG. 4. The
 pressing tools 18, 20 could be provided with a similar cutting tool. The
 cutting tools are important in forming the edge design.
 In another example of an arrangement of pressing tools, the lower tool 20
 could be replaced by a similar flat platten. In this case, it might be
 necessary to increase the depth of the shoulder portion 26 and the width
 of the vertical flat face 34 of the upper tool 18.
 In the pressing operation using the tools 18, 20, the entire sandwich is
 subject to a degree of compression. This is considered advantageous since
 the thickness of the sandwich is reduced for fitting into a toaster and
 its density is increased. It is also given added stiffness and strength
 since the filling tends to bond to the slices of bread under such
 compression. This compression could of course be carried out as a separate
 operation. Advantageously the dimensions of the tools 18, 20 and
 particularly the depth of the shoulder portions 26, 26' as aforementioned
 are chosen so that the thickness of the sandwich, after being formed, is
 such that it can easily be inserted in conventional vertical slot toasting
 machines.
 After the sandwich is removed from the pressing apparatus, it is
 advantageously subjected to further processing. It may be passed through a
 heating device which applies grill marks to the outer faces of the slices.
 Alternatively artificial grill marks could be applied by a roller which
 rolls a coloring agent in a predetermined pattern simulating grill marks
 or other decoration on the outer faces of the slices. Alternatively, or in
 addition, the entire surface of each outer face could be coated with an
 agent such as butter, margarine or oil containing one or more flavoring
 agents such as finely divided garlic. This also provides a more uniform
 browning of the sandwich when it is subsequently toasted prior to
 consumption.
 In some cases, particularly where the filling material becomes less viscous
 and therefore flowable when heated, the degree of flow that takes place
 can be reduced by pressing the grill or other marks into the outer faces
 of the bread, as at 70, FIGS. 15 and 16, to an extent to press the inner
 faces of the bread toward one another along the marks as at 72, FIG. 15,
 to form subpockets and restrict flow of filling within the subpocket
 between the bread slices. The degree of restriction will depend upon the
 depth of the markings 70, which can be made to cause the desired degree of
 restriction to flow. A depth of about three millimeters has been found
 satisfactory in most instances, such as when a cheese filling is used.
 Further, if desired, the product can be scored and weakened, such as by
 perforations, about a break line to enable the sandwich product to be
 easily broken into desired pieces after heating. Thus, the bread may be
 pressed together as along line 74 to form a score line and perforations 76
 may be added along the score line to further enhance separating of the
 pieces along such line. The joining of the inside opposing faces of the
 bread as at 78 prevents leakage of the filling through the perforations.
 Various patterns and locations of markings and score lines can be used as
 desired.
 Any moisture added to the product is likely to increase the time required
 to chill or freeze the product after it is made and to heat the product
 prior to consumption. Excessive moisture may also cause the product to
 become soggy. Both garlic and butter, as well as the ingredients of the
 filling, will in most cases add to the moisture content of the product. It
 is therefore desirable that the butter or other agent should have a low
 moisture content, preferably less than 16%. Furthermore, if necessary,
 moisture can be removed form the bread after the layers are bonded
 together, for example, by passing the sandwich through a dehydrating
 apparatus. Suitable such apparatus is commercially available.
 If a coloring agent is used to form grill or other decorative marks, the
 coloring agent may be applied by passing the sandwich, immediately after
 it has been pressed by the tools 18, 20 vertically between a pair of rolls
 120 as shown schematically in FIG. 11. The surfaces of the rolls are made
 up of spiral wire rings which pass through baths 122 of food coloring
 solution 124. The solution is picked up by the spiral wire rings and
 transferred to the outer faces of the sandwich in a pattern corresponding
 to those parts of the wire rings which come into contact with the
 sandwich.
 In somewhat similar fashion, a butter or oil coating mix may be applied by
 then passing the sandwich vertically between a second pair of rolls 130
 shown schematically in FIG. 12. The surfaces of the rolls 130 are
 absorbent. As the rolls 130 rotate, the absorbent surfaces thereof pick up
 coating mix 132 from baths 134 and then move past squeeze rolls 136 which
 press against the absorbent surfaces, squeezing out excess coating mix
 which drops back into the baths 134. The amount of coating mix which is
 then transferred to the outer faces of the sandwich by further rotation of
 the rolls 130 is thus closely controlled. The squeeze rolls are spring
 loaded so that the force which they apply to the absorbent surfaces of the
 rolls 130 can be adjusted.
 This an advantageous method of applying the coating mix as it is difficult
 to apply such coatings evenly with the sandwich in horizontal disposition.
 After the sandwich is prepared it is advantageously chilled or frozen by
 standard techniques. The chilling serves to solidify the butter or other
 coating agent. The sandwich can thus be stored for a long period and
 remain fresh up to the time it is heated prior to consumption. of course,
 the grill marks and/or the butter or other coating mix may be applied,
 and/or the slices may already be chilled, before the sandwich is subjected
 to the pressing operation.
 Although it is thought at present that the invention will have its greatest
 application to products in the nature of toasted sandwiches and the like
 which are eaten hot, it is also envisioned that there may be a demand for
 products which are eaten without being heated (or at least heated above
 ambient temperature). The invention will still be useful for such products
 since the fillings for such products may include sauces and the like which
 are non-liquid when chilled but which become liquid when heated to ambient
 temperature.
 The face 48 of the pressing tools shown in FIG. 4 are indented to form
 cavities 50 in the tools. The purpose of the cavities can be threefold.
 First, the cavities enable the tools to accommodate a sandwich which has a
 thicker filling leading to an increase in the thickness of the center part
 of the sandwich. Second, the sandwich takes up the shape of the cavities
 which might increase the customer appeal of the sandwich. The curved shape
 of the cavities shown is only one example of a shape which could be
 imparted to the sandwich. Third, it might be desirable to avoid
 compressing the center part of some sandwiches. For example, some fillings
 may comprise a sauce with a pasty consistency and which would be ejected
 if the filling was compressed. This can be avoided by providing cavities
 which are so deep that their faces do not come into contact with the
 center part of the sandwich during the pressing operation.
 As mentioned briefly above, the nature of the bread may vary widely. As
 shown in FIG. 5, instead of using two conventional slices of bread, a
 sandwich 52 can be made up by using a long single slice 56 and folding it
 over on itself. This allows a larger sandwich to be made from a loaf of
 bread of given size. Such a slice can be obtained by cutting a
 conventional loaf lengthwise. This slice is then folded across its middle
 to form a fold which is located along one edge of the sandwich as
 indicated at 54. The sandwich 52 so formed need only be sealed along its
 other three edges. The tools 18, 20 may be modified for this purpose. The
 shoulder portions 26, 26' along one edge of the tools 18, 20 may be
 omitted. Alternatively, the tools 18, 20 may be used without modification.
 They would then press the peripheral portions of the sandwich, including
 the portion adjacent the fold 54.
 Alternatively the sandwich 52 is sealed only along two opposite side edges,
 leaving the end 59 opposite the fold 56 open. This is particularly useful
 when the filling is garlic butter applied as described below with
 reference to FIG. 13. This avoids the need to seal the end which is butter
 coated and which, if sealed, opens up when heated. The end which opens up
 is inserted facing upwards in the toaster.
 The bread may alternatively be specially prepared for making sandwiches
 according to the method of the invention. In a more highly automated
 facility, the bread may be prepared in the form of an extra long loaf
 which is cut along its length into slices the length of which may, for
 example, be four times as long as the length of a sandwich. Each end of a
 single such slice 58 may be folded inwards to form a double sandwich 60 as
 shown in FIG. 6. This double sandwich comprises two sandwiches 60a, 60b
 which are separated from each other at the position 62 after the double
 sandwich has been subjected to the pressing operation for bonding and
 sealing the peripheral portions together essentially as described above.
 Special pressing tools will be required for this purpose.
 Whereas this invention is here illustrated and described with reference to
 embodiments thereof presently contemplated as the best mode of carrying
 out such invention in actual practice, it is to be understood that various
 changes may be made in adapting the invention to different embodiments
 without departing from the broader inventive concepts disclosed herein and
 comprehended by the claims that follow.