Abstract:
A method and an installation are provided for preserving desired seasoning flavour profiles during the manufacturing of food-seasoning sheets. The method includes the steps of; laying a thin layer of adhesive on a base sheet; removing air from the adhesive prior to the step of laying; reducing free moisture from the adhesive during the step of laying, and depositing food-seasoning ingredients onto the thin layer of adhesive. The installation for manufacturing food-seasoning sheets includes an adhesive dispenser having a reservoir and a delivery slot communicating with the reservoir for dispensing adhesive. The dispenser has a heating element mounted thereto for heating the adhesive. The adhesive is made under a partial vacuum and it is conveyed to the dispenser in a partial vacuum.

Description:
[0001]    This is a divisional application of application Ser. No. 13/137,155 filed Jul. 25, 2011 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention pertains to the manufacturing of food-seasoning sheets, and more particularly, it pertains to the calibration of ingredients in food-seasoning sheets. 
       BACKGROUND OF THE INVENTION 
       [0003]    Packaging material for curing or marinating fresh food during storage has been part of the art for some time U.S. Pat. No. 6,623,773 for example, issued to Mr. Hans J. Meier, one of the inventors of the instant application, has been granted on Sep. 23, 2003. This document explains the composition of food-seasoning sheet products. 
         [0004]    Other known documents describing similar sheet materials include:
   U.S. Pat. No. 5,705,214 issued to T. Ito et al., on Jan. 6, 1998;   CA Patent 2,007,522 issued to T. Ito, et al., on Mar. 14, 2000;   US publ. 2009/0274799 published by R. V. Lee et al., on Nov. 5, 2009.   
 
         [0008]    Referring back to the Meier patent, U.S. Pat. No. 6,623,773, which is incorporated herein by reference, it is explained therein that the calibration of seasoning ingredients bonded to a food-seasoning sheet is closely depending on the amount of adhesive that has been applied to the sheet. We might add that the calibration of seasoning ingredients in a food-seasoning sheet is also closely depending on the condition of the adhesive when seasoning ingredients are deposited over the sheet. 
         [0009]    Spice products for example, are granular or powdery in nature and their adhesion to a food-seasoning sheet depends on the portion of each granule that sinks into the layer of adhesive. The thickness and surface tension of the adhesive layer are contributing factors in the ability to retain the spice product to a food-seasoning sheet. When the layer of adhesive is too shallow, the surface of the adhesive tends to dry up and to form a shell that does not retain powdery spice materials. A thicker layer of adhesive tends to remain more fluid and wet, and to completely encapsulate and/or dissolve spice particles. In some instances, a thicker layer of adhesive may hinder the release of the spice particles from the sheet and into the food to be marinated. Furthermore, the air and water content of the adhesive are contributing factors to cause more or less absorption of the seasoning ingredients into the adhesive and to modify the potency of these ingredients. Therefore, both the thickness of adhesive and the wetness of this adhesive are important factors to consider in the manufacturing a high quality food-seasoning sheets. 
         [0010]    For example, it is well known that HVP&#39;s (hydrolyzed vegetable proteins) and sucrose are very moisture-sensitive elements that have the ability to extract moisture from a substrate. This makes these elements very difficult to work with without losing their effectiveness. 
         [0011]    The type of adhesive that is used in these applications has a viscous structure. When such an adhesive is discharged from a slot die for example, it may have a foamy texture with air entrapped in it. When air is released from the adhesive, the final volume of adhesive remaining on the sheet is less than the amount calibrated through the slot die. Also, when air is released from the surface of the adhesive, it promotes a faster drying of the surface. Consequently, the wetness of the adhesive applied to a food-seasoning sheet also depends on the air content in the adhesive exiting the slot die. Similarly, the free moisture present in the adhesive tends to dissolve the food-seasoning ingredients into the adhesive and/or into one another and to reduce the potency of the seasoning ingredients. 
         [0012]    Because of these factors, basically, it has been difficult in the past to precisely calibrated the amount of adhesive delivered onto a food-seasoning sheet. Therefore, there exists a need for precisely controlling the amount of adhesive that is laid on a food-seasoning sheet and there also exists a need for controlling the amount of air and free moisture present in that adhesive. 
       SUMMARY OF THE INVENTION 
       [0013]    In the present invention, there is provided an installation for dispensing adhesive onto a moving base sheet, wherein the amount of adhesive laid on a base sheet is precisely calibrated in a very thin layer. Air and free moisture are removed from the adhesive before the adhesive is dispensed onto the base sheet. The adhesive is in a more favourable state for receiving food-seasoning products thereon. 
         [0014]    In a first aspect of the present invention, there is provided a method for preventing a dissolution of food-seasoning ingredients into the adhesive. This method comprises the steps of
   laying a thin layer of adhesive on a base sheet;   removing air from the adhesive prior to the step of laying;   reducing free moisture from the adhesive during the step of laying, and   depositing food-seasoning ingredients onto the layer of adhesive.   
 
         [0019]    The removing of air and free moisture from the adhesive has been devised primarily for obtaining a better dispensing of the adhesive on a base sheet. Because the adhesive that is used in the method according to the present invention has less air entrapped in it and contains less free moisture, this adhesive can be applied in very thin layers and can be applied with clean edges and clean breaks. 
         [0020]    In addition to making the adhesive easy to apply on a base sheet, i.e. clean edges and clean breaks, a new and unexpected advantage has been obtained. It is believed that because of the low water activity and the extremely thin application of the adhesive, there is minimal (if any) dissolving of potentially soluble food-seasoning ingredients into the adhesive and/or into one another. The low water activity means that there is little free water available to dissolve anything. The thin application and the scarcity of air speed up the drying process to further reduce free moisture. As a result of minimal dissolving, there is nothing to diminish, mask or alter the seasoning flavour profile selected. The flavour profiles desired are more easily obtained and preserved. The flavour profiles desired are more precisely duplicated from one order to the next. 
         [0021]    In another aspect of the present invention, there is provided an installation for manufacturing food-seasoning sheets having a layer of adhesive laid onto on a base sheet and food-seasoning ingredients bonded to the layer of adhesive. This installation includes a first reservoir for making liquid adhesive therein. The installation also has a liquid adhesive dispenser having a slot die and a second reservoir in the slot die for receiving the liquid adhesive from the first reservoir; and a delivery slot in the slot die communicating with the second reservoir for dispensing the liquid adhesive onto the base sheet. There is also provided a pump and a piping system for pumping the liquid adhesive from the first reservoir to the second reservoir in an air free environment. A spice dispenser is included for dispensing spice product over the liquid adhesive on the base sheet. In this installation, the first reservoir has a mixer and a vacuum pump connected to it for generating a partial vacuum in the first reservoir when the first reservoir contains the liquid adhesive, and for removing air from the liquid adhesive prior to delivering the liquid adhesive to the second reservoir. As a result, the liquid adhesive laid on the base sheet has less air entrapped in it such that it is more easily applied in a very thin layer. 
         [0022]    In yet another aspect of the installation according to the present invention, there is provided a heating element mounted in or to the slot die for heating the adhesive as it is dispensed onto the base sheet. The heating of the adhesive promotes the evaporation of free moisture from the adhesive and the release of air entrapped in the adhesive. The adhesive is easily applied in thin layers with clean edges and breaks. 
         [0023]    In yet a further aspect of the installation according to the present invention, there is provided a vacuum box mounted under the delivery slot of the slot die for removing air from the base sheet and from the adhesive when the adhesive is laid on the base sheet. 
         [0024]    In yet another aspect of the installation according to the present invention, there is provided a system for winding the base sheet after spice products have been dispensed on it, and a monitoring and control system for setting and controlling a tension in the base sheet during a winding of the base sheet, for preventing damage to the food-seasoning sheets during storage and transport to a client. 
         [0025]    In yet a further aspect of the installation according to the present invention, a template is mounted in the slot die. The template has a dado edge extending in the delivery slot for locally obstructing a flow of adhesive through the delivery slot and for creating margins free of adhesive on the base sheet. 
         [0026]    This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiment thereof in connection with the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    A preferred embodiment of the present invention is illustrated in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which: 
           [0028]      FIG. 1  is a schematic representation of an adhesive dispenser and a spice dispenser in an installation for manufacturing food-seasoning sheets; 
           [0029]      FIG. 2  is a cutaway perspective view of the slot die in the adhesive dispenser; 
           [0030]      FIG. 3  is a cross-section view of the slot die as seen substantially along lines  3 - 3  in  FIG. 2 ; 
           [0031]      FIG. 4  is a cutaway view of a reservoir for making adhesive to be delivered to the adhesive dispenser of  FIGS. 2 and 3 ; 
           [0032]      FIG. 5  is a block diagram of the operation and control equipment included in the installation for manufacturing food-seasoning sheets. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0033]    Referring firstly to  FIG. 1 , the manufacturing of a food-seasoning sheets in the installation according to the preferred embodiment will be explained in a general manner. As a base, a film  20  of plastic material is supplied to the adhesive dispenser  22  from a roll of film for example (not shown). The film  20  can be made of polyethylene for example or other sheet material, but this is not the focus of the present invention. 
         [0034]    The film  20  is wrapped over a slot die mandrel  24  which is mounted close to a slot die  26 . The slot die  26  has a delivery slot  28  facing the slot die mandrel  24 . The film  20  passes in a small gap  30  between the delivery slot  28  of the slot die  26  and the slot die mandrel  24 . 
         [0035]    Adhesive is delivered under pressure from a reservoir (described later) to the slot die  26 , via the inlet tubing  32 . The inlet tubing  32  has a connection to a piping system represented by a dash line  34 . The adhesive is pumped through the body of a pull-back valve  36  and into the slot die  26 . The operation of the pull-back valve  36  and the slot die  26  will also be described later. 
         [0036]    The adhesive-covered sheet  40  is then passed under a spice dispenser  42  where a calibrated amount of spice product is delivered on the top of the sheet. The spice product is delivered over the wet adhesive, to bond to the adhesive. The spice dispenser  42  is located at a minimum distance from the adhesive dispenser  22  to minimize the drying of the adhesive prior to dispensing the spice product on the sheet  40 . The spice-covered sheet is then allowed to dry on the run to a winder (not shown), where it is wound on a storage roll. 
         [0037]    Although the words “spice” and “spice product” are used herein, these words are used for convenience only and should not be limiting in the interpretation of the present invention. The spice dispenser  42  may be used to deliver granular food products, salt, pepper, sugar, chocolate, nuts, fruits, spices, preservatives, seasoning formulations, anti-microbial compositions, medicinal products or any combination of these substances, or any product of that nature. 
         [0038]    The operation of the spice dispenser  42  is not described in detail herein because it is not the focus of the present invention. In the preferred installation, the calibration of the amount of spice product delivered per unit of surface of film  40  over time is done by weight and this is controlled by computer and load cells  44  mounted under the base of the spice dispenser  42 , and a speed sensor (described later) reading the speed of the slot die mandrel  24  on the adhesive dispenser  22  for example. 
         [0039]    Referring now to  FIGS. 2 and 3 , the structure and operation of the adhesive dispenser  22  will be described. In  FIG. 2 , the slot die  26  is shown with its top half  50  in a cutaway view. The pull-back valve  36  is connected to an opening  52  in the top half  50 . This opening  52  communicates with a reservoir  54  in the bottom half  56  of the slot die  26 . The reservoir  54  can be seen in the cross-section view of the slot die  26  in  FIG. 3 . The reservoir  54  communicates with the delivery slot  28 . 
         [0040]    The reservoir  54  further has two vent holes  58  along a top portion thereof to evacuate air entrapped in it. The vent holes  58  have a dimension to allow air to escape out, but to restrict the flow of adhesive there through. 
         [0041]    A flat template  60  is mounted between the top and bottom halves  50 ,  56  of the slot die  26  and over the reservoir  54 . The thickness of the template  60  is a same thickness as the gap of the delivery slot  28  in the slot die  26 . The template  60  has a dado edge with fingers  62  and recesses  64 . The fingers  62  block portions of the slot  28  of the die while the recesses  64  allow adhesive to flow though other portions of the slot  28  of the die. The local blocking of the slot  28  of the slot die  26  at the fingers  62  causes the formation of clean margins  70  along the adhesive-covered sheet  40  so as to define strips  72  of adhesive on the adhesive-covered sheet  40 , and margins  70  free of adhesive. 
         [0042]    The operation of the pull-back valve  36  creates a partial vacuum in the reservoir  54  and pulls back the adhesive upward in the conduit  52 . The pull-back valve  36  comprises a spool  80  that is movable in a valve body  82 , under the action of a pneumatic actuator  84 . The details of the spool  80 , the valve body  82  and the actuator  84  are not provided herein because these details are not the focus of the present invention and are known to those skilled in the art. The valve  36  is basically a two-way valve. 
         [0043]    The operation of the pull-back valve  36  causes interruptions in the flow of adhesive through the slot  28  of the slot die  26 . The operation of the pull-back valve  36  creates interruptions in the delivery of adhesive to the adhesive-covered sheet  40  when the sheet  20  is moving in front of the delivery slot  28 , thereby causing breaks  90  in the strips of adhesive  72 . 
         [0044]    The slot die  26  is separable in two halves  50 ,  56  and the template  60  is removably mounted between both halves. Different templates  60  may be used with different dado edges to define more or less margins  70  and margin widths. The operation of the pull-back valve  36  may be controlled by a timer and a programmable controller or other computer to vary the frequency and length of the breaks  90 . 
         [0045]    These clean margins  70  and breaks  90  free of adhesive are useful for manufacturing foldable food-seasoning sheet products such as envelopes and bags for examples. The clean margins and breaks provide clean surfaces that can be bonded to each other using heat-sealing equipment for example. 
         [0046]    The stroke length of the spool  80  of the pull-back valve  36  is selected so that air does not get into the reservoir  54 . The stroke length is selected to break the flow of adhesive through the slot  28  of the die  26 , without introducing air in the slot  28 . 
         [0047]    The movement of the valve spool  80  of the pull-back valve  36  and of the resulting movement of the adhesive inside the reservoir  54  associated with the partial vacuum that is created inside the reservoir  54  causes a certain amount of air to be released from the adhesive inside the reservoir  54  and to be evacuated through the vent holes  58 . 
         [0048]    A heating element  92  and a thermocouple  94  are mounted in or to the slot die  26 . The exact location of the heating element and the thermocouple can vary from the illustration in  FIG. 3 , according to the choice of the designer. This heating element  92  and thermocouple  94  are used to control the temperature of the adhesive exiting the slot die  26 . It has been found that a controlled heating of the adhesive prior to delivery through the slot die  26  improve trailing edge quality and uniformity in the adhesive layer. It also has been found that a heating of the adhesive helps to release air entrapped in the adhesive and from the reservoir  54 . It has further been found that the heating of the adhesive helps to reduce free moisture in the adhesive being delivered onto the film  20 . Reduced amounts of air and free moisture in the adhesive have been found to yield a better quality food-seasoning sheets with less dissolving of the food-seasoning ingredients. 
         [0049]    A vacuum box  100  is also provided immediately under the gap  30  and the delivery slot  28 . The vacuum box  100  is open at the top as can be seen in  FIG. 3 , with an opening facing the surface of the slot die mandrel  24  immediately below the delivery slot  28 . A partial vacuum is applied into the box  100  by a vacuum pump  146  as illustrated in  FIG. 5  for example, and an air flow is drawn therein from the surface of the slot die mandrel  24 , to remove air from the surface of film  20  immediately before adhesive is deposited to the film  20 . As may be appreciated, the vacuum box also has the ability to remove air from the lower laminae of adhesive exiting the slot  28  of the die. 
         [0050]    The removal of air from the film  20  and from the lower laminae of adhesive ensures that less air is be trapped under and into the adhesive. As may be appreciated, this removal of air reduces the amount of air permeating through the layer of adhesive on the adhesive-covered sheet  40 . 
         [0051]    Referring now to  FIG. 4 , there is illustrated therein a reservoir  110  for making and mixing a batch of adhesive, for use in the slot die  26 . The adhesive is pumped from the reservoir  110  though the piping system  34  shown in  FIG. 1 . The reservoir  110  is of a type that can be hermetically sealed. The reservoir  110  has a mixer  112  mounted therein. The reservoir  110  also has a tubing  114  connected to a top part thereof at connection  116  for example. The tubing  114  is connected to a vacuum pump  118 . 
         [0052]    In use, a batch of adhesive is prepared and mixed under at least a partial vacuum so that a minimum amount of air is entrapped in the adhesive. The adhesive is transferred to the slot die  26  and enters the slot die  26  under pressure from a pump  120  and tubing  34 . Both the pump  120  and tubing  34  are hermetically sealed as it is customary with equipment of that nature. The adhesive being pumped is not exposed to air between the reservoir  110  and the slot die  26 . 
         [0053]    Referring now to  FIG. 5 , there is illustrated therein a block diagram of the equipment included in the preferred installation for manufacturing food-seasoning sheets. The installation is controlled by a programmable logic controller (PLC)  130  with motion controllers. A touch-screen input device  132  is used to enter settings for different food-seasoning profiles. 
         [0054]    Servo drives  134 , encoders  136  and feedback loops  138  are used for controlling the speed of each function driver. 
         [0055]    Referring to individual function drivers, the adhesive delivery pump  120  is connected to the adhesive reservoir  110 . The reservoir  110  as shown in  FIG. 5  is a same reservoir as the mixing reservoir shown in  FIG. 4 . However, in some installations, two reservoirs may be used; one for batch mixing the adhesive and one for delivering the adhesive to the slot die  26  in a continuous mode. 
         [0056]    The adhesive delivery pump  120  is a volume-controllable pump and its delivery volume is controlled in relation to film speed measured at slot die mandrel  24 , in a control feedback loop  140 . The adhesive delivery pump  120  is programmable to set precise coat weight or thickness. 
         [0057]    The delivery of spice product from the spice hopper  42  to the web is also controlled in relation with the speed of the slot die mandrel  24 , by means of a feedback loop  142  between the spice delivery mandrel  150  and the slot die mandrel  24 . 
         [0058]    The spice application is based on a loss-of-weight feeding system, including load cells  44  under the spice hopper  42 , and a first summing module  152  reading the load cells  44 . The speed of the servo motor  150  on the spice mandrel  150 ′ is controlled by weight loss over film speed and recipe request. The location of the spice mandrel  150 ′ can be seen in  FIG. 1 . 
         [0059]    The film speed and film tension are controlled through a feedback loop  154  between a web-unwind roll  156  and a web rewind roll  158 . Each of the film unwind roll  156  and film rewind roll  158  is driven by a gear box  160  and a servo motor  162 . 
         [0060]    The film speed and film tension are also controlled by measurement of the radial strain on a tension roll  164 . The tension roll  164  can also be seen in  FIG. 1 . A pair of load cells  44 ′ are installed on the tension roll  164  to measure film tension. The signals from these load cells  44 ′ are integrated in a second summing module  166 , and are used to adjust speed and torque of both the film unwind roll  156  and film rewind roll  158 . Torque is recipe-dependent and is controlled especially for preventing product damage on roll-up of the coated film  40 . 
         [0061]    The installation according to the preferred embodiment for manufacturing food-seasoning sheets has the ability to precisely control the thickness of the adhesive layer and the volume of food-seasoning ingredients deposited on the film surface. The preferred installation also has the ability to control film tension at roll-up. Further, the preferred installation has the ability to control free moisture and air content in the adhesive. As a result, a better calibration of the food-seasoning ingredients is obtained. 
         [0062]    The preferred installation has limited absorption of the food-seasoning elements into the adhesive or vice-versa, or into one another. The food-seasoning elements keep their maximum potency. 
         [0063]    As to other manner of usage and operation of the manufacturing of food-seasoning sheets, the same should be apparent from the above description and accompanying drawings, and accordingly, further discussion relative to these aspects is deemed unnecessary.