as used herein , the moisture barrier is formed from any water swellable material including cold water swelling starches , carageenan , gums ( including guar , xanthan , locust bean , gellan gum , cellulose gum , konjac gum and gum arabic ), methylcellulose , propylene glycol alginate and pectin . when the material is a starch , it may be derived from any source , including cereal or root starches . typical sources for the starches are cereals , tubers , roots , legumes and fruits . the native source can be any variety of corn ( maize ), pea , potato , sweet potato , banana , barley , wheat , rice , oat , sago , amaranth , tapioca , arrowroot , canna , sorghum and waxy and high amylose varieties thereof . as used herein , “ waxy ” is intended to include a starch containing no more than about 10 %, particularly no more than about 5 %, more particularly no more than about 3 %, and most particularly no more than about 1 % amylose by weight . as used herein , the term “ high amylose ” is intended to include a starch containing at least about 40 %, particularly at least about 70 %, and more particularly at least about 80 % by weight amylose . as used herein , the term “ amylose - containing ” includes those starches containing at least about 10 % by weight amylose . the starch may be a native starch or a modified starch . modified starch as used herein is intended to include starches that have been modified physically , chemically and / or by hydrolysis . physical modification includes by shearing or thermally inhibiting , for example by the process described in u . s . pat . no . 5 , 725 , 676 to chiu et al . the starch can be chemically modified . chemically modified starches include , without limitation , crosslinked , acetylated , organically esterified , hydroxyethylated , hydroxypropylated , phosphorylated , inorganically esterified , cationic , anionic , nonionic and zwitterionic , and succinate and substituted succinate derivatives thereof . such modifications are well known in the art , for example , as described in modified starches : properties and uses , wurzburg , o . b ., editor , crc press , inc . florida ( 1986 ). the starches can also be hydrolyzed . suitable starches include fluidity or thin - boiling starches prepared by oxidation , acid hydrolysis , enzyme hydrolysis , heat and / or acid dextrinization . these processes are well known in the art . any starch having suitable properties for use herein may be purified by any method known in the art to remove starch off - flavors and colors that are native to the polysaccharide or created during processing . suitable purification processes for treating starches are disclosed in the family of patents represented by european patent no . 554 818 to kasica et al . alkali washing techniques are also useful and described in the family of patents represented by u . s . pat . no . 4 , 477 , 480 to seidel and u . s . pat . no . 5 , 187 , 272 to bertalan et al . the material is used in its cold water swellable form . it can be obtained commercially in such form or can be converted to a cold water soluble material using techniques well known in the art , such as by drum - drying , spray - drying , extrusion , etc . typical of such processes are those disclosed in u . s . pat . nos . 3 , 137 , 592 , 4 , 600 , 472 , 4 , 280 , 851 , 5 , 131 , 953 , 5 , 188 , 674 , 5 , 281 , 432 , 5 , 318 , 635 , 5 , 435 , 851 and 5 , 571 , 552 , the disclosures of which are incorporated herein by reference . further suitable starches include cold water swellable ( pregelatinized starches ) that are known in the art and disclosed , for example , in u . s . pat . nos . 4 , 465 , 702 , 5 , 037 , 929 and 5 , 149 , 799 . conventional procedures for pregelatinizing starch are also known to those skilled in the art and described , for example , in powell , e . l ., production and use of pregelatinized starch , s tarch : c hemistry and t echnology , vol . ii — industrial aspects , chpt . xxii , pp . 523 - 536 , whistler , r . l . and paschall , i . f . editors , academic press , new york ( 1967 ). the ideal barrier should be continuous and consistent throughout the temperature ranges to which the food product is subjected . the ideal barrier should also maintain and preferably contribute to the integrity of the composite food product . the application of a dry , cold water swellable ( hydratable ), edible powder to at least one surface of a food product having components of differing water activities provides moisture barrier properties . the barrier can be applied before or after par - baking the crust or pastry dough . for swellable / hydrating powders to work as moisture barriers , a dry , uniform layer should be spread at the interface where migration occurs . a solution of the powder is not as effective because it incorporates too much water in the food system . the powder may be combined with any other components / compounds to enhance any functionality and / or ease of application and manufacturing , such as films , adhesive agents , flow aides , lipids , waxes , proteins and coatings . the desired composition should form a continuous layer and , once contacted with moisture , should swell sufficiently so as to act as a moisture barrier within less than about one minute from contact . the powder provides a barrier that allows needed migration , thereby preventing pooling of the high moisture content . the swellable powder can be used in a variety of storage conditions , such as frozen , refrigeration and ambient . in addition to inhibiting moisture migration , the dry powder - based barrier of the present invention adds to the appearance of products . for example , when added to pizza , after baking the pizza it has a more “ full ” appearance , the cheese is not as burnt and the crust cell structure is maintained . in other applications , e . g ., cheesecakes and ice cream sandwiches , the barrier helps stick the filling to the base with an overall firmer product base achieved . with pies , the product with the barrier does not have as much leakage and keeps its structure once cut . the disclosed barrier &# 39 ; s organoleptic properties of taste , mouthfeel and aftertaste are imperceptible . the disclosed barrier is eaten as part of the whole food and the consumer is not aware of the barrier when the food product is consumed . water migration rate was measured by a gravimetric absorbency testing system ( gats , manufactured by m / k systems , inc .). the sample to be tested is placed on a porous filter mounted in a movable stage . the movable stage is attached to a reservoir through a tube filled with water . the water reservoir sits on an analytical balance . during the test , water is drawn through the tube , and water lost from the reservoir is measured as a function of time . the instrument incorporates a mechanism that offsets the effects of gravity on absorbency tests . for the test , 0 . 500 +/− 0 . 001 g of dry powder is weighed and spread evenly inside a plastic ring ( 45 mm inner diameter and 60 mm height ) sitting on the surface of the filter paper ( circles , 70 mm from whatman ®). the sample , including filter paper and plastic ring , is placed on the porous plate of the gats , with the water lost from the reservoir recorded as a function of time . the experiment is conducted at room temperature . the samples were repeated to prove the reproducibility of the experiment . the settling volume test procedure is as follows : 1 . 000 +/− 0 . 001 g ( anhydrate basis ) of dry powder is weighed and dispersed into a 100 ml beaker containing 50 ml deionized water under vigorous stirring . after the sample is completely wet and dispersed in water , it is completely transferred to a 100 ml graduated cylinder . water is added to bring the solution to 100 ml . the sample is kept undisturbed for at least 24 hours to allow complete settling . the settled phase volume is recorded as the settling volume . a food model system (“ fms ”) was developed consisting of milk crackers ( nabisco ), pure nylon fabric cut from the leg of pantyhose , and commercially obtained ragu ® pizza sauce . samples were run in at least triplicate with a control . initial weight of the cracker was taken and the pieces of nylon fabric were applied . barriers were applied over the cracker / nylon construction . after the barriers were evenly distributed , two tablespoons of sauce was spread over the cracker . the system was allowed to sit at room temperature for four hours . after time elapsed , the nylon fabric containing the barrier and sauce was removed and the final weight of the cracker was recorded . the texture of the cracker , powder and sauce were noted . the results were reported as average amount of weight gain per cracker . pre - formed films , formed - on coatings and disclosed barriers were evaluated using the fms . typically , the fms with no barrier has a weight gain between 4 . 5 and 5 . 0 grams , with the cracker being soaked and falling apart . a weight gain of less than three grams is acceptable , with the cracker retaining some textural properties . a weight gain of two grams or less is ideal . the fms is also used to test the temperature stability of the barrier . water absorbency of the disclosed barrier measured by gats is attributed to two mechanisms — wicking and swelling . wicking and swelling play an opposite role in moisture barrier performance . therefore , it is important that these two contributions be separated . [ 0050 ] fig1 shows water absorbency curves of a granular starch and of the disclosed barrier ( here , a cold water swellable (“ cws ”) starch ). because the granular starch is not swellable at room temperature , the water absorbency reflects only the amount of wicking . as shown in fig1 the water absorbency of the granular starch reaches equilibrium absorbency within about 100 seconds , and 90 % absorbency within about 50 seconds . in contrast , the water absorbency of the disclosed barrier keeps growing during the measurement due to the swelling . hence , wicking processes faster than swelling . thus , the water absorbency of first 100 seconds measured by gats is dominated by wicking . barriers according to the present invention ( here , drum - dried and spray - dried starch ) were compared with granular ( non - swellable ) starch in the fms . the weight of the cracker was measured at various times over a twenty - two hour interval . fig2 illustrates the weight gain of samples over a four - hour period since the control with no barrier leveled out at this point . monitoring the weight gain of the cracker demonstrated that the control and the granular starch did not provide resistance to moisture migration as illustrated in fig2 . the barriers according to the present invention provided resistance to moisture migration and had a weight gain of less than three grams . the correlation between gats measurement and fms test is shown in fig3 . the samples include swellable powders ( here , gums and cws starches ). the y - axis represents the weight gain in the food matrix at four hours of the fms . a small weight gain in the matrix indicates that a small amount of water migrated into the matrix , i . e ., good moisture barrier performance . the more water absorbency at 100 seconds , the more weight gain in the food model system . during migration , the powder layer hydrates gradually , starting from the area contacted with water . the fine particle size sample requires more time to completely wet the whole layer than the coarse particle layer . some samples form a soft film - like layer that can be peeled off from the filter paper holding the powder layer . some samples form a gel - like or very viscous layer after the samples swell . these samples have a very good moisture barrier performance based on fms study . it is known that swellable particles change to larger and softer particles when they are swollen . these soft swollen particles , especially those particles possessing large swelling ratio ( defined as the volume ratio of fully swollen particle to dry particle ) are able to “ fuse ” to form the layer based gats result . further , the larger the swelling ratio , the softer the particles are when fully swollen . the layer blocks water wicking and slow down water diffusion , thereby working as a moisture barrier . a majority of the hydrocolloids that are swellable , such as guar gum , methylcellulose , sodium alginate , and locust bean gum , provided inhibition to moisture migration in the fms as illustrated in fig4 . all - purpose flour did not form a barrier and was comparable in weight gain and texture to the control . gums that do not swell due to particle size or viscosity do not work as well . other hydrocolloids tested were propylene glycol alginate , gellan gum , cellulose gum , pectin and konjac gum . all were comparable to the hydrocolloids above with improvements beyond the control . the swellable particles work as a moisture barrier for food application not only by means of reducing wicking and diffusion rate of water , but also by holding water in the particle due to swelling . fig5 shows a plot of a trend of settling volume effect on moisture barrier performance ( water pickup on substrate ) as a function of swelling volume . generally , the larger the swelling volume , the better moisture barrier is . accordingly , samples with relative high amount of wicking ( based on the gats measurement ) are able to block more than half the amount of water moving from the sauce into the matrix . these samples normally have relative large particle size , low packing density and low swelling volume . after swelling , the samples form a grainy or pulpy wet layer . the moisture barrier performance of the grainy layer is not as good as the one forming a soft film - like or viscous layer . the difference between the gats measurement and fms test is that a large amount of water immediately reaches the front of moisture barrier for gats , but in the fms test , water gradually moves from the sauce to the moisture barrier . as shown on the fig2 control curve of the fms , 60 % of the water drains into the matrix in 15 minutes and 80 % of the water reaches the matrix in a half hour . therefore , the moisture barrier has time to swell and hold water in the barrier layer , although the swelling is a slower process than wicking . in addition to the amount of water held in the barrier layer , the swelling volume also indicates the rigidity of the wet particle . the larger the swelling volume , the softer the particle is . as a result , it is easy to “ fuse ” and form a continuous layer that reduces wicking and diffusion . this is another attribute of higher swelling materials . [ 0055 ] fig6 shows the particle size effect on wicking . all different particle size fractions were separated from one commercial product ( here , a drum dried modified starch ). therefore , the chemical and processing variables are same for all fractions and , consequentially , the swelling volumes are same for all fractions . the amount of wicking increases with particle size from about 30 to about 150 microns , and then levels off as shown in fig6 . it is also seen that the packing or tapped density increases with decreasing particle size , as illustrated in fig7 . obviously , a smaller size particle has larger surface area per unit mass and will swell faster than a larger size particle having less surface area per unit mass . accordingly , the smaller size particle has a better position in the competition of swelling and wicking than the larger size particle . the packing density reflects the porosity of the sample . the higher the packing density , the lower the porosity is , with less wicking occurring . also , a continuous layer forms faster from a densely packed sample that blocks wicking and improves the moisture barrier properties . the freeze / thaw (“ f / t ”) stability of barriers according to the present invention was tested and compared against a control having no barrier and a wax preformed film using the fms . fig8 shows the results at various cycles . both the wax film and the disclosed barrier prevented the initial moisture migration that adversely effects texture within the first four hours . however , the wax preformed film cracked during f / t cycling , indicating its undesirability for use as a moisture barrier . the disclosed barrier had significantly less weight gain than the control and retained textural properties even after nine f / t cycles . through commercial product evaluation , potential was observed for a moisture barrier in other products such as pizza , lemon meringue pie , cherry pie , cheesecake , cherry cobbler , ice cream sandwiches , and yogurt . the moisture barrier powder can be applied in a variety of manners . in industry , waterfall ( stream of powder ), flour duster or sifter , or powder sprayer techniques are typically used to apply powders . in the waterfall system , powder is flooded over the substrate and the excess vacuumed or blown off . spraying systems include both powder and liquid sprayers . powder sprayers generate an electrostatic charge so that food oppositely charges sticks on the product . liquid sprayers can be used to spray a solution that helps stick the powder or contain the powder . most of these techniques require a recovery system for the powder . the type of technique utilized can affect the type of powder used . for example , the waterfall technique requires a denser and less dusty powder . the density of the powder can be changed to make the powder heavier , less dusty and easier to apply . this can be accomplished by a variety of means , including but not limited to changing the particle size of the powder , combining the powder with fillers such as sugar , granular starch and / or flour , dry blending and / or coprocessing the powder with a fat such as vegetable oil , mineral oil , butter and / or shortening , and changing the moisture content of the powder . the barrier powder can also be delivered by dispersing it in a solution such as water or fat , including vegetable oil , butter and shortening . each has their shortcomings . for example , the water solution limits the amount of solids . butter and shortening solidify at room temperature , making them difficult to apply . the oils tend to make food applications taste oily . a sticking agent can also be applied to the food substrate either before or after the powder barrier is added to the substrate . examples of sticking agents include water , oil , and high solids solutions . pizzas were made using pizzeria - baked crusts , commercial pizza sauce and barriers according to the present invention . a descriptive analysis panel was used to evaluate the pizza after freeze / thaw cycling . the reproducibility of the panel was checked periodically with blind controls and fresh samples with the standard deviation of +/− 1 score . sensory evaluations are presented in fig9 . the fresh pizza was prepared just prior to cooking , simulating the ideal with little moisture migration . the results show that the addition of the barrier of the present invention ( here , a cws starch powder ) improved the crust texture beyond the control and approached the fresh sample . in fig1 , sensory aspects of the pizza food system were evaluated by comparing barriers of the present invention ( here , drum - dried and spray - dried starch ) with a granular ( i . e ., non - swellable ) starch barrier of the same base . the granular starch barrier did not inhibit moisture migration and was comparable to the control . both the spray - dried and drum - dried products , which are made to hydrate in water without cooking , performed the best . both had significant improvement in resistance to bite , above the bottom crust texture , and bottom crust texture . other hydrocolloids that swell when placed in contact with water , including carageenan , guar gum , gellan gum and alginate , were organoleptically evaluated with cws starch . the sensory results compared with the control are reported in fig1 . alginate and guar gum had very crunchy bottom crusts and good crust cell structure . all four gums adversely affected the flavor of the sauce . the gums , especially guar and alginate performed similarly to cws starch . barriers according to the present invention were compared with a control in lemon pies . the barriers were sprinkled over commercially available frozen 9 - inch deep - dish piecrusts ( flower industries ® pet - ritz ®) and then baked at about 400 ° f . for about 13 minutes . the crusts were allowed to cool to room temperature before the lemon pie filling was added . the lemon filling contained water , sugar , cornstarch , egg yolks , lemon juice butter , and salt . the pies were stored in the refrigerator and evaluated after one , two , and three days of storage . overall , the barriers absorbed some of the water from the filling , thereby inhibiting water migration during refrigeration storage . the crust with the barrier was firmer and crispier than the control with no barrier after three days in the refrigerator . the control was mushy and wet after two days in the refrigerator . in the lemon pie , the barrier also aided in the pie remaining intact once cut into , maintaining structural integrity and / or preventing syneresis . barriers according to the present invention were compared with a control in cherry pies . the barrier was sprinkled over a commercially available frozen deep - dish piecrust ( flowers industries ® oronoque orchards ®). commercial cherry pie filling ( comstock ® from birds eye ® foods ) was added and the pies were baked on a cookie sheet at 400 ° f . for about 55 minutes . evaluations were conducted on pies initially , day one , and day two after refrigeration . another set of pies were baked , then frozen . frozen pies were evaluated after 3 , 7 , and 10 cycles . a single cycle consisted of six hours at room temperature and eighteen hours frozen . in cherry pies with the disclosed barrier the filling did not spill over as was seen in the control pies . the barrier absorbed some of the water from the filling , which formed the barrier while keeping the pie intact . the crust with the disclosed barrier was firmer and crispier than the control with no barrier after two days in the refrigerator . in the frozen pies , after three cycles the control was mushy and wet . after ten cycles the crust of the frozen pie with the barrier was firm and dry . the disclosed barrier may be also added to partially baked piecrust prior to adding the filling . ice cream sandwiches with and without the present barrier were compared . the disclosed barrier was spread evenly on the inside of commercially available cocoa cookies . using a 1 - inch thick cookie cutter the ice cream was sliced and placed in between two cookies . the sandwiches were put in bags and placed in a cycling freezer that cycled at 20 ° f . for twelve hours and 0 ° f . for twelve hours . the ice cream sandwiches were evaluated after one and two weeks . in ice cream sandwiches the barrier provided a firmer textured cookie . the control cookies were soft and mushy , while the cookies with the barrier were firmer after two weeks of cycling . the barrier may also be applied before baking the cookies / wafers for the ice cream sandwiches . chocolate compound coatings with and without the present barrier mixed in were compared using ice cream sandwiches . the chocolates were melted and the cookies were enrobed . the disclosed barrier at 20 % ( w / w ), ideally 5 - 10 % ( w / w ), was mixed in the coating . the coatings were applied to previously baked commercially available sugar cookies . using a 1 - inch thick cookie cutter , ice cream was sliced and placed between two cookies with the coating touching the ice cream . the sandwiches were put in bags and placed in a cycling freezer that cycled at 20 ° f . for twelve hours and 0 ° f . for twelve hours . the ice cream sandwiches were evaluated after two weeks . the swellable powders can be added to films or coating that cover the food substrate to aid in inhibiting moisture migration . the chocolate compound coatings that contained the disclosed barrier inhibited moisture migration more than the chocolate compound coating without the added disclosed barrier . the disclosed barrier absorbed some of the water from the ice cream so the excess water during cycling did not further wet the cookie substrate . after two weeks in the cycling freezer , cookies with the barrier / powder in the compound coating had a firmer texture . the crumb topping on the cherry cobbler was evaluated with or without the disclosed barrier . the cherry filling containing cherries , sugar , cornstarch and other flavor / colors was added to a pie dish and partially frozen . the barrier was applied to the top of the partially frozen cherry filling . the crumbs made from flour , sugar , shortening and salt were sprinkled over the cherry filling . the cobblers were frozen and cycled for four cycles , with one cycle being 1 hour at room temperature and frozen for at least three hours . the cobblers where baked from the frozen state at 400 ° f . for at least forty minutes depending on the size and depth of the cobbler . in this application example the barrier was added to the high moisture substrate , then the low moisture component was added . the barrier may also be added to the pie shell prior to filling and on top of the filling prior to topping ( crust or crumb ). the cobblers with the disclosed barrier between the filling and crumbs looked more ascetically pleasing . the fruit filling did not bleed through the crumbs . the crumbs were also crisp and not sunk into the filling . the product had an overall higher or fresh appearance . after scooping , the cobbler with the disclosed barrier did not have excess juice / filling come out and further wet the crumbs . dry granola was either applied at the bottom or top of yogurt . the barrier was applied in between the dry granola and yogurt . the yogurts were stored at refrigeration temperature for one , two and three days . the yogurts were evaluated by stirring in the dry component and tasting . the barrier between the yogurt and dry component inhibited migration and allowed the dry component to stay intact and firmer . the barrier also prevented syneresis of the yogurt , allowing the topping to stay drier . the barrier may be added between other layers in a yogurt , including fruit , cookies , puffed pieces , and flavor / spices . reference tests were conducted on lemon pies and cherry pies . lemon pies were prepared according to example 3 and stored in the refrigerator for two days . the cherry pies were prepared according to example 4 and were stored for two days in the refrigerator . the reference tests were conducted as follows : 1 . a ballot instructing the panelist to evaluate firmness of the crust or cookie was given to 20 - 25 panelists . 2 . panelists were instructed to taste the control , which was either the sample with or without a barrier . the control was given a rating of 5 on a 10 - point scale . 3 . the panelists were given a coded test sample . the panelists were asked to rate the test samples using the reference score as an anchor point . if the test sample was better / firmer than the control , the sample was rated higher than 5 on the scale . likewise , if the test sample was soggier than the control , it had a value lower than 5 on the scale . 4 . the scores of each panelist for each test sample were tabulated and averaged . the least significant difference ( lsd ) intervals were calculated for each test sample . the reference taste test confirmed significant differences in firmness of the lemon piecrust between the pies with the disclosed barrier and without as illustrated in fig1 . test results on the cherry pies confirmed a significant difference between the crusts of the pies with and without the barrier as illustrated in fig1 . the pie with the disclosed barrier had a drier , firmer texture . with reference to fig1 and 13 , the higher the texture rating the firmer the product . although the present invention has been described and illustrated in detail , it is to be clearly understood that the same is by way of illustration and example only , and is not to be taken as a limitation . the spirit and scope of the present invention are to be limited only by the terms of any claims presented hereafter .
hydrocolloids useful as a barrier in multi - component food systems for the inhibition of moisture migration and methods for using the barrier are disclosed . the hydrocolloid can be applied as a powder . the hydrocolloid containing barrier is able to inhibit the migration of moisture across the system , thereby improving the shelf life of the food product , as well as enhancing the ability of the product to survive freeze / thaw cycles . in doing so , the organoleptic qualities of the food system are enhanced .