NO790117L - COMPOSITION AND PROCEDURE FOR APPLYING A MOISTURE BARRIER COAT ON FOOD - Google Patents

Description

Composition and method for applying a moisture barrier coating to foodstuffs.

The present invention relates to a composition and method for applying a moisture barrier coating for foodstuffs.

One of the persistent problems in the bakery industry concerns food becoming hard due to moisture loss.

In addition, the starch component in some bakery products, and especially when it comes to doughnuts, will break down. Of these two types of problems, the hardening of the crust due to moisture loss will be the most important in terms of making baked or fried products hard and unusable. This problem is particularly acute when it comes to doughnuts, and it is so serious. in yeast-raised donuts that these have a very limited shelf life that can be measured in hours.

The baking industry has long sought a yeast-raised donut that has a shelf life that can be measured in days rather than hours. To mass-produce doughnuts, whether cake-raised or yeast-raised, and to allow for normal distribution and display in retail stores, several days are required. To some extent, the cake type of donut is not subject to as much crust, pete drying and hardening. like yeast-raised doughnuts. In an experiment, donuts were stored without whole egg or glaze in polyethylene bags. The donuts became firm and slightly mealy, which is a typical aging effect after two. to three days, but they did not dry out and were therefore edible. When the same experiment was repeated using donuts that had a sugar-water stabilized glaze applied, the donuts hardened very quickly and were unsatisfactory within 2k to 8 hours. The rapid hardening was thought to be due to moisture being drawn from the doughnut's crust to the glaze coating.

The water content of a prepackaged, multi-component baked or fried product will migrate from the components with high water pressure. to components with low water pressure until equilibrium is reached. The water vapor pressure, which can be determined individually for each component, is controlled by the amount of water, the amount of soluble solids and the amount of water binding agents. In the case of yeast-raised glazed doughnuts, the glaze is a saturated sucrose solution that has a relatively low vapor pressure, while the yeast-raised donuts have a relatively high vapor pressure due to the absence of significant amounts of soluble solids

(low initial sugar content, much of which is metabolised)', relatively high water content and a minimum of water-binding components. The overall effect is a rapid transfer of moisture from the crust through the surface of the donut to the glaze which not only dries and therefore hardens the crust, but which also supersaturates the glaze solution and leads to the breakdown of the glaze.

The mechanism for the breakdown of the glaze can be described as follows: The glaze consists of small sucrose crystals (powdered sugar) which are held together and bound to the surface of the donut by a saturated sucrose solution (syrup). The ratio between sucrose crystals and syrup controls the firmness, translucency and eating properties of the glaze. The main difference between a glass watch and a so-called "icing" is one. higher ratio between crystals and syrup, in terms of "icing". When the moisture draws from the donut crust into the glaze, and the sugar crystals dissolve. When there is a sufficient amount of solid sugar crystals left to maintain an intact glaze, and when the syrup phase becomes dominant, the glaze melts, drains away, absorbs into the product, sticks to the packaging and is characterized by the expression called glaze degradation.

The placement of a water barrier between the surface of the donut and the glaze will prevent moisture movement and thus prevent the donut crust from drying out and protect the glaze from degradation.

The application of water barriers to food products, including baked and fried products, is not new. "Crystal Gum", a tapioca dextrin sold by National Starch and Chemical Corporation, Bridgewater, New Jersey, has been used as an aqueous dextrin sucrose spray applied to baked cakes and tarts before icing to extend the shelf life of the products and. reduce glass urn degradation. In addition is

there are many literature and patent references describing the use of coatings on food products to reduce moisture loss or moisture transfer. Much such work has been done on meat products which are of course processed and cooked before

consumption. In fruit, the coating with the skin is removed and therefore does not affect the eating properties. On non-porous, semi-smooth products such as nuts, candy etc. different coatings and different precisely controlled thicknesses have been used for similar purposes.

None of the previously used coating materials or methods have been satisfactory when it comes to meeting the desired goals for shelf-stable, yeast-raised, glazed doughnuts. It must be emphasized that the relationship in the case of donuts is particularly difficult, requiring a special preparation and special coating techniques to obtain a satisfactory product. to the yeast-raised type, must be an effective water barrier above the highly porous donut surface and at the same time not reduce the eating quality of the doughnut. The coating must have a sufficient amount of flexibility so that it does not crack or peel off during the subsequent glazing, or packaging of the product.

In view of these special requirements, the following is an overview of literature and patents that describe available techniques with regard to specific preparations and processes that are described to produce a satisfactory water barrier on a baked or fried food product, and especially when concerns the critical requirements for glazed, yeast-raised doughnuts. In an article by Allen, L., et al, "Edible Corn-Carbonydrate Food Coating", in I, Food Technology, page 99j November 1963 and II, Food Technology, page 104, November 1963j describes corn starch and corn sugar together with

alginates used as moisture and oxygen barrier films on food products. The articles refer in particular to an adverse taste effect which would be enhanced if the same type of coating or film were applied to yeast-raised doughnuts.

In an anonymous article - "Outlook for Grapes: Better Raisins", Canner Packer, page 52, March 1977, it is described that egg or soy protein coating has been shown to effectively reduce moisture loss in raisins. Such protein coatings have been evaluated and found to perform poorly as a water barrier when applied to porous donut surfaces. in addition, it has . proved to be difficult to apply under commercial conditions.

An article by Ayres, J., C, "Use of Coating Materials", Food Technology, page 512, September 19593 lists prior work for pre-coating and claims for an agar-glycerol solution or diacetyl-triglycerides, which , when used as a coating for meat, mostly have the purpose of inhibiting microbiological growth. The films described can be torn off, and the barrier properties of the agar film with respect to moisture were minimal. The diacetyl triglycerides are described as having good moisture barrier properties, but evaluating this type of coating on yeast-raised donuts based on the current experience with fat-based coatings would lead to serious problems in controlling the thickness and eating properties of these films on a porous donut surface. be unacceptable. Furthermore, the thermal stability of diacetyl-triglyceride coatings would not be satisfactory with regard to

the subsequent glazing.

In Bauer, CD. , et al. U.S. Patent No. 3-^06.081,

from 15 October 1968, describes a lipid meat coating which is applied as a water-in-oil emulsion. The application as an emulsion removes the usually brittle character of ordinary lipid coatings. The pre-coating according to the present invention is also applied

as a water-in-oil emulsion, and it is conceivable that it is an-

the conversion' of an emulsion which allows satisfactory weight control and the excellent bending properties in the precoat preparations according to the invention.

In Bauer, C.D., U.S. patent no. 3-483,004 describes the addition of a thermally gelatinizing methyl cellulose to the preparation described in Bauer et al, U.S. patent No. 3,406.

08l to preserve the coating while cooking the meat. This does not concern the preparation and method according to the present invention.

In Canonne, J.E., U.S. patent No. 4,010,283 is there

a description of the application of gum arabic coatings.

Such coatings have been assessed during the present work,

and it has been proven that dextrin coatings are better than gum arabic coatings. However, dextrin coating alone was unsatisfactory for yeast-raised doughnuts and, consequently, it is very unlikely that gum arabic coating would be satisfactory.

end for yeast-raised doughnuts.

In ClarkjW.L. "Hot Melt Transparent Peelable Coating

for Food", Food Technology, page 105, October 1965, describes an acetylated, monoglyceride-cellulose acetate butyrate coating. Cellulose acetate butyrate was added to overcome the deficiency

on translucency and to satisfy the need for emollients when straight, acetylated monoglycerides are used. The coating is a film that can be peeled off, and it cannot be used on a porous, baked food product. Additional translucency is not a problem in the case of precoat preparations according to the present invention, and satisfactory flexibility in the coating is provided without the use of the special additives mentioned in this article.

In the article by Feuge, R.O. "Acetoglycerides - New

Fat Products of Potential Value to the Food Industry", Food Technology, page 314, July 1955, there is a discussion of the properties and potential uses of acetylated monoglycerides. In this article, the use of acetylated monoglycerides as coating agents particularly concerns their waxy character and although the author refers to a potential use as a coating on baked products, no details are given.

In Hamdy, M.M, U.S. patent no. 3-471,304, the use of a combination of acetylated monoglyceride and ethyl cellulose is prepared with the aim of overcoming negative qualities in each component when they are used separately as a coating material..

In Hullinger, C.H, "Starch Film and Coating", Cereal Sciejice Today, page 508, October 1969, the starch films are discussed, which, since they have poor water barrier properties,

not suitable for use in accordance with the present invention.

In the article by Jokay, L. "Development of Edible Amylaceous Coatings For Foods", Food Technology, page 12,

August 1967, the advantages of hydroxypropyl derivatives of amylose starch compared to other starchy coating materials are discussed. This type of coating does not have good moisture barrier properties. In addition, however, this article discusses various other coating application equipment, and it contains literature references to such previously used equipment.

In the article by Lazarus, C.R., "Evaluation of Calcium Alginate Coating", Journal of Food Science, page 639,

Vol. 4l (1976) discusses the in situ production of calcium alginate which forms a film. Such films were evaluated during the present work, and it was found that these were unacceptable, since they have gelatin-like eating properties when applied to doughnuts, which significantly affects the eating quality of doughnuts.

In Lowe, E., "Continous Raisin Coater", Food Technology-, page 109, November 19633 there is a discussion of acetylated lipid coating. This type of coating was tested during the present work on doughnuts, and it was found that the porosity of the doughnut, together with an inability to apply a thin but continuous coating, limited its application either due to unsatisfactory eating properties or, due to poor moisture barrier properties.

In the article by Myer, R.C, "Edible Protective Coating for Extending the Shelf Life of Poultry", Food Technology, page 146, February 1959, there is a description of an agar-glycerin and carrageenan coating used as a moisture barrier on poultry. Such a coating would tend to produce gelatin-like eating properties when applied to porous products such as doughnuts, and consequently would be unsatisfactory.

In an article by Miers, J.C., "Pectinate and Pectate Coating", Food Technology, page 229, June 1953, there is a description of calcium precipitated pectinate coatings. (See also Swenson, H.A, "Pectinate and Pectate Coating", Food Technology, page 232, June 1953.) Such coatings were investigated during the present work and found to have unacceptable gelatin-like eating properties.

An article by Murray, D.G., "Low DE Corn Starch Hydrolysates", Food Technology, page 32, March 1973, describes the general purpose of solid low DE corn syrups and the beneficial use of such a moisture barrier coating on fruits and nuts. It has been found that such low DE solids alone do not provide adequate moisture protection when applied

doughnuts, but they are one of the components in the preparation according to the invention, where all the components together have a synergistic result and provide a satisfactory pre-coating that acts as a water barrier on doughnuts.

In an article by Newman, A.A, "The Acetoglycerides", Food Manufactures, page-525, November 1962, there is a list of acetylated monoglycerides corresponding to the description in the article by Feuge mentioned above. The list at the end of the description in the text makes no reference to the application of such materials to baked goods.

In an article by Paredes-Lopez, 0., "Use of Coating of Candelilla Wax for the Preservation of Limes, J. Sei. Fd. Agric., page 1207, vol. 25, 1974, there is a description of the use of a wax emulsion as a moisture barrier on lemons This would have similar limitations for use with yeast-raised donuts as the products disclosed in Bauer, U.S. Patent No. 3-406,081 described above.

In Stemmler, M., U.S. patent no. 3,851,677 the use of acetylated monoglyceride is described as a protective coating on fresh meat. As described in connection with the Lowe article above, this type of coating is not satisfactory on donuts.

Ukai, N., U.S. patent no. 3-997-674 there is a description of a coating preparation comprising an aqueous solution or dispersion of a water-soluble polymer and a hydrophobic (fatty or waxy material) component stabilized by the use of a suitable emulsifying agent. In column 7, lines 10-30, it is stated that the ratio between the components is critical for the specific use of the preparation, described as preserving relatively low-porous materials such as eggs, apples, grapefruit etc. A corresponding ratio between the components of the unique preparation according to the invention,

is also critical for use in baked and fried products. The Ukai patent lists water-soluble polymers in column 8, lines 35-40. which include hexosans, starches etc'. One of the preferred materials in the preparation according to the present invention is a solid, low DE corn syrup which is a hexosah. In column 8, lines 52-575, there is a list of hydrophobic substances, including lipids and waxes, which can be used.

The article by Walters, G., "Stabilized Raisins for Dry Cereal Products", Food Technology, page 236, May 1961, describes the use of beeswax dispersed in a vegetable oil as a moisture coating- Although the oil reduces the moisture barrier properties of the wax, and therefore should reduce the problems of applying a thick, continuous wax coating, which is a major difficulty limiting the application of waxy materials to doughnuts, we have demonstrated that this specific application does not produce a satisfactory precoat that is a water barrier to doughnuts.

In Werbin, D., U.S. patent no. 3-526,515 there is a description of coating baked goods with a mixture of oil or hydrogenated lard and a high-melting fat. In the present work, it has been demonstrated that such a coating is not satisfactory for baked and fried products according to the invention.

The literature references and patents reproduced above describe the scope and content of previously used techniques, and in many cases the same or similar preparations were tried and evaluated as a pre-coating of the water barrier type for baked or fried products, and especially yeast-raised, glazed doughnuts. None proved to have the combination of properties required to produce a satisfactory yeast-raised glazed donut that has a long shelf life and yet retains satisfactory eating properties.. Although the use of an edible coating to protect a food product from moisture loss is well known , none of those described in prior techniques have been shown to solve the problems, which is further confirmed by the fact that yeast-raised, glazed donuts with a long shelf life did not exist as a satisfactory commercial product before the present invention. Other proposals that have previously been put forward, such as the use of a wrapping on the food products with a suitable packaging film to reduce the transfer of moisture, do not prevent the transfer of moisture between the different components

'in a multicomponent food product - and is therefore unsatisfactory.

The present invention was thus intended to provide an edible coating that could be applied

in such a way that it isolates one product component from another, and in this particular case, to isolate the donut from the glaze with. a water barrier to prevent or significantly delay moisture transfer. Previously known coatings in the literature which are removed with peel or skin, which are removed during processing such as baking or preheating before consumption or which are applied to relatively non-porous, solid products such as apples, nuts etc. which allows a very

thin film is applied, does not directly relate to the present situation, and which presented a problem which required a solution which was first obtained by the present invention.

When it comes to baked or fried food products, the surface of the food is very porous, and in many cases soft and pliable. When coatings such as wax or triglycerides are applied to such a surface, two main problems are encountered. The first is the inability to apply a thin coating that will provide water barrier protection and still not have thick stains that will affect normal eating properties. The second problem is the ability to provide a coating that has the necessary softness or elasticity so that the coating does not peel off or crack when the food product is slightly deformed during processing or transfer.

The pre-coating which forms a moisture barrier and

which consists of a water-in-oil emulsion and which is the preferred preparation according to the invention, comprises the following components or elements: a saccharide or polysaccharide and preferably a solid, low DE corn syrup in an amount between 6 and 40 and preferably approx. 26$. Water in amounts from approx. 12 more. 43$ and preferably approx. 36.4$. (including a 10$ loss of water during manufacture) and acetylated monoglyceride in an amount of from 25 to 75$ and preferably approx. 36.4$ and a flavoring such as vanilla in an effective amount and preferably from approx. 1.2$.

It is understood that the preferred preparation has been determined on the basis of extensive work so that it represents the optimum for a coating for yeast-raised doughnuts. However, it must also be understood that variations in the amounts can be made 'without this removing one from the scope of the invention. and that the optimal preparation for other baked or fried products such as sweets, cakes, rolls, bread etc. can easily be determined for each particular application.

The pore coating material, which is a moisture barrier, is produced by a method that can be broadly described as follows: The water is heated to the boiling point, and the solid, low DE corn syrup is mixed in, taking into account that no solid lumps form during the addition of the corn syrup. The acetylated monoglyceride component is first melted and then added to the aqueous solution of the solid corn syrup with relatively slow stirring until a water-in-oil emulsion is formed. Sufficient stirring to provide an emulsion is required, but too vigorous stirring will produce too much air entrainment. Too little stirring will result in a lack of emulsification, while overmixing can lead to air admixture which will reduce the effectiveness of the coating, reduce translucency and increase viscosity. Preferably, a water-in-oil emulsion (or colloidal dispersion) is formed there, where the water phase

is dispersed as small droplets through the continuously acetylated monoglyceride phase.

The surface temperature of the donut when the coating is applied should be between 32 and 38°C so that the coating material will harden relatively quickly, but not penetrate too deeply into the surface of the doughnut, while at the same time forming a thin, even coating that does not affect the eating properties of the donut .

To achieve the . for best results, the temperature of the coating preparation should be approx. 6o°C is satisfactory, but it may be satisfactory if the temperature is between 46 and below 80°C, and the mixture should be agitated so as to reduce the possibility of the emulsion separating.

The coating can be applied to the surface of the product by practical, mechanical devices such as dipping, spraying, brushing or pouring. It is important that excess coating is removed, and again devices such as air blowing, mechanical vibration or centrifugation can actually be used while reducing external marks due to the fact that the donut must be supported during drying or curing of the coating. Large marks on the doughnut's surface will reduce the moisture-retaining properties.

The drawing is a color photograph and a corresponding black-and-white image of three sample donuts compared

with three control donuts on the third day after they were produced. The test donuts were pre-coated in accordance with the present invention, and. the control donuts made from the same dough were not precoated.

As described above, the preparation for a moisture-inhibiting precoat according to the invention is a water-in-oil emulsion or a colloidal dispersion prepared from an emulsified triglyceride or an emulsifying agent in combination with an aqueous solution of a dextrin or another soluble saccharide or polysaccharide. Suitable emulsified triglycerides or acetylated monoglycerides can be used. E.g. is Myyacet 5-07 the trademark for a product from Eastman Chemical Products, Inc., Kingsport, Tenn., USA, - illustrative of a satisfactory acetylated monoglyceride which can be used as a component in the preparation according to the invention. - Such materials are relatively insoluble in water , but they form an emulsion with water and will also act as an emulsifying agent. Other materials that are successfully used for the oil part of the emulsion include triglyceride, which is a cooking fat, to which partially hydrogenated flakes can also be added together with a monoglyceride to promote and stabilize the emulsion formation. Certain waxes, such as rice wax, have also been shown to provide excellent moisture barrier properties when used in conjunction with various polysaccharides. Similarly, satisfactory results can be obtained using any lipid or waxy material comprising suitable solids at room temperature provided an emulsifying agent such as a monoglyceride is used to stabilize the water-in-oil emulsion.

For the saccharide or polysaccharide component in the preparation according to the invention, an example is Frodex lo a trademark for firm, low DE corn syrup which can be obtained from American Maize Products Co., Hammond, Indiana, USA, and which has shown

proved to be an excellent choice for the polysaccharide component in the coating according to the invention. Tests that have assessed the moisture-heat barrier properties of other malto-dextrins, of which Frodex 10 is an example, suggest that the moisture barrier properties decrease as the 'dextrose equivalent (DE-

a measure of the degree of conversion from starch to monosaccharide in the solid corn syrup) is increased. We have also found practical ones

considerations and limitations in the use of higher DE solids. With a material that has a high dextrose equivalent, there is an increase in the curing or drying time of the preparation. This is a practical limitation since it is desirable to use a preparation, which after it is applied, will dry or harden within a relatively short time so that the normal production rate of the donuts will not be lowered.. In other words, if one uses a high DE material that leads to longer drying time, it may be necessary to increase the conveyor belt length to allow a longer drying time. This will increase the cost of the operation and is probably not practical from a commercial point of view. However, this is a choice, and it is within the scope of the invention that the maximum dextrose equivalent in the material may well depend on the purpose, e.g. if drying time is not a problem and other conditions were satisfactory, a material with a higher DE than Frodex 10 could be used. It has also been shown that pure dextrose with a DE

of 100 did not give a satisfactory emulsion or produce a satisfactory coating. The ratio between dextrin component and water is controlled by the solubility of dextrin in water. The level approaching the saturation point has been shown to

be desirable. Using an excess of water serves no purpose and, on the other hand, can have the effect of reducing the curing time in the coating or causing a lack of stability in the emulsion.

Sucrose has been found to be an acceptable saccharide for the preparation according to the invention, especially if the additive is combined with small amounts of gum such as gum arabic or dextrins such as "Crystal Gum" from National Starch and Chemical Corporation, Bridgewater, New Jersey, USA, since sucrose hair

a tendency to reduce the stability of the emulsion and to increase curing times.

Other dextrins saw such as "Film Set" a trademark for

a food dextrin from the National Starch and Chemical Corporation, has also been shown to be acceptable as a polysaccharide element, and it is within the scope of the invention that the most commonly used polysaccharides would be functional

in the preparation according to the invention.

As indicated above, the preferred oil in the preparation according to the invention is an acetylated monoglyceride. where Myvacet 5-07 is typical. Tests were conducted to determine acceptable levels of acetylated monoglycerides, and a level of approx. 36$ as described above has been shown to be optimal. As the level of acetylated monoglycerides increases in the emulsion, the coating becomes heavier. This is not necessarily unfavorable in some baked or fried food product applications, since the specific product involved may allow higher levels than are optimal for yeast-raised, glazed doughnuts. Reducing the level of acetylated monoglycerides as an oil or as an emulsifying agent in the preparation, according to the invention below 30%, results in an increase in viscosity, presumably because the stability of the emulsion increases. Reduction of acetylated monoglycerides to 25$ results in a thin coating. which requires a long curing time, presumably due to an excess of free water in the emulsion.

The preferred acetylated monoglycerides which form the oil and the emulsifier in the preparation according to the invention have unique properties which make it suitable for use in accordance with the invention. The. can crystallize in alpha form, which makes them very stable, and when added to the result this leads to a non-greasy but waxy coating. Non-acetylated 'monoglycerides' are not stable in the alpha form. This is presumably the reason why acetylated monoglycerides are superior to a combination of triglycerides and monoglycerides as the oil part in the preparation according to the invention. In addition, acetylated monoglycerides have significantly lower melting points than non-acetylated monoglycerides. Acetylated monoglycerides tend to form a

disordered network of interconnected, ribbon-like crystals,

while the crystals from unacetylated monoglycerides collect in frag-. ments1of disordered crystals. This characteristic feature

can also partly explain why acetylated monoglycerides form a more stable emulsion type for the coating than triglycerides.

Generally speaking, the commercial forms of acetylated monoglycerides used in the experiments are Myvacet 5-07 from Eastman Chemical Products, Inc., Kingsport, Tenn., USA and Cetodan 50-OOA from Grindstead Products, Inc., Overland Park, Kansas, USA with the following characteristics:

Both Myvacet 5_07 and Cetodan 50-OOA are acetostearins with a considerable amount of palmitic acid. Both have emulsifying ability which makes them a good component in an acetylated monoglyceride/polysaccharide pre-coating material that should act as a water barrier.

If the pre-coating preparations according to the invention are to be evaluated on yeast-raised doughnuts, three types of data collection techniques have been used to obtain both subjective and objective assessments of the effect. The first of these techniques is to measure the weight loss in identically produced doughnuts, a control donut without pre-coating and a test donut with pre-coating preparation according to the invention. In such a test was

.it was found that after 72 hours the weight loss in the control donut which was uncoated was $19.82 compared to $6.12 for the same donut made in accordance with the invention. Upon repeating the test, it was found that the weight loss after 72 hours in the uncoated donut was $25.5 compared to $6.99 for the same donut made in accordance with the invention. In addition, the donuts were subjected to organo-

leptic evaluation, of panels which were given control or standard donuts to compare with the same donut, to which the preferred preparations according to the invention had been applied.

The results of the panels' assessment suggest that the preparation applied according to the invention significantly improves the quality of

the doughnut, and seems to be the most important reason why you get a good, glazed, yeast-raised donut with a long shelf life.

The second objective test involved the use of a standard "Instron" instrument■to measure the relative softness of the donuts. In a typical test, the softness after one day in the donut was made with the same dough that was not precoated compared to donuts that had been pre-coated in accordance with the invention and the one-day softness values were compared and the four-day softness values were also compared.This test demonstrates that the one-day softness increased from 187 to 127 in the coated donuts, and the paints of softness after four days showed that the uncoated had an Instron value of 486 compared

with an increased softness of 232 on the donut produced in accordance with the invention.

It is important to understand that the results obtained when using the preparation and the method according to the invention to provide an effective moisture barrier are subjective in many ways. While objective measurements of the moisture loss (weight loss) and. softness measured with Instron instruments, can be provided as described above, the subjective quality is such that it. evident from sample data from the panel, and especially from the physical appearance of a standard, glazed, yeast-raised donut compared to a donut according to the invention, is very important from a commercial point of view.

The photograph shown was taken of pre-coated and uncoated donuts and illustrates excellently the effect in terms of glaze stabilization which is obtained as a direct result of the use of the composition according to the invention. When identical donuts were produced and mechanically glazed

with an identical glass watch at exactly the same time, it was found that after three days it had an uncoated doughnut.

an unstable glaze, while the glaze on the pre-coated ones. donuts in accordance with the invention showed no signs of degradation of the glaze.

During the present work, tests were conducted to investigate the effect of surface temperature on the donut at the time the precoat was applied to determine the functional effect. As a result of extensive testing, it has been shown that the temperature of the surface of the donut should be between 32 and 38°C. and that the temperature in the stirred preparation for coating should be approx. 60°C. Since the donuts usually leave the fryer with a surface temperature of approx. 94°C, it is therefore desirable and important from a functional point of view to reduce the surface temperature (but not necessarily the internal temperature) of the freshly baked donut from approx. 94°C to the range between 32 and 38°C.

During the work, the use of dispersants as part of the preparation was investigated. In this regard, polysorbate 60 was used as part of the preparation. Such materials. is satisfactory, where. the spreading agent will significantly contribute to a thin, even coating of the preparation being applied to the product being coated. However, when using dipping techniques or application techniques which in themselves provide the desired, thin, even coating, such dispersants may be unnecessary.

As mentioned above, sucrose can be effectively used as saccharide or polysaccharide in the preparation. During the work, both sucrose and dextrose were evaluated as substitutes for Frodex 10, which was the preferred polysaccharide. It was concluded that sucrose can be used effectively, but it is still inferior to Frodex 10, if it is used at higher concentrations to come closer to the relative saturation in the preferred preparation comprising Frodex 10 in solution.

Other work demonstrated that triglycerides or waxes cannot be substituted alone for acetylated monoglycerides. However, further work demonstrated that when used in conjunction with an emulsifying agent such as a monoglyceride,

are the triglycerides functional and produce the desired results

taters. The importance of this subsequent work is that the emulsion required to provide the necessary coating is not formed when only a single triglyceride is used. If a stable emulsion can be formed from a triglyceride, however, it should perform satisfactorily and provide a functional coating.

One of the ways to provide an effective assessment of the preparations and to determine whether a satisfactory water-in-oil emulsion has been obtained is to obtain a measure of the electrical conductivity of the solution compared to water.

Other work has shown that there is a relationship between the temperature in the material and the satisfactory formation of a suitable water-in-oil emulsion. Furthermore, the presence of excess salt, which has the well-known effect of breaking down the emulsion and causing a lack of stability, should be avoided.

The degree of saturation of the saccharide or polysaccharide

in the water phase appears to be functionally important. As indicated above, where Frodex 42 from American Maize Co, Hammond, Indiana, USA, which has a higher solid DE corn syrup content, is used either with or without gum arabic, this was not a satisfactory substitute for Frodex 10, from the same source without that the concentration was increased to correspond to the degree of saturation

in the optimal and preferred preparation..

The following alternative preparations form satisfactory emulsions and provide satisfactory moisture barriers, when used as a pre-coating on yeast-raised, glazed doughnuts.

Example_el_l

<Eczema>]2<el>_<II>• .

Éksemgel_III EksemDel_IV 1. Myvacet 5-07 - acetylated monoglyceride from Eastman Chemical Products Inc., Kingsport, Tenn., USA. 2. Myverol 1800 - an emulsifier from Eastman Chemical Products Inc., Kingsport, Tenn., USA. 3. Frodex 10 - a trademark for a low DE corn syrup from American Maize Products Co., Hammond, Indiana, USA.

These preparations were prepared by first boiling the water and gradually mixing in the polysaccharide element. The solution was then transferred to a Hobart mixer, to which was added a liquid oil portion and/or the emulsifying agent, after which mixing was done at low speed with a paddle mixer to form a water-in-oil emulsion. The resulting material for a precoat to act as a water barrier is applied to donuts in the manner described above.

In the following example, the amount of the three preferred materials was varied in order to determine the usefulness of the amount range in the materials for producing water-in-oil emulsion. Frodex 10 described above was used as the polysaccharide component, and Myvacet 5-07 was used as the acetylated monoglyceride component. In each case, a water-in-oil emulsion was prepared and used to coat six donuts prepared from a standard dough. In each case, the oil-in-water emulsions were also prepared as described above. The variations in the compositions are reproduced below:

Example_V

Each of the kits was used to coat six donuts that were fried and kept in a plastic bag overnight. The donuts were taken out and forcibly cooled for exactly 5 minutes, and the pre-coating in all cases had a temperature of between.

82 and 84°C. To assess the effectiveness of each of the different sets, the average weight loss was recorded, and the results are reproduced in the following tables:

One can note from the results that the acetylated monoglyceride component can be used in the ..ni_vået_ that can be used,

from 27 to 65$ with satisfactory results. Obviously, this range can be extended below $27 and above $65 with satisfactory results in accordance with the comments given above. The polysaccharide portion of the samples varied from 14.5$ to .30$, but the percentage saturation of the water phase was kept constant, as the work suggested that this was important to keep a relatively short curing time.

,1 the various tests and evaluations as described above, standard donuts were prepared to determine the effectiveness of the pre-coating as a moisture barrier that can effectively increase the shelf life of yeast-raised glazed donuts and not affect the eating quality. The donuts themselves were prepared in accordance with standard recipes, or when recipes that deviated from this were used, in each case donuts made from the same recipe were used. Likewise, the glaze was either a standard glaze or a special glaze. In each case where the effect of the pre-coating was to be assessed, the composition of the dough and glaze was the same as for the different doughnuts.

In summary, it has been demonstrated that a preparation comprising a water-in-oil emulsion or a colloidal dispersion comprising a saccharide or polysaccharide near the saturation level in water, together with an acylated monoglyceride or a similar oil element with added emulsifying agent is sufficient to either the acetylated monoglyceride or the second oil element plus emulsifying agent forms a standard water-in-oil emulsion, is satisfactory for the production of a pre-coating on freshly fried donuts or similar fried or baked products such as sweets, cakes, rolls, bread etc. and significantly increases the shelf life of donuts where the coating is applied without this affecting the eating properties of the product. The product is dipped, sprayed or has the coating added in another way in accordance with the invention at a temperature of between 32 and 38°C, preferably by immersion in a bath with the material where the temperature is between 46 and 82°C. The time that has been found to be ideal for reed dipping is 1 to 2 seconds, and the characteristic properties of the water-in-oil emulsion are that it preferably cures within seconds after excess of the pre-coating material has been removed by suitable facilities.

Variations can be made within the aforementioned application without this going beyond the scope of the invention.

Claims (15)

1. Edible, pre-coating preparation suitable for forming a moisture barrier on a relatively porous surface of baked or fried bakery products to inhibit moisture transfer through said surface, - characterized in that it consists of a water-in-oil emulsion or colloidal dispersion comprising a) an oil moiety selected from the group of materials consisting of acetylated monoglycerides, a triglyceride together with an emulsifying agent and a fatty or waxy material together with an emulsifying agent; b) a saccharide, polysaccharide or dextrin moiety, and c) water, where the said preparation comprising the said parts b and c is evenly dispersed as droplets in the said oil part. 2. Preparation according to claim 1, characterized in that said oil part is present in an amount of from 27 to 65%, said saccharide, polysaccharide or dextrin part is present in an amount of from approx. 14.5$ to 30$ .dissolved in water to form an aqueous solution around the saturation point. 3. Preparation according to claim 1, characterized in that it. also contains a flavouring. 4. Edible, pre-coating preparation suitable for forming a moisture barrier on the relatively porous surface of donuts in a sufficient amount to inhibit moisture transfer from the interior of said donuts through the surface thereof, characterized in that it is a liquid water- in-oil emulsion or colloid! dispersion that includes a) an oil moiety selected from the group consisting of acetylated monoglycerides, a triglyceride together with an emulsifying agent and a fat. or waxy material together with an emulsifying agent, b) a saccharide, polysaccharide or dextrin part, c) water, and d) a flavouring, where said preparation comprises the elements b, c and d uniformly dispersed as droplets in the said oil part. 5. Preparation according to claim 4, characterized in that the mentioned oil part is present in an amount of approx. .27 to 65$, said saccharide, polysaccharide or dextrin part is present in an amount of from approx. 14.5 to 30$ dissolved in water to form a. aqueous solution around the saturation point and by the fact that the flavoring is present in an amount of approx. $1.30. 6. Edible, pre-coating preparation suitable for forming a moisture barrier on the relatively porous surface of yeast-raised donuts which can inhibit moisture transfer from the interior of said donuts through the surface thereof, characterized in that it consists of a liquid water-in-oil emulsion .or colloidal dispersion comprising a) an oil part selected from the group of materials consisting of acetylated monoglycerides, a triglyceride together with an emulsifying agent and a fatty or waxy material together with an emulsifying agent, b) a saccharide, polysaccharide or dextrin moiety, and c) water, where said preparation comprises the said parts b and c evenly dispersed as droplets in the said oil part. 7- Edible, pre-coating preparation which can form a moisture barrier on the relatively porous surface of yeast-raised donuts and which can inhibit moisture transfer from the interior of said donuts through the surface thereof, characterized in that it consists of a liquid water-in-oil emulsion or colloidal dispersion comprising a) a liquid, acetylated monoglyceride and b) a maltodextrin comprising a solid, low DE corn syrup in a near saturated aqueous solution, wherein said aqueous solution of maltodextrin is dispersed as droplets in said liquid acetylated monoglyceride. 8. Preparation according to claim 7, characterized in that it also contains a flavor component in a. effective amount. 9- Preparation according to claim 7, characterized in that the amount of acetylated monoglyceride is from 27 to 65%, and the said solid, low DE corn syrup is present in an amount of from 14.5 to 35%, and the said amount of water is from . 12 to 43$. 10. Method of providing a baked or fried bakery product with an edible, effective moisture barrier sufficient to substantially inhibit moisture transfer from the interior of said product through the outer, relatively porous surface, characterized by the fact that a) preparing a water-in-oil emulsion or colloidal dispersion comprising a uniform dispersion of droplets of a solution of saccharide, polysaccharide or dextrin in water in an oily substance selected from the group consisting of acetylated monoglycerides, a triglyceride together with an emulsifying agent and.a fatty or waxy material together with an emulsifying agent and by maintaining said emulsion or dispersion at a first temperature where it remains. a stable liquid, b) bake or fry the said bakery product and reduce the temperature of the surface thereof to a temperature which is less than the said first temperature, c) applying said emulsion or dispersion to the cooler surface of said product and providing a thin, uniform coating on said surface, and' d) by curing or drying said pre-coating before further processing of said product. 11. Product, characterized in that it is produced in accordance with the method according to claim 10. 12. Method for providing a multi-component, baked or fried bakery product with an edible, effective moisture barrier sufficient to substantially inhibit moisture transfer from the interior of said product through the outer, relatively porous surface comprising a) prepares a water-in-oil emulsion or colloidal dispersion comprising a uniform dispersion of droplets of a solution of saccharide, polysaccharide or dextrin in water in an oily substance selected from the group consisting of acetylated mono-glycerides, a triglyceride together with an emulsifying agent and a fat or waxy material together with an emulsifying agent and by keeping said emulsion or dispersion at a first temperature where it is a stable liquid, b) bake or fry the said bakery product and reduce the temperature of the surface thereof to a temperature which is less than the said' first temperature, c) applying said emulsion or dispersion to the cooler surface of said product to provide a thin, uniform coating on said surface, d) hardening or drying of the said pre-coating before further processing of the said product and by that one e) glaze coating the said bakery product, where the said pre-coating is present between the said product and the said glaze. 13. Product, characterized in that it has been produced in accordance with the method in claim 12. 14. Method for producing a shelf-stable, glazed, yeast-raised doughnut, characterized in that a) produces a water-in-oil emulsion or colloidal dispersion comprising a uniform dispersion of droplets of a solution of saccharide, polysaccharide or dextrin in water in an oily substance selected from the group consisting of acetylated monoglycerides, a triglyceride together with an emulsifying agent and a fatty or waxy material together with an emulsifier. agent and by maintaining said emulsion or dispersion at from 44 to 82°C, b) preparing a yeast-raised donut dough and forming donuts from it and baking said donuts at a temperature of ■approx. 93°C, c) cooling said fried, yeast-raised donut to a temperature of approx. 32 to 38°C,. d) applying said emulsion or dispersion to the surface of said yeast-raised donut by dipping said donut in said emulsion or dispersion for a sufficient time to apply a thin, even coating to the surface of the doughnut; e) curing or drying said pre-coating, f) prepare a glaze of sucrose, water and stabilizing agent, and g) coating said glaze on said hardened or dried pre-coating material. 15. Bakery product, characterized in that it is produced according to the method in claim 14.