WO1994028744A1

WO1994028744A1 - Egg-yolk-based emulsifier made by a heat-denaturing process

Info

Publication number: WO1994028744A1
Application number: PCT/US1994/006595
Authority: WO
Inventors: Dan A. Neumeister
Original assignee: Board Of Regents Of The Universtiy Of Nebraska
Priority date: 1993-06-10
Filing date: 1994-06-10
Publication date: 1994-12-22
Also published as: AU7105794A

Abstract

An egg-yolk-based emulsifier for aiding the processing, particularly extrusion of a food product, containing an egg-yolk-based product that has been heat-denatured to render it effective as an emulsifier for processes such as extrusion of food stuff. The heat-denaturing may be done by oven-heating, spray-drying, flash drying, etc. Also provided is a method of making this egg-yolk-based emulsifier, and an extruded food product that contains this egg-yolk-based emulsifier but with reduced amounts of a nonegg-yolk-based emulsifier.

Description

EGG-YOLK-BASED EMULSIFIER MADE BY A HEAT-DENATURING PROCESS

BACKGROUND OF THE INVENTION Pasta products are consumed and enjoyed all over the world. Reasons for their popularity are health, nutrition, convenience, and economy. In many parts of the world, for religious, tradition-related, and cultural reasons, products made from "all natural" ingredients are desirable. The term "all natural products" refers to products that are processed without chemical modification of molecular structures by reaction with another chemical agent.

In recent years there has been an effort to develop precooked pasta products that would not require extensive cooking time in boiling water in order to provide a cooked product. Processes for manufacturing precooked pasta products in a continuous extrusion apparatus utilizing high temperature and high pressure extrusion have been developed. For example, Myer et al., U.S. Patent No. 4,540,592 disclose a method for making a precooked pasta product that utilizes a twin screw extruder and subjects the pasta component to substantial back-mixing at elevated pressure and temperature prior to cooling in an extruder.

Typically, in the production of a precooked pasta product by extrusion, processing aids such as surfactants and emulsifiers are used to coat the flour particles and facilitate the passage and extrusion of the dough through the die in the extruder. These processing aids (emulsifiers) interact with the other ingredients to improve the appearance of the product and to eliminate clumping by reducing stickiness in the cut product. The incorporation of emulsifiers facilitates the smooth flow of the other ingredients through the cooking barrel, forming die and a cutting device. Such emulsifiers are also applicable, in certain formulations, for the production of foods such as instant pasta, snack foods, half products (food products that require further processing before consumption), candies, pet foods, baked products, puddings, pie fillings, dairy products, and the like.

The common emulsifiers used as in food manufacturing are semisynthetic chemicals typically derived from vegetable oils. Examples of such emulsifiers are mono- and diglycerides, propylene glycol, glycerol and sorbitan stearates and polysorbates, as well as combinations thereof. For example, the aforementioned U.S. Patent No. 4,540,592 discloses the use of such semi-synthetic chemicals as emulsifiers for extrusion. McMillin, U.S. Patent No. 5,124,168 discloses the use of glycerol monostearate and monoglycerides as emulsifiers. Gillmore et al. , U.S. Patent No. 5,063,072 disclose the use of glycerol monostearate and other monogylcerides as emulsifiers in the extrusion process. Food products containing such semi-synthetic emulsifiers are acceptable in the United States but they are not widely accepted overseas. Food products with "naturally occurring" emulsifiers would be acceptable, however. Food processors concerned about product labeling requirements would also have an interest in natural emulsifiers. However, production of food products with natural emulsifiers presents a challenge. Typically, natural ingredients used for emulsification do not perform effectively often because they chemically combine with other ingredients. Thus, none of the aforementioned patents discloses the use of "natural" emulsifiers. Consequently, there is a need for development of emulsifiers that are made entirely from natural products.

SUMMARY OF THE INVENTION

The invention is directed to a process for making an emulsifier suitable for use in the extrusion or manufacture of food products. The invention is directed also to the emulsifier product and to a food product made with the emulsifier. The emulsifier is or contains an egg-yolk-based material that has been heat-denatured. To perform the process of the invention, a starting material is selected from whole egg or egg-yolk. According to the invention, mixed liquid whole egg or liquid egg-yolk is converted to emulsifier by the steps, in any order, of drying and heat-denaturing. The drying step may be separate from, or may be combined with, the heat-denaturing step. If desired, either or both of the heat-denaturing and the drying steps may be divided into stages of various temperature and time. The heat-denaturing step of the process can be accomplished using any conventional drying technique in a conventional heat dryer. Variables to control the heat- denaturing/drying steps include temperature, air flow and heating time. The selection of values for these variables depends on a number of parameters such as, for example, the type of dryer used, the moisture content of the starting material, the temperature and moisture content of ambient air, and the interrelation of the variables. Generally, when an oven dryer is used, a suitable heating temperature is about 65°C to about 205°C (150 to 400°F), preferably about 70°C to about 150°C (160 to 300°F) . A heating time of about 10 to about 100 hours is adequate, although a longer or shorter heating time may be used. The preferable heating time is less than 24 hours. When a spray-dryer is used, the dryer outlet temperature typically is about 65°C to about 125°C (150 to 255°F), preferably about 70°C to about 105°C (160 to 220°F) . The time involved is minimal since the formation of spray droplets cause flash drying due to the large surface area attained. Any air flow adequate to dry the spray in a hot and dry atmosphere is appropriate. Typically, after combination of heat-denaturing/drying, the emulsifier will be substantially dry, having a moisture content of about 2 wt-% to about 7 wt-%, although a moisture content outside this range is possible and is within the contemplation of the invention. Heat-denaturing without drying can also be accomplished by means of a heat exchanger. In such case, the moisture content may be higher than 10% and the product may be semi- solid to liquid. Preferably such a product is dried further to reduce the moisture content to less than 10% to improve the functionality of the material as an emulsifier. Techniques for such drying include spray treatment, forced air treatment and evaporation treatment.

The emulsifier of the invention is a composition of heat- denatured, dried egg-yolk-based material. The term "egg- yolk-based material" refers to a material that contains egg yolk. Such egg-yolk-based material may contain egg-yolk, whole egg or their solids. The proteins present in the egg- yolk are denatured under conditions that render the denatured egg-yolk effective as binder, slip agent and surfactant for a farinaceous product. Preferably the denatured condition is accomplished by heat. The heat-denatured egg-yolk-based material is also referred to as "heat-denatured egg-yolk- based emulsifier (HDEYE)." The extruded farinaceous food product of the invention is an extruded combination of a farinaceous material and the emulsifier of the invention. The level of the egg-yolk-based emulsifier constitutes about 1 to about 20 wt-%, preferably about 2 to about 5 wt-% of the food product on a dry ingredients weight basis. The food products containing the heat-denatured egg-yolk-based emulsifier demonstrate unexpected and superior character. Foods such as pastas, candies, half products, snacks, puddings, pie fillings, bakery products, dairy products and the like may be produced according to the invention as products having unexpected, superior characteristics.

The heat-denatured egg-yolk contributes several advantages to the food products in which it is incorporated. For example, the emulsifier can be used in pasta, cookie products or the like for the reduction of the amount of fat used in such products. The incorporation of the heat- denatured egg-yolk emulsifier helps to improve the freshness and texture of the product while reduced amount of oil and fat is used. Syneresis in products such as puddings, custards, pie fillings, gravies and dairy products is reduced by the incorporation of the heat-denatured egg-yolk material in such products. Half products made by using the heat- denatured egg-yolk show superior expansion in the final heat processing step of such products.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph of tracings obtained in Brabender tests, showing the results of retrogradation in formulations containing a conventional emulsifier, a heat-denatured egg- yolk emulsifier and a combination of the two emulsifiers.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to (a) a heat-denatured egg-yolk- based emulsifier suitable for use in aiding the extrusion or manufacture of a food product, (b) a method of making the emulsifier and (c) food products containing the emulsifier. The emulsifier unexpectedly improves the appearance and functional properties and eliminates clumping of the formed product. A farinaceous substance is a substance that is rich in starch. Exemplary farinaceous substances are grains, flours, and starches.

Emulsifier From Egg Products According to the invention, egg or egg-yolk is heat- denatured to render it suitable for use as an emulsifier for facilitating the smooth extrusion and enhancing the characteristics of a food product. Either whole egg or egg- yolk is a suitable starting material for making the heat- denatured egg-yolk-based emulsifier (HDEYE) and egg-yolk is preferred. Combinations of egg-yolk and whole egg are also appropriate. Typically, a liquid egg product is well mixed before heat-denaturing.

Liquid whole egg and liquid egg-yolk are commercially available. Such materials are suitable for making the emulsifier of the present invention. Spray-dried egg and egg-yolk are also commercially available. In the conventional spray-drying of egg products, great care is taken to keep the dryer temperatures at levels that will not denature proteins. In the present invention, however, temperatures are deliberately selected to denature the protein.

Normally, egg or egg-yolk contains water, which according to the invention is removed to prevent spoilage of the product. This drying process may be a separate step or may be incorporated into the heat-denaturing process. Commercially available dried egg can also be utilized to produce the emulsifier. The whole egg or egg-yolk may be dried first, and then subsequently heat-denatured, optionally with a different dryer. In such a case, a liquid egg product is pre-dried to a nonflowable solid form, and then heat- denatured to obtain the desirable emulsifying properties. Preferably, liquid whole egg or egg-yolk may be spray-dried first, and then further treated in an oven to obtain the desired emulsifier properties.

The heat-denaturing can be accomplished as a continuous technique or in stages. The egg may be partially denatured in one oven, and later further denatured in another oven. The egg-yolk or whole egg may be heat-denatured to render it effective as an emulsifier before further drying. However, a preferred processing sequence is simultaneous drying and heat-denaturing. The heat-denaturing and/or drying can be done with any conventional means for drying. For example, conventional dryers such as tray dryers, reel dryers, rotary dryers, spray-dryers, flash dryers and the like may be used. The parameters for the heat-denaturing/drying conditions are selected so that the proteins in the egg-yolk are denatured to an extent such that the heat-denatured egg product is effective to reduce clumping in the extrusion of the food product and to provide desirable changes in the binding property, appearance, texture, firmness and slip of the food product. A factor that affects the selection of the heating time and temperature is the moisture content of the starting material. Typically, a higher moisture content requires longer heating time and more air flow. Oven type dryers such as tray dryers and rotary dryers are effective in drying solid products.

The heat-denaturing step generally takes up to about 48 hours, preferably 10 to 48 hours although longer or shorter period of heating time may be used. The heating time will also depend upon the mechanics of the heating operation. For example, if only a very thin layer of an egg-yolk-based material is heated in an oven, the heating time may be significantly less than 10 hours, possibly one hour, or even a few seconds. Preferably, the heat-denaturing time is less than 24 hours, although if desired, a heating time of much longer than 100 hours may be employed. The heating temperature in the oven is typically about 65°C to about 205°C (150 to 400°F), and preferably about 70°C to about 150°C (160 to 300°F). Although a temperature higher than about 205°C (400°F) may possibly be used, it is not preferable because of the risk of charring. The heating time and temperature may be adjusted depending on the other parameters selected.

Liquid egg or egg-yolk can also be heat-denatured by subjecting it to heating in a medium such as a boiling liquid. For example, liquid egg-yolk can be placed in a container which is placed in boiling water. The container acts as a heat exchanger in heating the egg-yolk material. Obviously, other liquids, for example, oil can be used as the liquid heating medium. An important factor in the selection of such heating methods is temperature. Other variations of a heating method using a heat exchanger include heating with steam and using a heat exchange device such as a scrapped- film heat exchanger or a drum dryer. In such instances, a temperature of about 65°C to about 150°C (150 to 300°F) is adequate. The preferred temperature is about 90°C to about 110°C (195 to 230°F) . The resultant heat-denatured product can have moisture content of more than 10 wt-%. Generally, a substantially dry emulsifier can be mixed with other dry ingredients more efficiently than a moist emulsifier. To improve the functionality as an emulsifier and to obtain longer shelf life, it is preferable to reduce the water content of such a product to less than 10 wt-%, and more preferably to about 5-7 wt-%. To this end, drying methods such as freeze drying, oven drying, air drying, etc can be used.

Further, it has been found that heat-denatured material of a suitable emulsifying character can be produced by heat spray-drying, which affords heating time in the range of fractions of a second to seconds. Dryers such as spray- dryers or flash dryers are suitable for simultaneously drying and heat-denaturing liquid egg or egg-yolk. If a spray-dryer is used, typically the outlet temperature of the spray-dryer is from about 65°C to about 125°C (150 to 255°F), but may be even higher. The preferable outlet temperature is from about 70°C to about 105°C (160 to 220°F) . Drying equipment and operation are discussed in Perry's Chemical Engineers' Handbook, Section 20: Gas-Solid Systems, McGraw-Hill, 5th ed., which is incorporated by reference herein.

To produce a substantially dry emulsifier, water is removed from the egg-yolk-based material in the drying process. Generally, air is circulated to remove the moisture and facilitate drying. In heat spray-drying or flash drying, large volumes of hot air are forced through the dryer to heat the emulsifier and remove the moisture. The air flow rate can vary widely depending on the dryer type, the temperature selected, the humidity of the air, the ambient air temperature, the water content of the dryer feed, etc. In general, for a typical spray-dryer, the typical air flow is about 85 to about 130 M³/M per Kg of dryer feed, and preferably about 95 to about 110 M³/M per Kg of dryer feed when the dryer feed is liquid egg yolk. By varying some of the aforementioned variables, air flow rates outside these ranges can also be suitable. In heat-denaturing by oven-drying, the starting egg-based emulsifier material is generally relatively low in moisture and air circulation is of less importance than in spray- drying and flash drying. However, air flow, whether heated or not, can be used to remove water vapor evaporated from the heat-denaturing eggs. For a starting material such as spray- dried egg-yolk, the heating-denaturing can be done in an oven-dryer with no special provision of air flow. Heat- denaturing can also take place in a device where the heating medium is hot air. Depending on the moisture content of the starting material, the type of oven used, the temperature selected, etc., the rate of air flow can vary greatly. An example is the heat-denaturing of sprayed dried egg-yolk with a convection oven. The air flow is typically about 0 M³/M per M³ of dryer volume to 28 M³/M per M³ of dryer volume. After oven heat-denaturing or spray-drying heat- denaturing, the egg-yolk-based emulsifier will typically be substantially dry, having a moisture content of 2 wt-% to about 7 wt-%. Often, the moisture level in the emulsifier is less than 5 wt-% after such heat-denaturing processes. Of course, the egg-yolk-based emulsifier can absorb moisture, either from the environment or from other materials added during the processing of the final product. Generally such a post-heat-denaturing increase in moisture will not affect the emulsifying property of the product.

If desired, heat-denatured egg-yolk-based emulsifier (HDEYE) can be stored at refrigeration temperature or freezing temperature for preserving the product against spoilage. Refrigerated storage is generally at about 0°C to about 5°C (32 to 40°F) . Storage can also be in a freezer at a temperature lower than 0°C (32°F).

Using the Heat-Denatured Egg-Yolk-Based Emulsifier Although the application of this invention is not bound by any theory, it is believed that heating the egg-yolks under the specified conditions denatures some of the proteins in the egg-yolk, thereby changing their functional properties. The molecular structures of the proteins are believed to be uncoiled by the process of the invention. The uncoiling is believed to allow the proteins to interact, or complex with the other ingredients of the product being extruded or otherwise prepared. This emulsifier interaction is believed to be the reason for the improvement in the appearance, texture, firmness and impartation of a non-stick surface to the product being manufactured.

Further, oils in the egg-yolk are also believed to improve the product and act as lubricants to facilitate the manufacture of the food product.

The amount of the egg-yolk-based emulsifier used in formulating a product is dependent on the product made, the other ingredients used and the manufacturing conditions. An effective amount of the egg-yolk-based emulsifier is used to produce a product with desired properties. All percentages in this disclosure are weight percents of total dry ingredients unless otherwise indicated. The factors that determine the proper level of use are similar to those for the application of other nonegg-yolk-based emulsifiers, even though the absolute amount of emulsifier used may be different.

Generally, a person would perform routine and usual testing to determine an appropriate amount of an emulsifier to be used for a particular product to be made under a certain set of manufacturing conditions in a particular application. The testing can also be done using a conventional emulsifier to establish operating conditions before the egg-yolk-based emulsifier is used. To do so allows direct comparison of the emulsifier under identical (except for emulsifier) conditions. The level of incorporation of the egg emulsifier in the manufacture of a food product is adjusted to be consistent with production of a product of a certain desired property, such as improved organoleptic characteristics, reduced stickiness to prevent clumping, reduced syneresis, proper texture, decreased or delayed retrogradation, increased expansion, and the like. The addition of too little of the egg-yolk-based emulsifier would not produce the desired effect, while the addition of too much of the egg-based emulsifier would impart an "egg¬ like" taste, which may not be desirable. Generally the addition of about 1 wt-% to about 20 wt-% of the heat-denatured egg-yolk-based emulsifier of the invention to a food product would be adequate. A concentration of about 2 wt-% to about 10 wt-% is preferred. In a pasta product, the preferred level is about 2 to about 5 wt-% of the heat-denatured egg-yolk-based emulsifier on a dry ingredient basis.

In certain cases, an emulsifier composition containing both a heat-denatured egg-yolk-based emulsifier and a nonegg- yolk-based emulsifier produces a synergistic effect. For example, experimental results indicate that an emulsifier containing heat-denatured egg-yolk emulsifier and a glyceride-based emulsifier, such as a monoglyceride ("MYVAPLEX™" from Eastman Chemical Products, Kingsport, Tennessee), or a diglyceride, is effective for producing extruded pasta containing corn flour. Other nonegg-yolk- based emulsifiers that may be used in combination with this invention include lecithin, propylene glycol, glycerol and sorbitan stearates, polysorbates and the like. The emulsifier effect varies with different combinations. Typically, when used in conjunction with the egg-yolk-based emulsifier, these conventional emulsifiers are added in an - amount effective in achieving the desired characteristics, such as preventing clumping, facilitating uniform mixing, improving mouthfeel, etc. Typically, in such instances, a conventional emulsifier is added in an amount of between about 0 wt-% and about 5 wt-% on a dry ingredient basis, preferably between 0 wt-% and about 1.5 wt-% and more preferably between about .25 wt-% and about 1.0 wt-%. In such a product, the heat-denatured egg-yolk-based emulsifier typically constitutes between 0.25 wt-% and about 10 wt-% of the product on dry ingredient basis. Pasta Ingredients The basic ingredients which can be used in a pasta product include flour, starch, dough emulsifier, oil, salt, water and the like.

A. Cereal and Flour The cereal or starch material commonly used for making pasta products can be ground or milled corn, wheat, rice, oats, potato, barley, and mixtures thereof. Pasta products may contain corn meal, corn flour, wheat flour, rice flour, oat flour, potato flour and mixtures thereof. If desired, starch can be used also. Starch may be derived from cereals or roots such as wheat, corn, rice, rye, potato, tapioca, legumes, and mixtures thereof. Any of the usual flours can be used for making pasta. The formulation may be adjusted as required for the particular pasta with regard to the kind of flour, the grade of flour, and the amount of additives needed to obtain the desired texture, color and flavor of the product. A generally preferred flour for making pasta product is durum or semolina flour. Most flours used in the conventional pasta products can be used in making acceptable extruded pasta products which incorporate the heat denatured egg-yolk-based emulsifier of the present invention. Using an emulsifier of the present invention, products containing combinations of flours and/or starches of different grains are also feasible.

B. Emulsifier The egg-yolk-based emulsifier can be used in conjunction with the conventional emulsifiers to produce the desired emulsifying effect in food processing. By doing so, less conventional emulsifiers are needed for achieving the same effect. In conventional processes of making pasta products, the commonly used emulsifiers are typically glycerol monostearate, mono- and diglycerides and combinations thereof. For example, a commercially obtainable complexing compound that can be used as an emulsifier is a monostearate mixture, "P.ANIPLEX™" (ADM Arkady, Olathe, Kansas). Emulsifiers containing glycerol monoglyceride, "MYVAPLEX 600™," and "MYVATEX™" are commercially available from Eastman Chemical Products, Kingsport, Tennessee. These commercially available emulsifiers are generally derived chemically from vegetable oils. Other emulsifiers include lecithin, propylene glycol, glycerol and sorbitan stearates, polysorbates and the like.

C. Other Ingredients

Water is an important ingredient in a pasta formulation. Water helps the mixing of the solid ingredients and the plasticizing of the solid ingredients during extrusion. The amount of water added depends on the moisture of the non- pasta flour ingredients and the functionality of the final finished pasta product. By following typical and usual understanding about food extrusion, the amount of water and/or other ingredients can be adjusted to obtain a desirable product. Another commonly used component of a pasta product is vegetable oil, for example, olive oil. Although vegetable oil components are sometimes important for emulsifier properties, they are often used for organoleptic purposes, i.e. mouthfeel, and for functionality. In a food product processed with an emulsifier of the present invention, vegetable oil can also be an ingredient. The use of a relatively small amount of vegetable oil such as olive oil in the pasta formula assists in a more uniform dispersal of the pasta ingredients. As a result, the finished product has a more uniform flavor, texture, and consistency. Typically, vegetable oil is present in the pasta formula in an amount of about 0.5 wt-% to about 5 wt-%, and preferably in an amount of about 2.0 wt-% to about 3.0 wt-%.

Vegetable oil is also important for flavored pasta products. Oil carries fat soluble flavor components, disperses flavors, enhances the impact of fat soluble flavors, and binds the flavoring components with the flour in a homogeneous manner throughout the pasta product.

A vegetable oil also facilitates the extrusion of the pasta forming ingredients through the extruder. It is believed that the vegetable oil coats the rough edges of the pasta flour particles and helps to make the surface more slippery. As a result the pasta dough can pass through the extruder auger and die with more ease. Other vegetable oils, such as safflower oil, sunflower seed oil, soy bean oil, peanut oil and the like may be used.

Alternatively, in this invention a pasta formulation without the use of any vegetable oil may be used. For farinaceous snack products, the vegetable oil can interfere with later expansion of the product by application of heat. Such interference is reduced if a heat-denatured egg-yolk- based material is used as an emulsifier.

Extrusion The flour, water, additives and ingredients may be mixed in any way conventional in the art, such as by mixing in a vertical cutter mixer for a sufficient time to prepare the pasta formula for extrusion. Alternatively, the components of the pasta product may be separately introduced into the extrusion system without prior mixing. The extruded pasta products may then be subjected to a drying process.

The extrusion process may be done in any acceptable extruder. The ingredient mixture for pasta product is forced through the holes of the extruder die to obtain a desired shape. The holes in the die of the extruder dictate the profile of the extruder product. The pasta passing through the die is extruded by the internal pressure generated by the rotating screw or screws of the extruder. Certain sections of the extruder can have pressures that are lower than that of other sections because of reverse screws. The conventional extrusion operating guidelines may be varied according to the usual and typical knowledge in the art to fully optimize the conventional extrusion process to obtain a desired product. Typical extruder conditions include barrel temperature of 50 to 120°C (122 to 250°F), die orifice gauge pressure of 200 psig to 1,000 psig. It is also possible to control the temperature of the extruder by heating and/or cooling sections of the extruder with cooling water, hot water, hot oil, or the like. The temperature of a section is adjusted by controlling the amount of water or oil passing through the water jacket to maintain a preset temperature. A wide variety of extruders are commercially available. Examples of suppliers of extruders are Wenger, Brabender, Buhler, Breibanti, Clextral, Baker, Perhus and Warner Pheidler. The type of extruder used will determine the amount of starting ingredients and the operating parameters of the extruders. There are single and twin screw extruders. A twin screw extruder may have co-rotating or counter- rotating screws. There may be many sections on a screw, each for a specific function, which may be kneading, pressurizing, reduction of pressure, and the like.

Advantages of the Egg-yolk-based Emulsifier

Heat-denatured egg-yolk-based emulsifiers are effective in aiding the manufacture of food products. These emulsifiers not only can replace the commonly used nonegg- yolk-based emulsifiers, but in many instances result in products that are superior to those produced with conventional emulsifiers. The facilitation of extrusion of a food product is one aspect of the aiding of manufacturing. Other aspects include the improvement of stretching property and durability, the retardation of retrogradation, the prevention of syneresis and the reduction of fat usage in a product.

A thicker walled product which is slower to rehydrate can be made using the HDEYE. Compared to conventional products, expansion of the extruded product as it exits the die is greater with the use of the HDEYE. This is surprising because usually the combination of emulsifiers in a product does not increase die swell and rehydration times are similar. The thicker wall also contributes to the increased strength or stretch of the product, thus improving the durability of the product in water. Such products with increased stretch are said to have "long" texture whereas those with less stretch are "short." This property presents the possibility of applications that require more durable products than are now available in instant precooked pasta. Mouthfeel of a product containing HDEYE is better than conventional products. The smoothness of the surface is evident on the lips as well as in the mouth. Also, the product appears to have more body.

HDEYE has an effect in delaying retrogradation (or set back) of starch. Retrogradation is the formation of crystallinity in cooked starch, and is an indication of staleness. Products containing only HDEYE show very little set back. Products with a combination of HDEYE and conventional emulsifiers showed a delay in set back which was indicated by a rise in viscosity in the Brabender test. The comparison of the formulations containing "MYVAPLEX™" as the emulsifier, no emulsifier, and emulsifier with both HDEYE and "MYVAPLEX™" shows that deterioration of the products are delayed when the HDEYE is used in combination with other emulsifiers.

The HDEYE can be used in the inhibition of staling of bakery products such as breads, cookies and crackers. It may also be added as an ingredient in baked products to increase tenderness and freshness of the baked products. Usually shortenings or oils are added for such purposes. For example, cookies can be made by employing the heat-denatured egg-yolk material as an emulsifier.

Such reduction of fat/oil and prevention/delay of retrogradation is also achievable through the application of HDEYE in other cooked food products containing starch, for example, cakes, danishes, muffins, etc. The HDEYE is also effective in reducing the amount of liquid lost in puddings during freeze/thaw cycles. The reduction in syneresis is also useful in the production of pudding-like products such as custards, pie fillings, gravies, and dairy products (i.e., yogurt, ice cream and the like) . Such reduction in syneresis is of significance to the frozen food industry for the preservation of products that tend to deteriorate from freezing and thawing. The heat-denatured egg-yolk emulsifier can also significantly improve the expansion factor over conventional monoglyceride type emulsifiers in the production of final products from half products.

Simply heating the egg-yolk does not involve the addition of a chemical that reacts with the egg material. Therefore heat-denatured egg-yolk-based emulsifier of the present invention can be considered to be a "natural ingredient" for the production of food products such as pasta. Conventional dried egg products are currently heated for pasteurization. Therefore, heat-denatured egg-yolk would be acceptable in the U.S. as well as in foreign countries to those processors who are concerned about listing the "nonnatural" emulsifiers such as glycerol monostearate and monoglyceride, etc. on labels. The invention will now be described by reference to particular embodiments and examples. The foregoing description of the invention, however, fully sets forth the parameters and elements of the invention. The following examples are not meant to convey any limitation thereon. To evaluate the products, samples were taken from the products and analyzed with different techniques. Some of the techniques were conducted with laboratory equipment and are described as "laboratory analysis." Subjective evaluation of samples were also conducted and are described as "sensory analysis."

Sensory Analysis The sensory analysis of extruded food products was designed to provide subjective evaluation of products to give direction to the development of appropriate products. Because food is consumed by individuals, subjective evaluation is an important factor in the production of food. Most observations were made on a visual basis and informally recorded. Products were evaluated in this manner as they exited the extruder as well as when they were removed from the dryer and subsequently rehydrated and tasted. The sensory analysis was employed to assist the determination of the effect of using different heat-denaturing methods, proper time, temperature, and the level of use of the emulsifier. For example, sensory analysis was important in establishing that a preferred incorporation rate for the egg-yolk-based emulsifier was at the 5% level, which produced a high composite score of product quality. Sensory analysis also indicated that compounding the commercial emulsifier "MYVAPLEX™" at a reduced rate with 2% of the egg-yolk-based emulsifier produced a good product.

Sensory analysis was also important in evaluating stretch (strength), mushiness, mouthfeel, etc.

Example 1 Heat-denaturing by Oven-Heating Commercially available spray-dried egg-yolk (4.5 kg, i.e. 10 pounds) from Henningsen Foods, Inc., Omaha, Nebraska was placed into a reel oven at about 74-80°C (165 - 175°F) for heat-denaturing. A portion of the spray-dried egg-yolk was removed at 24 hours and the remainder was removed at the end of 72 hours. The 24 hour product showed very little change in appearance. The 72 hour product changed in appearance in that it had become darker yellow.

The treatment of the spray-dried egg-yolk in the oven involved only heating. There was no agitation of the product while it was being heat-denatured. There was virtually no air circulation in this type of oven and no humidity control was used. The rotating shelves of the reel oven were kept stationary. The shelf containing the product was positioned at the back of the oven.

The heat-denatured egg-yolk produced was used as the emulsifier in some of the following examples. Example 2 Heat-denaturing by Oven-Heating The same equipment as in Example 1 was used to heat- denature egg-yolk as well as spray-dried whole egg and spray- dried egg white from Henningsen Food Company. Again, a batch containing 4.5 kg (ten pounds) of the spray-dried yolk was treated at each of the following sets of conditions: about 65°C (150°F) for 24 hours, 48 hours, 72 hours and 96 hours; about 74°C (165°F) for 24 hours, 48 hours, and 72 hours; about 104°C (220°F) for 12 hours, 24 hours and 48 hours.

Spray-dried whole egg and egg white were treated at about 74°C (165°F) for 24 hours, 48 hours and 72 hours.

The products made in this example were tested as the emulsifier in some of the following examples.

Example 3 Heat-Denaturing by Spray-Drying Liquid egg-yolk (Henningsen Foods, Inc., Omaha, Nebraska) was spray-dried on a tower spray-dryer, Henningsen Pilot Plant Tower Spray-dryer Model T-20. The spray-dryer inlet temperature was set at about 155 to 157°C (312 to 314°F) and the outlet temperature was set at about 74°C (165°F) for one batch of yolk.

A second run was conducted with a batch of yolk dried with an outlet temperature of about 104-105°C (219-221°F) and an inlet air temperature in excess of 205°C (400°F) . The furnace temperature gauge indicated that the inlet temperature was about 232°C (450°F) for the second run.

In another run, 27 kg (60 pounds) of liquid egg-yolk was spray-dried on the spray-dryer. This time the inlet temperature was kept at about 201 to about 204°C (394 to 400°F) with an outlet temperature of about 94 to about 98°C (201 to 208°F) .

The spray-drying operation produced products that were not discolored by heat. The product was as effective as those produced in the oven runs. Table 1 shows the typical operational conditions for the spray-dryer. A nozzle with a 0.094 inch orifice was used. The feed rate to the dryer was approximately 13.6 kg per hour of liquid yolk, corresponding to a pump speed setting of about 2 on the Model T-20 spray-dryer system.

Table 1

Operating Parameters of 20- -T Pilot Plant 1

Vacuum

"F ^βF In

^•F Pump Air ^•r Inlet Outlet Drying

Nozzle Liquid Speed Pres. Furnace Air Air Chamber Time Type Temp. Setting Psig Temp. Temp. Temp. ln./H₂0

8:50 Large 130 1.9 30 626 400 202 .04 Exter

9:55 " 120 1.9 30 630 394 204 .55

10:25 " 120 2.0 30 624 400 207 .55

11:00 " 120 2.0 30 628 396 208 .55

11:15 " 120 2.0 30 626 397 201 .55

Example 4 Heat-Denaturing in Boiling Water

Liquid egg-yolk (10 pounds) was placed in a plastic cooking bag and submerged in boiling water for 30 minutes. The cooked egg-yolk was then freeze-dried to a product with moisture of about 6 wt-%. The resulting material was reduced to granules.

This granular HDEYE was used in making extruded pasta using standard methods as disclosed in the following Example 5 at 2 wt-% and 5 wt-% levels. The HDEYE preformed adequately as an emulsifier.

Example 5 Comparison of Emulsifiers in Extrusion In all cases the utilization of heat-denatured egg products was tested on the University of Nebraska, Food Processing Center's TX52 Extruder (Wenger Manufacturing, Inc., Sabetha, Kansas). The extruder was a twin screw extruder consisting of a bin feeder for the flour and other dry ingredients, a premixing chamber where moisture and steam could be added to the formulation before entrance into the barrel of the extruder, a barrel containing two co-rotating screws that were configured for pasta extrusion using commercial emulsifiers, a die arrangement for shaping the cooked starch, and a knife assembly for cutting the product to length. Water and steam could also be injected into the extruder.

The extruder had ten sections. The first section was open for receiving feed. The last section was the die head. The temperatures of the second to the ninth section were controlled by circulating oil or water of a predetermined temperature.

The product was carried to a gas fired Wenger dryer through a pneumatic conveying system. The dryer discharged the dried product into an Wenger Air Cooler conveyor where ambient air was drawn through the product to remove the heat from drying.

The forming die in the extrusion process used in almost all cases was a 0.016 inch (0.041 cm) elbow die nominally suitable for making a tubular product with a wall thickness of 0.016 inch (0.041 cm). This die was chosen because it produces a very thin walled, small diameter macaroni product and is one of the most difficult dies with which to form products. Limited tests were performed with other less severe dies. A ziti die was used on one occasion. This die produced a ribbed macaroni product that was thicker walled and larger in diameter. A folded noodle die was also tested. This die produced a thin walled pasta product. A chip die was also used. This die produced a half product (which is a product that requires further processing, usually deep fat frying, microwave or air puffing, before it is ready for consumption) .

For each extrusion run, the conditions of operation of the extruder were first established using a standard base formulation for precooked pasta consisting of durum flour and about 0.75 wt-% of a commercial emulsifier "MYVAPLEX™." These conditions were then maintained for the subsequent runs using the heat-denatured egg-yolk-based emulsifier. Extruder head pressures would vary and some changes were made on the operating conditions to maintain these pressure as much as possible. Only on initial runs with "MYVAPLEX™" was there any effort to make the product to achieve a particular physical property. Table 2, as related to Example 5, shows the typical operation conditions of the extruder. In the other extrusion examples, the extruder was run with conditions similar to those of Example 5. Heat-denatured egg-yolk emulsifier that had been treated with about 74°C-80°C (165-175°F) heat for 72 hours was incorporated into a formulation consisting of 50 pounds of North Dakota Mills Extra Fancy Excello Durum at rates of 2 wt-% (Run #2) and 5 wt-% (Run #3). See Table 2 for the Extrusion Data. In Table 2, the premixing conditions and the extrusion conditions for each run were shown. The speed of the feed screw controlled the rate of introduction of dry ingredients into the premixing chamber whereas the speed of the extruder shaft controls the extrusion rate. The load on the motor driving the extruder indicated how smooth the operation was and whether additional steam or water was needed. The temperatures and pressures were maintained within preset ranges to facilitate cooking and shearing of the materials. The pressures of only the last four heads were recorded because they were more influential on the property of the extruded products.

A macaroni product with open ends was produced at the 5 wt-% HDEYE level. At standard extruder conditions, the process using the heat-denatured egg-yolk produced a thicker walled product than the formulations containing "MYVAPLEX™" (Run #1) . The operating conditions were held relatively constant during the runs.

Nonheat-denatured commercial spray-dried egg-yolk was also tested (Run #4). In addition, a combination emulsifier containing egg-yolk which had been heat-denatured at about 73.9°C (165°F) for 73 hours and a reduced amount of "MYVAPLEX™" (Run #5) was tested. The operational conditions for Runs #4 and #5 were not shown in Table 2, however, they were similar to the conditions shown in Table 2. The run using nonheat-denatured spray-dried egg-yolk produced an unacceptable product . The macaroni was extremely sticky and clumped severely at the die head. Run #5 which used the combination emulsifier, produced acceptable products with normal wall thickness.

Table 2

Operational Conditions by Extrusion

Extruder: Wenger TX 52 Run #1 Run #2 Run #3

RAW MATERIAL INFORMATION: Control Test 2Z HDEYE Test 5Z HDEYE

Emulsifier •75Z "MYVAPLEX" Yolk Yolk

Feed Screw Rate: (RPM) 14 14 14

PREMIXING INFORMATION:

Mixing Cylinder Speed: (RPM) 110 110 110

Steam Flow to Mixing Cyl, Kg/h 23 23 23

Water Flow to Mixing Cyl, lb/min 0.353 0.353 0.353

Mixing Cylinder Temperature, °C 99 99 99

EXTRUSION INFORMATION:

Extruder Shaft Speed: (RPM) 160 160 160

Z of Full Motor Load 28 24 20

Steam Flow to Extruder, Kg/h 5.6 10.9 11

Water Flow to Extruder, lb/min 0.324 0.247 0.247

Control/Temp. - 2nd Head, ^•c CW 65 64 54

Control/Temp. - 3rd Head, °c HO 110 110 110

Control/Temp. - 4th Head, •c HO 110 110 110

Control/Temp. - 5th Head, ^•c HO 110 110 110

Control/Temp. - 6th Head, ^•c HO 110 110 110

Control/Temp. - 7th Head, ^•c CW 90 90 90

Control/Temp. - 8th Head, °c CW 90 90 90

Control/Temp. - 9th Head, °c CW 90 90 90

Control/Temp. - Die Head, ^•c 84 88 90

Head/Pressure 7TH (PSIG) 100 100 50

Head/Pressure 8TH (PSIG) 400 450 400

Head/Pressure 9TH (PSIG) 700 750 700

Head/Pressure DIE (PSIG) 330 320 330

FINAL PRODUCT INFORMATION:

Extrudate Rate . (Wet) (lb/h) 186 186 186

Extruder Performance GOOD GOOD GOOD

Duration of Run (Min) 20 20 20

Die Description .016 ELBOW .016 ELBOW .016 ELBOW

CH: Cold Hater was used to bring the barrel temperature down, HO: Hot oil (source of heat to bring the barrel of the extruder to a warmer temperature). Example 6 Comparison of Emulsifier at 2% Concentration for Extrusion The effect of various heat-denaturing temperatures on the emulsifying property of the HDEYE was tested with extrusion conditions similar to those of Example 5. The level of HDEYE was held at 2 wt-% in the formulations. The acceptability of other heat-denatured egg products such as heat-denatured egg white (Run #20) and heat-denatured whole egg (Run #10) was also tested. The heat-denatured whole egg and egg white were obtained from Example 2.

The heat-denatured egg whites performed poorly, resulting in severe clumping of the products as they exited the die. Clumping is in indication of the stickiness of the product. Due to the stickiness of the products, no sample from Run #20 was evaluated.

Heat-denatured whole egg was more effective than heat denatured egg white in preventing clumping, though not as effective as the heat-denatured egg-yolk. With 2 wt-% of heat-denatured whole egg, clumping was more severe than at 5 wt-% level, but the products were still processable. The temperature range tested varied from about 65°C (150°F) for 24 hours to about 104°C (220°F) for 12 hours for the oven- dried products. Products that were heat-denatured using the spray-dryer were also tested. Further, the combination of "MYVAPLEX™," and heat- denatured egg-yolk was also tested on a formulation containing corn flour. This formulation utilized the HDEYE and 0.75 wt-% "MYVAPLEX™." "MYVAPLEX™" alone was ineffective as an emulsifier in producing nonclumping products with corn flour. By combining a HDEYE with "MYVAPLEX™" an acceptable product was produced with very little die swell and no clumping. The ends of the product were open.

Example 7 Producing Extruded Multi-Grain Chips

A half product was made using a formulation that contained corn flour, rice flour, whole wheat flour, bran, sugar and 2 wt-% heat-denatured egg-yolk. This product is a Multi Grain Chip that requires puffing after extrusion and drying. The extrusion conditions were similar to those of Run #2 in Example 5. The extrusion process ran well and a nonclumping product was made. The product was later deep fat fried in vegetable oil at an oil temperature of approximately 400°F (204.44°C) and found to be an acceptable snack. The product initially sank when it was first put in the oil. When it floated, it was then removed from the oil.

Example 8 Further Comparison of Emulsifiers in Extrusion Laboratory Analysis Tests were done to determine the suitable levels of incorporation of heat-denatured egg-yolk emulsifier into standard formulations. Table 3 contains the summary of data on representative samples taken from the various extrusion runs.

The column entitled "MYVAPLEX™" indicates the level of incorporation of this conventional emulsifier in the formulas of the runs. Likewise, the column entitled HDEYE indicates the level of incorporation of the HDEYE. The column on Formula indicates the general nature of the product and what kind of emulsifier was used in each run. In the laboratory the samples were analyzed for cohesiveness by measuring the Water Solubility Index (WSI) and degree of cook by measuring the Water Absorption Index (WAI). Sensory analysis data are also included for each of the samples analyzed in addition to extruder head pressure data.

Raw formulations were evaluated for total starch and the level of enzyme susceptible starch to determine interactions between the emulsifier and the starch.

Brabender VISCO/amylo/GRAPH analysis were done using the standard procedures of CW. Brabender Instruments, Inc., Hackensack, New Jersey, to analyze viscosity of the formulations and set back (initial retrogradation) using durum flour. These analyses were also repeated on wheat starch.

In this example, all percentages are expressed as percent of the durum flour in the formulation, i.e. 2 wt-% is 2 wt-% of 50 kg of flour or 1 kg of heat-denatured egg-yolk. The range tested was from 2 wt-% to 20 wt-% of heat-denatured egg-yolk. Extrusions were carried out under standard operating conditions commonly used for making precooked pasta using the commercial emulsifier "MYVAPLEX™." Water was held constant compared to the control experiment with 22.7 kg (50 pounds) of durum and 0.17 kg (0.38 pound) of "MYVAPLEX™." A product was also made containing both emulsifiers where the "MYVAPLEX™" was incorporated at about 0.5 wt-%, 0.75 wt-% and 1.0 wt-% levels with about 2 wt-% heat-denatured yolk in 22.7 kg (50 pounds) of Durum flour. Also tested was a formulation with only "MYVAPLEX™" as a emulsifier at about 0.5 wt-%, 0.75 wt-% and 1.0 wt-%. Samples of the flour mixtures and the finished product were evaluated in the laboratory for water absorption and starch modification. The data was correlated with sensory analysis done on the product. The relevant data was incorporated into Table 3.

The procedures for measuring WAI and WSI are described in Conway et al.. Cereal Science Today, 14(1): 4-12 (1969). In a WAl/WSI analysis, a gel and a supernatant are formed. WSI is related to the solids content of the supernatant. WAI is related to the water content of the gel. The water absorption index (WAI) is a measurement of the degree of swelling of a product in water. Water absorption is related to the degree of cook of the extruded product, an indication of how well-cooked the product is. Generally, the higher the WAI, the higher the degree of cook. In the application of HDEYE in extruded products, the degree of cook was unaffected by variations of the heat-denaturing treatment of the HDEYE or the level of incorporation up to 10 wt%. The HDEYE can be heat denatured using a good range of time and temperature without affecting the degree of cook in the resulting products. The water solubility index (WSI) is a measure of the processing damage to the starch. A high WSI indicates a lack of cohesiveness of the product in water. If the WSI is high, the extruded product tends to disintegrate when cooked in water.

The results of WSl/WAI analyses indicated that whether a conventional emulsifier or HDEYE was used did not have a significant effect on the WSI, therefore the processing damages were similar. Furthermore, the WAI scores were similar between products made with a conventional emulsifier, and a combination of conventional emulsifier and HDEYE. This shows that HDEYE can be used in conjunction with conventional emulsifiers in food formulations without affecting the WSI and WAI. This is important for applications where conventional emulsifiers are not effective in producing acceptable products.

The extruder head pressures in extrusion experiments with HDEYE as emulsifiers were lower than the pressures in experiments with conventional commercial emulsifiers. Extrusion experiments using HDEYE made with treatment at about 65°C (150°F) for 24 hours to about 93°C (200°F) for 12 hours showed that these were effective emulsifiers.

Table 3

THE DIE CONFIGURATION FOR ALL PRODUCTS PRODUCED FOR THE TESTS WAS .016 ELBOW ALL PRODUCTS PRODUCED WERE MADE USING NORTH DAKOTA MILLS EXTRA FANCY EXCELLO FLOUR THE CONTROL IN ALL CASES WAS THE STANDARD FLOUR USING .75Z OF KODAK'S MYVAPLEX

THE CONTROL BATCH SIZE LISTED IS 68 KG AND ALL OTHER BATCH SIZES ARE 22.7 KG OF FLOUR

RUN (Z) FORMULA (Z) SENS WATER WATER EXTRUSION HEAD CODE MYVAPLEX HDEYE ABSORP SOL PRESSURE PSIG

7 8 9 DIE

Control Product and Commercial Uncooked Pasta #1 .75Z Control 20.0 3.64 6.78 350700 1100640

Commercial Emulsifier and Untreated Egg-yolk

#7 .75Z Comc'l 2Z 17.5 3.79 5.23 200550 900560 Sd Yolk

Modifying Methods and Temperature Range

#8 150"F, 24 hrs2Z 17.5 7.24 6.48 300600 1000380

Oven Yolk #4 220°F 2Z 18.5 7.90 7.01 250650 1150540

Sd Yolk #9 160°F, 12 hrs2Z 16.5 14.52 6.01 250650 1100520

Oven Yolk #10 165°F, 73 hrs2Z 14.5 16.37 5.95 200650 1150550

Oven Whole Egg

Emulsifier Incorporated with Commercial Emulsifier #11 .50Z 18.5 4.44 6.57 200550 900610

#12 1.00Z 18.5 3.69 5.66 250600 1000 640

#13 .50Z Sd Yolk 2Z 20.5 3.62 6.32 250600 1000640 200-210-F

#14 1.00Z Sd Yolk 2Z 19.0 3.83 5.24 200550 850560 200-210"F Range of Incorporation of HDEYE

#15 200-210°F 2Z 15.0 4.78 6.48 300 600 950 600

Sd Yolk #16 200-210°F 3Z 15.5 4.91 6.36 200550 950580

Sd Yolk #17 200-210°F 5Z 19.5 5.93 6.70 250500 900 600

Sd Yolk #18 200-210^βF 102 20.0 5.40 5.96 200500 900600

Sd Yolk #19* 200-210°F 202

Sd Yolk

* No samples were obtained for Run #19 - Product not runable at extruder settings

Sd - Spray-dried

Sens - Sensory Score

Water Sol- Water Solubility Index test score

Water Absrp-Water Absorption Index test score Non-Extrusion Applications of the Egg-Yolk-Based Emulsifier In addition to application as an emulsifier in the extrusion of food products, the heat-denatured egg-yolk-based emulsifier possesses superior properties that may be advantageously employed in making other food products. Such properties include retrogradation inhibition (including preventing and delaying retrogradation), reduced syneresis, increased capacity in retaining moisture, and the ability to reduce the fat level in the formulation of products such as cookies and crackers.

Example 9

Syneresis in Puddin /Custard HDEYE was tested for evaluating the effect on syneresis in a gel using a standard formula for a cooked vanilla pudding made with corn starch. The formula used for the test was described in the Joy of Cooking cookbook (1973 edition, paperback, p. 689, Cornstarch Custard Pudding or Blancmange):

Control (Formula #1):

1/2 c. granulated sugar 102.15 g

6 T. corn starch 51.85 q

1/4 t. salt 1.70 q

4 c. milk* 985.00 q

2 eggs** 119.70 g

1 t. vanilla 6.00 g

*2% milk was used for the tests (HyVee brand) .

**The fresh eggs used in the tests were "large" sized eggs.

(HyVee brand) .

Starch, sugar, salt, and milk were mixed in a boiler container. The mixture was then heated over boiling water and stirred constantly for about 8-12 minutes. When the mixture began to thicken, it was covered and cooked for about 10 minutes more. In a separate container, the eggs were beaten and one cup of the mixture was stirred into the eggs. This egg-containing material was returned to the mixture and cooked for about 2 minutes with stirring. Then the mixture was removed from heat and cooled by gentle stirring. As the mixture was stirred, the vanilla was added into it.

A custard pudding using conventional spray-dried egg-yolk in place of fresh eggs was made using the same control formula as above. The amount of spray-dried egg-yolk and water was calculated so that the equivalent amount of egg and water as in the control was used. The spray-dried yolk was mixed with water in a spray-dried egg-yolk: ater ratio of 1:1.25 (53.2 grams of spray-dried egg-yolk and 66.5 grams of water) .

In a third formulation, the same ingredients were used as in the control formula except that heat-denatured egg-yolk was used in place of the fresh egg. The amount of the heat- denatured egg-yolk to be used was calculated the same way as in the formula employing spray-dried egg-yolk. The procedures for making the custard pudding was the same as in the control formula.

The pudding made with the heat-denatured egg-yolk appeared to be thicker. The control had a lighter color than the others. The product made from conventional spray-dried egg- yolk did not rehydrate smoothly for the final product contained lumps of material.

Three samples, each containing 50 grams were separated from each of the products made with the above procedure. The samples were frozen and stored in the freezer for approximately 5 days, thawed for 24 hours at room temperature, refrozen for approximately 5 more days, and thawed again for 24 hours at room temperature. The free fluid in each sample was decanted and weighed after each thaw cycle. Table 4 shows the average percentage of fluid loss from the products of the three formulations after the freeze/thaw cycles. Table 4

Sample Containing Average % Fluid Lost (Total)

Control Fresh Whole Egg 24.39

Conventional Spray-dried Yolk 8.10

Heat-Denatured Spray-dried Yolk 2.39

The result showed that puddings made with the heat- denatured yolk showed much less water loss due to syneresis than the other formulas. The control lost 24% of its weight in liquid whereas the pudding made with denatured egg-yolk lost 2.4% of fluid, indicating a 90% reduction in syneresis.

Example 10 Reduced-Fat Cookies Heat-denatured egg-yolk was tested in formulations for low fat sugar cookies using the cookie recipes of AACC (American Association of Cereal Chemists) Method 1-50D. The following formula for making cookies was used:

Shortening 64.0 g

Sugar 130.0 g

Salt 2.1 g

Soda 2.5 g

Dextrose Solution* 33.0 g

Distilled Water 16.0 g

Flour (14% m.b. ) 225.0 g

^♦Dextrose solution: 8.9g dextrose hydrous USP to 150 ml water or 8.1 g dextrose anhydrous to 150.8 ml water

"Dummy" cookies were baked to condition the cookie sheets and the oven before making test cookies. Creamed shortening, sugar, salt, and soda were mixed at low speed for about 3 minutes. The dextrose solution and distilled water were then added into the resulting mixture. The mixture was mixed for about one minute on low speed, scraped from the container and mixed for one more minute at medium speed. The flour was added to the mixture and mixed for about 2 minutes at low speed. The mixture was scraped from the container after each half minute. The resulting dough was rolled to 7mm thickness using gauge strips and cut with a 2 inch cutter. The cut pieces of dough were placed on an ungreased cookie sheets and baked for 10 minutes at about 204°C (400°F). Cookies made this way were designated as "control." Test cookies were made by reducing the fat content by 50% to 32 grams and employing the heat-denatured egg-yolk-based emulsifier. The fat content of 32 gram was equivalent to 26.24 grams of shortening and 9.45 gram of heat-denatured egg-yolk emulsifier. An additional 16 grams of water was added to make the dough manageable.

The control cookies and the reduced fat cookies that contained the HDEYE were similar in texture and appearance, although the control cookies were somewhat softer than the test cookies. In all other aspects, the reduced-fat cookies were similar to the controls.

Example 11 Delayed Retrogradation and Syneresis Reduction Retrogradation was tested using a standard Brabender method on formulas containing heat-denatured egg-yolk, conventional emulsifier, glycerol monostearate, and a combination of heat-denatured egg-yolk-based emulsifier and glycerol monostearate. Figure 1 is a set of Brabender/VISCO/amyl/GRAPH tracings showing the viscosity- time result of the test. The unit for viscosity is the Brabender unit. The formula containing 3% heat-denatured egg-yolk showed no sharp increase in viscosity or a second peak representing retrogradation. The formula containing .75% glycerol monostearate showed a high second peak viscosity at 80 minutes into the test. A third formula that contained 2% HDEYE and .5% glycerol monostearate showed a second peak at 100 minutes into the test. These results indicate that retrogradation is delayed by the addition of HDEYE to a formula containing glycerol monostearate. In a product containing only HDEYE as emulsifier, the retrogradation appeared to be much reduced. Example 12 Moisture Retention in Dried Extruded Product In this experiment, extruded pasta products of three formulas were made in a manner similar to that in Example 5 and dried to compare the effect of the emulsifier in moisture retention in a drying process. In the control products, .75% glycerol monostearate was used as the emulsifier. In test product #1 and #2, heat-denatured egg-yolk was used as the emulsifier at a concentration of 2% of the dry ingredients. The extruded products were dried in a gas fired Wenger dryer. The product made two passes under a stream of high viscosity heated air in the dryer before exiting. The dwell time for each pass was 15.9 minutes. Table 5 shows the moisture content of the products before and after drying. The results indicate that the extruder product containing HDEYE retained more moisture than a product containing glycerol monostearate.

Table 5

Run # Control #1 #2

Emulsifier .75% Glycerol 2% HDEYE 2% HDEYE Monostearate

Extrudate Moisture 43.16% 40.93% 36, .96%

Dryer Exit Moisture 11.19% 18.22% 18, .40%

Percent Moisture Loss 74.07% 55.49% 50, .22%

Even though the products containing heat-denatured egg- yolk came off the extruder with 2.23% to 6.20% less moisture than the control, after drying they retained 63 to 64% more moisture than the product containing glycerol monostearate as an emulsifier.

Example 13 Expansion of Half Product Through Application of Heat Extruded products were made using a combination of wheat flour and tapioca flour with extrusion conditions similar to those of Example 5. The same formula was used except for the variations caused by the addition of the emulsifiers to the formula. The emulsifiers used were vegetable oil, monoglyceride and HDEYE. Baking soda and baking powder were also incorporated as ingredients. After extrusion, the half products were subjected to heat by deep fat frying. Table 6 shows the result of fat frying on the extruded products. Sample #1, containing only HDEYE and no baking soda gave the best expansion factor of 3.36. The incorporation of baking soda reduced the expansion factor as shown in sample #2. The incorporation of 2% vegetable oil as shown in #3, in addition to the 2% HDEYE, did not result in a change of expansion factor. In sample #4, the emulsifier employed was 0.5% monoglyceride with 2% vegetable oil on ingredients. This resulted in the lowest expansion factor of the four samples. Table 6

Sample HDEYE MonoG Oil Bp Bs F Wall UF Wall Expansion Factor

#1 22 .5Z .2588" .07770" 3.36

#2 22 .52 22 .2236" .0786" 2.85

#3 22 22 .52 22 .2162" .0760" 2.84

#4 02 .52 22 .52 22 .1945" .08860" 2.26 HDEYE-Heat Denatured Egg- olk: MonoG-Monoglyceride: Oil-Vegetable Oil

Bp-Baking Powder: Bs-Baking Soda: F Wall-Fried Wall Thickness: UF Wall - Unfried Wall Thickness

It is generally known that the addition of emulsifiers such as glycerol monostearate/monoglyceride will decrease the expansion of half products that are puffed through deep fat frying, hot air puffing or microwave heating. Applicants found that (data not shown in Table 6) in one instance, increasing the glycerol monostearate from 0.5% to 1.0% caused a 17.2% decrease in expansion. By using a HDEYE, a normally sticky formulation containing tapioca was successfully extruded. Such a product had a higher degree of expansion after deep fat frying as compared to products that were made using a conventional emulsifier such as monoglyceride.

Example 14 Making Crackers, Candies, Spreads and Snacks Using HDEYE Crackers, candies, snacks, and spreads can be made using the HDEYE. Procedures for making these products are found in Food Product Formulary, Volume 4, Fabricated Foods, The AVI Publishing Company, Inc. (1982).

Bran crackers are to be made using the formula described in Food Product Formulary, page 14. In the 25 pounds of shortening called for in the formula, 50% is to be substituted with 6.25 HDEYE and 3 pounds of water.

Stand-up caramels are to be made according to the formula described in Food Product Formulary, page 49. The lecithin called for in the formula is to be substituted with 1.5 times by weight of the HDEYE.

Imitation mayonnaise is to be made according to the formula described in Food Product Formulary, page 135. The liquid egg-yolk called for the formula is to be substituted with the HDEYE on an equivalent solids and liquid basis.

"High energy/high protein snack," "sesame seed snack," "puffed snack," and "fiber bar" are to be made according to the formulas described in Food Product Formulary, page 123- 127. HDEYE is to be incorporated into these formulas at 1.0 wt-% level to reduce stickiness.

Instant pudding mix is to be made according to the formula described in Food Product Formulary, page 61. The mono and diglycerides called for in the formula are to be substituted with HDEYE at 5 wt-% level.

It is believed that employing the HDEYE in making these products will produce crackers, candies, snacks and spreads of acceptable quality. Although the examples presented in the above describe standard pasta products that contain wheat flour, the present invention can also be applied in making products containing other less commonly used flours such as rice, rye, etc. and starches such as potato, corn, tapioca, etc. A person in a relevant trade will be able to adapt the present invention to the making of candies, half products, snack foods, bread products, pet foods and the like.

The characteristics, advantages, and functions of present invention have been disclosed in the above specification. However, it will be understood that changes can be made based on the foregoing description without departing from the spirit of the present invention. The embodiments are presented for illustrative purposes only, and are not to be interpreted as limiting the scope of the invention, which is set forth in the appended claims.

Claims

WHAT IS CLAIMED IS:

1. An emulsifier composition for aiding the processing of a food product, comprising a heat-denatured, substantially dry egg-yolk-based material.

2. An emulsifier composition of claim 1, which will reduce clumping in the food product.

3. An emulsifier composition of claim 1 wherein the heat- denatured, substantially dry egg-yolk-based material is obtained from a material selected from the group consisting of whole egg, egg yolk, liquid whole egg, liquid egg yolk, solid whole egg and solid egg yolk.

4. An emulsifier composition of claim 1 wherein the heat- denatured, substantially dry egg-yolk-based material is produced by oven-heating, spray-drying, or heating in a heat exchanger and drying.

5. An emulsifier composition of claim 1, further comprising a non-egg-yolk-based emulsifier.

6. An emulsifier composition of claim 1, wherein the emulsifier is suitable for producing a stretchy extruded food product.

7. An emulsifier composition of claim 1, wherein the emulsifier is suitable for producing a durable extruded food product.

8. A method for making a substantially dry egg-yolk-based emulsifier, comprising heat-denaturing the egg-yolk-based material.

9. A method of claim 8, further comprising the step of reducing the moisture content of the egg-yolk-based material to less than 10 wt-%.

10. A method of claim 8, wherein the method produces an emulsifier suitable for preventing clumping in an extruded food product.

11. A method of claim 8 wherein the egg-yolk-based material is selected from the group consisting of whole egg, egg yolk, liquid whole egg, liquid egg yolk, solid whole egg and solid egg yolk.

12. A method of claim 8 wherein the heat-denaturing is accomplished by oven-heating, spray-drying, or heating in a heat exchanger and drying.

13. A method of claim 8 wherein the heat-denaturing comprises spray-drying at an outlet temperature of about 65°C to higher than 125 °C (150 to higher than 255°F) .

14. A method of claim 8 wherein the heat-denaturing comprises spray-drying at an outlet temperature of about 70°C to about 105 °C (160 to 220°F) .

15. A method of claim 8 wherein the heat-denaturing comprises oven-heating at a temperature of about 65°C to about 205°C (150 to 400°F) .

16. A method of claim 8 wherein the step of heat- denaturing comprises oven-heating at a temperature of about 70°C to about 150°C (160° to 300°F) for a time period of about 1 to about 100 hours.

17. A method for making a pasta product, comprising providing an egg-yolk-based material; heat-denaturing the egg-yolk-based material to form a heat-denatured egg-yolk-based material; combining the heat-denatured egg-yolk-based material and ingredients for making the pasta product to form a mixture; and extruding the mixture through an extruder under conditions of pressure and temperature suitable for forming the pasta product.

18. A method of claim 17 further comprising providing as an ingredient a nonegg-yolk-based emulsifier.

19. A method of claim 17 further comprising providing as an ingredient an emulsifier selected from the group consisting of glycerol monostearate, monoglyceride, diglyceride, lecithin, propylene glycol, sorbitan stearate, polysorbate, as well as any combination thereof.

20. A product made by a method of claim 17 wherein the heat-denatured egg-yolk-based material is suitable for preventing clumping in the pasta product.

21. A product made by a method of claim 17, wherein the heat-denatured egg-yolk-based material is suitable for producing a stretchy extruded pasta product.

22. A product made by a method of claim 17, wherein the heat-denatured egg-yolk-based material is suitable for producing a durable extruded pasta product.

23. A product made by a method of claim 17 wherein the heat-denatured egg-yolk-based material is present at a level of about 1 to about 20 wt-% of the dry ingredients of the pasta product.

24. A product made by a method of claim 17 wherein the heat-denatured egg-yolk-based material is present at a level of about 2 to about 5 wt-% of the dry ingredients of the pasta product.

25. An extruded food product made by a process which comprises providing an egg-yolk-based material; heat-denaturing the egg-yolk-based material to form a heat-denatured egg-yolk-based material; combining ingredients for making the food product, and the heat-denatured egg-yolk-based material in an amount of 0.25 to 10 wt-% of the food product on dry ingredient basis; and extruding the mixture through an extruder under conditions of pressure and temperature suitable for forming the food product.

26. A food product of claim 25 further comprising a nonegg-yolk-based emulsifier up to about 5 wt-% of the pasta product on dry ingredient basis.

27. A food product of claim 25 wherein the ingredients for making the food product comprises flour or starch of at least two different grains.

28. A food product of claim 25 wherein the food product is a candy.

29. A food product of claim 25 wherein the food product is a half product that requires further processing before consumption.

30. A food product of claim 25 wherein the food product is a snack.

31. A food product comprising a heat-denatured, substantially dry egg-yolk-based material and a farinaceous substance.

32. A food product of claim 31 wherein the heat- denatured, substantially dry egg-yolk-based material will reduce clumping in the food product.

33. A food product of claim 31 wherein the heat- denatured, substantially dry egg-yolk-based material is obtained from a material selected from the group consisting of whole egg, egg yolk, liquid whole egg, liquid egg yolk, solid whole egg and solid egg yolk.

34. A food product of claim 31 wherein the heat- denatured, substantially dry egg-yolk-based material is produced by oven-heating, spray-drying, or heating in a heat exchanger and drying..

35. A food product of claim 31 wherein the emulsifier composition contains up to about 5 wt-% of a nonegg-yolk- based emulsifier.

36. A food product of claim 31 wherein the food product is a pudding-like material, and the heat-denatured, substantially dry egg-yolk-based material will reduce syneresis in the pudding-like product.

37. A food product of claim 31 wherein the food product is a baked product, and the heat-denatured, substantially dry egg-yolk-based material will inhibit retrogradation in the baked product.

38. A food product of claim 31 wherein the heat- denatured, substantially dry egg-yolk-based material will reduce the amount of fat use in the food product.

39. A food product of claim 31 wherein the heat- denatured, substantially dry egg-yolk-based material will improve expansion in the further processing of a half product.