CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of United States Provisional Application No.

60/023.647 entitled "Heat-Stable Protein Microparticles and No-Shear Process for Producing

Same ^* , filed by applicants on August 9, 1996.

BACKGROUND OF THE INVENTION The invention relates to lat-like protein compositions tor use in foods and cosmetics. The food art is continuously searching for improved fat substitutes which retain the texture.

taste and appearance of fatty substances, and which can be used in a vaπety of food products. While the art has developed a number of products which have attempted to solve this

problem, these products are often either poor fat substitutes, impractical to produce, or both.

Moreover, products containing fats and oils often have a short shelf life.

In the cosmetic an. there is a need for improved substances capable ot compiexint with numerous cosmetic substances to extend shelf life, and enhance stability and delivery ot these substances.

Various types of protein compositions and processes for their formation have been

described in the patent literature U.S. Patent Nos. 5.021.248 and 5.145.702 (to Stark and

Gross) describe water-insoluble proteins (prolammes) which are denatured and precipitated

trom alcoholic solutions, and then dispersed under shear as microparticles. However, a

special apparatus providing tor controlled feed of reactants and for dispersion by rapid

stirπng is required for this process These products are stable only up to 70°C ( 158°F),

making them unsuitable as a fat replacement for baking or similar purposes.

U.S. Patent Nos. 4.855,156 and 4.961,953 (to Singer), and U.S. Patent Nos. 5.147.677

(Ziegler). 5,173.322 (Melachouπs). EP/0345226 (to Habib), EP/0340035 (to Chen), and

WO90/05460 (to Liao) describe precipitation by heat-denaturation and microparticulation by

shear (in a special apparatus) of water-soluble proteins such as egg white, casein, whey

protein and cereal proteins, with addition, in some instances, of lecithin, polysaccharides. and other substances.

U S. Patent No. 5.374.441 to Gibson et al. describes precipitation and microparticulation ot water-soluble proteins by heat-denaturation under shear, combined with a crosslinlαng reaction using phenolic acids and an oxidizing agent. The microparticles produced by this

process are stable at temperatures of 350-400°F when used for baking This product, while

having certain desirable properties, is difficult to manufacture on a large scale because it

requires an injection step and high-shear agitation

U.S Patent No 4.734.287 to Singer, et al describes protein product bases produced by

subiecting sweet whey to high shear while simultaneously heating the whey to produce the

proteinaceous microparticles.

U.S. Patent No 4.308.294 issued December 29. 1981 to Rispoli et al describes oil

replacement compositions prepared by formation ot a protein phase, forming a separate acid

modified starch phase, heating the acid starch phase to swell the starch, followed by cooling and mixing the protein and acid phases.

SUMMARY OF THE INVENTION

The invention relates to fat-like protein compositions tor use in foods, pharmaceuticals, and the like The compositions compπse water-insoluble microparticle

compositions compπsmg protein, carbohydrate, and phospholipid stabilized by cross-linking them with naturally occurring phenolic acids The protein portion compπses gelatin and optionally a water-soluble heat-denaturable albumin The carbohydrates compnse at least one polysacchaπde having lonizable groups, and the phospholipids compπse a mixture of charged and uncharged phospholipids These microparticles can function as a fat replacement in foods, cosmetics or pharmaceuticals They can also serve to form complexes with a variety ot oils or other lipids. The invention also relates to methods tor making these compositions Complex coacervates in the form of water-insoluble microparticles are generated when solutions of gelatin, an albumin, and a polysacchaπde are mixed at between about 40°C and about 45°C, and then acidified This temperature is important because in order to blend the two proteins, the temperature must ordinarily be above the 37°C melting temperature of the gelatin but below the temperature range where albumins denature (45-60°C) The gelatins include acid-processed and alkali-processed gelatins The albumins include, but arc not limited to. egg white, casein, and sov protein The polysacchaπdes include, but are not limited to, pectin, carrageenan. al inate. and carboxvmethvi cellulose Λ vaπetv ot art- known albumins and polvsacchaπdes are suitable for use in the instant invention

As used herein, the term "complex coacervation" is understood to mean the aggregation of colloidal polyelectrolvtes from solution when they have acquired opposite net ionic charges, brought about by an appropriate pH change In contrast to other processes that generate microparticles by heat-denaturation. the present process uses coacervation without

any denaturation by heat. The gelatin component, in fact, cannot be denatured this way. The

particle size, yield, and rigidity of the coacervates is affected by the concentrations and pH

levels used. It is understood that those skilled in the art can modify the pH and

concentrations according to their specific needs.

The present process provides for optional subsequent heat treatment, but this step is not

an essential part of this invention. Coacervates are more easily generated in high yields when

the gelatin solution is first blended with the albumin solution and the phospholipid solution pπor to mixing with the polysacchaπde solution and acidification. Further, it has been found

that the resulting coacervates can be stabilized by adding a phenolic acid, and allowing a

crosslinking reaction of such acids with the proteins in the microparticles to proceed under oxidizing conditions. Phenolic acids are understood to include hydroxylated and/or alkoxylated cinnamic and benzoic acids. Such substituted cinnamic acids include, for

example, caffeic, fcrulic. coumaπc. and chlorogenic acids. Such substituted benzoic acids

include, for example, vanillic. syπngic. cllagic. and gallic acids. Also included are glycosidic deπvatives of all such acids and their esters. Additionally, it has been found that the phenolic

acids need not be added as the purified compounds but can be added in the form ot a natural

extract of potato, coffee (green or roasted), tea. grapes, plums, or other fruit, all of which are

rich sources of the above phenolic acids. It has also been discovered that the crosslinking reaction occurs under the combined effects of alkaline pH and exposure to atmospheric

oxygen, thus eliminating the need oi ^' an added oxidizing agent. While other crosslinking

agents (such as formaldehyde and gluteraldehyde) are suitable for use in the instant invention,

phenolic crosslinking is the preferred method for use in food or health products.

As noted above, the crossiinked coacervates can optionally be further stabilized by briefly heating the aqueous suspension of microparticles to boiling. This step can be performed before or after the crosslinking step. The final suspension can then be concentrated by centrifugation or filtration, and washed free of uncoacervated material by washing.

This basic process can be modified in several ways. The size of the microparticles can be controlled between about 0.1 up to several hundred micrometers by varying the pH levels and concentration during the coacervation step. Removal of uncoacervated material is optional. The degree of crosslinking can be controlled by varying the amount of phenolic acid introduced by the natural extract, and by varying the time and temperature of incubation of the alkaline solution.

The resulting product is a concentrated suspension of microparticles. having a semi-solid consistency. It can be used as replacement, with only one-half the calorific value, of some or all the fat normally present in foods, including foods baked at temperatures at or about 400°F. The product has a smooth mouth feel. When used in baking muffins, in place of a standard shortening, the resulting food is quite similar in appearance, fiuffiness. and taste from a control preparation made with butter. Fiuffiness can. in some cases, be even superior to a product made with butter.

This product is substantially free of oxidizable lipids. Therefore, foods made with the product are far less susceptible to becoming rancid over time compared to foods containing fats or oils. Consumables made with the present compositions will therefore have a greatly extended shelf-life.

The product can also be used to replace oils in pharmaceutical and cosmetic creams and

emulsions. Due to its gelatin and lecithin content, the product retains moisture, and thus can

serve as a humectant in cosmetic and pharmaceutical applications.

DETAILED DESCRIPTION OF THE INVENTION

The invention thus relates to microparticle protein compositions comprising, (/) a

crosslinked protein comprising gelatin and a water-soluble, heat-denaturable albumin. ( _* ^■ ; ^' ) a carbohydrate comprising at least one polysaccharide having ionizable groups, and (Hi) a

phospholipid comprising a mixture of charged and uncharged phospholipids: wherein said

gelatin, albumin, carbohydrates, and phospholipids are in the form of a water-insoluble

complex coacervate.

The resulting microparticles are preferably in the range of from about 0.1 to about 250

microns. More preferred are microparticles in the range of from about 0.1 to about 10

micrometers, and microparticles in the range of from about 10 microns to about 250 microns. The albumin is preferably egg white or lactalbumm. The preferred carbohydrate is pectin

or carboxymethyi cellulose.

The invention also relates to processes for producing tat-like protein compositions using

suitable amounts ot gelatin, albumin, carbohydrate, and phospholipid. These elements may

be dissolved separately in water at a pH between about 4.5 and about 9.0. Next, the gelatin. albumin, carbohydrate, and phospholipid are combined to form a mixture. The mixture is

then acidified to a pH ot between about 4.4 and about 3.8 to produce a precipitate of

coacervated microparticles. An effective amount of phenolic acid or derivative thereof is then added to the suspension of microparticles: and the pH of the suspension is raised to a pH of between about 7 and about 9 The suspension can be contacted with air for a suitable period

ot time if desired The suspension is then acidified to a pH between about 4 and about 5.

heated until boiling, then allowed to cool to room temperature

The suspension can optionally be concentrated by centπfugation or filtration.

Additionally, the suspension can be optionally washed with an alcohol, and the suspension allowed to dry to a powder, capable of reconstitution to the original fat-like suspension

through rehydration with water

The preferred phenolic acids in the invention are chlorogenic acid, caffeic acid, feru c acid, coumaric acid, other suitable members of this class ot acids, and mixtures and denvatives thereof

A preferred procedure tor forming the protein microparticles. is as follows

1 A 5% solution of gelatin is made by allowing the gelatin to hydrate at room temperature, then warming it to 40°C I he pH is adjusted to 4 8 by addition ot acetic acid or

sodium hydroxide Acid-type or alkali-type gelatins of bloom strengths up to 300 can be

used, depending on the desired texture of the microparticles

2 A 6% solution ot egg white ( egg albumin ) is made slowlv adding dried egg white to water at room temperature while stirring, and continuing stirring lor one hour

Centπfugation at 2000 rpm for 5 minutes is used to remove undissolved material Before use

the solution is warmed to 40° C Other albumins such as milk or soybean proteins can also be used

3 A 1% suspension of phospholipids is prepared by stimng a phospholipid fraction

containing at least 50% lecithin (phosphatidvl choline) into water at 40°C Phospholipids from egg yolk or soybeans can be used

4 A solution containing 0 1% ot sodium hexametaphosphate and 0 1% ot pectin is prepared by adding these solutes to water at 40°C and slowly adding a 1 Normal sodium

hydroxide solution to bring the pH to 8. The solution is stirred for about one hour until the

pectin is dissolved. Acetic acid or vinegar is now added to bπng the pH to 4 8. Pectins from

apples or citrus fruit are suitable Other polysacchaπdes with lomzable groups, such as

carboxymethylcellulose. can also be used. \ pectιn:gelatιn weight ratio higher than given here can be employed. This ratio affects the yield, and particle size of the microparticles.

5 Four parts of the 6% egg white solution is slowly poured into 36 parts of the 5%

gelatin solution at 40°C and gentlv blended bv stirring for 15 minutes Six parts ot the 1 %

phospholipid suspension is added and stimng is continued for 10 minutes. This mixture is poured into 54 parts of the sodium hexametaphosphate-pectin solution with stirπng which is

continued for another 10 minutes, maintaining the temperature at 40°C.

6. Vinegar or 12% acetic acid is slowly added with stirπng. As the pH is lowered a precipitate of coacervated microparticles gradually forms Acidification is continued to a pH

of 4 3 Under these conditions, particles of 1 -3 micrometers result. Stirπng is continued for a

further 1 5 minutes \t this point the reaction mixture contains about 2% ot suspended particles plus solutes The particle size can be controlled bv varying the pH values before and

after mixing. Larger particles (up to several hundred micrometers) result when the gelatin-

albumin solution and the pectin solution are above pH 4 8. possibly as high as 9. before

mixing and if acidification after mixing is earned to a point below pH 4 3. possibly as low as 3.5. Smaller particles (between about 1 and 10 micrometers) result when the solutions are

below pH 4 8 before mixing, in which case coacervation and precipitation can occur even

before further acidification after mixing, and if such acidification stops at a point above 4 3.

7 The suspension is filtered or centπfuged to concentrate it and to remove most of the

supernatant solution containing uncoacervated mateπai. Remaining uncoacervated mateπal

is removed by washing of the filter cake or by re-centπfugation. Removal of uncoacervated

mateπal can be omitted. In this case the final product will be a much thicker suspension, with excellent mouth feel.

8 The proteins in the concentrated particle suspension are then subjected to a

crosslinking reaction by adding the juice from raw potato pulp. Peeled potato pulp at 10°C is passed through a juicer 12% acetic acid is added immediately, bπngmg the pH to 4 9 The juice is kept cold and filtered through a paper filter, then added to the concentrated particle

suspension that had been precooled to 10°C The potato juice was analyzed bv UV

absorption at 280 and 320nm relative to a standard, and found to contain 150 micrograms of

phenolic acids, expressed as chlorogenic acid, per ml of juice Enough potato juice is added

to provide I 0 to 1 2 milligrams of chlorogenic acid per gram of gelatin present The pH of

the suspension next is raised to 8 or 9 by addition of sodium hydroxide with rapid stirπng,

then kept at 10-15°C with slow stirnng in an open vessel exposed to air for a minimum of 4 hours Less alkaline conditions such as pH 7 5 can be used, with air exposure tor 12 to 18

hours I he pH is then readjusted to 4 bv adding acetic acid

9 Optionally the particle suspension at pH 4 can be heated to boiling, then cooled back to room temperature This step can be omitted where heat-stability of the final product is not required In this case the final product will have a thinner consistencv

10 Sodium benzoate is added in a concentration ot 0 01% to the coacervated.

crosslinked. and heat-denatured particle suspension which is then concentrated bv filtration or centπfugation Typically, a suspension containing 40-45%) by weight of particles can be

prepared which is a semi-solid, smooth, fat-like material. This procedure can be described by the following flow chart:

ILLUSTRATIVE PROCESS FOR PREPARATION OF MICROPARTICLES

Re-centrifuge; decant supernatant

Final Concentrated Microparticle Suspension

The crosslinked microparticles can optionally be washed with 70% isopropanol and

evaporated to dryness. The resulting powder can be rehydrated by adding water and vortexing. The microparticles retain their original size and shape. Additives such as

glycerine can be added to aid in the rehydration.

It has been found that the microparticles are capable of complexing with water insoluble

substances. For example 0.25% powdered beta-carotene was mixed into the 1% phospholipid suspension at 40°C. and the 5% gelatin and the 6% egg white solutions were warmed to 40°C

and added This mixture was poured into the 0 1 % phosphate-pectin solution, as in the above

procedure. This technique provides for administration of a water-insoluble substance in an

aqueous medium.

The protein microparticles can also be complexed with an oil. Typically a 3% emulsion

of vegetable oil is prepared with rapid stirπng into a 40°C. 1 8% gelatin solution until the oil

droplets are of the desired size (usually less than 5 micrometers) The high gelatin concentration is needed to aid in the emulsification ot the oil \ 40°C. 6% solution ot egg

albumin is then stirred in The gelattn/oil/egg albumin mixture is then poured into a solution containing 0.1% sodium hexametaphosphate and 0 1% pectin at 40°C The pH is then

lowered with acetic acid to around 4 0. resulting in the formation of microparticles complexed with small oil droplets. These microparticle complexes are then crosslinked and concentrated as above.

The following examples will serve to further typify the nature of the invention, but should not be construed as a limitation on the scope thereof.

EXAMPLE I

Solutions were prepared in beakers of appropπate size, equipped with motoπzed stirrers.

and set on thermostatically controlled hotplates.

Solution 1 : 50 grams of acid-type gelatin of 300 bloom strength was added with stirring

to l OOOmi water at room temperature. This was allowed to hydrate for 30 minutes, and then

warmed to 40°C. The pH was adjusted to 4.8 by addition of a small amount of 1 Normal NaOH.

Solution 2. 7.5 grams of dried egg white was slowly stirred into 125ml water. Stimng was continued for one hour. The solution was centπfuged in a bench centπfuged to remove traces of insoluble material (2000 rpm for about 5 minutes). The clear supernatant was

decanted and warmed to 40°C

Solution 1 7 grams of soybean phospholipids was stirred into 1 75ml water at 40°C, producing a colloidal solution.

Solution 4 1 5 grams of sodium hexametapho phate and 1.5 grams of citrus pectin were

added to 1 500mi water at 40°C The pH vvas brought to 8 through addition ot 1 Normal NaOH. and the solution was stirred to dissolve the pectin ( about an hour). The pH vvas then

brought to 4.8 through addition ot 1 % acetic acid.

The 125ml egg white solution vvas slowly poured with stirring into the 1000ml of gelatin solution, and stirring was continued for 15 minutes. The 175ml of phospholipids vvas added next and stirring was continued for 1 minutes. The resulting 1300ml of mixture vvas then

slowly poured with stirring into the 1500ml of phosphate-pectin solution, and stirring

continued for 10 minutes.

The pH was then brought to 4.3 through addition of 12% Acetic acid in small aliquots with continuous measurement of the pH. Increasing precipitation occurred during this

addition, indicating the formation of an insoluble gelatin-pectin-egg white coacervate.

Examination of the precipitate under the microscope showed it to consist of spherical particles of 2 to 3 micrometer in diameter.

The suspension was centrifuged in a bench centrifuge at 2000 rpm for 15 minutes. The

microparticles were readily thrown down. They were freed of uncoacervated material by decanting the supernatant, adding fresh water and recentrifuging.

An extract of peeled raw potato was prepared by passing 600 grams of cold (10°C) potato

pulp through a juicer. 400ml of juice were obtained. The pH was then brought pH to 4.9 through immediate addition of 12% acetic acid. Low temperature and acidification without delay is necessary since the freed phenolic acids otherwise would oxidize and polymerize,

with darkening, in the absence of protein. The juice was clarified by passing it through a

paper filter, and added to the washed suspension of microparticles. The 400ml of potato extract provided 60 milligrams of chlorogenic acid (caffeoylquinic acid) for reaction with 50

grams of gelatin. The suspension vvas adjusted to pH 7.5 by addition of 0.12% NaOH. and

kept in an open beaker at 10°C to 15°C with slow stirring for 18 hours. The pH was then

lowered to 4 by addition of acetic acid.

The particle suspension next was heated to boiling, then cooled back to room

temperature. Microscopic examination showed no change in size or shape of the

microparticles after this treatment. After this treatment, the suspension became whiter in appearance and more viscous.

Sodium benzoate (0.1 gram per liter of suspension) was added as a preservative. The suspension was centrifuged again to concentrate it. After decanting the supernatant, the concentrated residue amounted to 135 grams, with a solids content of 45%.

EXAMPLE 2

Retention of Uncoacervated Material

The procedure of Example 1 was repeated but the removal of uncoacervated material was omitted. The final product, containing the ingredients both in the coacervated and in the free state, had a much thicker consistency than the product of Example 1.

EXAMPLE 3

Crosslinking with Grape Juice

Commercial grape juice was analyzed and found to contain 300 micrograms of phenolic acids per ml. The procedure of Example 1 was used but the potato extract was replaced with grape juice in an amount sufficient to provide 3.5 milligrams of phenolic acids per gram of gelatin present. After addition of the grape juice to the particle suspension at pH 4, the mixture was brought to pH 9 and kept stirred and exposed to air for two hours at 15°C. The solution was then returned to pH 4. and further treated as in Example 1.

EXAMPLE 4 Crosslinking with Coffee

Instant coffee (which was found to contain 100 milligrams of chlorogenic acid per gram of coffee powder) was dissolved in hot water and enough coffee extract was added to the microparticle suspension to provide 5 milligrams of chlorogenic acid per gram of gelatin present. The mixture was brought to pH 7.5 and kept exposed to air for 18 hours.

EXAMPLE 5 Microparticles as Fat Replacement in Baking

Microparticles were prepared without washing as set forth in Example 2. then

crosslinked with coffee as in Example 4 Muffins were baked, using these micropamcles in

the following recipe:

1) 1 cup flour. 1/2 teaspoon salt, 2 tablespoons sugar, and 1 teaspoon baking powder

were mixed together.

2) In a second bowl. 1 egg, 1/2 cup milk, and 2 tablespoons of crosslinked microparticles were mixed together

This wet mixture was poured into the dry ingredients and stirred just until there were no

large lumps The batter was poured into paper baking cups placed in a muffin tin The muffins were baked in a 400°F oven for 20 minutes The muffins were similar in appearance. fiuffiness, and taste from muffins made in the same way, using butter instead of the

microparticles.

EXAMPLE 6 Compiexation of Microparticles with a Water Insoluble Compound

The quantities of Example 1 were used One-half gram of beta-carotene (from Sigma

Chemical Co ) was added with stirπng to the phospholipid solution The phospholipid solution was then added to the egg white and gelatin solutions The phospholipid was found to aid in dispersion of the crystalline carotene. The mixed solution was then poured into the phosphate-pectin solution, and the procedure was continued as in Example 1 When the final

microparticle suspension was washed with water and diluted, the carotene remained associated with the microparticles. as indicated by its the strong red color.

EXAMPLE 7 Complexation of Microparticles with an Oil

1. A gelatin solution was prepared by dissolving 5.4g of 300 Bloom gelatin in 25. Ig of water.

2. 0.7g of egg albumin was dissolved in 1 1.8g of water.

3. 1ml of vegetable oil was emulsified into the warm gelatin until small droplets (less than 5«m were formed.

4 The centπfuged egg albumin was warmed to 40°C and gently stirred into the gelatin/oil mixture.

5. To 150ml 40°C water. 0.1ml of 2N NaOH, 0 2g sodium hexametaphosphate and 0.2g pectin was added When the pectin was dissolved, pH was adjusted to 4 81 with the addition of 0.2ml of 12% acetic acid.

6 The warm gelatin egg/oil mixture was poured into the pectin solution with stirπng. The pH of mixing was 4 66 3ml ot acetic acid was added to a final coacervation of 4 04

7 Microscopic examination confirmed the formation of gelatin/egg albumin microparticles approximately 15-20 microns in diameter These microparticles were complexed with several tiny oil droplets.

8. The protein microparticles were crosslinked with 60ml grape juice as in Example 3