GB1602505A - Process for making an edible complex of casein and starch - Google Patents

Description

(54) PROCESS OF MAKING AN EDIBLE COMPLEX OF CASEIN AND STARCH (71) I, ANNE-MARIE IRIS HER MANSSON, a subject of the King of Hdgalyckan 23, S-416 60 Sweden of Göte- borg, Sweden, da hereby declare the invention, for which I pray that a patent may be granted to me. and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a process of preparing an edible complex of casein or a caseinate and starch, and to the complex thus produced. which is useful as a modified starch in various food products.

When foodstuffs or foodstuff components are combined. the raw materials are destroyed and protein, carbohydrate, fat and spices recombine to form different products.

Proteins and carbohydrates are used for their traditional functions. The most common carbohydrate for human consumption is starch. which is used as a thickener and as a binder in several foodstuffs. It lacks certain functional properties, such as foam and emulsion-stabilizing properties and is limited in its utility.

Physical and chemical modification of starch has been effected to modify its properties.

Starch combines with gluten to provide a product having the properties of bread.

Starch is used to improve the properties of skimmed milk. According to Swedish patent specification No. 129026, starch increases milk-protein foam stability. The amount and ratio of starch used for these purposes and the fact that the same effects are obtained with such substances as pulverized fruit seeds. pips and stones, kefir. kefir casein and lecithin indicate that the normal binding properties of the starch are being utilized to obtain the desired effect. In order to utilize the properties of the milk protein.

this must also be swollen by increasing the pH value.

According to Norwegian patent specification No. 67,483, starch is used in the production of a dry-milk protein product.

From the process conditions and weight ratios of ingredients it is appreciated that normal swelling properties of the starch are responsible for improving the properties of the milk protein.

A gelatinized starch product is referred to. Souring of the milk seems to be prerequisite for preparing the actual milk protein product.

British Patent Specification No. 1.262,510 discloses a process of mixing solutions of casein and corn starch to give a crumbly mass which is then pressed. The starch is not modified since the mixture is not heated.

According to the present invention we provide a process of making an edible caseinlstarch complex, which comprises heating an aqueous mixed dispersion of (a) casein or a caseinate and (b) a starch in a weight ratio of (a):(b) of 1:20 to 4:1 at a temperature and water content high enough to cause the starch granules to gel and breakdown so that the casein or caseinate complexes with the liberated starch and breakdown products of starch, and then cooling the mixture.

The modified starch is useful in substantially the same way as unmodified starch, but does not have the stickiness and gumminess of starch. In addition, it is useful for emulsion stabilization. The modified starch can further be prepared to form dispersions of various viscosities.

The protein employed to modifv the starch is a caseinate, such as ammonium caseinate, calcium caseinate or sodium caseinate, or casein which may be in the form of paracasein, acid-precipitated casein or self-soured casein. The casein or caseinate need not be in pure form or separate from other ingredients, but should preferably be free of ingredients such as lactose which impede complex formation. Thus the casein is preferably free of milk or milk powder.

The properties of the complex formed are substantially independent of the nature of the employed form of casein or starch.

Although starches vary in molecular structure and in properties, depending upon their botanical origin, they all have fundamental common properties which are similarly modified by the present invention which is thus substantially independent of the source of starch employed. The starch may thus be that of arrowroot, barley, bean, buckwheat, cassava (tapioca), corn, oat, pea, potato, rice, rye. sago, sorghum, waxy maize and/or wheat. Naturally-occurring starch is separated from different parts of plants. Starch from corn, wheat, waxy maize. sorghum and rice is obtained from the seed; that from cassava. potato and arrowroot is obtained from the root; and that from sago is obtained the stem. The manner in which the starch is thus obtained is conventional and well known; it does not constitute a part of this invention. Although the amylose/amylopectin ratio may vary from starch to starch, this is not a critical factor with regard to this invention.

Since the degree of swelling varies substantially from starch to starch, the maximum starch concentration in any admixture may well depend upon the source or origin of the starch. Of the three most common types of starch, the order of preference (because of their starch concentrations) is wheat starch. corn starch, potato starch.

Further details of the process conditions are as follows: The ratio of casein or caseinate to starch must be 1:20 to 4:1. and preferably is 1:16 to 4:3, and is 1:4 to 4:3 when it is desired that the viscosity of an aqueous dispersion of the product be low.

The pH can vary widely. e.g. from 2 to 12 but preferably from 2 to 4 or 5 to 10, and most preferably 5.5 to 8.0. Casein has low solubilitv at its isoelectric point of around pH 4.5 so such pH is preferably avoided. No increase in pH during reaction is needed.

The water content must be high enough for the gelation of the starch granules and the diffusion of the starch molecules and starch breakdown products out of the granules, and is usually 8 to 30C/c by weight.

For the complex-forming process of the invention, conventional equipment such as that used for producing cold-swelling starch can be employed.

The casein or caseinate can be first dispersed in water, and then starch added to the dispersion which is then heated. Mixing of the casein and starch and the heating can take place in the same vessel (e.g. in a heat exchanger marketed under the Trade Mark Contherm' by Alfa-Laval AB, Sweden); in this case the temperature should not exceed the boiling temperature of the aqueous medium. Alternatively, after mixing, heating and drying can take place simultaneously, e.g. in a roll dryer; the upper temperature limit can then exceed that of the boiling temperature. The lower limit in both cases is the gelation temperature, if native (undamaged) starch granules are used, as in the Examples below. At the gelation temperature, usually 65 to 80"C, the heat causes swelling and breakdown of the crystalline regions, and therefore loss of the birefiringence of the starch granules. If the starch granules have been damaged, e.g. by mechanical treatment, and some of the crystalline regions already have been broken, a lower temperature may be sufficient. Thus, the amount of energy required for breakdown depends on the pre-history of the starch granules and the reaction conditions.

In the accompanying drawings: Figures 1 and 2 graphically depict the effect of temperature on the viscosity of a mixed dispersion of caseinate and corn starch in Examples 1 and 2; Figures 3 to 6 graphically depict the relation between shearing force and shearing speed in the mixtures of Examples 3 to 6: Figure 7 graphically depicts the effect of temperature on the viscosity of various mixtures of milk powder and potato starch; Figure 8 is a micrograph showing swelled corn starch granules at 95"C dispersed in a 0.2 M NaCI solution.

Figure 9 is a micrograph showing starch/ protein complexes obtained according to the invention and emptied granules, after corn starch and caseinate were heated to 950C in 0.2 M NaCI; Figure 10 graphically depicts the effect of different ratios of corn starch to caseinate ratios on the viscosity in Example 12: and Figure 11 graphically depicts the effect of various salts on the viscosity of a corn starch and caseinate dispersion in Example 13.

The modification of the starch obtained by the invention depends on a specific action on starch granules and has no relationship or relevance to other swelling or foaming agents. When native starch granules are heated they lose their birefringent properties and start to swell. Water penetrates into the granules and solubilized amylose and amylopectin diffuse out into the solution. There will be an equilibrium between solubilized amylose and amylopectin inside and outside the granules. The swelled starch granules can be seen in Figure 8 showing swelled corn starch granules at 95"C. If casein or caseinate is added the protein forms complexes with the starch components. The complexes make up particles of various sizes which are seen in the micrograph of Figure 9. If an insoluble but colloidal stable particle of starch-caseinate complex is formed, the equilibrium between soluble starch components inside and outside the granule will be affected. This means that more soluble starch components will leave the granule. and if the reaction is permitted to exceed far enough, the granules will be completely emptied. Such a case is illustrated in the micrograph of Figure 9, where some granules appear as emptied ghosts. The complex is thus best identified by microscopy. For large complexes light microscopic methods are sufficient. For small complexes electron microscopy may be necessary. Figures 8 and 9 are examples of light micrographs. The degree of complex formation can be controlled and thereby the physical properties of the starch granules. Properties like viscosity, stickiness and gumminess can be changed. By controlling the complex formation properties induced by the formed complexes can be "tailored" and controlled. The complex formation induces properties such as emulsion stabilization of animal fat, important to meat products. By controlling the interactions between starch granules, solubilized starch and complexes (particles) various types of textures can be created. The forces involved are electrostatic forces, hydrophobic bonds. hydrogen bonds and van der Waal's attraction forces. The complex formation starts immediately as swelling and solubilization of the starch granules takes place. The number and size of complexes increase with time.

The reaction time and temperature will determine the properties of the formed complexes as well as the properties of the modified starch granules. The reaction time can be 1 to 45 minutes or longer; times longer than 1 hour can be used at lower temperatures. With increasing time and temperature the identity of the original starch granules will be gradually lost.

In order to keep the cost of processing low. the water content of the mixture should be kept as low as the processing equipment permits. but the water content must be high enough for swelling and diffusion out of the granules of the starch macromolecules, and is usually 8 to 30 weight C/c. The less the water content. the higher the viscosity and the more difficult the handling of the mixture. Theoretically there is no upper limit.

The water content will influence the reaction time necessary to obtain certain properties of the complexes.

After the heating, the complex may be dried to form a powder and/or may be treated to give it a texture, e.g. by extrusion or spinning.

The ratio of casein/casinate to starch has a considerable effect on the properties of the product. There are different optimum ratios for the several properties.

If it is desired to avoid gelation and thickening, the greatest possible portion of the starch should be formed in to complexes. In that case, the casein/casinate concentration should be relatively high.

Good effects as far as a decrease of the viscosity and gelatin is concerned have been obtained at a weight ratio of casein/caseinate to starch ranging from 1:4 to 4:3. It is preferred to use a ratio of at least 1:1.

The stickiness is largest for untreated starch, and decreases with increasing degree of complex formation. The stickiness decreases with increasing addition of caseini caseinate and increasing addition of salt.

Optimum conditions are entirely dependent on the product wherein the starch is to be used. Because of the good control possibilities, starch products having different degrees of stickiness can be "tailored" for different fields of demand.

The incorporation of a salt in the reaction medium is desirable; it reduces or prevents gelation of the modified starch and has a positive effect on complex formation and thus on properties of the resulting modified starch. Optimum conditions for complex formation therefore include salt in the reaction medium. The effect of salt is not limited to any one or group of salts but is obtained with different salts. The largest effect is obtained when the reactants (casein or caseinate and starch) are in contact with polyvalent ions during reaction. Under such conditions, considerably lower concentrations, e.g. up to 0.3 M, of salt (polyvalention-containing salt) are required than for monovalent ions containing salts (e.g., NaCI) for which the concentration may be up to 0.6 M. The greater the salt effect. the lower the thixotropy and the elasticity component of the final product. Complexes are also formed in the absence of salt, but the reaction equilibrium is not so heavily displaced towards complex formation, which is advantageous in some applications. The complex formation is not dependent on pH within ranges of interest in foodstuff technology.

The discussion has so far referred to applications wherein it is of interest to reduce the viscosity of a dispersion of the modified starch. For use in meat products such reduction is not a requirement. For this purpose the complex formation should proceed far enough for new functional properties to occur and far enough to reduce the gumminess of the final product but the viscosity should not be decreased too much.

The new functional property this is created is "emulsion stability" of the fat used. Such a product can e.g. be created if the casin :starch weight ratio is 1:8 to 1:4 and if the complex is formed in the presence of 0.2 M NaCI or in the absence of any salt.

Characteristics of the protein/starch complex are dependent upon the degree of complex formation and thus the ratio of protein to starch, reaction time. reaction temperature and ions in the reaction mixture. Naturally, the modified starch retains the basic properties of the starch which is modified. but the nature of the modification is substantially the same for each starch used.

The modification makes it possible to use starch in ways and for purposes not previously possible, particularly where swelling, gelation and thixotropy were limiting or preclusionary factors. As compared with properties of the employed starch, the complex is devoid of thickening and gelation properties or has these properties only to a significantly reduced extent. The ability of the starch to thicken and/or gel is altered by rupturing starch grains and forming aggregates under the noted reaction conditions.

When the complex (rather than unmodified starch) is admixed with other material. the composite total solids may be increased by more than 100 percent, even though the viscosity of the admixture is concurrently drastically decreased and no gelation occurs. Such a result is extremelv important for products which must be sterilized and for semi-fluid products, such as baby food, wherein bulk is a problem.

The consistency of the protein/starch complex differs from that of the starch from which it was prepared; it is less sticky and less gummy. The extent to which these particular properties are changed is controlled by varving the previously-noted critical factors. Generally. increasing the proportion of protein. introducing ions into the reaction mixture or increasing the amount of such ions. and increasing the reaction time or temperature reduce the stickiness and gummy nature of compositions otherwise containing modified starch. With these properties thus altered, the protein/starch complex is more-easily used in different semi-solid products, such as meat and fish products. By controlling stickiness, the modified starch is more useful. e.g. for pasting particles together. in those instances where unmodified starch normally provides a consistency which is too gummy.

The flow properties of the protein/starch complex are signficantlv different from those of. e.g.. cold-swelling starch. The degree of thixotropy and elasticity is materially reduced or entirely eliminated bv altering reaction conditions in the same manner as suggested in the preceding paragraph.

The present modification of starch does not only reduce or eliminate undesirable properties; it also introduces desirable properties in the obtained product. The complex is thus useful for emulsion stabilization. a utility not possessed by cold-swelling starch.

As the modified starch does not have any residual flavor of its own, it does not alter the taste of food products with or in which it is used.

The uses of the starch modified by complex formation with casein or caseinate according to the invention can be summarized as follows: Sausages such as Frankfurters: The modified starch gives good water and fat holding properties. There are good possibilities to tailor" the consistency of the final products.

Minced meat products: The modified starch can be used in order to paste particles together which facilitates the formation of minced meat products. The consistency is improved compared to unmodified starch.

Half-solid and liquid products, such as soups, sauces, youghurt, dressings. ketchup, baby food. and porridges: The viscosity can be controlled. The modified starch can be frozen and due to the complex formation the degree of retrogradation is substantially decreased.

Replacers for eggwhite in such products as toppings, meat products and bread: Functional properties can be created compatible with those of eggwhite.

The invention will be explained be reference to the graphs in the drawings and to the following illustrative examples, wherein all temperatures are in degrees Centigrade and all parts and percentages are by weight unless otherwise specified.

Example 1 Disperse 4 parts of caseinate in 100 parts by volume of a 0.1 M phosphate buffer solution having a pH of 7.0 (neutral pH value), and then add 4 parts of corn-starch to the thus-obtained dispersion to form a reaction medium, Heat the reaction medium in a Viscograph (marketed under the registered Trade Mark "Brabender") from ambient temperature to 95" at a rate of 1.5 per minute. Maintain the temperature of the reaction medium constant at 95" for 30 minutes, and then cool the reaction medium to approximately ambient temperature at a rate of 1.5 per minute.

Conduct the preceding steps separately with each of two difference caseinates: Sodium Caseinate Sodinol (Trade Mark) from A/S Lidano, Denmark. and sodium caseinate from DMV. Holland. Dry and grind the resulting starch according to conventional producedures used for starch.

Repeat the entire proceding procedure without any caseinate in the phosphate buffer.

Figure 1 provides a comparison between the viscosity at different temperatures of the aqueous starch composition which was not reacted with caseinate, that which was reacted with Sodinol (A) and that which was reacted with sodium caseinate from DMV (B). Both curve A and curve B illustrate significant reductions in viscosity at the different temperatures noted. Figure 1 further shows that the viscosity decreased substantially at the addition of each type of caseinate. With the caseinate from Lidano, gelation was entirely eliminated, and swelling ceased after a very short initial period.

With the caseinate from DMV the resulting modified starch failed to form any gel and reflected materially-reduced swelling.

Example 2 Effect two separate reactions, each in 100 parts by volume of a 0.1 M phosphate buffer, according to the procedure of Example 1 (except as otherwise indicated). one with one part and the other with 4 parts of caseinate from DMV and both with a reaction-mixture pH of 5.5. (The specified conditions simulate those which prevail in a meat svstem.) Maintain the pH constant at 5.5 and heat only to 70". Maintain the temperature at this level for 30 minutes before cooling.

Repeat the procedure without any caseinate in the reaction mixture.

Figure 2 shows the viscosity/temperature relationship throughout the preceding procedure for preparing the comparative product A with zero percent caseinate, the reaction product B with one percent caseinate and the reaction product C with four percent caseinate. Figure 2 confirms the material decrease in viscosity with increased caseinate concentration. Swelling and viscosity are very much reduced when the reaction mixture contains 4 percent by weight of caseinate, i.e. when the total solids of the employed starch are increased by 100 percent by weight, as shown by curve C.

Example 3 Following the procedure of Example 1, prepare a corresponding product with 5 parts of pure corn-starch in 100 parts by volume of distilled water (no casein or caseinate and no other additive). Dry and grind the resulting product according to conventional procedures employed for starch.

Example 4 Following the general procedure of Example 1, react 5 parts of corn-starch with 4 parts of caseinate (from DMV) dispersed in 100 parts by volume of distilled water (no additive). Dry and grind thus-obtained modified starch-according to conventional procedures used for starch.

Example 5 Following the procedure of Example 1, react 5 parts of corn-starch with 4 parts of caseinate (from DMV) in 100 parts by volume of an aqueous 0.2 M NaCI solution.

Dry and grind the resulting modified starch according to procedures conventional for starch.

Example 6 Following the procedure of Example 1, react 5 parts of corn-starch with 4 parts of caseinate (from DMV) dispersed in 100 parts by volume of universal buffer (containing phosphate and citrate ions, see Example 13) at a pH of 7. Dry and grind the resulting modified starch according to procedures conventional for starch.

Examples 3 to 6 are directed to producing products differing in degree of complexing, stickiness and thixotropy. The degree of thixotropy can be measured, as can the degree of gel structure, but to a lesser extent. Stickiness must be estimated by sensory evaluation and is correlated to the other noted properties. This group of examples reflects the effect on starch of casein or caseinate alone, with a salt, and with polyvalent anions.

Figure 3 to 6 represent the relationship of shearing force (vertical axis) to shearing rate (horizontal axis) for products prepared according to Examples 3 to 6, respectively.

The area between the upper and the lower curves in each of these figures is a measure of thixotropy (gelation). The measurements were made in a Haake Rotovisko. Model RV3 (Gebru"der Haake K.G.) with a MVI measuring system. During the measurement the temperature was kept constant at 370C.

The shearing force is represented by T, and the shearing rate is represented by D. T" is the force necessary to put the system into motion. The greater the thixotropy and T(), the stronger the gel structure in systems of this type.

Figure 3 presents the flow curve for corn-starch treated without any additive. A high T(, prevails, and the thixotropy is great.

Moreover, there is a clear maximum in shearing force, which means that the structure is broken down at shearing.

When 4 percent caseinate is added (Example 4) and the solids content is thus increased by 80 percent, both 1() and thixotropy decrease, as shown by Figure 4. No maximum in shearing force is observed.

When the reaction is effected in the presence of 0.2 M NaCI solution (Example 5), thixotropy and 1(, decrease substantially, as shown in Figure 5. In the presence of polyvalent ions (Example 6), the obtained product reflects no sign of gel structure; neither to nor thixotropy is evident from Figure 6.

Example 7 Disperse 0.5 part of sodium caseinate in 100 parts by volume of 0.2 M calcium sulfite (aq) solution having a pH of 9, and then add 8 parts of wheat starch to the thus-obtained dispersion to form a reaction medium. Heat the reaction medium in a Brabender Viscograph from ambient temperature to 85" at a rate of 1.5 per minute. Maintain the temperature of the reaction medium constant at 85" for 45 minutes, and then cool the reaction medium to approximately ambient temperature at a rate of 1.5 per minute. Stir the reaction medium throughout the preceding procedure to maintain all solids dispersed throughout the aqueous medium.

Dry and grind the resulting modified starch (starch complex) according to conventional procedures used for starch.

Example 8 Disperse 9 parts of calcium caseinate in 10() parts bv volume of 0.1 M calcium tartrate (aq) solution having a pH of 8, and then add 6 parts of tapioca to the thusobtained dispersion to form a reaction medium. Heat the reaction medium in a Brabender Viscograph from ambient temperature to 90 at a rate of 1.5 per minute.

Maintain the temperature of the reaction medium at 90" for 25 minutes, and then cool the reaction medium to approximately ambient temperature at a rate of 1.5 per minute. Stir the reaction medium throughout the preceding procedure to maintain all solids dispersed throughout the aqueous medium.

Dry and grind the resulting modified starch (starch complex) according to conventional procedures used for starch.

Example 9 Disperse 2 parts of acid-precipitated casein in 100 parts by volume of 0.5 M NaCI (aq) solution having a pH of 6. and then add 4 parts of rice starch to the thus-obtained dispersion to form a reaction medium. Heat the reaction medium in a Brabender Viscograph from ambient temperature to 85" at a rate of 1.5 per minute. Maintain the temperature of the reaction medium constant at 85" for 35 minutes, and then cool the reaction medium to approximately ambient temperature at a rate of 1.5 per minute. Stir the reaction medium throughout the preceding procedure to maintain all solids dispersed throughout the aqueous medium.

Dry and grind the resulting modified starch (starch complex) according to conventional procedures used for starch.

Example 10 Disperse 4 parts of self-soured caseinate in 100 parts by volume of 0.1 M calcium citrate (aq) solution having a pH of 5, and then add 3 parts of sago starch to the thus-obtained dispersion to form a reaction medium. Heat the reaction medium in a Brabender Viscograph from ambient temperature to 90" at a rate of 1.5 per minute.

Maintain the temperature of the reaction medium constant at 90" for 20 minutes, and then cool the reaction medium to approximately ambient temperature at a rate of 1.5 per minute. Stir the reaction medium throughout the preceding procedure to maintain all solids dispersed throughout the aqueous medium.

Dry and grind the resulting modified starch (starch complex) according to conventional procedures used for starch.

Example 11 Following the procedure of Example 1, add 4 parts by weight of potato starch separately to each of the following: a) 100 parts by volume of distilled water; b) a dispersion of 6 parts by weight of milk powder in 100 parts by volume of distilled water; c) a dispersion of 8 parts by weight of milk powder in 100 parts by volume of distilled water; d) a dispersion of 10 parts by weight of milk powder in 100 parts bv volume of distilled water; e) a dispersion of 12 parts by weight of milk powder in 100 parts by volume of distilled water.

Heat each reaction medium (a) through (e). maintain its maximum temperature for the prescribed period and then cool it as specified in Example 1.

The change in viscosity of each of (a) through (e) during the noted treatment is reflected in Figure 7.

As demonstrat powder mixtures rapidly reach a thicker consistency than pure starch. When caseinate, rather than milk powder (containing casein), is combined with starch in corresponding systems, the viscosity decreases with increasing caseinate concentration, and gelation is completely avoided when 4 percent by weight of caseinate (corresponding to 13 percent by weight of milk powder) is combined with 4 percent by weight of starch.

Example 12 In order to further illustrate the effect of starch-caseinate ratios on the viscosity, the following procedure is adopted. Make caseinate dispersion in 0.1 M phosphate buffer at pH 7.0 of the following concentrations by weight: 0%, 1 %, 2%, 4%, 6%. AddS % corn-starch to each dispersion. Heat in a Brabender Amylograph with 1.SoC/min. to 95"C. After a holding time of 30 min. at 95"C cool the dispersion at a cooling rate of 1.5 C/min. The effect of caseinate concentration on the viscosity can be seen in Figure 10 wherein the curves designated A, B, C.

D. and E relate to the concentrations 0 %, 1 Chic, 2 %, 4 SS, and 6 Se caseinate, respectively. The viscosity is decreased by increasing caseinate concentration to a concentration of 4 %, where the gelation is completely suppressed.

Example 13 In order to illustrate the effect of various salts on the viscosity of modified starch dispersions the following procedure is adopted: Make a 5 % corn-starch dispersion in 0.1 M phosphate buffer at pH 7. Composition of buffer, see below.

Make 4 % caseinate dispersions at pH 7 in the following solutions: a) No salt, distilled water b) 0.2 M NaCI c) 0.1 M phosphate buffer d) 0.019 M citrate e) 0.019 M phosphate f) universal buffer Add 5 % corn-starch to the caseinate dispersions.

Composition of buffers: Phosphate at pH 7: 610 ml O. 1 M Na2 HPO4 + 390 ml 0.1 M NaH2PO4 Universal buffer: I I solution is made which contains 6.008 g citric acid. 3.893 g KH2PO4, 1.769 g H3BO3 and 5.266 g Barbitol. 0.2 M NaOH is added to the solution until the desired pH is obtained (approx. 1.000 ml NaOH to 2.000 ml solution).

The dispersions are heated at 1.5 Clmin.

to 95"C, held at 95"C for 30 min. and cooled at 1.5 C/min. The result is shown in Figure 11 wherein the curves A to F relate to the dispersions a to f, respectively, defined above and curve G relates to the 5 % pure corn starch dispersion.

It is seen that the effect of complex formation on viscosity is small in the absence of salt. The strongest effects are obtained in the presence of polyvalent ions.

Example 14 For making a stabilized emulsion of animal fat potato starch is added to a 4 % caseinate dispersion at a starch-protein ratio of 4.1. No salt is added. The dispersion is heated to 95"C for 10 min., roller-dried and ground.

Example 15 For the same purpose as in Example 14 potato starch is added to a 4 % caseinate dispersion made in a 0.2 M NaCI solution.

The starch/protein ratio is 4:2. The mixture is heated to 90"C for 10 min., roller-dried and ground.

The products made according to the procedures in Examples 14 and 15 are tested for emulsion stability in the following way: Starch-casein complex, pork fat and water in a ratio of 1:6:6 are mixed in a turbomixer at high speed. The emulsion thus obtained is sealed in a can and cooked for 30 min. After cooling the cans are opened and the fat and water release measured. No fat or water release was obtained when the two caseinstarch complexes were tested. For reference native starch and caseinate were mixed in the above described proportions without complex formation. In this case a substantial fat and water release of the heat-treated emulsions was observed. This procedure gives information on how the fat will be stabilized in a meat emulsion.

WHAT I CLAIM IS: 1. A process of making an edible casein/ starch complex, which comprises heating an aqueous mixed dispersion of (a) casein or a caseinate and (b) a starch in a weight ratio of (a): (b) of 1:20 to 4:1 at a temperature and water content high enough to cause the starch granules to gel and break down so that the casein or caseinate complexes with the liberated starch and breakdown products of starch, and then cooling the mixture.

2. A process according to Claim 1, wherein the ratio of (a):(b) is 1:16 to 4:3.

3. A process according to Claim 2, wherein the ratio is 1:4 to 4:3.

4. A process according to Claim 1, 2 or 3, wherein the water content of the dispersion during the heating is 8 to 30 % by weight.

5. A process according to any preceding claim, wherein the pH is 2 to 4 or 5 to 10 during the heating.

6. A process according to any preceding

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (17)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   powder mixtures rapidly reach a thicker consistency than pure starch. When caseinate, rather than milk powder (containing casein), is combined with starch in corresponding systems, the viscosity decreases with increasing caseinate concentration, and gelation is completely avoided when 4 percent by weight of caseinate (corresponding to 13 percent by weight of milk powder) is combined with 4 percent by weight of starch.

   Example 12 In order to further illustrate the effect of starch-caseinate ratios on the viscosity, the following procedure is adopted. Make caseinate dispersion in 0.1 M phosphate buffer at pH 7.0 of the following concentrations by weight: 0%, 1 %, 2%, 4%, 6%. AddS % corn-starch to each dispersion. Heat in a Brabender Amylograph with 1.SoC/min. to 95"C. After a holding time of 30 min. at 95"C cool the dispersion at a cooling rate of 1.5 C/min. The effect of caseinate concentration on the viscosity can be seen in Figure

   10 wherein the curves designated A, B, C.

   D. and E relate to the concentrations 0 %, 1 Chic, 2 %, 4 SS, and 6 Se caseinate, respectively. The viscosity is decreased by increasing caseinate concentration to a concentration of 4 %, where the gelation is completely suppressed.

   Example 13 In order to illustrate the effect of various salts on the viscosity of modified starch dispersions the following procedure is adopted: Make a 5 % corn-starch dispersion in 0.1 M phosphate buffer at pH 7. Composition of buffer, see below.

   Make 4 % caseinate dispersions at pH 7 in the following solutions: a) No salt, distilled water b) 0.2 M NaCI c) 0.1 M phosphate buffer d) 0.019 M citrate e) 0.019 M phosphate f) universal buffer Add 5 % corn-starch to the caseinate dispersions.

   Composition of buffers: Phosphate at pH 7: 610 ml O. 1 M Na2 HPO4 + 390 ml 0.1 M NaH2PO4 Universal buffer: I I solution is made which contains 6.008 g citric acid. 3.893 g KH2PO4, 1.769 g H3BO3 and 5.266 g Barbitol. 0.2 M NaOH is added to the solution until the desired pH is obtained (approx. 1.000 ml NaOH to 2.000 ml solution).

   The dispersions are heated at 1.5 Clmin.

   to 95"C, held at 95"C for 30 min. and cooled at 1.5 C/min. The result is shown in Figure

   11 wherein the curves A to F relate to the dispersions a to f, respectively, defined above and curve G relates to the 5 % pure corn starch dispersion.

   It is seen that the effect of complex formation on viscosity is small in the absence of salt. The strongest effects are obtained in the presence of polyvalent ions.

   Example 14 For making a stabilized emulsion of animal fat potato starch is added to a 4 % caseinate dispersion at a starch-protein ratio of 4.1. No salt is added. The dispersion is heated to 95"C for 10 min., roller-dried and ground.

   Example 15 For the same purpose as in Example 14 potato starch is added to a 4 % caseinate dispersion made in a 0.2 M NaCI solution.

   The starch/protein ratio is 4:2. The mixture is heated to 90"C for 10 min., roller-dried and ground.

   The products made according to the procedures in Examples 14 and 15 are tested for emulsion stability in the following way: Starch-casein complex, pork fat and water in a ratio of 1:6:6 are mixed in a turbomixer at high speed. The emulsion thus obtained is sealed in a can and cooked for 30 min. After cooling the cans are opened and the fat and water release measured. No fat or water release was obtained when the two caseinstarch complexes were tested. For reference native starch and caseinate were mixed in the above described proportions without complex formation. In this case a substantial fat and water release of the heat-treated emulsions was observed. This procedure gives information on how the fat will be stabilized in a meat emulsion.

   WHAT I CLAIM IS: 1. A process of making an edible casein/ starch complex, which comprises heating an aqueous mixed dispersion of (a) casein or a caseinate and (b) a starch in a weight ratio of (a): (b) of 1:20 to 4:1 at a temperature and water content high enough to cause the starch granules to gel and break down so that the casein or caseinate complexes with the liberated starch and breakdown products of starch, and then cooling the mixture.
2. 2. A process according to Claim 1, wherein the ratio of (a):(b) is 1:16 to 4:3.
3. 3. A process according to Claim 2, wherein the ratio is 1:4 to 4:3.
4. 4. A process according to Claim 1, 2 or 3, wherein the water content of the dispersion during the heating is 8 to 30 % by weight.
5. 5. A process according to any preceding claim, wherein the pH is 2 to 4 or 5 to 10 during the heating.
6. 6. A process according to any preceding

   claim, wherein the dispersion is mixed and heated in the same vessel and the temperature during heating does not exceed the boiling point of the aqueous dispersion.
7. 7. A process according to any preceding claim, wherein the starch granules used have been damaged and the heating is to a temperature below the gelation temperature of the starch.
8. 8. A process according to any preceding claim, which comprises dispersing the casein or caseinate in water, adding starch and heating the mixed dispersion.
9. 9. A process according to any preceding claim, wherein an ionic salt is present in the dispersion during the heating.
10. 10. A process according to Claim 9, wherein the salt has polyvalent ions.
11. 11. A process according to any preceding claim, wherein the complex obtained is dried to a powder.
12. 12. A process according to any of Claims 1 to 10, wherein the complex obtained is treated to give it a texture.
13. 13. A process according to Claim 12, wherein the treatment comprises spinning or extrusion.
14. 14. A process according to any preceding claim, wherein the starch is wheat, corn or potato starch.
15. 15. A process according to Claim 1, of making an edible casein/starch complex, substantially as herein described with reference to any one of Examples 1 to 15.
16. 16. A casein/starch complex, which may contain ions, when produced by a process according to any preceding claim.
17. 17. A complex as claimed in Claim 16.

    substantially as shown in Figure 9 of the accompanying drawings.