NO145937B - PROCEDURE FOR THE MANUFACTURING OF MICRO-COOKED, LIPID-CONTAINING FOOD AND CONDITIONS. - Google Patents

Description

The present invention relates to a method for the production of microencapsulated, lipid-containing food and feed additives for the production of meat products such as sausage and bologna and canned soups, which contain microencapsulated fat, for use as pet and ruminant feed additives characterized by high lipid contents, and which have the ability to

pass through the rumen of ruminants essentially unchanged for subsequent digestion in the rumen and lower intestine.

Many methods for treating proteinaceous materials are set forth in prior publications such as U.S. Pat. patents 3,137,631, 3,821,453 and 3,925,560. While these prior publications relate to methods of denature proteins by treating them with acid, alkali and aldehydes, or by subjecting them to high temperatures and pressures, there is still a need for a efficient method for microencapsulating lipids in dietary proteins for the production of foodstuffs for humans and animals.

The meat production industry has long searched for methods to incorporate fat and water into meat products such as sausage

and bologna. Two problems are usually associated with the manufacture of such products. One problem concerns frictional heating that occurs during mixing of emulsion-type processed meats. If ice is not added during emulsification, the fat dispersed in the meat will melt and separate from it. Another problem concerns the separation of fat and water from such products during cooking. This separation not only leads to product shrinkage, but also reduces the desirable juiciness usually attributed to higher fat and moisture content in the cooked

product.

Other problems facing the meat processing industry relate to the production of canned meat intended for human or pet consumption. The high energy value associated with fats makes their incorporation in such canned meat products highly desirable. Treated by previously known methods, however, grease has shown a tendency to migrate out of the product and collect at the container wall or float on top of the container, spoiling the aesthetic appearance of the product.

Another problem concerns the production of canned soups. Fats contained in soups prepared by known methods tend to separate and float on the surface during cooking.

Due to increased concern regarding heart disease associated with high saturated fat diets, there is also a need for food products with low saturated fat content. A problem has previously existed in the manufacture of such products in a form which is palatable, yet sufficient for the dietary needs of people who are concerned about heart disease. The present invention will allow the inclusion of polyunsaturated vegetable oils in meat-protein in a stable form that will not separate during cooking. This method will greatly increase the taste and acceptability of such nutritional products.

In addition, the meat industry has long searched for better methods of utilizing animal bones and other nutritious waste materials. The present invention provides an efficient way to utilize such materials to form nutritious animal feed supplements without the disadvantages associated with the previously used heat-releasing and extraction processes.

Because meat, meat by-products and milk all contain large amounts of fat, the purpose of modern livestock feeding methods is to increase the amount of lipids ingested by the animals. Currently, most of the lipid materials used in nutritional supplements are incorporated in liquid form. Hot, liquid lipids are showered onto the other nutrients and allowed to combine with them before feeding. A disadvantage of this method is that such precursors cannot be stored for any particular time due to their tendency to go rancid, to become contaminated and to attract insects. Furthermore, ruminants create a particular problem with regard to lipid supplement feed. High-fat diets fed to ruminants in the form of free fat have been shown to cause severe indigestion, resulting in loss of appetite and reduced weight gain. Protein-encapsulated lipids according to the invention will effectively resist digestion in the rumen and therefore do not cause digestive difficulties.

According to the present invention, a new method is provided for the production of foodstuffs and supplements containing microencapsulated lipids, which method is evident from the characteristics of claim 1.

Meat products produced by the present method are characterized by increased juiciness and reduced shrinkage due to the presence of microencapsulated lipids. The new method according to the invention also enables the production of foodstuffs and raw materials with a low content of saturated fat and cholesterol, which are more palatable than those previously known. The invention also enables better utilization of waste materials from packaging plants for animal products by a method that is more environmentally acceptable than the currently used heat treatment methods. The invention also provides improved lipid-containing feed supplements suitable for pets and ruminants.

The present invention relates to a method for the production of microencapsulated lipid-containing foodstuffs and food supplements, and the method is characterized by the features indicated in the characteristic in claim 1. Protein-containing materials suitable for use in the present invention can be obtained from either animal or vegetable sources. Examples of suitable proteinaceous materials include beef, pork, poultry, fish, whey, cheese, soybeans and the like.

Proteinaceous materials suitable for use according to the invention will contain at least 5% by weight of protein. When the amount of protein in the emulsion formed is less than 5% by weight, the microencapsulation remains stable in a wet system, but releases fat upon drying.

The dissolution of the proteinaceous material will generally require the presence of an aqueous medium that amounts to from 50%

to 70% of the formed solution. The aqueous medium may include water contained in meat, blood or other proteinaceous material, as well as water contained in the solubilizing agent or added by itself.

When the protein has been dissolved, the resulting solution is mixed with a lipid material so that an emulsion is formed. Lipids suitable for use in the present invention include both animal fats and vegetable oils. According to one embodiment of the invention, the lipid material is combined with the proteinaceous material before the addition of the solubilizing agent. In order to facilitate dispersion, it is desirable that lipids which are in solid form at the ambient temperatures are raised to their melting points before or during the emulsification process. Hydrogenated lipids suitable for use in the present invention should melt at temperatures in the range from 40°C to 55°C,

or in some cases up to 6o°C. Overheating should be avoided as it makes the protein insoluble in the aqueous medium. The mixing device used to emulsify the lipid material in the proteinaceous solution should be capable of reducing the size of the lipid droplets to a range of from 0.5 to 50 µm, and preferably from 0.5 to 10 µm. After emulsification, the lipid droplets should be homogeneously dispersed in the continuous phase of dissolved proteinaceous material.

The emulsion is then contacted with a sufficient amount of a pH adjusting agent to lower the pH of the emulsion to its isoelectric point. The isoelectric point is generally defined as the pH at which the net charge on a molecule in solution is zero. The isoelectric point of the proteinaceous materials suitable for use according to the present invention varies from a pH of 3 to 8.5, depending on the particular protein used. It may be desirable to set the pH of the emulsion below the isoelectric point when mixtures of proteins are used, or when the intended product is a dry particulate material. in the latter case, the lower pH causes syneresis, which causes water to separate from the emulsion. The pH-adjusting agents suitable for use in the present invention include phosphoric acid, hydrochloric acid, lactic acid, acetic acid, sulfuric acid and salts of polyvalent metals. Some further mixing may be necessary after the addition of the pH adjusting agent to ensure that the emulsion comes into uniform contact with it.

According to a preferred embodiment of the invention, animal fat is microencapsulated in the proteinaceous material contained in processed meat products such as sausage, bologna, meatballs and the like. The improved food products according to the invention are produced by first mixing together the desired components of the particular meat product to be produced. Desired ingredients may include both animal and vegetable proteinaceous materials, animal fats, vegetable oils, spices, flavorings, preservatives and the like. These ingredients are preferably ground to a particle size of less than 3.2 mm to prepare them for dissolution and emulsification.

A protein solubilizing agent, sodium hydroxide, is then mixed with the ground ingredients in the presence of an aqueous medium. Sufficient solubilizing agent is added to the mixture to raise its pH to a level of from 9 to 13, and preferably from 10 to 12.

After the protein has been dissolved, the ingredients are emulsified by any suitable mixing device including commercially available mixers and high speed homogenizers. During the emulsification, the friction<y>arm produced by the mixing device should be allowed to bring the temperature of the emulsion to rise above the melting point of

the lipids contained in the mixture. A temperature from 40°C

to 60°C is usually sufficient for this purpose. The lipid material in the emulsion should be dispersed in discrete droplets in the range of 0.5 to 50 µm in size, and preferably in the range of 0.5 to 10 µm. The emulsion should contain from 50% to 60%

water, although it is possible to carry out the procedure with smaller quantities. The product can also be diluted by adding more water to the point at which a liquid dispersion is formed.

The emulsion is then treated with a pH adjusting agent to lower its pH to the isoelectric point. At the isoelectric point, the proteinaceous material in the emulsion will aggregate, thereby encapsulating the lipid. A preferred pH-adjusting agent for use in this embodiment is hydrochloric acid, which when it reacts with the sodium hydroxide contained in the emulsion, will form common salt (sodium chloride). The isoelectric point at which the emulsion will aggregate is usually at a pH in the range of 6.5 to 8.5. Although the ratio of protein to fat is almost optional as the method will be applicable over a wide range of mixtures, at least 5% of the mixture should be protein to ensure microencapsulation of all the lipid.

According to another embodiment of the invention, a method is provided for producing animal meal from waste materials from slaughterhouses, poultry and fish processing plants. Such animal waste can include meat waste, fat, bones, blood, entrails and the like. The improved animal meal according to the invention is suitable for feeding animals such as ruminants in a commercial feeding operation, as well as pets such as dogs and cats. The improved animal meal can be used in aggregated form, or dried into a granular to powder-like particulate solid. Fat microencapsulated in the flour will not be prone to excretion as with other commercially available products.

According to this embodiment, the animal waste is first ground into a slurry. Other proteinaceous material such as vegetable protein can be added to supplement the animal waste. Although any ratio of animal fat to protein can be

is turned, at least 5% by weight of the mixed slurry should be protein

to ensure microencapsulation of all the fat.

When protein-rich material intended for use in the present invention contains animal bones, the bones must be mechanically reduced in size so that they do not adversely affect the animal that will consume the product. Preferably, the bone should be reduced in size to a width of no more than 38 mm, and the broken bone should not contain sharp splinters, which, when ingested by an animal, could penetrate some part of the digestive tract and lead to peritonitis.

A typical method of processing animal bones to achieve the desired result involves passing the bones, together with the associated protein and fat resulting from deboning operations in packing plants, through a machine that reduces the bones to a broken particulate material with particle dimensions of about 38 mm in length. The crushed bone is then passed, sometimes with the addition of water to aid mobility and reduce frictional heat build-up, through a conventional grinding or cutting machine fitted with an aperture cutting plate which further reduces the bones to a size with a particle size of no more than 12mm in length. . The size of the cutting blade is preferably in the range of 12 mm to 19 mm at this stage. A suitable machine for this purpose is a "Wyler grinder", a machine commonly used in the meat processing industry which consists of a feed screw driven by an electric motor which forces a particulate material through an aperture cutting plate. The crushed material can then be treated with further cold water to again increase mobility and reduce frictional heat. The material is then taken to a disintegrator where it is homogenised, and there an emulsion of the meat protein and fat is thus formed while the bone particles are reduced to a particle size of less than 3.2 mm.

Before, during or after grinding, the animal waste is added

an effective amount of a protein solubilizing agent to the mixture to raise its pH to a range of 9 to 13. Sufficient solubilizing agent should be added to dissolve all the protein contained in the slurry. The preferred solubilizing agent in this embodiment is sodium hydroxide, but other alkali or alkaline earth metal hydroxides can be used. Dissolution should take place in an aqueous medium, and the moisture content of the emulsion formed should preferably be from 50%

to 60%. If the solubilizer is added to the ground animal waste before or during the grinding step, it will be sufficiently mixed during grinding. However, if added after the grinding step, additional mixing is required to effect dispersion of the solubilizing agent in the slurry. After the solubilizing agent is added, the slurry should be maintained for a sufficient time to solubilize the protein content therein. When working with fresh animal waste from packing plants, a period of 1 to 3 minutes is required

to effect dissolution. If, however, biodegradation of the animal waste occurs before treatment, large amounts of solubilizing agent and long treatment times may be required. The solubilized slurry is then ready for emulsification.

The formation of a satisfactory emulsion depends on the degree of mechanical movement applied to the slurry, the temperature of the slurry and the degree to which the protein has been dissolved. In a prepackaged embodiment, the temperature of the slurry containing the protein and fat should be set at least that of the melting point of the fat to facilitate dispersion in the emulsion. A temperature range of 45°C to 60°C is suitable for most animal fats. These temperatures can be achieved by frictional heating effected during mechanical stirring, or by external heat sources. The size of the individual lipid droplets formed during the emulsification will vary from 0.5 to 5 µm, and preferably from 0.5 to 10 µm.

After emulsifying the slurry containing the dissolved protein and fat, the emulsion is contacted with a pH adjusting agent to lower the pH to at least its isoelectric point. At the isoelectric point, the proteinaceous material contained in the emulsion will aggregate and at the same time microencapsulate the lipid. The amount of pH adjusting agent required to effect aggregation will vary depending on the quality of the animal waste. The isoelectric point for emulsions of the type described here varies from 3 to 8.5. If, however, the animal waste is biodegradable, and depending on the desired degradation, the isoelectric point may fall outside this range.

Although it is believed that any acidic material could be used as a pH adjusting agent, some acids

as nitric acid, which should not be used in the production of animal

flour. Acceptable acids for use in the present embodiment include phosphoric acid, hydrochloric acid, sulfuric acid and acetic acid.

In the above embodiment, the pH-adjusting agent is a

75 - 85% concentrated phosphoric acid.

After aggregation of the proteinaceous material in the emulsion, the fat globules contained therein are essentially encapsulated by the proteinaceous material. The product obtained can be used in wet aggregate form or dried into a granular to powder-like, free-flowing, particulate material. To produce a dried particulate product, water should be separated from the aggregate. This can be achieved by lowering the pH level below

6.5 by adding more pH-adjusting agent, thereby causing syneresis. During syneresis, a considerable part of

the water is separated from the unit. The aggregate can then be pressed or centrifuged to remove the free water. The dry product should not contain more than 14% by weight of water, and preferably from 10 to 12% by weight of water. When the product contains more than 15% water by weight, there is a tendency for the product to mold during storage.

A drying device suitable for use in the present embodiment is a commercially available agricultural dehydrator.

After drying, the desired particle size can be achieved by using a hammer mill or similar particle reducing device.

According to another embodiment of the invention, improved lipid-containing pre-supplements suitable for pets and ruminants are also produced. The lipid-containing protein-containing emulsions according to this embodiment should contain from 5 to

40 wt% protein, from 50 to 70 wt% water, and from

6 to 25 wt% lipid.

The proteinaceous solution can be prepared in a stainless vertical vessel fitted with a powerful stirrer. Water is placed in the tub, and a proteinaceous material is mixed with it until it is thoroughly wetted. Proteinaceous materials suitable for use in this embodiment include blood, casein, oilseed protein, soybeans, soybean meal, and other animal or vegetable proteinaceous materials. A preferred proteinaceous mixture for use in this embodiment consists of 100 parts soy flour to 35 parts sunflower flour.

When the proteinaceous material is thoroughly wetted, an amount of solubilizing agent sufficient to ensure complete dissolution of the protein is added to the mixing vessel. Although suitable solvents include the non-toxic alkali

and alkaline earth metal hydroxides, sodium hydroxide is the preferred agent for use in this embodiment.

After solubilization, a lipid material is added to the protein-containing solution and stirred carefully. The lipid-containing material should constitute from 6% to 25% by weight of the emulsion,

and may include vegetable oils, fish oils and animal fats. If hydrogenated animal fat is used, it is melted by heating to a temperature in the range from 40°C to 60°C before mixing. The mixture of the proteinaceous solution and lipids should be stirred until an oil-in-water emulsion is formed. The droplets of lipid materials should be dispersed in the proteinaceous continuous phase and have sizes varying from 0.5 to 50 µm,

and preferably from 0.5 to 10 µm.

After the emulsion is formed, a gel is formed by lowering the pH of the emulsion to 6.0 or lower. The degree of gelatinization that occurs can be regulated by varying the pH level to which the emulsion is lowered. If the pH is above 6, a poor gel that cannot be dried effectively with conventional agricultural drying equipment can be formed, especially if a relatively large amount of the protein is a vegetable protein. However, when the pH of the emulsion is lowered to a value from 3.5 to 5.0, a solid gel suitable for use with conventional drying equipment is formed.

Examples of some acceptable pH adjusting agents include phosphoric acid, hydrochloric acid, sulfuric acid and acetic acid. The preferred pH adjusting agent for use in this embodiment is a 75-85% solution of phosphoric acid. The amount of pH adjusting agent required to form the desired gel will vary according to the type of lipid material used. In general, the higher the free fatty acid content of the lipid used, the more pH adjusting agent must be used to achieve the desired pH value.

Before drying, removal of free water by centrifugation, pressing and the like is desirable. Conventional types of agricultural dryers include rotary drum dryers, tumble dryers and flash or floating bed dryers. The gel described above can be dried using any of these drying methods. The moisture content of the gel is reduced by drying to no more than 14%, and preferably from 10% to 12% by weight of the gel. The particle size of the presupplement will depend on the amount of movement that occurs during drying.

The powdered supplement will generally contain from 20% to 60% by weight of lipids. Absorbent materials such as silicate, bentonite, alfalfa meal, oats, bran and bagasse can be added, if desired. When such absorbent materials are present, the protein content of the pre-supplement should be from 5%

to 35% by weight thereof. Also, various drugs, such as common types of antibiotics and lipid-soluble vitamins, can be added to the lipid before the emulsion is formed.

The high-lipid feed supplement produced by the above method can be used for different types of animals including dogs, cats and even fish feed. The fat content of conventional dry food for dogs and cats has previously been limited by the processing options with commercially available extruders. Due to the high energy content of fats and oils, it is often desirable to include in such animal forms more lipids than can be processed through an extruder. Spraying molten lipids over the spent liners has also proven ineffective as the lipids migrate to the container walls and become rancid when exposed to oxygen. The microencapsulated fats and oils of the present invention incorporate fats and oils into the front pieces in higher amounts than previously possible.

Another important application of the present method concerns ruminant feed supplements. Generally, ruminants cannot be fed a diet containing more than 2% to 6% fat.

Too much fat apparently inhibits rumen function and has a serious adverse effect on the complex ruminant digestive system. The food supplements produced according to the present invention have been used to increase the fat content of ruminants - fodder up to 12% without any harmful effects that have previously accompanied such a high-fat diet. It is believed that the astonishing results are achieved because the lipid content of the forage supplement is enclosed or encapsulated in the proteinaceous material, and therefore does not inhibit the action of the microflora contained in the rumen. First, most of the lipid in the pre-supplement is released after it has passed through the rumen into the rumen or the lower intestine. The present invention provides a high lipid pre-supplement with improved handling properties and with the unexpected ability to allow the fat content of a ruminant's diet to be increased to approx. 15%, depending on the balance of the ruminant's ration.

The present invention can be more easily understood by reference to the following examples which describe in more detail the embodiments discussed herein.

Example 1

1000 g of a mixture of lean meat and trimmed fat containing approx. 20% protein, was ground through a 3.2 mm hole plate, and then contacted with 215 g of a 7% solution of sodium hydroxide. The mixture was heated to a temperature of 41°C in a pan with a water jacket while stirring. The heated mixture was then homogenized in a "Waring blender" for approx. 30 seconds to form an emulsion. The emulsion thus formed had a pH of 11.8 - 25 g of an 85% solution of phosphoric acid was then mixed into the emulsion. A solid granular textured gel was obtained which had a pH of 6.5. A sample of the gelled material was boiled in water for 2 minutes. No evidence of free fat was observed, indicating that the fat was effectively encapsulated and remained stable in a wet, warm environment.

Example 2

100 g of trimmed fat with a fat content of 55.5% as determined by "Hobart" analysis was contacted with 310 g of a 3.2% solution of sodium hydroxide. The mixture was heated to 54°C

in a pan with a water jacket, and then mixed in a "Waring blender" to form an emulsion with a pH of 10.9. The emulsion thus formed was brought into contact with 12 g of an 85% solution of phosphoric acid. The resulting solid textured gel had a pH of 7.5. The gel was ground through a plate with 3.2 mm openings to a granular form suitable for mixing into meatballs and sausages.

Example 3

A sample of the microencapsulated fat prepared as described in Example 2 was subjected to a fat analysis with the same "Hobart" fat determination equipment and gave a reading of 15.5% fat. The sample was calculated to have a fat content of approx. 42%, which shows that approx. 63% of the fat remains encapsulated when subjected to the dry heat action of the "Hobart" equipment.

Example 4

Microencapsulated fat prepared as described in example 2 was formed into meatballs with a fat content of approx. 30% before roasting. These cakes were compared with meat cakes prepared without microencapsulated fat and likewise with a fat content of 30% before frying.

Recipes:

(a) Containing 25% microencapsulated fat:

Three 100 g meatballs were prepared from recipes (a) and (b). These were fried at the same time in an oven for 15 minutes (7.5 minutes on each side). The meat cakes were then weighed again after frying. The meat cakes made according to recipe (a) weighed an average of 69.8 g. Those made according to recipe (b) weighed an average of 65.0 g. The shrinkage percentage was therefore 30.2% for recipe (a) and 35% for recipe (b). This represents a 4.8% reduction in shrinkage when using microencapsulated fat in the patties.

Example 5

lOOO g fat containing approx. The 5% collagen was ground through

a 3.2 mm perforated plate, and then contacted with 512 g of a 2.3% solution of sodium hydroxide. The resulting mixture, with a pH of approx. 11.7, was heated to approx. 60°C in a pan with a water jacket. The heated mixture was then transferred to a Waring blender and blended for 1 minute to form an emulsion. The emulsion was allowed to stand for half a minute, and was then brought

in contact with 20 g of an 85% solution of phosphoric acid. The pH of the emulsion formed was approx. 7,5- A good gel was obtained when the phos-for acid solution was mixed in the emulsion. In this case, the fat was microencapsulated in the collagen proteins associated with the fat.

Example 6

A meatloaf was prepared containing 50% encapsulated fat as described in Example 5, 25% lean meat and 25% fat. These were mixed together and formed into a meatloaf weighing 100 g. The meatloaf was cooked for 15 minutes in an oven (7.5 minutes on each side) and again weighed. After frying, the meatloaf weighed 90.2 g. This represents a shrinkage of 9.8% - The fat content of the meatloaf before frying was 51.1%, determined by "Hobart" analysis.

A lOO g cake was prepared from standard meat trimmings containing approx. 50% lean meat and 50% fat. This was baked at the same time as the cake containing 50% microencapsulated fat. After baking, this cake weighed 74.2 g, corresponding to a shrinkage of 25.8%. This experiment shows the effectiveness of the microencapsulation process in retaining more of the power of the meatloaf compared to an untreated product.

Example 7

This experiment was carried out in three parts:

I. 48 g of textured vegetable protein ("Supro 50"

Ralston Purina) was brought into contact with 196 g of a 1% sodium hydroxide solution and mixed in a food mixer fitted with a whisk until a smooth texture was obtained, after approx. 5 minutes mixing time. 160 g of safflower oil was then added and the mixture stirred at high speed until an emulsion was formed. The pH of the emulsion thus formed was 11.7. The emulsion was then contacted with 8 g of an 85% solution of phosphoric acid to lower the pH of the emulsion to its isoelectric point, approx. 7,5- The product formed was a solid granular gel. A sample of the gel was boiled in water for 5 minutes and showed a negligible amount of free fat. II. The microencapsulated safflower oil was then mixed together with ground, lean beef in a ratio of 600 g of beef to 400 g of encapsulated oil. III. Using mixtures of ground beef and encapsulated oil as described in Part II, a meat pudding was prepared according to the following recipe:

Approach:

1. The mixture of encapsulated oil and beef, breadcrumbs, carrot, tomato sauce, salt and pepper were mixed together. 2. The eggs and milk were beaten together and then mixed with the mixture from step 1.

3- The resulting mixture was placed in a pudding mold and baked at 163°C for 1.5 hours.

The result was a well-textured product with no sign of free fat. the taste was good without any unpleasant taste of vegetable oil. A laboratory fat analysis showed 15% fat in the finished meat pudding, 13% calculated as vegetable oil and the rest attributed to the other ingredients.

Example 8

100 g of ground cheddar cheese was brought into contact with 50 g of a 4% solution of sodium hydroxide and then mixed in a "Waring blender" until homogeneous. The pH of the homogeneous mixture was 9.3. The mixture was brought into contact with 5 g of an 85% solution of

phosphoric acid, which gave a pH of 4.7. The mixture thickened and formed a crumbly gel. The gel was dried in a fluid bed dryer to form a granular to powdery material with no evidence of free fat. A sample of the dried material was roasted in an oven and produced a tasty powder with a grated cheese flavour.

Example 9

Cow offal containing approx. 50% fat and 50% lean meat,

was treated by the method in example 2. The material thus formed was then mixed with additional cow offal in the ratio of 20% treated material to 80% untreated material. The mixed material was subjected to a standard bacteriological plate count and compared to a similar sample of 100% untreated cow offal. The results were as follows: Total plate count before treatment: 12,000 organisms/g Total plate count after treatment: <10 organisms/g Total plate count of mixed material: 710 organisms/g The sterilizing effect of the microencapsulation process is hereby clearly demonstrated.

Example 10

200 g finely ground beef bone containing approx. 55% water by weight and approx.

23% by weight protein was heated to a temperature of approx. 55°C.

After transferring the slurry to a Waring blender, 2 g of sodium hydroxide was added and the slurry was mixed for 1 minute. The alkali-treated slurry was allowed to stand for an additional 2 minutes and then mixed again for 15 seconds. With the mixer still running, 4 g of an 85% solution of phosphoric acid was mixed in to form an emulsion. The proteinaceous material in the emulsion aggregated within seconds to the point where the stirrer no longer mixed effectively and the mixer was stopped. Mixing was continued by hand stirring until a uniformly aggregated texture was obtained. The pH of the slurry was 12.4 after the addition of sodium hydroxide,

and 7.5 after the addition of phosphoric acid.

A sample of the aggregated mixture was placed in a beaker containing cold water, and a similar glass beaker was prepared with a sample of untreated ground bone material. After the samples were stirred to disperse the mixtures in the water, both samples were heated simultaneously with occasional stirring until both mixtures boiled. After a few minutes of boiling, both samples were removed from the heat and set aside until they were cold. After cooling, free fat could be observed on the surface of the water containing the untreated bone mixture, while on the surface of the water

containing the treated sample no fat was observed. This experiment demonstrates the effectiveness of the fat microencapsulation method.

The aggregated material was then dried in a laboratory fluidized bed dryer, yielding a granular to powdery free flowing granular material of brown color and containing ground bone particles. No signs of free fat were observed.

Example 11

A supply of poultry processing waste containing the necks and backs obtained as a by-product of the decomposition treatment in poultry package eggs was ground in a standard meat grinder fitted with a 3.2 mm cutter. The material formed was slurry-like with obvious signs of free fat and water. 200 g of this slurry, which had previously been stirred to give a smooth mixture, was heated in a water-jacketed boiler to a temperature of approx. 55°C. The heated slurry was then transferred to a Waring blender and 2 g of sodium hydroxide was added to dissolve the proteinaceous material. The slurry was stirred for 1 minute and allowed to stand for an additional 2 minutes. After standing, the slurry was again stirred for 15 seconds, and while the stirrer was still running, 4 g of 85% phosphoric acid was added to the emulsion. After a few seconds, the emulsion aggregated to the point where the paddle no longer mixed effectively and the machine was stopped. Mixing was continued by hand stirring until the phosphoric acid had been thoroughly mixed in and a uniform aggregate had formed. A sample of the treated aggregate material was placed in a beaker of cold water, and a similar sample of untreated material was likewise prepared in another beaker. The two samples were stirred to thoroughly disperse them in the cold water and then heated simultaneously until the water in both samples boiled. The boiling was allowed to continue for a period of from 2 to 3 minutes, after which the samples were removed from the heat and allowed to cool. After cooling, the untreated sample had obvious signs of free fat on the surface of the water, while the treated sample gave no obvious signs of free fat, thus demonstrating effective microencapsulation of the fat.

Example 12

200 g of chicken waste prepared as described in example 11,

was heated to a temperature of approx. 54>5°C. About. 0.25 g of papain, a proteolytic enzyme, was added to the heated mixture which was stirred to disperse the papain. The mixture was transferred to a "Waring blender" where the bowl was preheated to prevent cooling of the heated chicken waste. When stirring the mixture, a rapid change in viscosity was obtained after the protein was absorbed. This procedure led to a mobile liquid with the appearance of an emulsion. The sample digest was divided into two equal parts, with one part (approx. 100 g of the digested material) being treated with 1 g of sodium hydroxide and stirred in a "Waring blender" at a temperature of approx. 52°C for 30 seconds. The slurry was allowed to stand for 2 minutes and was then stirred again for approx. 15 seconds during which time 2 g of 85% phosphoric acid was added, which led to a slight thickening of the thus formed aggregate. This sample and the untreated sample were placed in separate beakers with cold water and heated simultaneously until boiling. The samples were then allowed to stand until they had cooled, after which signs of free fat were visible on the surface of the untreated sample. The treated sample showed no visible signs of free fat, indicating that the fat present in it had been effectively microencapsulated.

Example 13

200 g of chicken waste prepared as described in example 11 was heated to approx. 6o°C, 2 g of sodium hydroxide was added and stirred into the chicken slurry which was then transferred to a "Waring blender" where the slurry was mixed for approx. 1 minute and then allowed to stand for approx. 2 minutes. The slurry was again stirred for 15 seconds, and while the mixer was still running, 4 g of 85% phosphoric acid was added. The slurry quickly thickened and effective stirring with the stirrer ceased. The machine was stopped, and a smooth aggregate was produced by hand stirring. The pH of the slurry was 12.1 after the addition of the sodium hydroxide and 7.3 after the addition of the phosphoric acid.

The resulting aggregate was transferred to a preheated beaker and stirred by hand for a few seconds to distribute the heat, after which 0.5 g of papain, a proteolytic enzyme, was mixed in with continued hand stirring. After approx. 30 seconds the aggregate began to liquefy, and after 2.5 minutes a liquid solution had formed. The liquid solution was then heated to boiling and after boiling for approx. 2 or 3 minutes, the solution was allowed to cool. No sign of free fat was observable on the surface of the liquid solution, indicating that the fat therein was effectively microencapsulated.

Example 14

A high-lipid pre-supplement was prepared in the following way. A 757 1 vertical stainless steel vessel fitted with a powerful stirrer with a rotational speed of approx. 34 r/min was filled with 204 kg of water in approx. 65°C. With the powerful stirrer running, 45j4 kg of soy flour and 15.9 kg of sunflower flour were mixed into the water until thoroughly wetted. A solvent in the form of 2.5 kg of sodium hydroxide dissolved in 9.1 kg of water was added to the slurry, and the mixture was continued for approx. 10 minutes. Then 40.8 kg of tallow at 45°C was added and mixed for a further 5 minutes. The mixture was pumped into a 757 1 vertical stainless steel storage vessel fitted with a conical bottom having an outlet of approx. 5 cm in diameter. From the storage vessel, the mixture was pumped to a stone mill (model 830 obtained from Moorehouse Industries, Fullerton, California) with the mill set to a 0.20 mm gap. The formed emulsion was emptied into a mixer, and when approx. half of the above emulsion had been transferred to the mixer, 9.1 kg of 75% phosphoric acid was added to the mixer while stirring. Stirring was continued until a solid gel had formed. The gel was then transferred to an agricultural dryer (Heil Model S75-22B) which operated at an outlet temperature between 82 and 88°C. The product was dried until its moisture content was approx. 10 - 14%. A small amount (about 1.13 kg) of an absorbent in the form of calcium silicate ("Microcell E" sold by Johns Manville) was added to the final product to improve the trickling properties. The product obtained from the dryer was a dark brown, odorless powder. The particle size varied from very fine to aggregate particles of approx. 6.35 mm in diameter. The product obtained was easy to handle and could be placed in paper bags without visible migration or leaching of the lipid materials. The product contained approx. 35 wt% lipids and was suitable for mixing with common types of premixes.

Example 15

A forage supplement prepared according to the procedures set forth in Example 14 was tested for its effect on the fat content of cow's milk. Three pre-mixes were prepared for use in the experiment, the first mixture being the basic mixture which did not contain any pre-supplement according to the invention. The other two experimental mixtures contained 10% by weight, respectively 20% by weight, of a pre-supplement prepared according to the methods in example 1. Table 1 shows the composition of each of the three mixtures.

Each of the three mixtures was fed to the same cow under essentially the same conditions. The cow was fed each of the mixtures separately for a period of 6 days each. Every day the total milk production of the cow was measured, and the milk was analyzed for fat content. The results of this procedure are shown in Table 2.

As shown in Table 2, the milk production of the cow was only slightly affected by the addition of forage supplements, while the fat content formed increased remarkably. When e.g. mixture no. 1 containing 10% of the forage supplement according to the above invention was fed to the cow, the fat content of the milk increased by 20% above the fat content of milk produced while the cow was on the basic mixture feed. Mixture no. 2, containing 20% foresupplement, led to a 23% increase in fat content in the milk.

Example 16

The methods in Example 15 were followed with the exception that the supplement content was raised to 30% by weight. Table 3 shows the content of the test mixture and the base compounds, and table 4 shows

the results obtained:

As will be seen from Table 4, trial mixture No. 3 containing 30% by weight of pre-supplement led to an astonishing increase of approx. 26% in the fat content of the milk produced.

Example 17

Soft waste (sheep and cattle intestines) containing approx. 50% fat D.M.B, was passed through a "Rryma plate mill" with 8 mm holes. The product obtained was a thick homogenate. It was added to a Leyland mixer and 1% sodium hydroxide (in water) was introduced

5 minutes. This led to gelation. Hydrochloric acid was then added

(33% commercial solution) to lower the pH to 3.5. The gel was left overnight for syneresis and was dried the following morning through a ring drier. An analysis of the dried product gave the following results:

Lining test

The following transition method was applied and fed to a milk-producing cow.

Period I - 7 days' feeding of 4.5 kg of barley per head and day. Period II - 10 days of feeding a 3.2 kg barley and 1.4 kg

product per head and day.

Period III - 10 days of feeding at 4.5 kg of barley per head and day.

Palatability problems arose and were overcome by using liquid molasses. However, note that the product was 30% pre-concentrate compared to 10-15% in a commercial situation.

Daily milk yields and milk compositions were recorded. For analysis purposes, data from the last 7 days in each control period and the last 5 days in the treatment period were used.

Results

These are indicated for milk and fat in the following table.

Claims (4)

1. Process for the production of microencapsulated lipid-containing food additives and pre-additives, characterized in that (a) particulate, edible, protein-containing material selected from the group consisting of animal bones, animal tissue, fish bone, fish tissue, poultry bone, poultry tissue, vegetable protein, milk whey and/or collagen, is dissolved in water with a sufficient amount of sodium hydroxide to give a pH of 9-13, possibly during painting, (b) an emulsion is prepared in a known manner by mixing together liquid lipid and dissolved, proteinaceous material, the lipid constituting the disperse phase and the protein material the continuous phase, and wherein the total mixture of protein and lipid consists of from 5 to 94 wt% protein and from 6 to 95 wt% lipid, and (c) the emulsion is contacted with a sufficient amount of a pH adjusting agent to lower the pH of the emulsion to its isoelectric point or lower, whereby the protein is obtained in an aggregated form and the lipid is microencapsulated. 2. Method according to claim 1, characterized in that the lipid material is liquid or is heated to at least its melting point before mixing with the dissolved proteinaceous material. 3. Method according to claim 1 or 2, characterized in that the pH is set at the isoelectric point of the emulsion, which is from 3.0 to 8.5. 4. Method according to claims 1-3, characterized in that the emulsion is formed at a temperature from 40° to 60°C.