The present invention relates to the manufacture of natural cheese from a non-fat milk source. More particularly, the present invention relates to a process for the manufacture of non-fat natural cheese from skim milk wherein the fat is replaced with a fat substitute. Background of tha Invention Natural cheese is the term used in the cheese making art to describe varieties of cheese which are made from various milk sources, such as whole milk, milk adjusted to various fat levels with cream and wherein the milk source is set either by microorganisms alone or by a combination of microorganisms and a milk coagulating enzyme, such as rennet, and which involves a whey drainage step. Well known examples of natural cheese are swiss cheese, cheddar cheese, colby cheese and the pasta filata cheeses, such as ozzarella and scamorze.

Three species of bacteria have conventionally been used as starters during a fermentation period in the manufacture of swiss cheese: these being a coccus culture, and a rod culture and a propionic acid forming microorganism. Usually, Streptococcus theπnophillus is used as the coccus culture; Lactobacillus bulgaricus or Lactobacillus lactis is used as the rod culture. Propionibacterium shermanii has been used as the propionic acid-forming microorganism. A milk clotting enzyme, such as rennet, is also used and added in an amount such that curd firm enough to cut is formed in about 30 minutes. The fermentation proceeds at a temperature of from about 88* F. to about 94' F. Curd is cut and worked for about 30 minutes to an hour. The curd is then heated over a period of about 30 minutes to a cooking temperature of between 120* F. and 128* F. The curd is stirred at the cooking temperature for about 30 minutes to an hour. Whey is then removed and the curd is processed into blocks for curing to

produce swiss cheese with typical eye formation. The time required for fermentation, working and cooking is usually less than about 3 hours.

In the manufacture of Cheddar cheese by the stirred curd method, milk is pasteurized at a temperature of 162-164* F. for a holding time of 16 to 18 seconds. The milk is introduced into a cheese vat and a lactic starter, such as Sj. lactis. is added to the vat. Fermentation and ripening takes place at a temperature of 87* to 88* F. for a period of about 60 minutes. Rennet is added and coagulation occurs in a further 30 minutes. The curd is cut into particles over a period of about 15 minutes and is then cooked at a temperature of 101* F. to 103 ^* F. for 30 minutes. The curd is stirred out in the whey for a period of 30 to 75 minutes. The curd and whey are then transferred to a drain table, where the whey drains over a period of about 30 minutes. The curd on the drain table may be sprayed with water at a temperature of 105* F. for a period of 2 to 4 minutes. Salt is added and the curd is allowed to rest on the drain table for a period of about 10 minutes. The curd is then transferred to a container, usually a 640 pound container, where the curd is pressed under vacuum for a period of 75 minutes. The 640 pound block of Cheddar curd is then transferred to a cooler after a resting period of about 24 hours. The curd is held in the cooler at a temperature of 40* F. for 10 days and is then cured an additional period of 21-45 days at a temperature of 40* F. to 45* F.

The term "natural cheese" is to be distinguished from the term "process cheese". Process cheese generally refers to a class of cheese products which are produced by comminuting, mixing and heating lots of natural cheese into a homogeneous plastic mass. The comminuted cheese is blended and sent to cookers or the like which commonly heat the mass to a temperature of 165* F. to 185 ^* F. During cooking, fat is stabilized with the protein and water by

the addition of emulsifying salts, such as citrate or phosphate salts, usually at about a 3% level. The salts cause the protein to become more soluble. Under these circumstances, a stable emulsion of protein, fat, and water occurs to provide a smooth, homogeneous mass. The hot mass is packaged directly or formed into slices and packaged. In the United States, Standards of Identity apply to classes of process cheese and are established by the Food and Drug Administration (FDA) . Certain of these classes can contain various additives, such as cream, milk, skim milk, buttermilk, cheese whey and skim milk cheese. The moisture content of process cheese under the Standards of Identity may range from less than 40% tα 60%, and the fat content may range from 20* to 35*. The pH range for process cheese products typically is between 5.0 and 6.5.

There has been substantial technical effort directed to methods for producing a natural cheese from a non-fat milk source, such as skim milk. It has been proposed to produce non-fat cheese from skim milk by subjecting the skim milk to membrane processes to increase the solids level of the skim milk, followed by evaporation processes to produce a substrate having the required level of solids to produce a natural cheese. The production of a natural cheese from skim milk, however, is complicated by the fact that the fat is no longer present in the protein matrix. Cheese has a protein matrix which is broken up by fat particles. When the fat particles are not present, the cheese protein matrix becomes very firm and the texture and feel of the cheese is completely different from that normally associated with natural cheese.

In accordance with the present invention, a natural cheese is produced from skim milk to which has been added an additive which serves to provide the same function as the fat particles usually associated with the protein matrix of cheese. The additives provide particles which do not integrate with the casein network of the cheese, but

remain detached therefrom and provide spaced areas which provide a mouthfeel resembling that associated with fat-containing cheeses. fimwτn»*γ o the Invention The present invention is directed to a non-fat natural cheese which is made from skim milk. In the method an additive is provided for the skim milk which provides a fat-feel to the finished natural cheese product. The additive is a material which may be a microgei, a hydrocolloid or a polysaccharide/protein complex particle. The average particle size of the additive is within the range of .05 to 30 microns. The natural cheese is produced from the skim milk using either a Cheddar make procedure or a swiss make procedure. The natural cheese produced by the method of the invention has from about 55% to about 65% moisture and from about 30% to about 40% protein. In one embodiment of the invention, the natural cheese produced from the skim milk is debittered by use of an enzyme, preferably a peptidase, and/or a microorganism which produces an enzyme in situ.

In another embodiment of the invention, a portion of the skim milk that is used to produce a natural cheese is subjected to heat treatment which denatures substan¬ tially all of the serum protein. The portion of the skim milk which has been subjected to heat treatment to co-precipitate the whey protein is then combined with the remaining portion of the skim milk which is used to produce the natural cheese in conjunction with the additive.

In a further embodiment, the skim milk may be subjected to ultrafiltration to provide a retentate having from about 20% to about 30% solids. The additive may be combined with the skim milk prior to ultrafiltration or may be combined with the retentate prior to cooling the retentate below about 90* F. A natural cheese may then be made from the -retentate by forming a coagulum and employing

a whey drainage step or may be made by use of an evaporation step.

In a still further embodiment, a ropy culture is used to improve the texture of the non-fat natural cheese. These and other aspects of the invention are set forth in detail in the following description.

Detailed Description of tha Invention The present invention is directed to a natural cheese product which has properties normally associated with the presence of milk fat but wherein substantially all of the fat is replaced with a fat substitute additive. The additive is a microgei, a hydrocolloid or a microfragmented polysaccharide/protein complex. The additive is present in said cheese product at a level of from about 0.01% to about 50%. In another embodiment of the invention, a portion of the skim milk, preferably from about 10 to about 60% of the total skim milk, is treated by high temperature short time heat treatment conditions so as to substantially denature the serum protein of the portion of skim milk. By substantially denature is meant that at least 80% to about 100% of the serum protein is denatured. The denatured portion of skim milk is then combined with the remaining portion of skim milk to provide the skim milk component of the substrate used to manufacture the non-fat natural cheese product of the invention.

Another aspect of the invention is a method for reducing the bitterness of the natural cheese product produced by the method of the invention. Through use of an enzyme or through use of a microorganism that can produce a suitable enzyme in situ.

In another embodiment of the invention, an improved texture can be provided in the non-fat natural cheese product of the invention through use of ropy cultures. In one- method of the invention for making a non-fat natural cheese, a non-fat milk substrate is

provided. The non-fat milk substrate is a combination of skim milk, a fat substitute additive, a lactic starter culture and a milk coagulating enzyme. The substrate is coagulated and is cut to provide curd particles and whey. The whey is drained from the curd and the curd is pressed under vacuum to deaerate the curd. The pressed curd is then cured to provide the non-fat natural cheese product.

In another method for making the non-fat natural cheese of the invention, a non-fat milk substrate is provided which is a combination of skim milk, a fat substitute additive, a swiss cheese rod culture, a swiss cheese coccus culture, a propionic acid producing culture and a milk coagulating enzyme. The substrate is ripened and cut to provide curd particles in whey. The curd is cooked in the whey at a temperature of from about 95* F. to about 130* F. for 25 to 35 minutes. The curd is stirred out while being cooked and the whey is then drawn from the curd. The curd is then pressed under whey, the whey is drawn from the curd and the curd is pressed overnight to provide a slab. The slab is introduced into a brine tank and is brined for a period of 18 to 22 hours. The curd blocks are then passed in a pre-cooler where they are held for 10 to 14 days at a temperature of about 35* F.

The fat substitute additives of the invention are articles of a microgei, a hydrocolloid or a polysaccharide/protein complex which has been microfragmented.

The microgei is preferably produced from an alginate. Alginates have the ability to form gels by reaction with calcium salts. These gels, which resemble solids in retaining their shape and resisting stress incorporate a large amount of water. The term "microgei" is meant a gel which has been reduced to small micro range particles of these calcium alginate gels. The first step in providing a ^* calcium alginate gel is to prepare a solution of sodium alginate and of calcium chloride. The

sodium alginate solution is prepared by forming a vorte in water with a suitable mixer, such as a Lightnin mixer, and pouring the sodium alginate powder onto the shoulder of the water vortex. The sodium alginate is allowed to hydrate overnight under refrigerating conditions. Microgels are prepared by spraying the sodium alginate solution into a calcium chloride solution. 3000 ml. of sodium alginate is poured into a pressure tank which is attached to a spray gun. The spray gun is pointed over a small container which contains 3000 ml. of calcium chloride and a magnetic stirrer. The tank pressure is usually set at about 15 psi and the gun pressure at 12 psi which results in a flow rate of 2 to 2.5 ml. per second. After the 3000 ml. of sodium alginate has been sprayed, the resulting precipitate of calcium alginate is centrifuged at 4000 rpm for 20 minutes at 4*C. to 8*C. The supernate containing dissolved calcium chloride is then decanted and the pellets are combined, washed with 3000 ml. distilled water and recentrifuged to provide the microgels. The microgels produced by the above method are often of too large a size to be used. High pressure homogenization can be used to reduce the microgels produced by the above described method to further reduce their size. The pellets obtained after recentrifugation are combined, diluted with 3000 ml.- of distilled water and passed through a Rannie homogenizer. The microgei dispersion is then passed through the homogenizer as many times as is necessary to reduce the particle size to below 30 microns. By the term "hydrocolloid" is meant any of a group of materials that yield gels with water, such as alginic acid salts, agar, guar gum, carrageenan, xanthan gun and related polysaccharide guns.

The microfragmented anisotropic polysaccharide/ protein complexes useful in the present invention as a fat substitute additive are generally described in U.S. patent application Serial No. 292,568 to Chen, et al., filed

December 30, 1988, the teachings of which are incorporated herein by reference. A particularly preferred form of microfrag ented anisotropic polysaccharide/protein complexes is directed to insolubilized, microfragmented anisotropic xanthan/protein complex aqueous dispersions. The microfragmented xanthan/protein complex dispersions have desirable rheological properties including a stable lubricity and creamy mouthfeel which may be utilized as a fat substitute additive in accordance with the present invention. The microfragmented anisotropic xanthan/protein complex dispersions may be prepared by initially forming relatively large xanthan/protein complex fibers under fiber-forming conditions in which an anisotropic complex is formed, and subsequently shearing an aqueous slurry of such fibers under high energy shear conditions to comminute the fibers to smaller anisotropic fiber microfragments having a maximum dimension of 15 microns or less. As described in U.S. Patents 4,563,360 and 4,559,233, xanthan/protein complex fibers may be formed from aqueous fiber-generating solutions of xanthan gun and protein under specific fiber-forming conditions. It is desirable that the pre-formed xanthan/protein complex fibers, particularly those fibers prepared from protein sources such as whey protein concentrate, which nay contain undesired flavor components, be washed with water after formation. At least an equal volume of water to the volume of fibers should be used, desirably in a countercurrent process.

In a method of nicrofragmenting the pre-formed anisotropic xanthan/protein complex fibers, an aqueous xanthan/protein fiber slurry is subjected to high shear conditions. For example, a slurry containing from about 4 to about 5% by weight of pre-formed, relatively large xanthan/protein complex fibers (solids basis) with the viscosity not exceeding 1000 centipoise may be conducted through a high shear zone at initial linear velocities of

up to 1300 centimeters per second or more to achieve fragmentation of the fibers.

It is known that milk or skim milk may be subjected to high temperature treatment to cause partial or complete co-precipitation of the relatively hydrophilic serum protein with the casein protein component of the milk, and that calcium salts may be added after such heat treatment. Substantial effort has been directed over the years to recovery of whey protein with casein and/or to increase yields. Co-precipitation techniques have found considerable application in the manufacture of soft, high moisture cheese products, such as cottage cheese and cream cheese in which the hydrophilic nature and other physical properties of the co-precipitated serum proteins are not particularly disadvantageous, as shown by U.S. Patent Nos. 3,039,179, 3,297,451, 3,316,098, 3,492,129, 3,302,481 and 4,066,800. As shown, for example, in U.S. Patent 3,316,098, efforts have been made to produce a hard fat-containing cheese product, such as cheddar cheese, using co-precipitate techniques.

In accordance with the present invention, it has been determined that a softened texture can be provided in non-fat natural cheese products by subjecting the skim milk to co-precipitation heat treatment techniques. All of the skim milk used to make the cheese may be treated. In an important embodiment of the invention, however, only a portion of the skim milk which is to be used in the manufacture of the cheese is subjected to co-precipitation heat treatment techniques. In particular, it has been determined that if the portion subjected to co- precipitation heat treatment techniques is subjected to heat treatment conditions sufficient to denature from about 60% to 100% of the serum protein, that a softened texture can be obtained. The co-precipitate heat treated portion of the skin nilk is combined with the balance of the skin milk to provide the total amount of skim milk used in the

manufacture of the natural cheese. Preferably, from about 10 to about 60% of the total skim milk to be used in the manufacture of the non-fat natural cheese is subjected to co-precipitation heat treatment techniques. It is important that the portion of milk be heat treated sufficiently to denature a substantial proportion of the serum protein, but it should not be so subjected to such heat treatnent that the action of coagulating enzymes on recombined milk is not adversely affected and satisfactory coagulation occurs during manufacture of the cheese. In this regard, heat treatment of the milk at a temperature of from about 180* F. to about 220* F. for about 10 to about 45 seconds (or substantially equivalent time-temperature conditions) , provides a preferred degree of heat denaturation without adversely affecting the setting ability of the casein component.

The non-fat natural cheese product of the invention may be made by either of two techniques which are generally referred to as a Cheddar make procedure and a swiss make procedure. In the Cheddar make procedure, using a stirred curd method, starter cultures are used which are traditionally used in the manufacture of Cheddar cheese, such as Sj. lactis and S^ cremoris. The substrate containing the skim milk, and the fat substitute additive is set with a lactic starter culture and the addition of a milk coagulating enzyme. Fermentation after addition of the starter culture proceeds at a temperature of 85* F. to 90 ^* F. for a period of about 60 minutes. The coagulation occurs after rennet is added which takes place about 30 minutes after the initial ripening period. The coagulum is cut and is then cooked at a temperature of 95* F.to 105' F. for a period of about 30 minutes. The curd is then stirred out over a period of 30 to 75 minutes. The curd and whey are then transferred to a drain table and the whey is drained over a period of 30 minutes. The curd is sprayed with water which is at a temperature of 105* F. for a

period of 2 to 4 minutes. Salt is added and the curd is allowed to rest for 10 minutes. The curd is then transferred to a suitable size container, such as the 640 pound box, and is pressed under vacuum for about 75 minutas. The curd block is then transferred to a cooler and is held at a temperature of 40' F. for about 10 days. Curing of the curd takes place over a period of several weeks at a temperature of 40 to 45* F.

The curd produced by the Cheddar make procedure may result in a slightly bitter tasting cheese. In one embodiment of the invention, an enzyme having peptide cutting properties, such as an aminopeptidase, is added to the milk producing substrate at the same time as the starter culture. This enzyme or a microorganism capable of producing such enzyme is used in the method of the present invention for reducing bitterness in the non-fat cheese product of the invention. A suitable enzyme is manufactured by Imperial Biotech and is sold under the tradeπame Debitrase™. Another suitable enzyme is Accelase™.

In the swiss make procedure of the invention, a standard swiss cheese manufacturing process is used wherein a rod culture, a coccus culture and a propionic acid producing culture are added to the skim milk. In this method, the substrate containing skim milk and the fat substitute additive is placed in a cheese vat and a rod culture, a coccus culture and a propionic acid producing culture are added thereto. The rod culture is usually Lactobacillus bulσaricus or Lactobacillus lactis. although Lactobacillus helvet_i.cus can also be used. The use of lα. hβlveticus is believed to be particularly useful to provide a non-bitter, non-fat natural cheese product. Usually Streptococcus thermophilus is used as the coccus culture. Propionibacterium shermaηii is usually used as the propionic acid producing culture. A milk clotting enzyme, such as rennet, is also used and added in an amount such

that a curd firm enough to cut is formed in about 30 minutes. The fermentation proceeds at a temperature of from about 88* F. to about 94' F. The curd is cut and worked for about 30 minutes to an hour. The curd is then heated over a period of about 30 minutes to a cooking temperature of between 120' F. and 128* F. The curd is stirred at the cooking temperature for about 30 minutes to an hour. Whey is then partially removed and the curd is pressed into blocks for curing to produce the natural non-fat swiss-type cheese product of the invention. The swiss cheese make procedure is characterized by use of temperatures during fermentation and cooking temperatures after fermentation of from 88* F. to 94' F. and from 120* F. to 128* F., respectively. The swiss cheese make procedure of the invention using a substrate containing skim milk and a fat substitute additive produces a sweeter tasting natural cheese product than does the Cheddar make procedure described hereinabove. In a further embodiment of the invention, it has been determined that the use of ropy cultures can be used to further improve the texture of the non-fat natural cheese product of the invention. Ropy milk of bacterial origin is well known. Ropy milk is generally considered to be detrimental. The ropiness may be evident only as a slightly abnormal viscosity or it may be so pronounced that the affected milk may be drawn out in fine threads up to a yard long, and in some instances may assume a gel like consistency. The immediate cause of the ropy condition is the formation by bacteria of gums and mucins. The gums are the more common cause and are probably caused by the fermentation of the lactose to galactan and dextran. The development of ropiness is closely associated with capsule formation. In many cases, threads formed when the milk is drawn out contain many chains of bacteria held together by large capsules; In other cases, the capsule appears to be dissolved as fast as it is formed or a more or less

complete solution of outer cell walls occurs and the gummy material is diffused throughout the milk. Such a condition may accompany an unusual proliferation of bacteria or a formation of long-tangled masses of threads or chains. As used herein, the term "ropy culture" means a culture which adds to viscosity but which does not provide any undesirable off flavors.

Among the bacteria producing ropiness are active gelatin liquifiers. More frequently, however, ropy milk is caused by some members of the aerogenis group or the lactic streptococci, such as gj. lactis var. taette and SL. lactis var. hollandicus. Strains of microorganisms which are capable of producing ropiness are well known. The ropy cultures are used in the practice of the present invention as the primary culture in either the swiss make procedure or the Cheddar make procedure or can be used in addition to the normal microorganisms used as starter cultures in the swiss make procedure and the Cheddar make procedure.

The skim nilk nay be subjected to ultrafiltration to provide a retentate having from about 20% to about 30% solids. Such increase in solids aids in providing a uniform dispersion of the additive. The additive may be added prior to or after the ultrafiltration step. Ultrafiltration is usually effected at a temperature in the range of from about 100* F. to about 130* F. for most efficient operation of the ultrafiltration apparatus. When the retentate cools to a temperature below about 90* F., a coagulum may form. The additive must be combined with the retentate prior to forming any coagulum. A natural cheese may then be made by forming a coagulum and employing a whey drainage step or may be made by use of an evaporating step, such as is taught in U.S. patent application Serial No. 458,233, the techniques of which are incorporated herein by reference. When-the natural cheese is made from a retentate utilizing an evaporating step, other fat substitute

additives which cannot be used with a whey drainage step may be utilized. Such alternate fat substitute additives include cottage cheese fines, starch and microreticulated microcrystalline cellulose such as described in U.S. Patent Application Serial No. 395,800 filed August 18, 1989, the techniques of which are incorporated by reference.

A method for extracting and evaluating bitter cheese components from cheese samples is also used. In the method for evaluating bitter flavors, a cheese sample is combined with water and gently mixed for a period of from about 1 minute to about 10 minutes to provide a cheese suspension in the water. In general, the water is used at a ratio of about 1:1 to about 3:1 by weight based on the weight of the cheese sample. The suspension of cheese particles is then centrifuged for a period of time of from about 10 minutes to about 30 minutes at a speed of from about 4000 to about 6000 rpm using a GS-3 rotor. The pellet is discarded, and the supernate is diafiltered with water overnight at a temperature of from about 2* C. to about 10* C. An A icon 8400 diafilter apparatus using a

YC05 membrane is preferred. Diafiltration takes place at a pressure of 60 to 65 psig. The permeate is discarded and an aliquot of the retentate is centrifuged for a period of from about 10 minutes- to about 30 minutes at 10,000 to 20,000 rpm using an SS-34 rotor _* The supernate is filtered through a disposable Corning 25932 filtration unit and the filtrate is tested for bitter flavors. Testing may be by any suitable means such as the use of spectrographic analysis or by human tasting. If a taste test is used, a standard size aliquot is calibrated with 10 millimoles (mM.) of caffeine.

While the actual cheese products of the present invention are characterized as being non-fat products, from a practical standpoint, it is impossible to remove all butterfat from milk in ordinary commercial cream separation

processes. Usually, a few tenths of a percent of butterfat remains in the skim milk after separating cream from the milk in the most efficient separators. When the skim milk is further concentrated, such as by removing whey during the -cheese make procedures of the invention, the butterfat content is increased in proportion to the degree of concentration. The non-fat natural cheese products of the invention may contain up to about.1.5% fat. Accordingly, the term "non-fat natural cheese product" as used herein means cheese products which may contain up to about 1.5% butterfat.

In another aspect of the invention, the color of the non-fat cheese product of the invention can be improved through the use and addition of titanium dioxide. When used, the titanium dioxide is added at a level of from about 0.01% to about 0.25%.

Throughout the Specification and Claims, percentages and ratios are by weight and temperatures are in degrees Fahrenheit unless otherwise indicated. The following examples further illustrate various features of the invention, but are intended to in no way limit the scope of the invention which is defined in the appended clains.

Non-Fat Cheese with Microfracrmented Xanthan Protein A first batch of the cheese was prepared by standardizing and filtering 500 lbs of milk that has 0.15% fat level. The mixture was pasteurized at 162* to .164* F. for 16 to <18 seconds and cooled to 90* F. 10 lbs microfragmented xanthan protein complex was added. A Streptococcus lactis culture, 6.25 lbs, was added to the mix, the mix was held in a fermentation tank for 60 minutes at a temperature of 87 to 88* F. After fermentation 50 ml of rennet was added to produce a coagulum after 30 minutes. The curd and whey were cut with IΛ" knives. The -curd and whey were stirred for 110 minutes to provide a ciird with a pH of 5.95. The temperature was

maintained at about 90* F. throughout the fernentation, setting and stirring periods. The curd was separated from the whey on a drain table and was stirred for 30 minutes on the table. The curd was then salted over with 1 lb of salt, transferred to a container and pressed. A cheddar- type cheese was obtained after curing for a period of 21-45 days.

A swiss-type cheese was produced from 1000 lbs of pasteurized skim milk containing 0.15% fat. 20 lbs of microfragmented xanthan/protein complex was added. The mix was pasteurized at 163* F. for 16 seconds and then transferred to a vat containing 14 lbs of Streptococcus lactis, 10 ml Lactobacillus helveticus. 1 ml

Propionibacterium shermanii. 45 g Ti0 ₂ was added to the milk.

The mix was ripened for 15 to 45 minutes at 94* F.

The rennet, 100 ml, was added and the mixture was allowed to set at 94* F. The mix was cut and foreworked for 40-60

._.*' minutes. The mixture was then cooked at 120' F. for 25 to 35 minutes. The curd and whey were stirred out and a portion of the whey was drawn out. The curd and whey was then drawn and dipped for about 2 hours from set. The curd pH was 6.15 to 6.25.

The curd was then pressed under whey for 15 minutes and the whey was then drawn. The curd was pressed and cut into slabs and placed into a brine tank at 37-38* F. for 18 to 22 hours, after which it was cut and boxed. The pre- cheese was .cooled to 34* F. and held for 10 tα 14 days and then was cured at 72* to 78* F. for 22 to 28 days. Melt Test

Samples were sliced (home slicer) , a disk cut, and melted on a covered petri dish for 5 minutes in a 400* F. oven. The melt value is calculated by dividing the area of the melted sample by the area of the cut disk.

MFAPP = microfragmented anisotropic polysaccharide/ protein complex MCP = coprecipitated milk The size of the disk rather than its weight was kept constant. Differences in disk weight (grams) are presumably due to the curd packing in that sample.

Results show the MFAPP and addition of coprecipitated milk (MCP) do inhibit the melt. Loss of fat alone does not. Both the fat-free and KLN samples did not oil-off during heating.

Coprecipjtate Plus Microfragmented Milk MCP) Anisotropic Xanthan/ rotein Complex (MFAPq

The skim nilk was heat treated at a temperature between 190 and 220* F. for 10 to 45 seconds to provide

milk with coprecipitated serum protein. This milk was then used as in the procedure for making cheese.

Interaction of Co-precipitate and MFAPP on Cheese Texture and Yie^d

One pound of salted, stirred, no-fat curd was sprinkled with enzymes and then pressed into Gouda hoops overnight. The cheeses were stored at 45" F. - on Ge s

The gel data below illustrates that the bitter- forming enzyme systems attack the 0-casein protein. Proteolytic products of this protein are known to be bitter.

Comparison of NPN and free amino acids (FAA) indicates the difference in the enzymes ¹ ability to produce acid-soluble

peptides (NPN) and their ability to generate FAA (peptide hydrolysis or cellular metabolism) . Note that bitterness has no correlation with FAA production; it is most strongly related to β-casein breakdown and perhaps NPN. NPN may not be the best method to indicate bitterness since bitter peptides are likely to be acid-insoluble.

Microαels (uσelsi Composition of uσels .250.Og sample 1% cad., + 1% Na alginate 10.42 μ particle size 3.91% TS.

Skin nilk in a bath at 93* F. and 15 ml of S, thermophilus _r a starter culture, was added, μgels were added to about 1300 ml milk at 94* F. .3 ml rennet was added, cut, stirred, drained and rinsed under cold water. σ uσe s σ curd σ NaCl σ cheese Am PH

0 138 2.7 101 5.41

3 149 3.0 119 5.31 6 156 3.1 112 5.31

12 153 3.05 116.5 5.33

Whey solids (were separated by centrifugation) μgels bv ^p ellet

0 1.2 3 1.0

6 2.3

12 1.9

It appears μgels increase yield.

High Ranσe

settled layer plus about 350 g of whey.

Dependence of pellet size is on added amount of μgel and is probably due to production of curd fines, curds with higher concentrations were fragile. There appeared to be μgel in whey.

Ropy Cheese Cultures The ropy culture was a strain of Streptococcus theπnophilus and Lactobacillus bulσaricus. These cultures had a pH/TA of 4.60/0.70 and 3.90/1.00, respectively. 1500 ml of milk was placed in a water bath at

94* F. Add 15 ml of starter and .1 ml of Lactobacillus bulσaricus. The following was also added to each beaker. Beaker A - S. thermophilus - (non-ropy strain) Beaker B - £. thermophilus - (ropy strain) Beaker C - £. thermophilus - (ropy strain) and Lactobacillus bulσaricus Beaker D - £. thermophilus (non-ropy strain) and Lactobacillus btggaricqg Rennet was added, .3 ml. The culture was cut and stirred slowly at 98 ^" ' F. The nixture temperature reached 108* F. and was stirred for 20 minutes and the whey was drained, washed with water, drained and salted. Beaker σ curd σ salt σ cheese AM pH

A 151 1.9 118 5.39 B 137 1.7 121 5.29

C 151 1.9 115 5.55

D 135 1.9 114 5.31

Guar Gum Skim nilk was warmed to about 90' F. and separated into beakers 150 g each. Guar gum is added as a powder, swirl to dissolve and let stand 30 ninutes. Add .3 ml of 1/10 rennet and cut after 0 ninutes.

Appearance of slimy layer of whey on top of clot .1 and .05% sanples. The experinent was tried again with mixing with guar added to the milk at .3%, then diluting into nontreated milk.

It does not matter how guar is introduced. The guar addition must remain below .1% to allow coagulation.

Skim Milk + Gum

A total of 20 ml skim milk was homogenized into which was added to iota-carrageenan gum. The mixture was then mixed in about200 ml of skim milk at 35' C.

There was no problem of coagulation with 0.02% gum

A 850 0

B 850 .1

C 850 .85

Beakers were placed in a water bath at 37 ^* F. and the gum was. added. 3.48 ml of glucono delta lactone (GDL) was added. .1 nl rennet was added, then cut, stirred, heated at 97* F. , drained and salted. There was no problem in forming a coagulum with .1% iota-carrageenan gum. The pH of the cheese was high and more GDL should be added. The GDL can function as an acidulant and assists in whey expulsion.

Aσar Gum

200 ml skim milk was placed in a beaker, where the milk was pre-heated to about 90* F. Agar was added and the beaker was shaken to suspend the agar. .4 ml of rennet diluted 1:10 in water is added and then the beaker was returned to the H ₂ 0 bath (90* F.).

Mσ Aσar % ftqar S fc

60 .03 + 100 .05 + 200 .1 + 600 .3 +

Agar does not interfere with rennet coagulation

Xanthan Gum It was determined that the use of xanthan gum added at levels of 0.05% and 0.1% to skim milk and followed by homogenization of the skim nilk prevented good coagulation. The following vats of skin nilk cheese made with and without homogenization demonstrated that coagulation of the skim milk could be obtained at levels of xanthan gum of 0.01%.

*.15 grams of xanthan gum added to 1.5 liters of skin nilk corresponds to an addition of 0.01%.

A natural cheese was made from the above 4 vats of skim milk by the following procedure.

The skin nilk was warned to 82' F. and 13 nl of an S. thermophilus culture was added. The nilk was further

heated to a temperature of 87* F. over a period of 1 hour and .3 ml of rennet was added. After 45 minutes of additional warning, a coagulun had formed at a tenperature of 94*. The coagulum was cut and the curd was stirred in the whey for a period of 1 hour. The whey was then drained fron the curd at a tenperature of 104' F. The curd was then pressed into a cheese block.

It was determined that homogenization of the skim milk did not affect coagulation or yield and that a lower level of xanthan gum did allow coagulation.

A description of the present forms of the invention having been described by way of example, it is anticipated that variations of the described forms of the invention may be made without departing from the invention and the scope of the appended claims.