Process for preparing cheese milk.

The present invention relates to the preparation of ♦ cheese milk for the production of cheese. The invention

( 5 permits the production of cheese of a conventional acceptable texture and taste at significantly lower fat content than usual, and of cheese of a conventional higher fat content with better than usual taste and texture.

10 The invention provides a process for preparing cheese milk for cheese production, the process comprising providing a fat-in-water emulsion enriched with membrane substance, pressure homogenizing the emulsion to increase the fat globule surface area whilst maintaining the increased surface area

15 covered by membrane substance, and mixing the homogenized emulsion with aqueous liquid to yield the cheese milk of required fat content. The enriched emulsion suitably contains at least one fat selected from milk fat, other animal fats and vegetable fats. An important preferred feature is that said

20 enriched emulsion is formed, or heat-treated before said homogenization, at elevated temperature below its boiling point; suitable elevated temperature is for example 50-80°C.

In one procedure according to the invention the enriched 25 emulsion may be a cream - e.g. a cream of normal membrane substance content diluted with liquid enriched in membrane substance [e.g. diluted with one or more of whey, buttermilk, (semi-) skimmed milk, and butter and cream serum] or a cream reconstituted from fat or oil and such enriched liquid; in

! 30 these cases, the homogenized emulsion can be diluted [e.g. with preferably unhomogenized (partially) skimmed or whole milk or mixture thereof] to yield the cheese milk.

In another procedure according to the invention the enriched emulsion is selected from natural and reconstituted whey, buttermilk, (partially) skimmed milk and butter and cream serum; the homogenized emulsion can be mixed with preferably unhomogenized (partially) skimmed or whole milk or mixture thereof to give the cheese milk.

In all cases the fat content of the resulting cheese milk is preferably from 0.5 to 4 wt.%. In all cases the pressure homogeniza ion is preferably conducted at 40-400 bar.

The cheese milk obtained according to the invention can be converted to cheese using conventional starter culture, rennet and processing steps. The fat content of the resulting cheese can be increased by mixing it with fat, e.g. in the form of cream.

Herein, "enriched in [or with] membrane substance" has its normal meaning of having a higher membrane substance to fat ratio than natural whole milk. Butter and cream serum are butter and cream minus some [usually most] or all of the fat. The term "fat" herein includes oil where appropriate, e.g. in the case of vegetable oil. Herein, in accord with conventional usage, % fat for cheese means the wt.% of fat in the total dry matter content of the cheese, whereas for all other materials [e.g. for cream, cheese milk etc.] the % fat means the vol.% of fat in the material.

The- first step in a first type of embodiment according to the invention is the provision or preparation of a cream- type fat in water emulsion, this usually having a fat content of 10-60 weigh- percent, e.g. 30-50 weight percent. This emulsion may be a normal cream or an emulsion prepared from water and any one, two or more of fats selected from milk fat,

anhydrous milk fat, fractionated milk fat, decholesterized milk fat, butter, other animal fats and vegetable fat [natural and/or hardened and/or de-odorized] .

The fat content of this emulsion is reduced [e.g. to from 10-30 weight percent] , and its content of membrane substance is increased, by adding thereto material enriched in membrane substance-e.g. whey, buttermilk, skimmed milk, or butter or cream serum [butter or cream minus at least most of the fat] ; when cream serum is employed it is preferably made from a cream with a fat content of from 10-82 weight percent.

For best results it can be important to subject the resulting membrane substance-enriched emulsion to heat treatment below the boiling point [e.g. at 50-80"C] , preferably with stirring or mechanical working.

The resulting emulsion is then homogenized at high pressure, e.g. at 40-400 bar, preferably 150-250 bar. The high pressure homogeniza ion in the presence of enhanced levels of membrane substance gives significant increase in globular fat surface without undesirable homogenization of the milk solid non-fat whilst maintaining the increased fat surface covered by the membrane substance present.

Following homogenization, the emulsion is diluted to give a cheese milk of the required fat concentration e.g. 0.5 to 4 weight percent. Such dilution may for example be with [preferably un-homogenized] skimmed or whole milk or a combination thereof.

In a second type of embodiment, the enriched emulsion is formed by emulsifying fat [e.g. one or more selected from milk fat, fractionated milk fat, anhydrous milk fat, de-

cholesterolized milk fat, butter, other animal fats and vegetable fats] , preferably at elevated temperature below the boiling point [e.g. 50-80°C] , with membrane substance-enriched liquid [e.g. one or more of natural and reconstituted whey, buttermilk, (partially) skimmed milk and butter and cream serum] ; the resulting enriched emulsion can then be pressure homogenized and diluted as described above to give the cheese milk.

A low-fat cheese-making milk can also be made by the following third type of embodiment:

A membrane substance - enriched material such as one or more of natural and reconstituted whey, buttermilk,

(partially) skimmed milk and butter and cream serum [butter or cream without total fats] which has preferably been heated to a temperature below the boiling point [e.g. 50-80°C] is pressure homogenised [e.g. at 40-400 bar] and then adjusted to the fat content required for the cheese milk, e.g. by mixing with one or more of (partially) skimmed and whole milk.

Subsequent conversion of the cheese milk from the above types of embodiment to give cheese by the addition of starter culture and rennet followed by coagulation and re-heating etc. can be conducted in conventional manner.

The invention is illustrated by the following working Examples.

EXAMPLE 1 : Dairy cream with a fat con ent of 40 weight percent was diluted with cream serum [obtained by removal of fat from another batch of the same cream] to a fat content of 20 weight percent. The diluted cream was heated at 60°C with stirring

and then homogenized at a pressure of 200 bar. Skimmed milk was added to the homogenized emulsion to give a final cheese milk containing one weight percent fat.

To make Gouda cheese, the cheese-making milk is heated to 33°C and calcium chloride is added [20g to 100. cheese- making milk] to improve its ability to coagulate. After addition of 0.7% mesophyllic starter culture and after 20 minutes incubation time, rennet is added [25 ml rennet of strength 1 : 15,000 per 100J cheese-making milk] . After 30 minutes thickening time, the curd is cut [particle size 3-6 mm] and undergoes preliminary cheese making for 20 minutes while stirring. After taking off 40% of the whey and washing with 40°C warm water, so that a temperature of 36-37°C is reached, it is further stirred for 20 min. After preliminary take off of 20% of the whey, the curds-whey mix is put in a pre-press pan under whey.

Pre-pressing of 30 min duration follows, then main pressing for 2 hours after dividing into blocks.

After post-acidification to a pH of 5.3, the blocks are cut into 2 kg bars and salted in the salt bath for 20 hours.

The cheese ripens in foil and paraffin for at least 4 weeks at

15-16°C. The product cheese had a dry matter content of 50 wt.% of which 25 w .% was fat.

EXAMPLE 2 :

Example 1 was repeated using for dilution, instead of the initially formed liquid cream serum, the dried and powdered serum plus water. The cheese milk and Gouda cheese obtained were the same as in Example 1.

EXAMPLE 3 :

Example 1 was repeated, but with the addition of skimmed milk to the homogenized emulsion to give a cheese milk of 2.8 weight percent fat content. This cheese milk was processed in conventional manner [e.g. as in Example 1] to give a full fat Gouda cheese [dry matter content 53 w .% of which 48 wt.% is fat] having texture and taste markedly superior to that of conventional full fat Gouda cheese.

EXAMPLE 4 : Cheese-making milk is produced as in Example 1 but with a fat content of 1.5%. A fromage frais is then made as follows :

The cheese-making milk is heated in a pan to 22-24°C and 1% mesophyllic starter culture and rennet [1-2 ml for 100. cheese-making milk] are added.

After 16-20 hours fermentation to a pH of 4.6, the curds are pressed out by means of a sieve pan.

A fromage frais is obtained with 30 wt.% dry material and 30 wt.% total fats in the dry material, which is equal in taste and texture to a conventional double cream cheese with 65-70% total fats.

EXAMPLE 5 :

Low-fat fromage frais, which is fatted afterwards with cream, is produced as follows :

Skimmed milk, optionally heat treated at 65-75°C, is homogenized at 100 bar; 1% mesophyllic starter culture and rennet [1-2 ml for 100. cheese-making milk] are then added at 26-28°C and after 16-20 hours fermentation, the curds are

stirred and separated from the whey with a Quark centrifuge. A low-fat fromage frais is obtained with about 20 wt.% solids, which is then fatted to 20 wt.% total fats in the dry matter with the diluted [20%] cream obtained as described in Example 1 or 2.

This fromage frais is comparable to a fromage frais fatted with a conventional cream to 40% total fats.

EXAMPLE 6 : A low-fat cheese-making milk is produced by the following method :

A mixture of equal parts buttermilk and cream serum is heated to 70°C and homogenised at 100 bar. This mixture is diluted with four times the amount of skimmed milk. The cheese-making milk thus obtained is heated to 93°C for 5 min, then cooled to the fermentation temperature of 25°C and mesophyllic starter culture and rennet [0.5 ml for 100« cheese- making milk] are added. The fermentation time amounts to 16- 20 hours, until a pH of 4.5 is reached.

After stirring the curds and heating to 40-42°C, ultrafiltration is effected to a dry weight of 20% in the concentrate.

The fromage frais thus obtained in the low-fat range [about 5 wt.% total fats in the dry matter] is comparable with a conventional fromage frais with 20% total fats.

There is also the possibility of fatting the resulting fromage frais with diluted cream as obtained in Example 1 or 2 to a fromage frais with higher fat content, which is superior in taste and texture to a fromage frais which has

been fatted with conventional cream.

EXAMPLE 7 :

Cheese-making milk is produced according to Example 4, but with a fat content of 3%, and processed after fermentation and pressing out as in Example 4, to a fromage frais by ultrafiltration or as in Example 5, with a dry weight of about 35 wt.% and a dry matter fat content of 45 wt.%. By mixing with a diluted cream with 30% fat, [obtained with dilution as in Example 1 or 2] , a fat fromage frais is obtained with 65% total fats, which is far superior in its sensory characteristics and creaminess to a double cream cheese produced with conventional cream.

EXAMPLE 8 : Purified soya bean oil is pre-emulsified by intensive stirring in cream serum heated to 60°C, so that this emulsion has a fat content of 20%. The pre-emulsion is then

^■ homogenised at a pressure of 200 bar. Skimmed milk is added to this vegetable cream, so that a cheese-making milk with a fat content of 1% is obtained.

The further processing of the cheese-making milk follows Example 1.