FR2514615A1 - Electrodialysis of milk at low temp. - giving acidified milk for casein, cheese and whey prodn. - Google Patents

Abstract

Electrodialysis of milk (esp. skimmed milk) using cationic membranes is carried out at 0-4 (0-2) deg.C for sufficient time to reduce the pH of the milk to 4.6 or below (2-4.6). The acidic milk prod. is then recovered, and converted to casein (further processed to acid curds for cheese-making) and whey. Pref. both the milk and the acidic electrodialysis soln. are precooled to 0-2 deg.C. By maintaining a low temp., electrodialysis can be continued past the isoelectric pt. of casein without causing coagulation of casein. The acidified milk is stable for several days at room temp. against coagulation and microbial spoilage. The whey prod. is superior to that formed by direct acidification as regards both texture and vol. after churning.

Description

Method of treating milk by electrodialysis on
cationic membranes, decationized acid milk thus obtained and
use of the latter for the production of casein,
cheese curd and whey.

The present invention relates to a method of treatment
milk by electrodialysis on cationic membranes, to obtain
decationized acid milk, the product thus obtained and the use of
of the latter for the manufacture of casein, or curd of
milk for cheese, and whey.

The conventional processes for the manufacture of casein or milk curd for cheeses without presure involve the coagulation of the casein contained in the milk by lowering the pH of said milk to the isoelectric point of the casein which is at pH 4.6: - or by lactic fermentation of the milk, a process which however requires the storage of large volumes of milk throughout
the duration of the fermentation, which can reach 12 to 16 hours, or by acidification of the milk by addition of an acid
strong mineral (hydrochloric acid, sulphuric acid
inter alia), to lower the pH of the milk to the point where
isoelectric milk casein, which produces the coagulation of casein contained in this milk, which leads to a casein of good quality but also a large volume of acid whey and highly mineralized, difficult to value in the state, and most often requiring additional treatment of demineralization by ion exchange or electrodialysis; moreover, this
brutal treatment of the milk with a strong acid, risk of denaturing or degrading certain valuable products contained in the milk to be treated, or by passing the milk through a cation-exchange resin layer in acid form to replace the cations contained in the
milk with hydrogen ions and to precipitate the milk casein on the
particles of said resin, which process leads to obtaining a
quality casein and a whey of good nutritional value, but the precipitation of casein on the resin particles very quickly causes the inactivation of said resin.

In order to overcome these disadvantages, according to a method
recent patent described in the French patent application N078.06007 filed
March 2, 1978 for Process and Installation to Prepare the
casein ", it has been proposed to operate in two stages - a first stage of acidulation of skimmed milk
electrodialysis on cationic membranes, until reaching a pH greater than 4.7, and especially between 4.9 and 5, so
to avoid any coagulation of milk casein on the surface of
electrodialyzer membranes,
then the acidulation is terminated in a second stage by addition
diluted mineral acid, until a pH of 4.6 is obtained.
coagulate the casein that llon recovers.

However, the addition of a mineral acid in the second
stage to acidify the milk, besides representing a risk of
corrosion for manufacturing equipment, led to a whey
mineralized acid, requiring for its commercialization a demineralized
total or partial costly.

However, the inventors have found that by treating milk
electrodialysis on cationic membranes, we could lower
milk pH at the isoelectric point of milk casein (pH 4.6)
or below this point without causing coagulation of casein
contained in this milk, if the milk was kept during the electro-
dialysa in a range of low temperatures from 0 to 40C then
above this temperature range, coagulation of the
milk casein occurs as soon as the isoelectric point of the casein is
The result is an acidic decationized milk, largely
part of the calcium, sodium and potassium cations contained in the milk
initial concentration, with a mineral element content of less than 4 g / liter,
a pH less than or equal to 4.6, and containing all the substances
protein nitrogen and lactose from normal milk; this decationized milk,
acid, when its pH is less than or equal to 3.8, has the particularity of being able to be kept without particular precautions for several days at a temperature above 40C, for example at the normal temperature, without it occurring
coagulation of the casein it contains, nor microbial development.

This decationized milk can advantageously be used
acid for the manufacture of casein or sour curd for
cheeses without rennet and whey.

More particularly, it can be mixed with normal milk
untreated to bring the pH of the two milks to the isoelectric point of the milk casein and warm the mixture thus obtained to a temperature of
10 to 600C to cause coagulation of the casein contained
both in milk for the purpose of obtaining the
casein or acid curd for cheeses without rennet, and lacto
serum, which represents a significant economic benefit by
that electrodialysis treatment can be limited to a fraction
only the batch of milk intended for the manufacture of casein or
curd.

The subject of the present invention is therefore a method of
treatment of milk by electrodialysis on cationic membranes,
according to which the electrodialysis is conducted at a temperature of
at 4 ° C, preferably 0-20 ° C, for the time necessary to lower
the pH of said milk at a value of less than or equal to 4.6, preferably
at a value of 2-4.6, after which deca milk is recovered.
acid solution thus obtained.

More particularly, the milk and optionally the solution ac
electrodialysis are previously cooled to a
of Oo at 4 ° C, preferably 0-20C, before their introduction into
the electrodialysis.

The present invention also relates to a method
of using the decationized acid milk obtained according to the process
above described, for the preparation of casein and lacto
serum, a process according to which starting from an acidic decationized milk having
a pH of 4.4-4.6, and this milk is heated to a temperature of 10 to
600C to coagulate the casein it contains and recover casein
thus coagulated and the whey thus obtained.

 The subject of the present invention is also a process for the use of decationized acid milk, for the preparation of casein and whey, a process according to which the decationized acidic milk is mixed with a quantity of normal milk sufficient to raise the pH of the product. mixing to the vicinity of the isoelectric point of the casein, and then the mixture thus obtained is heated to a temperature of 10 to 60 C, to coagulate the casein contained in both the decationized acid milk and in the normal milk, and then recovering the casein thus coagulated and the whey thus obtained.

 More particularly, the decationized acid milk is mixed with a quantity of normal milk, sufficient to raise the pH of the mixture to a value of 4.4-4.6.

More particularly, we warm up
the mixture of decationized acid milk and normal milk at a temperature of 40 to 500C to coagulate the casein.

 Preferably, the volume ratio between the amount of normal milk and that of decationized acid milk is about 1: 1.

 The coagulated casein is separated from the whey and then washed and dried by conventional methods (spray drying, or by hot air in a fluidized bed) or converted into caseinates of alkali or alkaline earth metals (sodium, potassium, calcium) or caseinate ammonium.

 The recovered whey (which contains only the cations supplied by the normal milk) can then be dried in the state or after neutralization or undergo any usual technological operation such as demineralization, ultrafiltration, concentration by reverse osmosis.

 It is remarkable that this whey concentrate ultrafiltration or not has good swelling properties and in all cases superior to those of a casein whey obtained by direct acidification and this, both on the volume after threshing that the texture.

Furthermore, the subject of the present invention is a method for using decationized acid milk, for the purpose of preparing the
curd acid for cheeses without presure and whey, said method
comprising
- the mixture of decationized acid milk with normal milk, in quantity
sufficient to raise the pH of the mixture to the vicinity of the point
isoelectric of milk casein,
reheating the mixture thus obtained at a temperature of 10 to
600C, to coagulate in the form of curd the casein contained in the
in decatized acid milk, and in untreated milk,
and then - the cutting of the curd formed, its cooking at a temperature included
between 48 and 60qu, the withdrawal of the whey and its recovery, the
washing the curd with cold water and draining said curd.

In the latter process, the decationized acid milk is mixed with a quantity of normal milk sufficient to
raise the pH of the mixture to 4.4-4.6.

More particularly, the milk mixture is heated up
decationized acid and normal milk at a temperature of 30 to 350C
to coagulate the curd. Similarly, the volume ratio between
amount of normal milk and that of decationized acid milk is
About 1: 1

It can thus be achieved by the method according to the invention
described above, including the following types of rennet-free cheeses:
'Cheese Cottage', 'Queso Blanco', 'Quark', 'Cheddar-Like Cheese', 'Picota', 'Blue Cheese', and Pizza Cheese.

The invention will be described in the following with reference to
attached drawing on which the single figure represents so
schematic an industrial electrodialysis plant for the
implementation of the method according to the invention.

Such an installation comprises several electrodialysers
I, I ', I ", connected in series, each comprising a large number of
juxtaposed compartments of which one out of two, the, is a compartment
dilution and the other, lb, a concentration compartment, the whole
of these two compartments constituting an electrodialysis cell. The
compartments are separated from each other by single membranes
cationic substances 2 which, as their name suggests, are
cross only through the cations.

 The skimmed milk, fed through line 3 and cooled to 2 ° C. in heat exchanger 4, is discharged via feed line 5 into dilution compartments 1a of first electrodialyzer 1, the mineral cations contained in said milk being displaced. in the direction of the electric current when a tehsion is applied between the electrodes 6, 7 of the electrodialyseur and can out of the dilution compartments through the cationic membranes 2 to migrate into adjacent compartments lb concentration.Par, a acid solution, such as an aqueous solution of sulfuric acid at pH I, fed via line 8 and cooled to 20C in heat exchanger 9, is sent via feed line 10 to the concentration compartments lb of the first electro dialyzer 1, the H ions it contains circulate in the opposite direction of the electric current and pass through the cationic membranes-2 to migrate into the diluent compartments tion.

The concentration compartments lb are enriched in mineral cations while the dilution compartments deplete it in mineral cations and enrich themselves in H ions.
In other words, the skim milk decays and stacidifies in the dilution compartments 1a, while the acid solution is neutralized in the concentration compartments 1b.

 The milk leaving the first electrodialyzer is sent into the dilution compartments of the second electrodialyzer 1 'and then into those of the third electrodialyzer 1 "while the acid solution leaving the third electrodialyzer 1" is introduced into the concentration compartments of the second electrodialyzer 1' then in those of the first electrodialyzer 1.The number of dilution compartments crossed by the milk is calculated so that the amount of cation exchanged between the milk and the acid solution corresponds to a lowering of the pH of the milk to the desired value which is equal to or lower than the isoelectric point of milk casein (pHi 4.6).

 The cation-enriched acid solution leaving the concentration compartments is discharged through the outlet line 11.

 The decationized and acidified milk at 44.6 leaving the dilution compartments of the last electrodialyzer 1 "is combined in the discharge pipe 12, and mixed with normal milk from the pipe 13 connected to the milk supply pipe. 3.

 The amount of normal milk added is such that the pH of the mixture is raised to 4.4-4.6. The mixture is then heated to a temperature of 10 to 600C in the heat exchanger 14.

The flocculated curd is separated from the whey and directed to the manufacturing facility for casein or cheese. The whey is recovered for use in the state or neutralized or to be treated according to the usual technological processes such as athermic concentration, reverse osmosis concentration, drying, ultrafiltration, total demineralization.

 The examples which follow are intended to illustrate the invention without limiting its scope.

EXAMPLE 1 Manufacture of Casein and Whey

 100 liters of skim milk are treated in the above-described electrodialysis plant with 100 cells (100 cationic membranes representing an area of 2.3 m2).

 The milk is cooled to 2 ° C., the acid solution is an aqueous solution of sulfuric acid at pH 1, also cooled to 20 ° C. The voltage applied across the electrodes is 150 volts.

 After two successive passages, the decationized milk, acidified to pH 4.4, is collected and heated to 45 ° C; the coagulated casein is separated from the whey.

ANALYSIS OF PRODUCTS
MILK FROM DEPARTURE ACIDIFIED DECATTIZATION MILK pH 6.6 4.4 dry matter 91 g / l 84 g / l nitrogenous material 33.6 g / l 32.7 g / l chlorides (NaCl) 1.85 g / l 1.70 g / l calcium 1.5 g / l 1.0 g / l sodium o, sg / l 0.25 g / l potassium 1.6 g / l 0.30 g / l
WHEY
Dry matter 61 g / l nitrogenous material% ES. 11.9
chlorides (NaCl) Z ES. 2.75
calcium Z ES. 1.7
sodium% ES. 0.4
potassium% ES. 0.52 mineral matter Z ES. 7.5
(ES = dry extract)
CAILLEBOTTE AFTER
WATER WASH
Humidity Z 54 protein Z ES. 96.5 ash Z ES. 1.95 fat X ES. 40.5
lactose Z ES. 0.15
This whey is characterized by mineralization
overall low due in particular to the low chloride, potassium and sodium content, despite its high calcium content.

EXAMPLE 2 Manufacture of Cheese Curd "Cottage Cheese" and Whey.

 80 liters of milk are treated in the electrodialysis plant described above equipped with 100 cells.

Milk and acid solution (which is an aqueous solution
of sulfuric acid at pH 1.0) are cooled to 20C. The voltage applied across the electrodes is 200 volts.

After 4 successive passages, the decationized milk, acidified
at pH 3, collected, is mixed with normal milk for a final pH of 4.5.

The mixture is warmed slowly to 320C to cause the coagulation of the casein of both milks. When the texture of the curd obtained has a suitable firmness, it is proceeded to its cutting. After 15 minutes
at rest, the cut curd is subjected to cooking, by moderate reheating up to a temperature of 52 to 550C. The desired firmness of the curd is obtained after about an hour at this temperature. The whey is drawn off; the curd is washed and cooled with acidified water, pH 5.0, and drained. These operations are renewed and terminated by a washing operation with iced water (40C).

 The drained curd may be packaged with or without salt or creamed and salted in a manner known per se.

 The product obtained has the texture and the taste of the cheeses of the "Cottage Cheese" type.

CHEESE COMPOSITION
Dry matter Z 22
Z Proteins 21
Mineral matter X 0.6
Fat% 0,1 Lactose z <0,1
COMPOSITION LACTOSERUM LACTOSERUM
ACCORDING TO THE TRADITIONAL ACID INVENTION
Dry matter g / l 62.8 60-65 mineral matter% ES. 7.3 10.5-12 nitrogenous materials% ES. 11.3 10.5-11.5 chlorides (NaCl) Z ES. 2.75 7.0-7.5 calcium Z ES. 1.5 1.6-2.0 sodium Z ES. 0.45 0.7-0.9 potassium% ES. 1,2 2,4-2,6

Claims (13)

1. A method for treating milk by electrodialysis on cationic membranes, characterized in that the electrodialysis of said milk is conducted at a temperature of 0 to 40C, for the time necessary to lower the pH of the treated milk to a minimum. value less than or equal to 4.6, after which the decationized acid milk thus obtained is recovered.  2. Method according to claim 1, characterized in that  the electrodialysis is conducted at a temperature of 0 to 20C. 3. Method according to claim 1 or 2, characterized in that the electroialysis is conducted for the time necessary to lower the pH of the treated milk to a value of 2 to 4.6. 4. Method according to claim 1 or 2, characterized in that the milk is pre-cooled to a temperature of 0 to 40C, preferably from 0 to 20C before its treatment by electrodialysis.  5. Method according to claim 1 or 2, characterized in that the electrodialysis acid solution is previously cooled to a temperature of 0 to 4 C, preferably from 0 to 20C before its  introduction into electrodialysis.  6. Process according to claim 1, characterized in that the milk to be treated is skimmed milk. 7. Decatized acid milk obtained by the process according to any one of claims 1 to 6. 8. A method of using the decationized acid milk, according to claim 7, for the preparation of casein and whey, characterized in that one starts from an acidic decationized milk having a pH of 4.4. 4.6, and this milk is heated to a temperature of 10 to 600C to coagulate the casein it contains and the casein thus coagulated and the whey thus obtained is recovered. 9. A method of using the decationized acid milk, according to claim 7, for the preparation of casein and whey, characterized in that the acid decationized milk is mixed with a quantity of normal milk sufficient to raise the pH of the mixture to the vicinity of the isoelectric point of the casein, and then the mixture thus obtained is heated to a temperature of 10 to 60 C, to coagulate the casein contained both in the decationized acid milk and in the normal milk, then the casein thus coagulated and the whey thus obtained are recovered.  10. The method of claim 9, characterized in that the acidic decationized milk is mixed with a quantity of normal milk, sufficient to raise the pH of the mixture to a value of 4.4-4.6.  II. Process according to Claim 8 or 9, characterized in that the decationised acid milk or the mixture of decationized acid milk and normal milk is heated to a temperature of 40 to 500 ° C in order to coagulate the casein. 12. The method of claim 9 or 10, characterized in that the volume ratio between the amount of normal milk and that of decationized acid milk is about 1: 1.  ] 3. Process for the use of the acidic decationized milk according to claim 7, for the preparation of the cheese curd for rennet-free cheeses and for whey, characterized in that it comprises the mixing of the decationized acid milk with normal milk, quan  sufficient to raise the pH of the mixture to the vicinity of the isoelectric point of the milk casein - heating the mixture thus obtained to a temperature of 10 to 600C, to coagulate in the form of curd the casein contained both in the milk decationized acid, and in the untreated milk, and then - the cutting of the curd formed, its cooking at a temperature between 48 and 60C, the withdrawal of the whey and its recovery, washing the curd with cold water and draining said curd.  14. The method of claim 13, characterized in that the decationized acid milk is mixed with a quantity of normal milk sufficient to raise the pH of the mixture to a value of 4.4-4.6.  15. The method of claim 13, characterized in that  the mixture of decationized acid milk and normal milk is heated up  at a temperature of 30 to 350C to coagulate the curd. 16. The method of claim 13, characterized in that the volume ratio between the amount of normal milk and that of decationized acid milk is about 1: 1.