FR2507439A1 - PROCESS FOR THE PREPARATION OF QUAIL AND SERUM - Google Patents

Abstract

A PROCESS FOR THE PRODUCTION OF QUAIL AND SERUM FROM MILK BY ELECTROLYSIS, USING AN ELECTROLYTIC CELL IN WHICH THE ANODE AND THE CATHODE ARE SEPARATED BY AT LEAST ONE SEMI-PERMEABLE MEMBRANE WITH ION SELECTION. DURING THE ELECTROLYSIS HYDROGEN IONS ARE GENERATED IN THE MILK OR MILK-DERIVED LIQUID PRESENT IN THE ANODE COMPARTMENT, AND THE ACID SO FORMED IS USED TO ACIDULATE MILK OR A SIMILAR LIQUID CONTAINING CASEIN. THE MILK OR ACIDULOUS LIQUID IS TRANSFORMED AND SEPARATED INTO QUAIL AND SERUM BY KNOWN METHODS.

Description

1 2507439

  The subject of the invention is a process for preparing quail.

and serum.

  This invention relates to the production of curds and

  serum from milk, by means of electrolysis.

  Such a process is described in French Patent 0 352 'of 1905, and cited by Scherer in "casein, its composition, properties, its manufacture and its use" (Leipzig, 1919), pages 55, 56 For electrolysis , a carbon anode and an iron cathoc are used, separated by a porous container There are

  sodium hydrate at the cathode and skim milk at the anode.

  The milk is heated to -80 degrees centigrade The casein is separated

  11.0 Volts in 20 minutes and 18.0 Volts in 10 minutes.

  The intensity is always 160 Amps The resulting product is not pure casein but a protein co-precipitate

  denatured serum This explains why proteins coa-

  gulate when the amount of electricity passed is only one

  third to one sixth of the amount needed to form sufficient

  enough acid to acidulate the milk to the isoelectric point of pure casein Like the porous partition between the compartments to

  electrodes has no ion selection properties, some

  considerable amount of acid formed at the anode during electrolysis

gets lost in the process.

  In 1935, in the specification of Austrian Patent AT B 154131, precipitation of casein, which is considered to be a disadvantage for deacidifying milk by electrolysis, is avoided by surrounding the anode with a non-selective membrane, and

by separating it from the milk.

  The behavior of casein solutions during the election

  trolysis is described in the book by Sutermeister and Browne "Casein and its industrial applications" (New York, 1939) pages 86, 87 In casein solutions in acid, casein is deposited at the cathode; in an alkali solution the casein separates at the anode The quantity of precipitated casein satisfies Faraday's law, this quantity being directly

  proportional to the amount of electricity passed, and inverse-

  proportional to the amount of acid or alkali needed to dissolve casein In skim milk, casein is present not as a molecular solution, but as

  form of colloidal dispersion of micelles which, in addition to the

  tines, contain calcium phosphate.

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  Casein precipitation, by reducing the p H of milk to a kind of electrodialytic cell, is described by Kato in J Soc Chem Ind Japon, 35 (1933) suppli 158, cited in Sutermeister & Browne, "Casein and its applications industrial "(New York 1939), pages 21 and 47 This system of protein concentration by electrodyalization is also

  known as convection electrophoresis and electro -

  decantation with multiple membranes, as described in

  "analytical methods of Protein Chemistry" vol 1, pages 163 ff by Alexander and Block (London, 1960) In these methods, there is no direct contact between the electrodes and the liquid to be treated For a good separation between the proteins and the

  liquid phase, the liquid should be as little agitated as possible.

  In this respect, only a low intensity can be applied because of which the application on a technical scale would require very considerable apparatus For these reasons, the separation

  proteins, in accordance with these principles, are used exclusively

  as a laboratory process.

  The recovery of acidic casein from milk, is generally carried out by reducing the Ph to the isoelectric point of casein, which is in the vicinity of p H 4.6 Spellacy in "Casein, serum

  dried and condensed "(San Francisco 1953), described that this re-

  duction of p H can be obtained both by the transformation of milk sugar in milk into lactic acid, by fermentation

  microbiological and by addition of an acid, such as lac-

  tick, hydrochloric acid, sulfuric acid, acetic acid and the like The casein is then precipitated in the form of a curd which, with an appropriate choice of temperature, acidity and others

  conditions, can be separated by decantation, filtration, sieve

  sage or centrifugation of the remaining aqueous phase, called serum The resulting casein serum contains the residues of the added acid or lactic acid formed from lactose,

  which considerably reduces the value of such a serum compared to

  value of sweet serum produced during the production of

cheese.

  In particular for the use of serum as food,

  for example in the production of baby food and diet-

  ticks and in the production of feed for livestock it is

  traditional to remove the constituents of ash by electro-

  dialysis or by cation exchange, because the salts present in

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  the serum have a detrimental effect on its applicability.

  Casein serum produced by the most traditional method by adding acid, has this disadvantage in a further

  greater extent than mild cheese serum.

  In the description of Dutch Patent 138857 and

  Publication 161 348, methods are described for the production of casein, where the serum is adjusted to a very low p H, by means of

  cation exchange, and acidified serum is used to aci-

  feed the milk to the point where the casein precipitates As in this way, the milk is acidulated indirectly and the acid residues used are removed by washing during the regeneration of the ion exchanger, the casein serum thus produced contains a considerably lower amount of undesirable elements than the casein serum produced after the addition of acid or the fermentation of lactose A disadvantage of this method is that the regeneration of the ion exchanger requires much more acid only if acid is added directly

  Milk The resulting serum ash composition corresponds to

  lays in that of skim milk, where part of the cations have been replaced

  placed by hydrogen ions which are capable of forming

acids with the anions present.

  In the description of French Patent 1,479,361 and the

  particular additions 90,473 and 94,496, and Dutch Patent Application 67,03234 which belongs to the same family of Patents, describes a process for preparing coagulated milk products, where the serum is acidified by electrodialysis, and the acid serum

  is used to reduce the p H of milk to form a semi-curd

  blable with "cottage cheese" (white cheese) The application of this process requires complex electrodialysis equipment, capable of simultaneously treating at least four different liquids to

  using separate supply and exhaust pipes.

  The system then requires about the same amount of acid as is needed for direct acidification of milk, and in addition,

  uses electrical energy The resulting serum has again

  calf practically the same ash composition as the raw material for skim milk o part of the cations has been replaced

by hydrogen ions.

  In the Dutch Patent Application 66 09120, a met-

  more direct method for acidifying milk is described by the same inventor There, the milk is contained in a compartment

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  of an electrodialysis cell, compartment which is limited by two membranes and o, under the influence of an applied electric voltage, the hydrogen ions are forced to pass through the membrane located on the side of the positive electrode until to the milk compartment. A disadvantage of this method is that the proteins in acidified milk precipitate on the membrane and even in its pores, thus obstructing the flow of current and material. In a particular variant of this process, hydrogen ions are formed in the cell by water electrolysis

  present around the anode, in the compartment of the anode

  adorned by a membrane As the necessary cell includes both an anode compartment and a cathode compartment, where water with a relatively low controlled electrolyte content is contained, and as a result of a current efficiency generally

  rather unfavorable, resulting from the migration of anions, this pro-

  sold requires a relatively large amount of electricity

  with a relatively high resistance, taking into account the quan-

  tity of necessary acid equivalents We also use a

  device which is unnecessarily complicated and therefore expensive.

  However, it has been found that the above drawbacks of the

  previous methods for the precipitation of casein, can be avoided by using an electrolytic cell in which the anode and the cathode are separated by at least one membrane

  semi-permeable ion selection, generating hydro-

  gene in milk or a liquid derived from milk by electrolysis in the anode compartment of this cell, and using the acid thus formed to acidulate milk or a comparable liquid containing casein, and by known methods, by treating

  sour or liquid milk and separating it into curds and serum.

  In the electrolysis of solutions containing salts, one can succeed with an appropriate choice of the materials of the electrodes

  applied voltage, so that the net reactions follow

  occur at the anode and at the cathode, respectively 2 H O O + 4 H + 4 (e)

2 -2

  4 H 20 + 4 (e) __ + 2 H 2 + 40 H By separating the anode and cathode compartments using

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  of a semi-permeable membrane, with ion selection, it is possible to

  Sir that in the liquid surrounding the anode, the p H is reduced while simultaneously in the liquid surrounding the cathode, the

p H increases.

  Methods for dissolving electrolyte solutions in alkaline and acidic liquids by electrolysis, and the equipment that can be used for these processes, are described

  for example, in the description of the French Patent 1 324 549 bae

  on a US Patent Application filed in 1961.

  In the process according to the present invention, the re-

  duction of p H in the anode liquid is used to acidify milk and similar liquids containing casein, such as skim milk, semi-skim milk, whole milk, sweet or slightly acid buttermilk or a concentrate thereof can be carried out by direct contact of the liquid containing casein with the anoc It is also possible to reduce the p H of a liquid derived from casein-free milk by electrolysis, to an extent

  such as after mixing with milk or a similar liquid

  holding casein, the mixture reaches the isoelectric point.

  By choosing appropriate combinations of acidity, temperature

  and other conditions as is traditional in production

  tion of casein, it can be achieved that the casein precipitates at this isoelectric point, in the form of a curd which can be separated from the liquid serum phase, using current techniques, and that it can be treated with casein products However, at low temperature and / or high acidity, it

  it is also possible, using the invented method, to pro-

  to make a softer type of curd, comparable to the curd used for the preparation of acidic "cottage cheese" (white cheese) Subsequently, using traditional techniques of the production processes of "cottage cheese", such curd can be separated serum Generally speaking, such a curd is not suitable for the preparation of acid casein, unless special subsequent treatments can be used to obtain better washability The serum produced as a second product can be transformed into a serum product, traditionally At temperatures above 70 degrees centigrade, the proteins in the serum denature, so that in this case the process according to the invention does not produce pure casein , but a co-precipitate, while at the same time

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  produces a low value deproteinized serum.

  The most important advantage of the process according to

  the invention is that no acid, or anyway,

  significantly less acid, is necessary for the production of curds than by the previous techniques As a result, the serum produced as a by-product, is of better quality than by most traditional techniques, where lower quantities of

  liquid waste containing salts or acids, are produced.

  To carry out the process according to the invention, many

  lo traditional electrolytic cells, provided with a semi-permeable membrane, can be used It has been found that

  ion selection membranes based on organic polymers

  ion exchange properties, are particular-

  A satisfactory type of cell is that of the design used in particular for carrying out the electrodialysis processes. Here, the two electrodes consist of flat metal plates with membranes between them also having the form of flat plates, on the base of an organic polymer having ion exchange properties On

  found interposed between the electrodes and the membranes,

  flat spacers, made of a somewhat flexible synthetic plastic, which simultaneously achieve uniform spacing

  between the electrodes and the membranes, as much as possible,

  all, enclose the liquid compartments and make them watertight

  These leakage elements and the other parts have cutouts which coincide with each other, to define passages for the supply and evacuation of the treated liquid By compressing the elements of such a cell together , by lateral pressure, with an appropriate construction,

  we produce a cell of simple construction, which can be com-

  relatively simple hoeing with other similar cells

  laires, so as to form an electrolytic device, of small volume and of large active surface, namely, with a large

  processing capacity and low energy consumption.

  It has been found that, in an electrolytic cell where the anode and cathode compartments are separated by a membrane

  with anion selection, the milk can be acidified in the comparison

  anode anode, by electrolysis, until the casein pre-

  cipite in the form of a washable and suitably dehydrated curd

funny.

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  If the cathode compartment includes a salt solution, the serum is produced having the same composition as the casein serum produced by adding the acid corresponding to the saline solution to skim this milk. It is only in special cases that this variant of the process according to the invention has an advantage over and over traditional techniques, for example, when the price of acid is considerably

  higher than that of the corresponding salt.

  When a cation selection membrane is used between the two electrode compartments, during the electrolysis of the milk in the anode compartment, and of the salt in the compartment

  cathode, the milk cations will pass through the membrane to the solu-

  saline tion Consequently, the serum produced after separation of the curd contains, by comparison with skimmed milk, as many cation equivalents less than the acid equivalents

  were necessary for the reduction of p H The reduction of te-

  neur ash thus obtained, makes the serum more valuable than the acid casein serum produced after addition of acid to skim milk However, it is also possible to neutralize the acid serum or a liquid derived from it, by means hydroxyl ions formed in the cathode compartments If this is done in an electrolytic cell equipped with a cation selection membrane, it is possible to produce a neutral serum, with practically the same ash composition as the

  skimmed milk This is done in the same way, in an electro-

  lytic equipped with an anion selection membrane In this case, the acidulated mixture contains more salt than in the case where cation selection membranes are used. Consequently, on the one hand, the separated curd will contain more salt and will require more washing

  intense, but on the other hand, the electrical resistance of this

  lule will be less Depending on the importance of and the cost of washing the curd, and depending on the cost of electrical energy, it is therefore possible to choose one of these two possible variants

  of the process according to the invention.

  If as many hydroxyl ion equivalents are added to the separated serum as hydrogen ion equivalents are added to the milk, the neutralized serum may acquire p H

  greater than is desirable for most uses

  In fact, when the curd is separated, part of the acid produced is removed from the mixture, so that the

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  neutralized serum may have a p H higher than that of milk.

  This drawback can be avoided by acidifying part of the milk by means of electrolysis, where a saline solution passes through the cathode compartments. This alkalized saline solution is, in this case, produced as a by-product which can be used for the production of alkali or as a cleaning agent Instead of a saline solution, acid serum of other origin, can be neutralized cathodically By varying the ratio between the number of cells in which the serum produced from

  skimmed milk is cathodically neutralized, and the number of

  cells in which a different liquid passes through the

  cathode compartments, the p H of the neutralized serum can be adjusted from

so as to adapt to the needs.

  A different way to prevent neutralized serum

  to acquire an unduly high p H, is to regulate the milk by acidu-

  anodic lation, at p H above the isoelectric point of casein By virtue of this, no casein will precipitate in the anode compartments, so that the disadvantages of an increase in electrical resistance in the compartment

  anode, due to the presence of a casein deposit, and the ris-

  as clogging, will be avoided After electrolytic acidulation, add as much acid as necessary to reach the isoelectric point After the separation of the curd, the serum produced can be neutralized in the cathode compartments of the electrolytic cells used for acidulation, to a value

  p H depending on the p H reached in the anode compartments The se-

  neutral rum thus produced has an ash content higher than milk used as a raw material, of course, but this ash content is still considerably lower than that of the serum produced in the most traditional way, by adding acid

  skimmed milk, followed by neutralization.

  According to French Patent Application 2,418,627, the milk is also acidulated in a device equipped with membranes

  selection of ions at a p H at which no precipitation of pro-

  tins does not occur In this serum, the drawback found in the comparable process of Dutch Patent Application 66 09120, namely the formation of protein deposits

  on and in the membranes by which the hydrogen ions must

  wind pass, is avoided In the process according to this

  invention, there is no such passage and therefore the incon-

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  what to avoid is in this case of a different nature, except

  see obstructions in the liquid flow and affect the conduc-

  tivity of milk On this point, the French Demand process

  above, 2 418 627, concerns the double electro-

  dialytic, which requires as much added acid as acidulation

  milk directly by adding acid, and moreover,

  ment to as much residual solution of salts as when the acid is added to milk by electrodialysis In the process according to the present invention, these residual solutions are formed only if, at the same time, a corresponding amount of salt

  is eliminated from the milk, that is to say, if a serum is produced.

  The ash content of the serum may be even more

  reduced, in a simple way, by using electro-

  lytics each consisting of three compartments In such a cell, where the anode compartment is limited by a cation selection membrane and the cathode compartment by a membrane

  with anion selection, there is a concentration compartment in-

  These membranes Simultaneously with the acidulation in the comparison

  timent anode and neutralization in the cathode compartment, the liquid in this concentration compartment will be enriched with

  the equivalent amount of salt formed from the cations of the li-

  quide anode and anions of the cathode liquid.

  While a neutral casein serum produced by a traditional casein production process, by adding acid to skim milk, contains more salt than the raw material of milk, casein serum loses powder according to the present invention,

  will contain about as much less salt as milk.

  The above drawbacks of precipitation of casein in the anode compartment, namely the increase in electrical resistance and the risk of clogging, can also

  be avoided by acidulation in the anode compartment of a li-

  quide derived from milk, which does not contain casein, at p H au -

  below the isoelectric point of the casein, and by mixing the milk with this liquid to form an isoelectric mixture by which the casein coagulates in the form of curd This liquid can, for example, be the serum produced after the separation of the curd or a serum of different origin The stock solution produced after

  recovery of lactose from serum or permeate produced by ultra-

  filtration of milk or serum, or a concentrate of serum or one of the other liquids mentioned, can also be used to

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  this effect, provided that the serum produced is then treated in such a way that this addition has no harmful effect; Acidulation of milk with a liquid of p H reduced by a

  electrolytic medium, can be combined with various vari-

  antes of the methods of the present invention, as described

  previous For this indirect acidulation, electric cells

  trolytics with two compartments and a membrane with selection of

  cations or an anion selection membrane can be used

  and it is possible to neutralize the serum produced with the

  hydroxyl ions formed cathodically, with or without simulated desalination

  tanned, using a three-compartment electrolytic cell.

  It has been found that if the milk has been acidified directly by the anodic formation of hydrogen ions at the isoelectric point of casein, the presence of oxygen gas in the liquid can be

  used for a simple separation between the curd and the serum.

  If immediately after leaving the anode compartment, the

  diaper goes through a flotation tank with as little disruption

  mechanical as possible, the gas remains attached to the curd which, as a consequence, floats on the serum in the form of a foaming layer If the flotation tank is equipped with a conventional means for removing the liquid and the floating serum , a pre-separation between these two phases can be carried out

  this way Using traditional means like the pres-

  wise or centrifugation, the curd can later be released from the attached serum and gas Reduction in volume

  achieved by this separation by flotation, makes it possible to use

  smaller centrifuges for the dewatering process

  dratation, which consume less energy, and to do without

  stationary or vibrating screens used otherwise for this purpose

  comparable ceded where casein is separated by flotation, are

  known, for example, from French Patent 1,367,739 Con-

  In contrast to the process of the present invention, provision must be made to disperse the air in the serum mixture and

  The curd The process of the present invention makes these arrangements

  Superfluous The numerous possible variants of the process in accordance with the present invention offer the possibility of adapting the process to the various requirements which may be imposed on the products, which optimizes the cost of the material and of the treatment. acid than in previous comparable processes As a result, the serum products obtained contain less ash than is the case in traditional processes where, in any case,

  the same ash content can be obtained without producing a li-

  residual residue containing acid and / or salt.

  The process according to the invention is illustrated in and

by the following examples.

Example 1.

  The electrolytic cell used consisted of seven elements

  elements in the form of flat rectangular plates These elements

lom ents were in order:

  1 A support plate made of synthetic plastic.

  2 A titanium anode plate covered with platinum.

  3 A synthetic plastic plate with a cutout, fitted with supply and exhaust ducts, serving as a compartment

anode.

  4 A semi-permeable membrane with anion selection based on

ion exchange resin.

  A synthetic plastic plate similar to (1),

serving as a cathode compartment.

  6 A stainless steel cathode plate.

  i A support plate made of synthetic plastic.

  Cutting in the spacer elements made of plastic-

  synthetic tick, had a shape such that it leaves a sur-

  effective free transport surface of 167 square centimeters at the electrodes and the membrane The spacing between the anode and the membrane was 1.8 centimeters, that between the cathode and the membrane, 1.2 centimeters The seven elements were compressed together to form a leak-tight assembly by lateral pressure on the support plates The two electrodes were

  connected to a controllable direct current voltage source.

  A 5 liter buffer container was connected to the feed lines

  -mentation and evacuation-from the anode compartment A semi-container

  blable was connected to the cathode compartment The two receptacles were equipped with an overflow allowing, during the supply of new liquid, the excess to be evacuated in volume The liquid from the anode circulated in the anode compartment, at a speed

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* 800 liters per hour, the speed of the cathode liquid being

  500 liters per hour As soon as the liquid in the tam-

  pons reached the desired p H by electrolysis, the supply of fresh liquid to the container began, so as to keep the p H constant. At the start of the test, the tamporn containers were filled respectively with neutral fresh skim milk and with serum produced by acidulation of the skim milk with hydrochloric acid at p H 4.6

  and separating the aforementioned curds The two liquids have been

  held at 40 degrees centigrade After sufficient pro-

  serum by electrolysis of skimmed milk, this serum was used

  used to maintain the p H of the cathode liquid The anode liquid was checked at p H 4.6 and the cathode liquid at

p H 7.0.

  The acidulated skim milk from the overflow of the anode buffer container was collected in a different container. In this container, the casein curd floated as a result of the push of the attached gas bubbles, so that the separation of the serum was possible in a simple way. The remaining curd lent itself well to the transformation into casein purified by traditional methods of washing, sieving, centrifuging, pressing and drying.

  At an intensity of 1.5 Amps, corresponding to a den-

  9.0 m A / cm 2 current site, it was possible to acidify 1 Kilo-

  gram of skim milk per hour and neutralize 1.44 Kilograms

  acid serum at p H 7.0 The electricity supplied per hour corresponds to

  lays on the formation of 56 meq of hydrogen ions per liter of milk

  skimmed In traditional methods of preparing the

  seine, 50 to 60 meq / kg of mineral acid or 77 to 111 meq / kg of lactic acid are generally added to the skimmed milk In this test, the yield of hydrogen ion formation was greater than

  %, calculated on the amount of energy supplied.

  The analyzes specified in Table I show that the

  transmission of electricity between compartments can be explained

  quer essentially by the migration of chloride ions.

Table I.

  Skim milk Acid serum Neutral serum Dry matter% by weight 9.16 6.61 6.32 Proteins "3.58 0.68 0.65 Ash" 0.78 0.78 0.73 Chloride "0.10 0.28 0.16 The electrical resistance of the cell depended on the

  applied voltage according to specification in table II.

Table II.

  Voltage 24 8 Volts 5 7 8 5 11 3 14 2 16 9 19 6 2: Current 8 O Amperes 1 0 2 0 3 0 4 0 5 0 6 0 Current density 47 9 m A / cm 2 6 0 12 0 18 0 24 0 29 9 35 9 4

Example II

  Using the same apparatus and the same process as in

  Example 1, the skimmed milk was acidulated with p H 5.3 by electro-

  lysis, which did not lead to the precipitation of casein By adding hydrochloric acid to the acidified skimmed milk at p H 5.3, the casein precipitated at p H 4.6 After separation of the curd, the serum p H 4.6 was produced, which was neutralized at p H 7.0

  by electrolysis in the cathode compartment.

  At an intensity of 1 Ampere, it was possible to acidify

  1 kilogram of skimmed milk at p H 5.3 and neutralize 1 kilo-

  gram of serum from p H 4.6 to p H 7.0, per hour During the elect

  trolysis, 'the chloride content of skim milk has increased by 0.10%

  by weight at 0.21% by weight This shows that the transmission of elect

  tricity by the membrane can be explained mainly by the

migration of chloride ions.

Example III.

  Using equipment similar to the description

  of example 1, except that instead of an anion selection membrane, a cation selection membrane was interposed between the compartments of the electrodes, the skim milk was acidulated

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by electrolysis.

  At the start of the test, the anode buffer container was filled with neutral skim milk, and the cathode buffer container

  saline solution containing 2% by weight of potassium chloride.

  As soon as the p H in the anode buffer container has decreased to 4.6, the supply of fresh neutral skim milk to the container has

  started to control the p H at this value The p H in the reci-

  pient cathode buffer was checked between p H 3 and 4, by addition of dilute hydrochloric acid By adding water, the conductivity in this container was checked at 25 m Scm 1 The two liquids were kept at a temperature of 44 degrees centigrade The other test conditions were the same as at

Example 1.

  The precipitation and separation were carried out as described in Example 1 After washing and drying, the product was casein containing 94% by weight of dry matter, 92% by weight.

  weight of protein and 1.8% by weight of ash.

  At an intensity of 1.5 amps, 1 kilogram of milk

  mé could be acidulated at p H 4.6 per hour.

  The electrical resistance of the cell depended on the

  applied voltage as specified in Table III.

Table III.

  Voltage Volts 6 5 9 5 13 4 16 5 19 0 21 8 24 5 Current Amperes 1 2 3 4 5 6 7 Current density m A / cm 2 6 12 18 24 30 36 42 The analytical results specified in Table IV show that the transmission of electricity between compartments can mainly be explained by the migration of ions, sodium,

potassium and calcium.

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Table IV.

  Skim milk Acid serum Dry matter,% by weight 9.17 6.00 Proteins "3, 68 0.68 Ash" 0.72 0.40 wt "6.7 4.6 Sodium" 0.04 0.02 Potassium "0.15 0.06 Calcium" 0.14 0.08 Chloride "0.11 0.10

  Analysis of the saline solution in the tam-

  cathode pon for protein and lactose content, a

  showed that milk losses were negligible.

Example IV.

  The electrolytic cell used consisted of

  nine elements having the same form as in the description of the example

  ple 1 Between the two compartments of the electrodes, however, there was also provided a concentration compartment of the same shape, limited on the anode side by a membrane with selection of

  cations, and cathode side by an anion selection membrane.

  The thickness of the anode compartment was 1.2 cm, that of the concentration compartment 1.8 cm and that of the cathode compartment 0.6 cm. The concentration compartment was connected to a buffer container having a 1.5 liter capacity The liquid circulation speeds were: anode liquid 520 liters per hour, concentrating liquid 250 liters per hour, cathode liquid 220 liters per hour To fill the buffer container of the anode and keep

  later this liquid at p H 4.6, we used new skim milk

  be; to fill the cathode buffer container, and thereafter

  laughter keep it at p H 6.9, we used acidulated serum

  electrolytically from p H 4.6 The buffer container of concentra-

  tion was initially filled with a saline solution containing 2% by weight of potassium chloride This container has not been checked for p H or conductivity All liquids have

  been kept at a temperature of 42 degrees centigrade.

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  The precipitation and separation of the curd

  carried out as described in Example 1.

  At an intensity of 1.5 amps, 1 kilogram of milk

  skim may have been acidulated at p H 4.6 per hour Special analyzes

  shown in Table V show that the transmission of electricity

  between the cathode compartment and the concentration compartment

  tration can mainly be explained by the migration of chloride ions and the transmission between the anode compartment and the concentration compartment, by the migration of sodium ions,

1 opotassium, calcium and magnesium.

Table V.

  Dry matter% by weight Proteins "Ash p H VI Sodium" Potassium "Calcium" 2 o Magnesium "Chloride" Skimmed milk Acid serum

9.08 6.40

3.52 0.72

0.75 0.45

6.7 4.6

0.05 0.03

0.17 0.08

0.13 0.08

0.02 0.01

0.10 0.10

  Neutral serum 6.24 0.70 0.36 6.9 0.03 0.08 0.08 0.01 0.03 During the test, the salt content in the concentration compartment increased by 2% by weight at 18% by weight The p H a

varied between 5.5 and 6.1.

  Per kilogram of skim milk processed, an average of 3.8 grams of salt was concentrated in this compartment, of which 1.6 grams was in the form of cations from skim milk, and

  the rest as anions from the serum.

  At a salt content of 2% by weight in the concentration compartment, the resistance of the cell depended on the

  applied voltage, as specified in Table VI.

Table VI

  Voltage Intensity Current density Volts Amperes m A / cm 2 The reduction in the ash content of the serum which could be obtained during this test and during the tests described in the previous examples, compared to the ash content of a type The traditional casein serum appears in Table VII below.

Table VII.

  Acidulation mode Membranes Dry matter content,% by weight% of dry matter protein Ash p H addition of H 2504 n * t Electrolysis t and t none t selection of anions selection of anions selection of cations selection 4 cations + anions n? 6.4 6.4 6.6 6.3 6.0 6.4 6.2 11.4 11.4, 6, 3 11.3 11.3 11.2 12.5 14.0 11.9 4 .6 7.0 4.6

11.5 7.0

6.7 4.6

7.0 4.6

.8 7.0

Example V.

  The electrolytic cell used complied with the

  description in Example 1 At the start of the test, the two

  buffer patients were filled with p H 4.6 serum, produced in use

  reading the electrolysis as described in Example III The li-

  that in both containers was maintained at a temperature of 42 degrees centigrade As soon as the p H in the anode buffer container decreased by 1.2, new serum from p H 4.6 was fed at a rate allowing the p H to be kept at a constant value of 1.2 The p H of the cathode liquid was controlled in the same way to be kept at 6.8 The serum of p H 1.2 thus produced was mixed with skim milk at a temperature of

  42 degrees centigrade, to produce a mixture of p H 4.6.

  The curds thus formed were separated by sieving, washed 17 -

18 2507439

  and dried in the traditional way The remaining serum after separation

  curd ration was used to control the p H of liquids

  in the electrode buffer containers.

  At an intensity of 1 Ampere, it was possible to pro-

  down 0.34 kilograms of serum from p H 1.2 per hour, with which 0.68 kilograms of skimmed milk could be acidulated with p H 4.6 En

  at the same time, 1.1 kg of p H 4.6 serum could be neutralized.

read at p H 6.8.

  The analyzes listed in Table VIII show that the transport of electricity between the compartments of the electrodes could be explained essentially by the migration of chloride ions.

Table VIII.

  Serum isoelec Acid serum Neutral 1 S serum Dry matter% by weight 6.43 6.33 6.12 Proteins "0.60 0.63 0.60 Ash 0.75 0.73 0.70 wt" 4.6 1.2 6.8 Chloride N 0.29 0.65 0.17 The electrical resistance of the cell depended on the

  applied voltage as specified in table IX.

Table IX.

  Voltage Volts Current Amperes Current density m A / cm 2

Example VI.

  The p H 1.2 serum produced as described in Example

  ple V, was added to fresh skimmed milk until its p H was 5, 3 No curds precipitated Subsequently, dilute hydrochloric acid was added to the mixture, to adjust the p H to 4.6 The curd thus formed was separated from the mixture by

19 2507439

  sieving and then washed and dried to form casein Part of the separated serum was passed to the anode buffer container

  an electrolytic cell, as described in Example 1,

  tapn and the rest at the cathode container, after which the addition of skimmed milk with serum, after acidulation with chlorhy-

  drique, separation of the curd, and electrolysis, continued

  live continuously At an intensity of 1.0 Ampere, 0.34 kg of p H 1.2 serum could be produced, with which 1.11 kg of skim milk could be acidulated with p H 5, 3 On time,

  1.35 kg of p H 4.6 serum was produced, of which 1.01 kg

  gram was neutralized at p H 7.0 by electrolysis In this way

  Less, 100 kilograms of skim milk were processed to produce.

  in addition to casein, 91.0 kilograms of neutralized serum of p H 7.0 + minor amounts of neutral and acidic serum which, together

  matched the amount of serum with which the assay was com-

mencé (20 liters).

  The analyzes specified in Table X show that the transport of electricity between the compartments of the electrodes

  can mainly be explained by the migration of chlo- ions

rure.

Paintings.

  Serum isoelec Acid serum Neutral serum Dry matter% by weight 6.40 6.35 6.20 Proteins "0.64 0.65 0.62 Ash" 0.76 0.74 0.73 p H "4.6 1 .2 7.0 Chloride "0.28 0.66 0.15 The cell's electrical resistance depended on the

  applied voltage, as specified in Table XI.

Table XI.

Voltage Volts Current Amperes

Current density m A / cm 2.

_ 2507439

Example VII

  For the acidification of whole milk, a cell was used.

  The electrolytic cell formed by a cathode compartment and an anode compartment with a cation selection membrane between them. The cathode compartment was a closed chamber of synthetic plastic, comprising supply ducts

  and discharge for the circulation of a saline solution from

  shot from a buffer container with a capacity of 5 liters.

  The anode compartment was an open-top chamber also made of synthetic plastic, provided with supply and discharge conduits for the circulation of milk, and also with an overflow for discharging the acidulated product at an equal speed. to which fresh milk was

added to the circulating liquid.

  In these compartments there was a stainless steel cathode and a titanium anode covered with platinum, both having

the shape of a flat plate.

  Liquids circulated through the anode compartment at a speed of 120 liters per hour and through the cathode compartment at 250 liters per hour The temperature was maintained at 20 degrees

  centigrade At the start of the test, the compartments were replaced

  folds of whole milk and a saline solution respectively

  holding 2% by weight of potassium chloride After applying a voltage of 16 volts, with a measured intensity of 10 amperes, the supply of fresh milk to the anode liquid began as soon as the p H fell to 4.4 p H in the cathode liquid was controlled between 3.0 and 4.0, by supplying hydrochloric acid The acidulation of 1 kilogram of whole milk has

  required the passage of 59.5 milliequivalents of electricity.

  The curd resulting from the acidulation floated due to the presence of gas bubbles, and flowed from the anode compartment through the overflow. The serum was separated from the curd by passage in the traditional way for the production of " cottage

cheese ".

  The pressed curd contained 25.8% dry matter, 9.6% protein and 10.4% milk fat The product had a structure comparable to that of "cottage cheese" made by a traditional process The taste was soft acid without other

21 2507439

  characteristic bad taste, under which the curd is

  was good at processing into a tasteful product, being

  mixed, for example, with fruits, herbs and the like.

  The invention is in no way limited to that of its modes of application, nor to those of the embodiments of its various parts having more

  specially indicated; on the contrary, it embraces all its variants.

22 -

R E V E N D I-CAT 10 NS

  -1 A process for the production of curds and serum

  from milk by means of electrolysis, characterized by the use

  creation of an electrolytic cell in which the anode and the cathode are separated by at least one semi-permeable membrane with ion selection, by the generation of hydrogen ions in the

  milk or a liquid derived from milk by electrolysis in the compar-

  anode of this cell, and by the use of acid

  thus formed to acidify milk or a comparable liquid containing

  casein, and by known methods, by the transformation

  Omation of sour milk or sour liquid and its separation into

curd and serum.

  -2 A process according to claim 1, character-

  laughed at by the use of an electrolytic cell with a mem-

  brane with selection of anions, as separation between the compar-

  the cathode and that of the anode.

  -3 A method according to claim 1, characterized by the use of an electrolytic cell with a cation selection membrane, as separation between the compartment

cathode and anode compartment.

  -4 A method according to claim 1, characterized

  by the use of an electrolytic cell comprising a com-

  concentration compartment separated by a membrane with selection of cations from the anode compartment, and by a membrane with selection

  anions of the cathode compartment.

  -5 A process according to claim 1, 2, 3 or 4, characterized by the generation in milk or in a comparable liquid containing casein, as many hydrogen ions by

  the reaction of the anode that it takes to reach the isoepoint

electric casein.

  -6 A process according to claim 1, 2, 3 or 4, characterized by the generation of hydrogen ions in milk or a comparable liquid containing casein by the reaction of the anode, at a p H value to which no precipitation of 23 -

  casein does not occur yet, and after electrolysis, by the addi-

  tion of an acid or a liquid having a p H below the isoelectric point of casein, so that the mixture

  acquires the isoelectric p H of casein.

  -7 A process according to claim 1, 2, 3 or 4, characterized in that, in a casein-free liquid drawn from milk, the hydrogen ions are generated by the reaction of the anode to a p H value at - below the isoelectric point of casein and this liquid is added to milk or comparable liquid containing

  lode the casein, so that the mixture acquires the p H isoé

electric casein.

  -8 A process according to claim 7, characterized in that the casein-free liquid drawn from milk is serum

  produced by the process according to the preceding claims, ot

  -15 a product produced from such a serum.

  -9 A method according to one of the preceding claims.

  teeth, characterized by the generation in the cathode compartment of d 1 hydroxyl ions in the serum produced by a process in accordance with

  one of the preceding claims, or in a derived liquid

of such a serum.

  -10 A method according to claim 5, characterized in that the curd from the sour milk is separated from the serum

  by flotation, using the gas formed during electrolysis.