US3410701A - Process for the production of milk-product powders - Google Patents

Description

United States Patent 3,410,701 PROCESS FOR THE PRODUCTION OF MILK-PRODUCT POWDERS Jacques Jean Ciboit, Paris, France, assignor to Societe Anonyme dite: Etablissements Laguilharre, Courbevoie, Hauts-de-Seine, France, a company of France No Drawing. Filed Feb. 23, 1965, Ser. No. 434,617 Claims priority, application France, Feb. 21, 1964, 964,641 3 Claims. (Cl. 99-203) ABSTRACT OF THE DISCLOSURE Production of a milk-product concentrate containing more than 45% dry solids, at a temperature greater than 45 C., by spray-drying said product to obtain a powder having a water content within the range of 4.5 to 7%, an followed by subjecting the resulting powder to a different secondary drying treatment so as to reduce its water content to approximately 3.5%.

This invention is directed to a process for the production of milk-product powders and also comprises, by way of novel industiral products, the powders which are obtained by means of said process. The invention is applicable especially, although not exclusively, to the production of powders of skimmed milk and the numerical values indicated in the following description relate to this particular product.

It is known that, in conventional spray-drying processes in which the starting material is a concentrate containing as a rule less than 45% of dry product and in which a dry powder containing less than 4% water is collected at the outlet of the spray chamber, the powders of the above type which are produced by these processes have satisfactory real solubility. On the other hand, these powders have a high content of occluded air and low density. The presence of a high proportion of occluded air gives rise to a disadvantage in that troublesome foam formation results when dissolving the powder for the purpose of reconstituting the milk. Furthermore, the low density of the said powders results in high total bulk of the containers in which they are packed. This lastmentioned disadvantage becomes particularly marked when the powder which is produced by a conventional spray-drying process is subjected to a later moistening treatment or so-called instantaneization treatment which is intended to increase its wettability, the known treatments of this type having the effect of reducing even further the density of the powder.

It is an admitted fact that a number of means are already known for increasing the density of a powder produced in a spray-drier and which consist either in increasing the percentage of dry material contained in the initial concentrate, or in increasing the viscosity of the said concentrate, or in reducing the speed of rotation of the disc in the casein which the spray atomization of the concentrate is efiected by means of a centrifugal disc, or in reducing the pressure in the case of nozzles for spraying under pressure or with compressed air, or alternatively in modifying the inlet temperature of the drying air in the spary chamber. It is also known, however, that all the means referred-to result in the production of powders which have poor real solubility if the drying in the spray-drier is continued until a water content below 4% is reached. If the spray drying process is carried out under these conditions, the powder retains poor real solubility even after an instantaneization treatment.

In addition, there have already been proposed a num- 3,410,701 Patented Nov. 12, 1968 p CC her of different processes for the production of skim med-milk powder or lactoser-um in which a concentrate containing a proportion of dry material which is higher than 45 is subjected to a spray-drying process so performed as to collect at the outlet of the drying chamber a powder having a high water content which can in certain cases be as high as 18%. These known processes, which aim to achieve without any external addition of water the stabilization of the product by the more or less complete crystallization of the lactose contained in amorphous form in the starting concentrate, in fact require the presence in the powder of a free moisture content which is higher than 8%. This is essential in order to ensure crystallization, which takes place in different cases either within the drying chamber itself or within a secondary apparatus in which the powder extracted from the drying chamber is maintained for a certain period of time in the presence of this moisture, the powder being subjected if desired. to a subsequent complementary drying operation. Processes of this kind are attended by serious operating difliculties by reason of the sticky nature of powders which have such a high moisture content and which adhere strongly to the walls of the drying chamber, thereby calling for the utilization of mechanical or compressed-air means for the purpose of detaching them therefrom. In addition, this same moisture content has the effect of producing a certain degradtion of the proteins, thereby resulting in a reduction in the real solubility of the powder. It has further been observed that powders in which the lactose has crystallized do not lend themselves to a subsequent instantaneization treatment as readily as normal spray-dried powders, in particular when it is desired to obtain a powder in the form of granules.

The process according to the present invention has for its object to elimniate the various drawbacks which have just been outlined by making it possible to obtain milkproduct powders which have in particular the following combination of properties:

(1) Contrary to the powders produced by conventional spray-drying process, the lactose contained in the powders produced according to the invention is practically unmodified or, in other words, has remained in an amorphous form;

(2) The said powders have a high density;

(3) They contain a small proportion of occluded air;

(4) They have excellent real solubility.

To this end, the process in accordance with the in vention consists in principle in subjecting to a spraydrying process a concentrate containing a proportion of dry material which is higher than 45 and preferably between 50 and and having a temperature which is higher than 45 C. and preferably in the vicinity of to (3., by effecting the drying in the spray-drier until a powder is obtained having a water content within the range of 4.5 to 7% and preferably between 4.5 and 6%, .and in then subjecting the powder thus obtained to a secondary drying operation so as to reduce its water content to approximately 3.5%.

Apart from the characteristic properties with which the powder is endowed as indicated earlier, it should be pointed out that, by operating within the specified limits of water content at the outlet of the drying chamber, the process in accordance with the invention is not liable to result in the formation of any deposit on the chamber walls, thus considerably facilitating operating conditions with a view to achieving a continuous and steady manufacturing process on an industrial scale.

In the practical application of the invention, the spraydrying stage will preferably be eifected in a drying tower fitted with a spraying device consisting either of pressure nozzles or compressed-air nozzles. Good results can someture of the drying air in the spray-drier), While at the times also be obtained by making use of a spray device same time retaining the other characteristic features of with centrifugal disc. the invention (temperature of injection of the concentrate The secondary drying of the powder produced in the higher than 45 C. and preferably in the vicinity of 60 spray-drier is preferably carried out immediately after 5 65 C., water content of the powder at the outlet of the separation of the powder from the drying air, and can drying chamber within the range of 4.5 to 7%, and secbe carried out by any suitable means, for example in a ondary drying of the powder). However, it would appear compressed-air system which is supplied with hot air or that, among the known means for increasing the density on a drying table. of the powder, the increase in concentration of the start- In all cases, the powder which has been subjected to the 10 ing concentrate constitutes the most advantageous factor secondary drying process can be subjected if necessary to in the practical application of the invention since it addia bolting operation or to the action of a cyclone selector tionally results in a substantial reduction in the quantity for the purpose of separating the finest particles from the of water which is evaporated in the spray-drier and conseid powder. quently a very considerable economy in total consumption In all cases also, the powder which has been subjected of steam which is necessary for the entire process. to the secondary drying treatment can undergo a cooling Whatlclaim is: process, 1. Process for the production of milk-product powders, The comparative table given below indicates b way of comprising the steps of providing a starting milk-product nonlimitative example the results obtained in the producconcentrate containing a proportion of dry material which tion of a skimmed milk powder, on the one hand by is greater than 45% and having a temperature which is means of a conventional spray-drying process and, on the greater than 45 C., subjecting the starting milk-product other hand, by means of the process according to the inconcentrate to a spray-drying process by effecting the vention by making use in both cases of different types drying with drying air in the spray-drier until a powder of spraying devices. is obtained having a water content within the range of NORMAL TREATMENT WITHOUT REMOISTENING OF THE POWDER Pressure spraying nozzles Compressedair spraying Centrifugal disc nozzles Conventional Treatment Conventional Treatment Conventional Treat ment;

spraying according spraying according spraying accordin treatment to the treatment to the treatment to the invention invention inventi Concentration prior to spraying 43-44% 48 to 55%. -4 46 to 48%. 47% 50 to 75%. Temperature of the concentrate a. 45 C 60 C 45 C 60 C 45 C 60 C. Intermediate moisture content of the 5.5%. 5.5%. 5.5%.

powder.

Final moisture content 3.5% -5%- 3 5% 35%. Commercial density 0.6. r.. 0.7 .6 0,... 0.7 5 Occluded air 15 cmfi/IOO g 8 emf/100 16 (bin 00 g 8 0 20 to 30 emfl/IOO g. Real solubility Good Very good"... Good Go d,

4.5 to 7%, and separating the powder from the drying In the application of the process according to the inair and then subjecting the powder thus obtained and havvention, it is possible in all cases to increase the propor- 40 tions of dry material contained in the starting concening a Water content within the range of 4.5 to 7% directly trate as indicated in the above table so as to bring them, to a different secondary drying process for a period of for example, above provided that the evaporator tlme so as to reduce its water content to approximately which is employed for the preparation of this concentrate 3.5%. permits the possibility of obtaining such a degree of con- 2. Process for the production of milk-product powders centration in normal industrial operation. It is in that as defined in claim 1, wherein the starting milk-product case also necessary to increase the moisture content of the concentrate contains from 50 to 55% dry solids and is at powder at the outlet of the spray-drier to approximately a temperature within the range of to C. when it is 66.5%. r fed into the spray drier, and wherein the powder obtained Furthermore, as has been mentioned earlier, all the nufrom the spray-drying process has a water content within merical values which have been specified in the foregoing the range of 4.5 to 6%. have been given in the case of skimmed milk. However, it 3. Process in accordance with claim 2, further includshould be made clear that the invention also applies to ing the Steps of subjecting the powder from the secondary the treatment of other milk products and in particular to p drying process to a separation operation so as to separate milk having a high fat content (whole milk or enriched the finest particles therefrom, and then reintroducing the milk) and results in a similar improvement in the qualities separated fine particles into the spray-drier. of the powders which are finally obtained, although this last-mentioned application has higher concentrations of References Clted Starting Concentrates- UNITED STATES PATENTS It must finally be understood that the present invention 60 2183 5,586 5/1958 Peebles 99 56 also includes withln its scope any alternative form of ex- 2 934 434 M1960 H artman et a1. 99-56 ecutlon of the process described above, in WhlCh the 3 065 076 11/1962 W enner et al 99 203 X lncrease in concentration of the starting concentrate as a 3 231 386 N19 Hutton et a1 99 203 X means for increasing the density of the final product is replaced by one or a number of other known means for FOREIGN PATENTS achieving the same result and which have been mentioned 226,996 1/ 1959 Australia,

earlier (increase in the viscosity of the concentrate, reduction of the speed of the spraying disc or of the pressure RAYMOND JONES, Primary Examine!- of the spraying nozzles, modification of the inlet tempera- HEYMAN, Assistant