GB1598362A - Manufacture of food preparations - Google Patents

Description

(54) IMPROVEMENTS RELATING TO THE MANUFACTURE OF FOOD PREPARATIONS (71) We, KERRY CO-OPERATIVE CREAMERIES LIMITED, a Co-operative Society registered in the Republic of Ireland under the Industrial and Provident Societies Acts 1893 to 1936, of Listowel, County Kerry, Ireland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to manufactured food preparations of the kind which are based on dairy products, but which have a relatively low calorie content and a relatively high protein content as compared with "natural" dairy products such as butter.

The invention is particularly, though not exclusively, concerned with spreadable preparations of the above-mentioned kind, which can be used for domestic purposes in place of "natural" butter.

Low calorie, high protein preparations of the kind referred to consist of emulsions of water and fat (oil) and they may conveniently be made by emulsifying together, separately prepared aqueous and fat phases, the major part of the protein in the final product, being introduced by way of the aqueous phase.

According to the present invention, there is provided a process for making a preparation of the kind referred to, by emulsifying an aqueous phase with a fat phase, and in which the aqueous phase comprises skimmed milk or sweet buttermilk to which has been added a caseinate salt or salts. The fat phase may comprise fat or oil derived from full fat milk (for example, butter, butter-oil, cream or any combination thereof) with or without the addition of vegetable oil.

The caseinate salts used in the process of the invention may conveniently be derived from skimmed milk by acid precipitation, followed by treatment of the curd with alkali, so as to yield the caseinate salts, which may then be spray-dried so that they can be stored until required for use. Appropriate quantities of the spray-dried caseinate salt or salts are then dissolved in the skimmed milk or butter milk which constitutes the aqueous phase.

In carrying out the process of the invention, the protein-enriched aqueous phase is emulsified with the fat phase in proportions such that the aqueous phase accounts for from 25 to 65% by weight of the finished product. Emulsification is effected at a temperature such that the fat phase is in liquid form. The emulsion is thereafter pasteurised, cooled and homogenised by mechanical working. As will be explained later, we have found that the conditions under which the cooling and mechanical working of the product are effected are of great importance from the point of view of ensuring that the product does not deteriorate prematurely during storage.

As already mentioned, during the preparation of the aqueous phase, caseinate salts are added to skimmed milk or sweet buttermilk, so that the latter is enriched in protein. It will be understood that despite the fact that the added caseinate salts may be obtained by acid precipitation, the medium to which the caseinate salts are added (skimmed milk, or sweet buttermilk derived from sweet cream butter manufacture) is itself a "sweet" medium. Thus the final product is a sweet product which is highly acceptable as a substitute for butter, to persons whose palate is accustomed to sweet cream butter, unlike certain other spreadable preparations which are "sour" and therefore unacceptable to persons who are used to eating sweet cream butter.

The invention will now be described in greater detail, by reference to the manufacture of one particular form of spreadable preparation, this description being given by way of example only. The protein-enriched aqueous phase and the fat phase are prepared separately, before combined in the form of an emulsion.

Source of added protein The source of the additional protein to be added to the aqueous phase is casein which has previously been obtained from skimmed milk, by acid precipitation. For this purpose the milk is treated with hydrochloric acid and steam, so as to reduce the pH of the milk to the isoelectric point thereof. Commercially available 10.5N hydrochloric acid is used, diluted to 2N. Thus for example, 50 gallons of 10.5N acid are diluted with water to yield approximately 250 gallons of diluted acid, and this is sufficient to treat 7500 gallons of skimmed milk. The starting pH of the milk is about 6.6 and this is reduced by the addition of the acid to 4.6. The resulting precipitated curd is then recovered by filtering through a 100-mesh nylon screen.

The curd recovered in this way is then washed with water and treated with alkali such as sodium or calcium hydroside or carbonate. For example, 10% by weight of a commercially available food-grade alkali powder (consisting of sodium and calcium hydroxides) can be used, dissolved in water.

In this way the curd is completely redissolved in the form of caseinate salts. These salts have excellent water-binding properties and therefore assist in maintaining a stable emulsion, in the eventual product.

The caseinate salts produced in this way are dried by spray-drying and can then be stored until required for use.

Aqueous phase The basis for the aqueous phase may be skimmed milk or sweet buttermilk. Appropriate quantities of the spray-dried caseinate salts are dissolved therein to give a protein content in temixture of 10 to 15% by weight. When buttermilk is used, this is obtained as the by-product of sweet cream butter manufacture. Such buttermilk has a high content (relative to milk) of phospholipids. These substances have good emulsifying properties and thus they also assist in maintaining the stability of the water-in-oil emulsion in the final product.

The mixture comprising skimmed milk or buttermilk and caseinates will constitute the aqueous phase in the end-product. As it is prepared in the manner described above, it is transferred to a holding tank where it is stored for use as required.

When the mixture is withdrawn from the holding tank for use, any necessary water-soluble additives are added. These may comprise flavouring and buffering agents, such as sodium chloride sodium citrate and calcium hydrogen phosphate. The quantity of such additives may be in the range of from 1 to 3% by weight of the mixture. The mixture is then fed to a buffer storage tank, from which it is supplied as required in the emulsification step.

At this stage, the mixture is checked in respect of its pH, its protein content, its fat content and its flavour (the latter being monitored by organoliptic assessment). In addition, samples are taken for bacteriological analysis, for hygiene purposes.

When necessary, the pH of the mixture can be adjusted by the use of standard buffering agents. The pH should be on the acid side of neutral. A value anywhere in the range 6.4 to 7.0 is acceptable, the preferred value being about 6.8.

Fat phase Although there are various possible starting materials for the fat phase, they all originate in full fat milk. Thus butter-oil or butter may be used (both as produced by conventional methods) or cream (or ay combination of the three). These materials are used in liquid form, so that if butter is used, it must first be melted in a melting vessel. Since butter is itself, a water-in-oil emulsion, the liquified butter must be kept agitated in order to maintain the existing emulsion-state.

The liquid fat material (i.e. butter-oil, liquified butter and/or cream) is stored in a holding tank, in which the temperature is maintained at from 40 to 60 , the preferred temperature being 48"C. When the liquid is withdrawn from the holding tank for use, any necessary oil-soluble additives are added. These may comprise, for example, vitamins, colouring agents and emulsifying agents. The amounts to be added vary, depending on the required composition and physical characteristics of the final product. As emulsifying agents, there may be used lecithin and other monoglycerides and diglycerides in an amount up to 0.5% by weight of the finished product.

As previously mentioned, the fat phase may contain vegetable oil, but the dairy fat always predominates. Examples of suitable vegetable oils are soya bean oil and coconut oil, used in amounts of from 10 to 40% by weight of the total fat phase, depending on the desired characteristics of the final product.

The above-mentioned ingredients of the fat phase are thoroughly mixed in a mixing chamber before being finally transferred to a buffer storage tank. This tank also is maintained at a temperature of from 40 to 60"C, the preferred temperature being 45"C.

Emulsification Emulsification takes place in an emulsification chamber to which the aqueous and fat phases are supplied from their respective buffer storage tanks by means of proportioning pumps, which can be set to supply the exact blend of the two phases, required for emulsification purposes.

The emulsification chamber consists of a specially designed vessel which is equipped with agitators and paddles, and with both heating and cooling facilities, so that the temperature of the mixture in the chamber can be raised or lowered as necessary. Emulsification takes place in the temperature-range of 40 to 500C, the preferred temperature being 45 C, and is usually complete in approximately five minutes.

After emulsification has been completed, the emulsion is then checked for such parameters as fat content, protein content and pH. The pH of the emulsion should be between 6.4 and 6.8 (ideally 6.6) and it may be adjusted by the addition of standard buffering agents. If any of the other parameters is found to be outside the required range, it can be corrected by judicious addition of appropriate amounts of either phase, by way of the proportioning pumps.

The emulsion then passes to a pasteurisation vessel in which it is subjected by means of a heat exchanger, to "HTST flash pasteurisation", that is to say "high temperature short time" pasteurisation. A suitable temperature is 72"C for 15 seconds.

Since at this temperature the emulsion is liquid, a plate heat exchanger can be used having closely spaced fixed plates between which the liquid emulsion passes.

The emulsion is subsequently cooled to its solidification temperature (approximately 14"C). Due to the semi-solid state of the emulsion at this stage, a plate heat exchanger is no longer suitable. Instead, a "scraped surface" heat exchanger is used, that is to say an apparatus having a heat exchange surface (conveniently in the form of a tunnel) on which the emulsion congeals as it cools and from which the congealed material is scraped off and recirculated by means of moving blades. This heat exchanger is cooled by means of a refrigerant medium such as that known by the Trade Mark Freon. The product then passes to a second similar surface heat exchanger which is cooled by means of chilled water, and the temperature of the product is thereby reduced to approximately 11"C.

Finally the product is mechanically worked, so as to ensure that the droplets of aqueous phase are distributed uniformly throughout the mass. The resulting product is then packed m the usual manner, ready for distribution.

The process described results in a product which has been found to possess good spreadability at normal domestic refrigerator temperature, and to have a good shelf life, due to the fact that bacterial growth is inhibited, as referred to below.

Two typical examples of analyses of products produced by the process are as follows: Example A Example B Water 35% 40% Fat 55.2% 48.2% Protein 8% 10% Salt 1.8% 1.8% A product of the kind produced by the process of this invention, having a relatively high water content coupled with a relatively high protein content, at a pH-level in the range 6.4 to 7.0, is a ideal growth medium for micro-organisms. For this reason, hitherto products of this nature have been found to deteriorate very quickly during storage. Strict hygiene and sanitary practices are therefore essential in connection with plant used for the manufacture of products of this kind, but hygienic and sanitary precautions are not sufficient in themselves, to safeguard the product against premature deterioration. We have found, however, that if special measures are taken to effect an even uniform distribution of the aqueous phase in the fat phase, then good shelf life is ensured. In particular, we have found that the use of scraped surface heat exchangers for cooling the product, followed by through mechanical working, helps to achieve the degree of homogeneity necessary to ensure good shelf life for the product. However, the choice of the temperature levels during these stages and the time periods during which cooling and mechanical working are effected, are also critical from this point of view.

The process described is illustrated diagrammatically in the appended flow-sheet. It will be appreciated however, that the details described above and illustrated in the flow-sheet have been given by way of example only and may be modified in various ways within the scope of the invention.

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Claims (18)

WHAT WE CLAIM IS:

1. A process for making an emulsified food preparation by emulsifying an aqueous phase with a fat phase, wherein the aqueous phase comprises skimmed milk or sweet buttermilk containing caseinate salt or salts.

2. A process according to claim 1, wherein the aqueous phase and the fat phase are initially prepared separately, and are then emulsified together.

3. A process according to claim 1 or claim 2, wherein the fat phase comprises fat or oil derived from full fat milk.

4. A process according to claim 3, wherein the fat or oil comprises butter or butter-oil or cream, or any combination thereof.

5. A process according to claim 3 or claim 4 wherein the fat phase also contains vegetable oil.

6. A process according to any of the preceding claims, wherein the caseinate salt or salts used has or have been derived from skimmed milk.

7. A process according to claim 6, wherein the caseinate salt or salts used has or have been derived from skimmed milk by acid precipitation of curd, followed by treatment of the curd with alkali.

8. A process according to claim 6 or claim 7, wherein the caseinate salt or salts is or are used in spray-dried form when added to the skimmed milk or buttermilk.

9. A process according to any of the preceding claims wherein, during the emulsifying step, the fat phase is maintained at a temperature such that it is a liquid.

10. A process according to any of the preceding claims, wherein the aqueous and fat phases are used in such proportions that, in the emulsified product, the aqueous phase accounts for from 25 to 65% by weight of the whole.

11. A process according to any of the preceding claims, wherein the emulsification step is carried out at a temperature in the range of 40 to 50"C.

12. A process according to any of the preceding claims, wherein after the emulsification step, the pH of the emulsion is adjusted by means of a buffering agent, to a value in the range 6.4 to 6.8.

13. A process according to any of the preceding claims, wherein the emulsion is pasteurised by subjecting it to a temperature of about 72"C for about 15 seconds.

14. A process according to claim 13, wherein the emulsion is then cooled to a temperature of about 14"C and allowed to solidify.

15. A process according to claim 14, wherein the solidified emulsion is then cooled to a temperature of about 11"C.

16. A process according to claim 15, wherein the emulsion is then mechanically worked to achieve uniform distribution of droplets of the aqueous phase.

17. A process for making an emulsified food preparation, substantially as herein described.

18. A food preparation whenever made by a process according to any of the preceding claims.