The present invention relates to production of consumer milk with a defined fat content packed in packages.

On the market there is today a number of milk products with different fat content packed in packages. In Sweden there is for example minimum milk 0.1 % fat, light milk 0.5 % fat, "middle" milk 1.5 % fat and "standard" milk 3.0 % fat. Abroad there are products with other fat contents. The fat content given on the packages must be kept and production of milk wit a certain, guaranteed fat content, usually called standardization of milk, is therefore an important process ste in a dairy.

The standardization process has hitherto been carried out according to two different methods, batch-wise in tanks or by direct in-line standardization. The first step according to both these methods is to separate whole milk into cream and skimmilk. The term "whole" milk or raw milk is used for milk a it is delivered to the dairies with a ^' fat content around 4 %.

When carrying through the standardization in batches two methods are used, namely pre-standardization and post- standardization. The pre-standardization means that the milk i standardized prior to the pasteurization. When the milk shall be standardized to a fat content higher than the fat content i the raw milk, cream is mixed with the milk in proportions whic shall give the desired fat content. If the standardization shall take place to lower fat content, the raw milk is diluted with skimmilk. The standardized milk is pasteurized after analysis of the fat content and a possible correction of the same.

Post-standardization means that pasteurized milk is mixed with cream or skimmilk depending on if the fat content shall be adjusted upwards or downwards in the same way as practiced for

the pre-standardization. Some risks for re-infection are present since post-standardization means mixing of already pasteurized products. Both methods demand large tanks and analysis and a possible correction of the fat content is labour-intensive.

The second method, direct-standardization, has therefore been an attractive alternative for many years. According to this method the fat content is adjusted to the required level by re mixing a certain amount of the cream obtained from the separator with skimmilk also obtained from the centrifugal separator. This remixing takes place in the skimmilk pipeline connected to the skimmilk outlet from the centrifugal separator.

The pasteurization usually takes place in connection with the standardization. Whole milk is preheated to a temperature suitable for the separation of the cream from the skimmilk. Th standardized milk that is obtained after the remixing of suitable amounts of cream and skimmilk after passage of the centrifugal separator is then heated and pasteurized.

Many methods which make an automatic direct-standardization of the milk possible has been developed and are today operating i a number of dairies.

The methods described above are used for manufacture of milk with a preselected fat content. A desired amount of milk is produced. If milk with another fat content should be produced, the system must be adjusted to new preset values and volumes.

The different milk products with a varying fat content mentioned above may be produced by in-line standardization. The packaging does not take place immediately after the standardization but the milk products are intermediately store

in large tanks in the dairy. Usually, different kinds of consumer milk are packaged firstly when the distributors working on the market have delivered their orders for a suitable amount of packages of consumer milk with differing fa content.

According to the invention there is now proposed a method of producing consumer milk with a defined fat content packed in packages, which method fundamentally diminishes the number of storing tanks for prepared milk products earlier needed. The method according to the invention is mainly characterized in that two fractions comprising milk products, but with differen fat contents, are mixed. One of the fractions has a fat content below the required fat content of the consumer milk to be produced while the other has a fat content above the required fat content of the consumer milk to be produced. The mixing takes place immediately prior to, or during the filling of the consumer milk in packages.

The partial streams containing the two milk fractions are well miscible.

According to the method of the invention it is possible to rapidly switch between production of consumer milk with different fat contents with one and the same equipment without any risks for losses of valuable product.

The method according to the invention is with advantage carrie out in that the mixing of the two fractions takes place in the package by supplying predetermined amounts of the two fraction to the package.

If considered suitable, the mixing of the two fractions takes place immediately prior to the filling in the package in a separate mixing step in the filling machine by mixing of pre-

determined amounts of the two fractions corresponding to the size of the package or some multiple of the same.

If the mixing shall take place in the package, it is suitably carried out in such a way that the two fractions are simultaneously dosed into the package by means of two dosing devices. Of course, it is possible to dose first one and then the second fraction into the package instead by actuating one dosing device after the other.

The different fractions may also be added in such a way that one dosing device is used for one fraction, suitably the more fat rich one after which the package is moved to a new positio and another dosing device, where the second fraction is added.

The mixing of the two fractions may also take place in a pipeline leading to the filling machine or within the same.

The two fractions which are mixed may consist of milk products usually produced in the dairy. Normally, there is skimmilk available. The fat content of the same varies with the use of separation equipment and is usually in the interval 0.05 - 0.0 %. If suitable, light milk (0.5 % fat) may constitute the fraction with the lower fat content instead. Coffee cream or cooking cream with approx. 12 % fat content may be used as the fraction with the higher fat content, but it may also be suitable to use whole-milk, i.e. milk with a natural fat content which only has been homogenized. The dosing is preferably carried through in such a way that the fraction wit the highest fat content is dosed into the package at first. It is also possible to supply one fraction continuously and the other in an intermittent way.

According to the method of the invention it is possible, as mentioned earlier, to make great savings in that a number of

storing tanks with matching supplying equipment for standardized but not packaged product may be avoided. The additional equipment only consists of a further dosing device.

When milk products are filled into packages, this usually tak place with some system available on the market. A product may be filled by means of a filling pipe which is lowered into the package in such a way that the filling takes place under the level of liquid. If such a filling system is used, a mixing of the two fractions may take place in-line in immediate connection to the filling pipe.

The filling may take place by means of a controlling valve giving a constant flow after which the package is closed. Also here the mixing of the fractions takes place immediately prior to the filling in the package, preferably in a separate mixing unit holding mainly the same volume as the package or with a somewhat larger volume.

Other filling systems use metering pistons feeding a certain volume of product to the package, after which the package is closed. In such a case the mixing of the two fractions usually takes place directly in the package. The filling machine is either supplied with an extra metering piston for the second fraction, or the same dosing device is used for both fractions as described above.

Instead of using a metering piston a positive pump may be used for the the dosing.