SE508869C2 - Method for producing UHT milk with improved taste properties - Google Patents

Abstract

The disclosure relates to a method of producing UHT milk with improved flavour qualities. The method includes pretreatment of the milk by separation and standardisation, and also homogenisation and heat treatment. The treatment takes place at a temperature exceeding 135 DEG C. The method also includes enzyme deactivation, in one or more stages. The milk is then kept in holder cells at a temperature of 55-70 DEG C for a period of time of 2-10 minutes. Enzyme deactivation is carried out after the heat treatment, or alternatively before the heat treatment.

Description

Another object of the present invention is that the heating takes place at a high temperature for a very short time, while maintaining a killing effect, which also contributes to a gentler treatment of the milk and the associated better taste experience.

These and other objects have been achieved according to the invention by giving the method of the type initially described, the characteristics that pretreatment takes place at a temperature of 4-15 ° C and that the heat treatment takes place at a temperature exceeding 150 ° C.

Preferred embodiments of the invention have furthermore been given the features apparent from the subclaims.

A preferred embodiment of the invention will now be described in more detail with reference to the accompanying drawing, which: Fig. 1 shows a flow chart of a plant for carrying out the method.

When colostrum arrives at the dairy, it usually maintains a temperature of 4 ° C.

The incoming milk can optionally be stored in intermediate tanks, which storage takes place while maintaining the temperature. When the milk is to be treated, it is transported in a pipeline 1 to a separator 2. Separator 2 can be of a conventional type, but since it is not desired to heat the milk before separation, a so-called cold separator 2 is used. The milk is separated according to the invention at a temperature of 4-15 ° C, so a certain insignificant heating can take place before the milk reaches the separator 2. Experiments have shown that a certain, but negligible, increased fat content in the skim milk is obtained when separating at low temperatures. The advantage, however, is that you get a gentler treatment of the milk than when separating at conventional temperature. A cold separator 2 differs in principle from an ordinary separator in that the distance between the slices is slightly larger, since cold cream has a higher viscosity than the heated cream.

Through the separation, out of the separator 2, cream is obtained in a line 3 and skimmed milk in a line 4. Both the cream and the skimmed milk maintain a continued low temperature of 4-15 ° C. The cream is led in its pipeline 3 to a standardization equipment 5 in which one can get an exact part of cream for remixing in the skim milk, which gives a milk product with the desired fat content. The excess cream is led in a pipeline 6 out of the standardization equipment 5 for separate treatment.

By separation and standardization at the relatively low temperature of 4-15 ° C, a much gentler pre-treatment of the milk to be further processed into UHT milk is obtained. Conventional dairy handling and pre-treatment of UHT milk involves heat separation at 55 ° C and usually a pre-pasteurization at 72 ° C for 15 seconds, or at similar time-temperature combinations. These heatings have an unnecessary effect on the temperature of the milk which, at a later stage, must be exposed to significantly higher temperatures in order to obtain a commercially sterile product.

Conduction 4 with the cream mixed with the skimmed milk is led to a UHT equipment 7 of conventional type. The UHT equipment 7 usually also contains a homogenizer which is preferably placed after the heating of the milk, but which can also be placed before the heating. The homogenization is done to obtain a milk product where the fat globules are broken down into small, equal-sized fat globules. If the milk is not homogenized, you get so-called creaming, i.e. the fat balls, which are lighter, accumulate in the upper part of the finished package. Almost all drinking milk today is homogenized.

The UHT treatment itself takes place according to the invention by heating the milk to a temperature above 150 ° C for a short time interval. Preferably, the heating takes place to 150-175 ° C for a period of 0, 1-2 seconds, depending on the killing requirement, ie depending on the bacterial and spore content of the constituent milk.

Experiments have shown that a heating according to the invention gives a product which meets the requirements of commercial sterility. In a UHT equipment 7 of conventional type, the heating of the milk can take place either directly by meadow injection or meadow infusion or indirectly by heating the milk in some form of heat exchanger, or with a combination of these methods.

The finished milk is transported in a pipeline 8 on to one or more packaging machines 9. The packaging machines 9 are aseptic and can e.g. be of the type that packs the milk in disposable parallelepiped packaging containers.

With some UHT treatment of milk, there may be some instability with respect to enzyme activity, which can be remedied by cooling the milk after the UHT treatment in one or more steps at temperatures between 55-65 ° C in intervals between 2-10 minutes, for example 65 ° C for 5-8 minutes, after which it is completely cooled to packaging temperature.

Enzyme inactivation requires tube-type pouring cells or the like, which can be integrated into the UHT equipment 7.

By heating the milk, the milk changes chemically, which changes the taste of the milk. The aim is thus to have as little chemical impact as possible during the UHT treatment of the milk. Taste is a subjective factor, but by measuring lactulose in the milk, one can indirectly get a measured effect on taste. The higher the temperature load to which the milk is exposed, the higher the value of the lactulose content in the milk. Experiments with pretreatment and UHT treatment of milk according to the invention have shown that lower lactulose content is obtained and thus indirectly a better taste of the finished UHT milk. 508 869 As shown by the above method of treating the milk, an aseptic product is obtained which, by the gentle treatment, gives considerably improved taste properties.

Claims (3)

10 15 869 508 PATENT CLAIMS Method for the production of UHT milk, which comprises pre-treatment of the milk by separation and standardization, the method also includes homogenization and heat treatment, characterized in that pre-treatment takes place at a temperature of 4- 15 ° C and that the heat treatment takes place at a temperature exceeding 150 ° C. Method according to claim 1, characterized in that the heat treatment takes place at a temperature of 150-175 ° C for a time of 0.1 -2 seconds. Method according to one of the preceding claims, characterized in that the milk after the high-temperature treatment can be enzyme-inactivated in one or more steps, at a temperature of 55-65 ° C for 2-10 minutes.