FR2460627A1 - PROCESS FOR THE PRE-STERILIZATION OF A PASTEURIZED MILK SPILLING SYSTEM IN CONTAINERS AND PLANT PROVIDED FOR SAID SPILLING - Google Patents

Abstract

PROCESS FOR THE PRIOR STERILIZATION OF AN INSTALLATION FOR SPILLING PASTEURIZED MILK INTO CONTAINERS AND INSTALLATION PROVIDED FOR THESE SPILLING. THE HEATER 3 INCLUDING THE CONNECTING PIPE 7 IS STERILIZED WITH HOT WATER AT SENSITIVELY AMBIENT PRESSURE, WHILE THE SPILLING MACHINE 8 IS STERILIZED WITH OVERHEATED STEAM SEPARATELY FROM THE HEATER 3 AND 7 , FOR THE SPILLING, THE PASTEURIZED MILK IN THE HEATER 3 IS CONDUCTED, BY BYPASSING THE NON-STERILIZED STORAGE TANK 9, DIRECTLY TO THE SPILLING MACHINE 8 TO BE SPILLED INTO THE CONTAINERS.

Description

 Method for the prior sterilization of an installation for discharging pasteurized milk into containers and installation intended for said discharge.

 The present invention relates to a process for the production and pouring of pasteurized milk into containers of an installation which comprises a heater with a connecting sty pipe, a storage tank for pasteurized milk and a pouring machine, process in which before the production and the pouring of the milk, the line behind the heater and the pouring machine are sterilized. The present invention further relates to an installation for implementing said method.

It is known that the stability of pasteurized milk is considerably affected by its reinfection in the parts of the pouring installation which follow the heater. To avoid such reinfection and thus prolong the storage of pasteurized milk, it has already been proposed in the prior art to take all possible asepsis measures during the spill. For this purpose, the pipeline behind the heater, including the storage tank to the discharge machine, must be sterilized beforehand with hot water brought to a temperature of 120 to 1300C before the discharge process. Intermediate storage of milk in an aseptic tank must also be carried out with sterile air pressure (see "Die
Molkerei-Zeitung Welt der Milch ", 32nd year, 1978-48, pages 1542/43) '.

 These proposed measures to increase the shelf life of pasteurized milk are costly and unprofitable.

Above all, in already existing installations, they require considerable transformation or are even impracticable. Thus, the storage tanks to be kept sterile for pasteurized milk and which are mounted upstream of the pouring machine are extremely expensive to purchase and maintain, since the valves necessary for this purpose must also be kept sterile
and that a special installation is required for the
production of sterile air supplied under overpressure.
their, the prior sterilization of the pipeline behind
the heater with hot water at a temperature of 120
at 1300C, requires such high hot water pressure that the
pressure resistance of the tubular pipe of
existing installations, and in particular also the heater, is quickly reached if not exceeded.

Based on this aforementioned state of the art, the invention
therefore has the object of carrying out a process and a
corresponding discharge facility which allow by
extremely simple ways to avoid re-infections of the
pasteurized milk during the spill and thus prolong the
shelf life of pasteurized milk.

This result is achieved according to the invention by the fact
the heater, including the pipe connected to it,
are sterilized with hot water at a pressure substantially
ambient while the spill machine is sterilized
with superheated steam separate from the heater and
the pipe and that, during the spill, the pasteur milk
rised in the heater is brought in, bypassing the reser
see unsterilized storage, directly to the machine
spill to be spilled into containers.

Thus, in the context of the method according to the invention, one
uses separate sterilization circuits and means
for the prior sterilization, on the one hand, of the heater
and tubular pipe connecting to it and, on the other
hand, for the spill machine. In the heater and
the pipe, we sterilize with hot water which has a
temperature between 950 and 1150C maximum, in accordance
at ambient pressure. With this procedure, there is no
practically no pressure stress so that the
the heater itself can be sterilized.

Most spill machines are designed from
so as to allow sterilization with superheated steam
at a temperature for example of 130 to 1450C. Therefore,
in the process according to the invention, the dumping machine
is sterilized separately from the heater part and the tubular pipe connected to it. Thanks to steam sterilization, the spill machine can be sterilized with virtually complete destruction of all germs and sterilization times are reduced. Another advantage of separate sterilization of the spill machine is that sterilization can take place at times when the spill machine is not needed, since the heater is used on other parts of the machine. 1 installation.

Finally, it is particularly important that the actual pouring of pasteurized milk takes place bypassing the unsterilized storage tank. From the heater in which all of the existing germs have been completely destroyed, the pasteurized milk therefore comes directly to the previously sterilized pouring machine and therefore does not come into contact with the storage tank or into contact with the contaminated ambient air that 'it contains. Re-infection is therefore excluded
The method according to the invention can be implemented in existing installations without having to make significant modifications thereto. An installation for implementing the method according to the invention does not include, in addition to the heater, the pipe s' connecting it, from the storage tank and the pouring machine, as switching valves placed in front of the heater and at the end of the pipe connecting to it for the supply of hot water, this valve installed at the end of the pipe used to connect the heater, as desired, to the storage tank and the discharge machine. Other switching valves can be provided to connect the preheater to other processing devices for pasteurized milk. None of the essential elements of the installation, however, require restructuring or change.

 Since, as a general rule, the capacity of the heater is greater than that of the pouring machine, the procedure is known in the art for the pouring of pasteurized milk so that the total quantity of milk coming from the heater is stored in the storage tank serving as a buffer. In the process according to the invention, on the other hand, the storage tank, as already explained, is bypassed at least by the quantity of milk which is poured into the containers in the form of pasteurized milk by the pouring machine. Excess pasteurized milk exceeding the capacity of the pouring machine and coming from the heater can either be brought to the storage tank or directly to other treatment devices which, as far as reinfection is concerned, are not so critics.

The invention will be better understood using the description of an embodiment taken as an example, but not limiting, and illustrated by the appended drawing, in which
FIG. 1 represents, at the stage of prior sterilization, a block diagram of the installation used for implementing the method according to the invention;
Figure 2 shows, at the stage of production and discharge of pasteurized milk, a similar block diagram of the installation.

 On the block diagram of FIG. 1, the installation for the production and the pouring of pasteurized milk into containers comprises, for raw milk, a storage tank 1 which is connected by a pipe 2 to a two-stage heater 3 . To this heater 3 to which are connected a centrifuge 4 and a homogenization machine 5 placed between the two stages of the heater, is attached a cooler 6. To the tubular pipe 7 leaving the cooler 6 are connected a pouring machine 8, a tank storage tank 9 for pasteurized milk and other processing devices 10, 11. The components 8 to 11 of the installation are respectively connected to the tubular pipe 7.

 The block diagram according to FIG. 1 represents the stage of prior sterilization of the essential components of the installation. As indicated at the beginning, for the prior sterilization, the already existing pipe in the heater 3 is used up to the pouring machine 8 and inside it. The heater 3 and the connecting part of the tubular conduit 7 to the discharge machine 8 are sterilized with hot water substantially at atmospheric pressure. Therefore, hot water has a temperature between 950 and 1150C maximum. To determine the circuit in which the hot water travels through the heater, the tubular pipe 2 includes a switching valve 12 which opens the hot water circuit in the direction of a connector 13. Upstream of the discharge machine 8 in the tubular pipe 7 there is also a switching valve 14 through which the hot water is brought back to a hot water discharge pipe 15. In this way, an open circuit is obtained which makes it possible to simply preheat the water at the desired temperature; The water circuit is represented by a solid line thickened in Figure 1.

 The pouring machine 8 is sterilized with superheated steam from 1300 to 1450C, which is shown diagrammatically by the connections 16, 17 for the supply and evacuation of the steam. It goes without saying that the connections 16, 17 are placed at the level of corresponding switching valves which allow a steam circuit in the discharge machine 8 separate from the tubular pipe 7.

 As can be seen in FIG. 1, the centrifuge 4 and the homogenization machine 5 are not included in the hot water circuit passing through the heater 3.

 FIG. 2 represents the installation at the stage during which pasteurized milk is produced and poured into containers by the pouring machine 8. The milk flow path is shown diagrammatically by a solid line thickened in the block diagram. It can be seen that the raw milk leaving the storage tank 1 is brought, by the tubular conduit 2 and the switching valve 12 suitably positioned, to the heater 3 in the two stages from which it is first preheated to 550cri centrifuged , homogenized then consecutively pasteurized at 740C. In the cooler 6, the milk is then cooled to around 40C. The switching valve 14 upstream of the pouring machine 8 is now positioned so that the quantity of pasteurized liquid which is supplied by the heater 3 and which corresponds to the capacity from the pouring machine 8 reaches the latter directly where it is poured into containers. It is only the excess of pasteurized milk which possibly exceeds the capacity of the pouring machine 8 which is brought to the storage tank 9 and, where appropriate, to the other devices 10, 11. As the zone of the installation between the switching valve 12 and the pouring machine 8 is perfectly sterile, there is no re-infection of the pasteurized milk as it would be inevitable, for example, in the storage tank 9 due to the contact of the pasteurized milk with non-sterile ambient air and the valves provided therein.

In this way, the installation can be used as it was previously installed.

 The sterilization times for hot water sterilization of the heater 3 are of the order of magnitude of 30 minutes, and for the pouring machine of the order of magnitude of 15 minutes.

 The effectiveness of the process according to the invention can be demonstrated using the following example: at a storage temperature of 10 to 120C, a pasteurized milk produced and packaged in accordance with the process according to the invention had after four days 50 x germs / ml. It was only after seven days that the number of germs exceeded 100 x 103 / ml.

 The taste and appearance of. milk was still flawless after seven days. On the other hand, in a pasteurized milk which had been treated in a conventional manner in the same installation, a number of germs of more than 500 × 10 3 / ml was found after three days and a substantial deterioration in the taste.

Claims (6)

 1. Process for the production and discharge of pasteurized milk into containers of an installation comprising a heater with piping connected thereto, a storage tank for pasteurized milk and a discharge machine, process in which before production and the milk spill, the pipe behind the heater is sterilized as well as the pouring machine, characterized in that the heater (3) including the pipe (7) connected to it is sterilized with hot water at the substantially ambient pressure, while the pouring machine (8) is sterilized with superheated steam separately from the heater (3) and the pipe (7) and that, for the pouring, the pasteurized milk in the heater (3) is brought, bypassing the unsterilized storage tank (9), directly to the pouring machine (8) to be poured into the containers.  2. Method according to claim 2, characterized in that an excess of pasteurized milk produced by the heater (3) and exceeding the capacity of the pouring machine (8) is brought to the storage tank (9) or to d other treatment devices (10, 11).  3. Method according to claim 1 or 2, characterized in that the heater (3) is sterilized without the centrifuge (4) or the homogenization machine (5) which are connected to it.  4. Method according to any one of claims 1 to 3, characterized in that the pouring machine (8) is sterilized with superheated steam at a temperature of 1350 to 1450C.  5. Installation for discharging pasteurized milk for implementing the method according to claim 1, comprising a heater, a pipe connected thereto, a storage tank and a pouring machine, characterized in that the heater (3 ) and the pipe (2,7) connected to it include switching valves (12, 14) for the supply of hot water and for the optional connection of the pipe (7) to the storage tank (9 ) and to the dumping machine (8).  6. Spillage installation according to claim 5, characterized in that in the pipeline (7) are provided other switching valves for connecting the heater (3) to other treatment devices (10,11) for the pasteurized milk.