EQUIPMENT FOR SEMI-CONTINUOUSLY COAGULATING MILK PREFERABLY PRE-ACIDIFIED MILK FOR PREPARING YOGHURT

Abstract: Equipment for continuously coagulating preferably preacidified milk for preparing yoghurt, provided with means for keeping the milk at a desired temperature during coagulation, with means for feeding in the milk and with means for discharging the yoghurt, whereby the equipment consists of an essentially closed housing (1) containing an endless conveyor belt (3) on which containers (2) of the paternoster-lift type are suspended, provided with means for advancing the conveyor belt at uniform velocity in the housing at a velocity such that each container remains for a desired time in the housing, and with means for stopping each container stepwise outside the housing during filling and during emptying.

Description: The invention relates to equipment for continuously coagulating milk preferably pre-acidified milk for pre­ paring yoghurt, provided with means for keeping the milk at the desired temperatures during coagulation, with means for feeding in the milk and with means for discharging the yoghurt. Such equipment is described in Dutch Patent Appli­ cation 7204690 and consists of a coagulating column with a large capacity. The preferably pre-acidified milk remains in said column for approximately 2½ hours. The liquid level is always kept the same. The milk must be fed in very carefully because the milk particles must not have a relative velocity with respect to each other since otherwise preferred flows will be produced. The milk is continuously fed in and the yoghurt is continuously discharged to cooling equipment. At the end of the coagulating process it is necessary to agitate with a horizontal agitating plate provided with openings which is moved vertically in the column. The satisfactory operation of the said known coagu­ lating column is therefore very critical. The object of the invention is to provide equipment in which the preferably pre-acidified milk is coagulated in small quantities, but nevertheless continuously. According to the invention this is achieved in that the equipment consists of an essentially closed housing containing an endless conveyor belt on which con­ tainers of the paternoster-lift type are suspended, pro­ vided with means for advancing the conveyor belt at uniform velocity in the housing at a velocity such that each container remains for a desired time in the housing, and with means for stopping each container stepwide out­ side the housing during filling and during emptying. In this manner, the coagulation takes place in containers of limited capacity which are passed at uni­ form velocity through the coagulating space. The coagulation may require, for example, 1.5 - 2.5 hours. The yoghurt remains at rest in each container, which promotes the coagulation process. The intended coagulating temperature of approximately 45° C. The invention will be explained in more detail by reference to a diagrammatic drawing. The housing of the equipment according to the invention is constructed as a tower having an essentially rectangular cross-section. In the shown embodiment, there extend in said tower 1 four sections of a conveyor belt of the paternoster-lift type, i.e. containers 2 are rotatably suspended on chains 3 or the like, which sections are passed over two wheels 4 and 5 at the top of the tower 1 and one wheel 6 at the bottom of the tower 1. Patitions 7, which may be heated, may be placed between the ascending and descending sections. At least one of the wheels 4, 5 or 6 may be driven. Adjacent to both sides of the tower 1 are lower housing sections 8 and 9 containing wheels 10 and 11 respectively over which the conveyor belt 2, 3 is also passed. The filling of the containers 2 with preferably pre-­ acidified milk takes place in the housing section 8, the coagulation of the milk in the tower 1 and the tilting and emptying of the containers 2 into a discharge trough 12 in the housing section 9. Instead of pre-acidified it is also possible to depart from normal milk to which a certain quantity of yoghurt cultures is added. As it is evident from the drawing, the conveyor belt 2, 3 sags behind the wheel 10, in front of the wheel 11 and between the wheels 11 and 10. As a result of this it is possible to cause the conveyor belt 2,3 to move at a uniform velocity in the tower 1, but to cause the wheels 10 and 11 to move stepwise. This produces time for filling the containers 2 at the wheel 10 and removing the con­ tainers 2 from the chains 3 at the position of the wheel 11 in order to be able to empty the containers 2 into the dis­ charge trough 12. The coagulation of the milk in the container 2 which are situated in the tower 1 thus takes place continuously and at a uniform rate. The coagulation time is determined by the residence time of each container 2 in the tower 1. Said time is determined by the drive velocity of the chains 3, but it is also possible for the route in the tower to comprise more than four sections, for example six sections as a result of adding an additional top wheel and an additional bottom wheel. The wheels 10 and 11 can be stopped stepwise by conventional means. The emptied containers 2 may be placed upside down on a horizontal conveyor belt 13 by means of which the containers 2 are returned to the wheel 10. Over the first section of this horizontal path the containers 2 are rinsed clean by jets 14, then they drain out in order, finally, to be dried by hot air or the like. At the left-hand end of the conveyor belt 13, the containers 2 are returned by means not shown and suspended on the chains 3. The chains 3 are also rinsed clean by jets 15 between the wheels 11 and 10. A certain temperature and a certain humidity must be maintained in the tower 1. This may be implemented by means known per se in processing technology which do not need to be described here in further detail. A suitable temperature is, for example, approximately 45° C. An air feed and filtering equipment 16 is furthermore present which provides a reliable overpressure in the tower-like housing 1 blowing in filtered air with a higher than atmospheric pressure. The conveyor belt 2, 3 can be passed through the tower 1 with a uniform velocity such that the residence time is 1.5 - 2.5 hours. The wheels 4, 5 and 6 thus rotate continuously. The wheels 10 and 11 are stationary, for example, for 3/4 of the residence time in order to make filling and emptying of the containers possible. The containers 2 may have, for example, a capacity of 120 litres.

Claims: 1. Equipment for continuously coagulating preferably pre-acidified milk for preparing yoghurt, provided with means for keeping the milk at a desired temperature during coagulation, with means for feeding in the milk with means for discharging the yoghurt, characterized in that the equipment consists of an essentially closed housing containing an endless conveyor belt on which con­ tainers of the paternoster-lift type are suspended, pro­ vided with means for advancing the conveyor belt at uniform velocity in the housing at a velocity such that each container remains for a desired time in the housing, and with means for stopping each container stepwise outside the housing during filling and during emptying. 2. Equipment according to claim 1, character­ ized in that the housing is constructed as a tower in which the containers are advanced along vertical paths. 3. Equipment according to claim 1, character­ ized in that there are disposed at the top of the tower two reversing wheels and at the bottom of the lower one reversing wheel for the conveyor belt, at least one of which is driven at a uniform velocity. 4. Equipment according to one or more of the prece­ ding claims, characterized in that, near the bottom of the tower, there are disposed on both sides of the tower reversing wheels for the conveyor belt which can be stopped stepwise in order to enable filling or emptying of the paternoster-lift containers and/or other operations, it being possible for the conveyor belt to sag between said reversing wheels and between said reversing wheels and the upper reversing wheels in the tower. 5. Equipment according to one or more of the preceding claims, characterized in that means are present for cleaning and drying the paternoster-­ lift, containers after emptying separately from the con­ veyor belt, the latter being placed upside down on a horizontal conveyor belt which returns the containers to the filling point. 6. Equipment according to one or more of the preceding claims, characterized in that means are present in the tower for keeping the humidity in the tower at a certain desire value. 7. Equipment according to one or more of the pre­ ceding claims, characterized in that means are present for generating a slight overpressure in the tower. 8. Equipment according to one or more of the pre­ ceding claims, characterized in that heatable partitions are disposed between the sections of the conveyor belt in the tower.

Inventors: BOER, JORT
Applicants: N.V. MACHINEFABRIEK TERLET
Application year: 1987
Main classification: A23C9
IPC codes: A23C9