The Bacillus of Long Life / A Manual of the Preparation and Souring of Milk for Dietary Purposes, Together with an Historical Account of the Use of Fermented Milks, from the Earliest Times to the Present Day, and Their Wonderful Effect in the Prolonging of Human Existence

by Loudon M. Douglas

Fig. 53 Apparatus of the Willows Refrigerating Co., Ltd.

In the apparatus hitherto described the milk is sterilised in bulk, and is filled into bottles or jars after incubation, which is not a desirable thing to do, unless the soured milk is for immediate consumption, as there is likely to be contamination with injurious germs from the atmosphere. In the domestic apparatus the milk is usually incubated in covered jars in which it can be kept until required for use, and the practice on the larger scale should be the same.

The Dairy Outfit Co., Ltd., have recognised this in their "Lacto" apparatus (Fig. 54).

Fig. 54
"Lacto" Apparatus of the Dairy Outfit Co., Ltd.

A cylindrical vessel is set loosely on a stand, beneath which is a lamp calculated to maintain the incubating temperature. The milk is placed in bottles with metal screw tops, and these are put into the cylindrical vessel; water is run in round them through the side funnel, the vessel lifted off the stand, and heated to sterilising point on a stove. Cold water is then run in through the funnel until the temperature is low enough for incubation. Culture is added to each bottle and the lids screwed on, the vessel lifted on to its stand, and the lamp lighted. The cover of the apparatus has a thermometer fixed on it.

On the large scale the treatment of the milk would take place entirely in the jars in which it would be sent out, and the sterilisation and incubation would be conducted in different pieces of apparatus. The sterilisation would be effected either (1) by direct steaming, or (2) by hot water heated by steam. Fig. 55 shows the first type of sterilisation. The tank is of wrought iron or steel with strengthening pieces of angle iron. The door, with pulleys and counterweight for easy handling, is fastened steam-tight by hinged bolts. The apparatus is mounted on a stand at a convenient height for handling the bottles; and in front is another stand with channel iron rails to take the waggon in which the bottles or jars to be sterilised are packed. When the door is fast, steam is turned on, and regulated to produce the proper temperature by the thermometer fixed in the shell, in which a pressure gauge is also secured. After sterilising, the door is opened and the waggon drawn forward to the outside, allowed to cool, or removed elsewhere to cool, and allow space for a new charge.