Tuesday 4 July 2017

Pasteurisation at Carlsberg in the 1880's (part one)

Pasteurisation is a process which fascinates you, I'm sure. Well, maybe not. But it is an important process at many breweries still.

From the description, it sounds quite a fiddly process:

"The pasteurisation process is conducted as a secret, with attention to strangers not being admitted. The process is conducted by one man and this in an apartment where no one but the workman and the manager have access to. The bottles to be treated after wiring are placed in cages constructed of hoop iron. This cage being enclosed in a basket also made of hoop iron. Each cage contains 20 bottles. They are carried to the door of the pasteurising room from which place the pasteurizer lifts them with a cord terminating in hooks fixed on the top ends of the basket. The cord works through a pulley which is in its turn suspended to a pulley wheel running on an inverted rail seecurely fastened to the roof and is placed exactly above the centre of the heating troughs. In this manner he can deposit the cage at any spot with little trouble. The heating boxes for the process are 3 feet 9 inches wide and any length depending on the amount of work to be done. They have a false bottom five inches deep and a total depth of 16 inches. At half an inch from the top a funnel is fixed. This teminates in a pipe 1.5 inches in diameter. This is to carry away the excess of water when not otherwise required."
"Notes of a visit to the breweries of Messrs. Jacobsen Senr. & Junr. Copenhagen Sept 1881." held at the Scottish Brewing Archive, document number WY/6/1/1/11.
Why was their pasteurisation process such a secret? Well I guess it wasn't that much of a secret if they let their visitors from William Younger observe it.

Nowadays there's no faffing around with cages and baskets. Bottles motor through the pasteuriser on a belt of some sort.

"The heating boxes are placed close to the wall and extend the whole length of the three sides of the room. These all communicate withe each other through holes bored in the adjoining ends. These holes aare stopped with wooden plugs. In operating they begin with say the left hand box. After the bottles in their baskets are in this place the water is admitted at a temperature of 16º until the bottles are nearly covered. The water is now shut off and steam at a pressure of 45 to 60 lbs. per square inch admitted as fast as it can rush in until the temperature rises to 44º. The temperature is maintained at this point constant for ten minutes. They then cool as quick as possible by admitting cold water until the heat falls to 20º. When they are removed to the packing hall again by means of the overhead rail. During the heating they have in each box a clear bottle containing a thermometer suspended in water only. This bottle is wired like the others, and if quarts are being treated it is  quart. If pints it is a pint. They vary the ten minutes a little, if this bottle does not show a predetermined heat which is always 6º lower than the heating water in the box. The reason of this is that different glasses have different specific heats and as a consequence a different conductivity from the water to the beer. They aim at carrying out the operation as quick as they are able. The quicker it can be done, the better. The whole process occupies exactly one hour. The attendant has to note the heats of the water and the test bottle every ten minutes. 44 is the standard heat but this is varied for the market. Very warm climates as aa rule are supplied with a beer that was treated at 44.8 to 45. Colder climates at 43.2."
"Notes of a visit to the breweries of Messrs. Jacobsen Senr. & Junr. Copenhagen Sept 1881." held at the Scottish Brewing Archive, document number WY/6/1/1/11.
That seems a very low pasteurisation temperature. A quick look online implies that somewhere around 60º C is the usual temperature for pasteurising beer*. Were they reall pasteurising at just 44º C?

I suppose it makes sense to pasteurise beer destined for the tropics at a higher temperature.

It seems that they kept the man on pasteurising duty pretty busy:

"During the time this box was heating the second box would be filled with bottles, and whenever they commence to cool no. 1 box the plugs are drawn and the water allowedto flow into number 2 until it is filled. When the steam is turned on as before, during the heating of No 2 and the cooling of No 1, No 3 is being filled and so on, only the water from No 3 is run to the drain pipe. During the cooling of No 1 and the heating of No 2 the communication is closed. No 1 is cold and ready for removal when no 2 is cooling and No 3 up to its heat. Working in this manner the workman is kept fully employed and can turn out a large amount of work."
"Notes of a visit to the breweries of Messrs. Jacobsen Senr. & Junr. Copenhagen Sept 1881." held at the Scottish Brewing Archive, document number WY/6/1/1/11.

Though how many bottles could he be pasteurising at once? With only 20 bottles to a cage, it doesn't sound like that many.

Next time we'll be looking at breakages during pasteurisation. WHite knuckle stuff.

* Frickir, R. (1984) The flash pasteurisation of beer in the Journal of the Institute of Brewing May-June. 1984, Vol. 90. pp. 146-152.


Anonymous said...

The lower the temperature of pasteurisation the longer the product must held at temperature to lower microbial activity to a safe level.

The temperature of pasteurisation also has an effect on taste as well.

Jon Rice said...

I agree that 44 sounds wrong. In yogurt making that is the temperature used to maximize the growth of bacteria, not inhibit it.

Maybe it's a typo, or maybe some sneaky person at Carlsberg was trying to mess with corporate spies. Probably the first one.

Ron Pattinson said...

Joe Rice,

it can't really be a typo as it's a handwritten document.

rod said...

In my experience, 44c for 10 minutes is not sufficient to pasteurise beer. I believe there is definitely a mistake here.