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Manufacturing

  • Brewing

    The brewing house, partially modified at the end of 2008, includes two new stainless steel tuns (mashing and filtration) and two copper boilers dating back to 1920.
    We had to stop working with our old lauter tun dating back to 1844 because it deteriorated considerably during 2008. However, it remains on the brewery premises as testimony to our past.

  • Mashing and filtration

    In the mash kettle, we combine the barley malt crushed in water from our wells (pumped from 80m below the surface).

    The barley malt comes from our other concern: the malting plant. At the malting plant, the barley starts to germinate, releasing enzymes. It is then dried at a high temperature: 80°C to obtain a pale malt (light ale) or 100 to 130°C to obtain a dark malt (brown ale).

    In the mash tun, the mixture is slowly heated to 72°C, allowing the enzymes from the grain to convert the starch into sugars.

    Once saccharification is complete, the mixture is transferred to the lauter tun to separate the sweet liquid (wort) from the solid grain particles (spent grain). The wort is pumped into a boiler. The first wort collected is very dense (high in sugar). The spent grain is then washed several times in hot water to collect the residual wort.

    De oude beslagkuip, in 2008 vervangen door een kuip in inox
  • Boiling

    Once filtration is complete, the content of the boiler is brought to the boil using the traditional technique of heating over an open fire: the copper tun is heated in direct contact with a flame. This means that a small area of the base of the tun is heated to over 110°C and this phenomenon is responsible for the slight caramelisation of the sugars and the very specific convection movements within the tun. The hops is added during boiling to give the distinctive bitterness and aromas of the end product.

    The boiling time depends on the type of beer. For example, brown ale is boiled for 2½ hours to obtain its colour and caramelisation. Next, the wort is sent to the fermentation cellar.

    The volume of a mash tun is 55 to 60hl.

  • Fermentation and maturation

    In 2013, the Brasserie underwent expansion work with the aim of increasing the capacity of the cellar while maintaining the traditional technique of fermentation in square flat-bottom tuns. There the yeast produces lots of esters, responsible for the fruity characters and complexity of the beer. These tuns go against current trends because they take up more room than the cylindrical-conical ones used nowadays. However, they bring such specific characteristics to the beers that investments were made to be able to continue this tradition.

  • Fermentation

    The wort from the boiler is then clarified by centrifugation, oxygenated through the injection of sterile air and then cooled before being placed in one of the fermentation tuns.
    To this we add the yeast, which multiplies and converts the sugars in the wort into alcohol and carbon dioxide (CO2). The wort becomes beer!

    The fermentation of the sugars by the yeast is checked each day and after around 5 days the fermentation is interrupted (by cooling the tun) to leave a few of the residual sugars in the beer. The cooled beer is pumped into the maturation tank for 1 to 2 weeks. The yeast is collected from the bottom of the tun and used in the next mash where it multiplies and converts the sugars. The yeast is used is this way for two years, with the addition of cultures held in our laboratory, if necessary.

  • Maturation

    After maturing for one to two weeks, the beer is clarified by centrifugation and sent to a bright beer tank. For some beers, this phase is longer and combined with dry hopping (infusion of hops flowers within the beer): Saison Dupont Cuvée Dry Hopping, Avec les Bons Vœux, etc.

  • Bottling/barrelling and second fermentation

    In 2017, the brewery invested in a new bottling line. This includes an automatic depalletiser and bottle washer, making it possible to work with new or refillable bottles. The filler, also acquired in 2017, is used to refill the bottles. These are then labelled using a next-generation labelling machine which adds a body label and neck label. At the end of the line, the bottles are placed in trays by a packer, manufactured in 2012. This machine is quite special because it lies the 37.5 and 75cl bottles horizontally in the crates. This was a must for the brewery in order to ensure the best second fermentation (through a greater contact surface area).

  • Bottling

    Before bottling, the residual sugar content is checked and, if necessary, adjusted to a very specific value through the addition of liquid sugar. A special new yeast culture is then added for the second fermentation. The beer is bottled and, inside the closed bottle, this yeast multiplies and converts the sugars into alcohol and CO2. The multiplication of the yeast makes the beer cloudy and the second fermentation in the bottle gives the beer its fizz. The sugar content before bottling is therefore very important because the beer’s CO2 content (fizz) after the second fermentation is dependent on this.

    The bottling line can process 25, 33, 37.5, 75 and 150cl bottles, at a rate of between 5,000 and 12,000 bottles per hour.

    • The bottle washer empties the bottles, preheats them, soaks them in a bath of caustic soda at 80°C, turns them, cleans them by injection (inside and outside) of caustic soda at 80°C, rinses them by injection of hot water at decreasing temperatures and finally rinses them by injection of cold water.
    • The filler-capper first pressurises the bottles with sterile air, then fills them under constant pressure to prevent mould growth. Small bottles are then capped.
    • The corker is used for 37.5, 75 and 150cl bottles.
    • The wire hooding machine: is used for 37.5, 75 and 150cl bottles.
    • The labelling machine and ink jet adds a body label and neck label and prints a production batch number (traceability) and an optimal release for consumption date (compulsory from a legal point of view but not particularly useful for beers with a second fermentation in the bottle).
    • The crate washer cleans and rinses crates between the bottle washer and the labelling machine.
    • The packer takes the bottles and places them in trays (horizontally for the 37.5 and 75cl trays and vertically for the 25 and 33cl trays).
  • Barrelling

    The keg line can process 15, 20, 30 and 50l barrels at a rate of 50 barrels per hour.

    • The pre-washer provides residual pressure control, rinses the barrels and pre-cleans them using an alkaline cleaner.
    • The washer-filler empties the barrels after the pre-clean, rinses them, cleans them using alkaline and acid cleaners, steam sterilises them, fills them and rinses the top.
  • Second fermentation

    The bottles and kegs* are taken to rooms heated to 23°C for the second fermentation. They are kept at 23°C for six to eight weeks before being sold. Once in your possession, our products can be stored for several months, even several years, in a cellar at 12°C. This is because the combination of our traditional brewing technique and special yeast creates beers with no residual sugar and an interesting balance of flavours (after more than 6 months of the second fermentation in the bottle). The flavour of the beer matures, becoming more complex. That is why Dupont beers improve with age. Your beers will keep better in a cellar where the temperature and degree of humidity are consistent. The second fermentation continues in your cellar and the flavour of the beer slowly develops, all the sugars ferment and the flavour of the beer matures, becoming more complex.

    *Biolégère, Bons Voeux, Saison Dupont Dry Hopping.