The yeast added to the Rodenbach wort is a collection of yeasts. Such a collection of yeasts and lactobacilli is difficult to maintain. A stock culture of such a mixture would already be a selection. The only thing Rodenbach can do is to reuse this mixture over and over again. Selection starts by following the fermenting wort, to decide which yeast is going to be collected and in which amount.
Washing yeast is a strong acidification of the yeast shortly before adding it to new wort.
With this washing, a correction can be made in the number of lactobacilli compared to the number of viable yeasts. This is a difficulty for smaller brewers, who are trying to brew a Rodenbach like beers. To make sure that beers are good, Rodenbach provides yeast to these brewers, for every brew they make. 2.The Rodenbach process. The brewhouse dates back to 1920.