Lesson 7 - Design of Fermentation Vessels SAQ
This lesson enables you to test yourself on the material covered in the Design of Fermentation Vessels lesson and determine to what level you have attained the outcomes.
Suggested Response - Q4
**Why is it inherently difficult to carry out primary fermentation in a single-tank continuous fermentation system?
Response:
The principle of continuous beer fermentation is that wort is added continuously and is converted to green beer as a result of the activities of yeast cells held in the vessel. A continuous stream of green beer exits from the fermentation vessel.
In practice, this is very difficult to achieve. Fermentation is an ordered process where yeast nutrients are taken up in a fixed sequence. The presence of those nutrients that are utilised first prevents the yeast from taking up those nutrients that are normally used later in fermentation.
In a single tank continuous fermenter this natural order of nutrient utilisation is disrupted because of the continuous addition of fresh wort.
The way round the problem is to physically separate the different phases of primary fermentation either in separate compartments, as in a multi-tank system, or in different parts of a tower fermenter with an upward flow of fresh wort and no back-mixing.