Lesson 6 - Beer Flavour and Stability
In this lesson we will discuss beer flavour and beer flavour stability. This will include the effects raw material has on beer flavour, followed by a discussion on common taints, their flavours and consumer reaction. We will examine the flavour changes that occur during beer storage: focussing on oxidation reactions, the species of oxygen involved, and how we can utilise antioxidants to protect against aged beer flavour change. Finally, we will summarise the selection of raw materials and process optimisations available to improve beer flavour stability.
Point of Reflection – Reconvene:
Welcome back. So, what were your thoughts?
Since this is all about flavour, having a trained taste panel that can pick up and describe what a standard beer flavour profile is, as well as being able to identify what flavours are in the beer that are non-standard, is critical. This will be covered in more detail in the Quality Unit.
Once a non-standard flavour has been identified, you will need to find the source of where the off-flavour has come into the brewing process. This will involve checking all the raw materials that were used and ensuring there was no incorrect additions made (such as incorrect malt type or hops). An area that is often over-looked is the quality of the water. You need to check that the source water has not changed or the water treatment plant is functioning correctly. Incorrect levels of minerals in the water can have significant impacts on the beer flavour.
If your brewery uses multiple strains of yeast, it is critical to ensure that there is no cross-contamination of yeast as some yeast strains can cause a phenolic flavour in the beer. Contamination by bacteria (or wild yeast) can also cause a number of off-flavours, so it is important to check the cleanliness of the plant and that all the plant CIPs and environmental cleaning has taken place correctly and as per scheduled.
Cleaning materials can help prevent microbiological contamination, but they can cause off-flavours themselves if they are accidently dosed into the beer or there have been a CIP plant failure that has resulted in leakage of cleaning materials into the beer.
Check all materials that come in contact with the beer – both brewing and packaging plant (check for soiling, lubricants, worn plant) and packaging materials (lacquer inside cans) are in the correct condition.