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.
Taints from the Brewing Plant
Taints from the brewing plant and its supporting operations are uncommon, but care is needed in processing operations to avoid them.
Older brewing plants may have non-stainless steel as well as copper vessels. There is the possibility of introducing these metallic taints into the product from both these sources via the corrosion process which releases metal ions.
Iron can also be extracted from new stainless steel plant, if this is not passivated correctly. Passivation is covered in more detail in the Hygiene Unit, Cleaning Systems and Control lesson.
Metallic taints also arise from using poor grade diatomaceous earth filter powder. Reputable suppliers offer low beer-soluble iron grades, which should reduce this risk.
Lubricants used in plant maintenance are also a taint threat to beer: producing flavours of engine oil or diesel.
Diesel fumes themselves can migrate onto raw materials and end up as taints in beer. This is a risk when using diesel-powered forklift trucks. It is preferable in this instance to use battery-powered forklift trucks.
As you can see, there are many factors that can affect the final beer flavour that leaves the brewery and goes into the trade. How do you think you could reduce some of the risks in preventing non-standard beer from being released from the brewery, without the benefit of expensive laboratory equipment?
Give yourself 5-10 minutes to think about this, and then click ’Next’ to continue with this lesson.