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.
Residual Carbohydrates
Residual carbohydrates at high levels in packaged beer may contribute mouthfeel and sweetness. The article below includes a short review of the subject from 1989.
https://onlinelibrary.wiley.com/doi/epdf/10.1002/j.2050-0416.1989.tb04650.x
The level of sugar is sometimes increased in the finished beer to add sweetness. This may be achieved in one of four ways:
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By prematurely arresting fermentation through crash cooling
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By adding sugar after filtration
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By adding unfermentable sugars such as lactose at the boiling stage
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By adding enzymes post-fermentation to break down dextrins (e.g. amyloglucosidase)
The final option is seldom used because reducing the level of dextrins can reduce body, making the beer taste thin.
Sugars differ widely in their sweetness. Taking sucrose as a baseline of 100, we can compare their relative sweetness.
Table: relative sweetness of simple sugars
|
Sugar |
Relative Sweetness to Sucrose |
|
Fructose |
130 |
|
Glucose |
70 |
|
Maltose |
50 |
|
Maltotriose |
25 |
|
Lactose |
20 |
|
Dextrins |
15 |
It is interesting to see that if you add the relative sweetness of glucose to that of fructose and divide by 2 if gives you the sweetness of sucrose.