Development of Flavour and Colour Flashcards
(22 cards)
What happens to the colour of the wort during boiling?
The colour of the wort increases and new flavour compounds are formed.
What is the source of colour pick up during wort boiling?
Non-enzymatic browning.
What are the two forms of non-enzymatic browning that occur in the kettle?
- Caramelisation
- Maillard reaction
What is the Maillard reaction?
A multitude of reactions starting with a reaction between reducing sugars and amino compounds.
What are the starting components of the Maillard reaction?
Reducing sugars (e.g., glucose, fructose, maltose) and amino compounds (e.g., amino acids).
What are N-substituted glycosylamines?
Products formed when the carbonyl group on the sugar reacts with an amino group on the amino acid.
What happens to N-substituted glycosylamines after formation?
They change to Schiff bases with the loss of water.
What are Amadori compounds?
Compounds formed after Schiff bases undergo Amadori rearrangement.
What types of aromas do Strecker aldehydes produce?
Nutty, malty, and worty aromas.
Name three examples of Strecker aldehydes.
- 3-methylbutanal
- 2-methylbutanal
- 2-methylpropanal
What are melanoidins?
Larger, more highly coloured molecules formed as the Maillard reaction proceeds.
What is the optimum temperature for the Maillard reaction?
140°C-160°C.
True or False: The Maillard reaction produces only flavoursome and coloured compounds.
False.
What are reductones?
Compounds produced in the Maillard reaction that can provide reducing (antioxidant) power.
What is caramelisation?
The pyrolysis of sugar that leads to the breakdown of disaccharides into monosaccharides.
What is the optimum temperature for caramelisation?
160°C-180°C.
What conditions enhance caramelisation during wort boiling?
- Scorched wort
- Long boil time
What factors contribute to colour formation in the boil?
- High wort pH
- High wort polyphenols
- High wort FAN
- High temperature heating medium
- Long boil time
- Low vigour
How do polyphenols contribute to wort colour?
They increase in colour as they are oxidised.
What is the relationship between wort pH and polyphenol extraction?
Higher pH values favour their extraction.
In very pale beer brewed with adjuncts, what can be the majority source of total beer colour?
The boil.
What is the next process to cover after boiling?
Extraction and isomerisation of hop compounds.
