Effect of Heat on Carbohydrates (starch/sugar) Flashcards
What are the 2 browning reactions for sugar?
Maillard reaction
Caramelisation
What is caramelisation?
A non-enzymic reaction involving the oxidation of sugar
What happens during caramelisation?
The removal of water (as steam) and the breakdown of sugar to sugar anhydrides
Why is caramelisation done?
For its resulting nutty flavour
What 2 reactions are starch involved in?
Maillard reaction - dry heat
Gelatinisation- moist heat
What happens when making a roux sauce?
Gelatinisation
What 2 components come out at 70 degrees when making roux sauce?
Amylose - straight and wavy chain - comes leaks out first
Amylopectin - branched chains
What happens during gelatinisation?
Starch in the flour is cooked (removes flour taste)
Starch absorbs water
Starch grains burst
At 70 degrees Celsius, 2 components come out into solution
What is gelatinisation?
When starch thickens on heating and set while cooling
What happens after gelatinisation?
The amylose and amylopectin lattice together to form a gel with interstices inside it
What are interstices?
When water is trapped within the amylose and amylopectin lattice
What is retrogradation?
Ageing of the colloidal gel
What happens in retrogradation?
Once a sauce has been prepared, the colloidal infrastructure starts to collapse and shrink after a few hours/days of storage
What happens during syneresis?
In time, a gel ages so the amylose/amylopectin lattice tightens, making water squeeze out (weeping)
