Ye Flashcards
(23 cards)
What happens when proteins are heated
.when proteins are heated the intermolecular forces within the protein are broken. There is a change in the shape of the protein. The protein becomes denatured - this is irreversible cooking changes the texture of foods
Name the three types of alcohols
.primary secondary tertiary
Definition of oxidation when applied to _____ compounds
.invrease in oil and hydrogen ratio
Which of the three types of alcohols can be oxidised
.primary and secondary
Type of compound formed when a primary alcohol is oxidised is …
.carboxylic acid and aldehyde
Type of compound formed when secondary alcohol is oxidised ?
.ketone
What are aldehydes
.aldehydes are formed by the oxidation of primary alcohol. Aldehydes have the car only group . On the end of the molecule.
They end in “al”
What are ketones
.ketones formed by oxidation of a secondary alcohol. Have carbonyl functional group and end in one. Functional in middle
How can aldehydes and ketones be further oxidised
.aldehydes can be further oxidised to form carboxylic acids though secondary can’t wait to
Examples of oxidising agents
.potassium dichromate
Fehilings
Tollens
How can you distinguish between an aldehyde and a ketone
.plave substance in test tube with oxidising agent. Heat in water bath and see the colour change. ( aldehyde if colour change and no colour change is a ketone)
Why does an apple go brown when exposed to air and no skin
.substancws in the air are reacting oxygen causing it to go brown
Examples of manufacturing process used to prevent food being exposed to oxygen
.vaccuum packed ready meals to prevent oxidation
What are antioxidants
.they are good reducing agents which means they will get oxidised in preference to the food. Example of naturally occurring reducing agents are vitamin E and C
What is volatility
.volatility is a measure of how easily a substance vaporises. A volatile substance vaporises easily
What do the volatile molecules contained naturally in the food do
.volatile molecules contain naturally in food the food flavour
Why do some foods taste better when cooked in oil/water
.if the food molecule is non polar then it should be cooked in water
If polar should be cooked in oil
This is to prevent flavour loss
How does molecule size effect volatility and boiling point
.the larger the molecule the higher the boiling point due to stronger/ increased van der waals forces
The larger the molecule the less volatile is (due to increased van der waals forces
How does the functional group prevent a flavour molecule affect boiling point, solubility and volatility
.
Where is the best reducing agent in ECS
Top right best reducing bottom left best oxidising
Must be higher on the right than the left for reaction to occur
Why might no indicator need to be used?
It is self indicating
Definition for enthalpy or combustion
The enthalpy change when one mole of a substance is completely burned in oxygen
Definition for enthalpy of neutralisation
The enthalpy change when an acid is neutralised to form one mole of water
