2.5 - oxidation of food Flashcards
what is the hydroxyl group?
OH
what are the three ways in which an alcohol can be classified?
- primary alcohol
- secondary alcohol
- tertiary alcohol
what is a primary alcohol?
an alcohol which has a carbon attached to the hydroxyl bearing carbon
what is a secondary alcohol?
an alcohol which has two carbons attached to the hydroxyl bearing carbon atom
what is a tertiary alcohol?
an alcohol which has three carbons attached to the hydroxyl bearing carbon atom
what can alcohols be referred to when they have more than one hydroxyl group?
diols (2) or triols (3)
what are the oxidising agents used to oxidise alcohols?
- acidified potassium dichromate
- hot copper (II) oxide
which alcohols can be oxidised and which alcohols cannot?
- primary and secondary alcohols can be oxidised
- tertiary alcohols cannot
what is the colour change that happens when oxidising an alcohol with hot hopper (II) oxide?
black to brown
what is a primary alcohol oxidised to?
primary alcohol –> aldehyde –> carboxylic acid
what is a secondary alcohol oxidised to?
secondary alcohol –> ketone
what is organic oxidation?
an increase in oxygen to hydrogen ratio
what is organic reduction?
a decrease in oxygen to hydrogen ratio
what are the two oxidising agents used to oxidise alcohols to aldehydes?
- acidified potassium dichromate
- hot copper (II) oxide
what are the three oxididing agents used to oxidise aldehydes to carboxlyic acids?
- acidified potassium dichromate
- fehling’s solution
- tollen’s reagent
carboxylic acids are produced during the mild oxidation of what?
- primary alcohols
- aldehydes
what are flavour molecules oxidised to during the oxidation of food?
- carboxylic acids
- this can cause the food to have a bitter flavour
what are the two methods that food manufacturers use to prevent oxidation from taking place?
- packaging food in an inert atmosphere (nitrogen)
- adding antioxidants
what is an antioxidant?
a compound that is easily oxidised itself, therefore it protects other compounds from oxidation, i.e flavour molecules
what are two examples of antioxidants?
- vitamin c
- vitamin e
is vitamin c oil soluble or water soluble?
water soluble
why is vitamin e added as an antioxidant?
- vitamin e is added as an antioxidant to products containing edible oils since it is oil soluble (non-polar)
- this prevents the oils from spoiling and becoming rancid
