U2 P6 - oxidation of food

Question 1

oxidation reactions

Answer 1

oxygen molecules from the air damage the structure of the fat/oil causing degradation of long fatty acid chains and formation of short-chain oxidation products

Question 2

antioxidants

Answer 2

molecules that prevent unwanted oxidation reactions occurring
they oxidise in place of the compound they have been added to protect
they are reducing agents

Question 3

how do antioxidants work

Answer 3

antioxidants ‘mop-up’ free radicals and protect the food by donating an electron to the free radical
this forms a stable pair of electrons, stabilising the free radical
during this process the antioxidant molecules becomes oxidised as it loses an electron

Question 4

oxidation is an ….. in the oxygen to hydrogen ratio

Answer 4

increase

Question 5

reduction is an ….. in the oxygen to hydrogen ratio

Answer 5

decrease

Question 6

oxidation of aldehydes

Answer 6

primary alcohol->aldehydes->carboxyllic acids
secondary alcohol-> ketones
tertiary alcohols do not oxidise

Question 7

oxidation of ketones

Answer 7

do not oxidise

Question 8

oxidising agents

Answer 8

hot copper
fehlings solution
tollens reagent
acidified dichromate