pH indicators (sulphonphtaleins): m-cresol purple (1), o-cresol red (2), bromothymol blue (3), thymol blue (4), chlorophenol red (5)
Selective probes: Ellman’s reagent (6)
Linkage mechanism
Ion exchange
Reference colours
Food tested
Cod fillets
Beef slices
Chicken breast slices
Pork slices
EVOH (32%) based device
Solid phase
Ethylene vinyl alcohol copolymer (EVOH)
32% ethylene content
Receptors
pH indicators (sulphonphtaleins): m-cresol purple (1), o-cresol red (2), bromothymol blue (3), thymol blue (4), chlorophenol red (5), bromophenol blue (6)
Linkage mechanism
Covalent functionalisation
Reference colours for protein foods
Food tested
Cod fillets
Chicken breast slices
Reference colours for milk
Milk tested
Whole milk
Semi-skimmed milk
Skimmed milk
EVOH (29%) based device
Solid phase
Ethylene vinyl alcohol copolymer (EVOH)
29% ethylene content
Receptors
pH indicators (sulphonphtaleins): o-cresol red (solid foods) and bromocresol purple (liquid foods)