Biology Coursework - Decomposition of milkWatch
I measured the Ph of the two types of milk over two days at about 35oc.
When pasturised milk goes off, the bacterial enzymes in it convert lactose into lactic acid, which reduces the Ph of the milk. So the Ph of the pasturised milk should have dropped over the two days, which it did.
UHT milk shouldn't have any (or very few) bacteria in it so no or very little lactic acid should be produced and so the ph shouldnt really drop much over the two days.
However....a couple of us (doing seperate experiments) found the drop in Ph of the two types of milk to be the same (everything was sterialised and the procedure was fine). We used Ph probes and a data logger so it was definatly accurate.
Does anyone have any explanations for why the ph of the two types of milk dropped by the same amount, or why the UHT milk went off at all (which is shouldn't have really done as its not meant to contain any/many bacteria). It definatly shouldnt have gone off as much as the pastursied milk.??
Any help would be gratefull recieved......