Yoghurt and cream spoil at noticeably different speeds once opened: an unopened tub of yoghurt keeps for 1 to 2 weeks in the fridge, but once opened it should be used within 5 to 7 days. Cream, with its higher fat content, has a somewhat shorter life and should be used within 3 to 5 days of opening.
Both belong on an inner shelf, not the door — the door shelf's temperature swings every time it's opened — with the lid sealed tightly.
How should yoghurt be stored once opened?
An opened tub of yoghurt should be sealed tightly with its original lid or an airtight cover and kept on an inner shelf rather than the door. Eating straight from the tub with a spoon introduces bacteria from your mouth and can make it spoil a few days sooner than it otherwise would — spooning yoghurt into a separate bowl instead extends its shelf life.
The yellowish liquid that collects on top isn't a sign it's gone off; that's whey, and it can simply be stirred back in.
Why does cream spoil faster?
Cream has a higher fat content than yoghurt, and fat oxidises faster on contact with air, picking up a rancid taste sooner. An opened carton of cream should be used within 3 to 5 days; whatever's left after that can be whipped and frozen instead of thrown out.
If cream starts turning watery or you notice small clumps forming, use it up quickly even if the taste hasn't turned yet.
Can yoghurt and cream be frozen?
Plain yoghurt releases liquid and loses its smooth texture once thawed, so it's better suited to soups or baking than eating straight — freezing it for later cooking makes more sense than freezing it to eat as is. Cream holds up better whipped: frozen that way, it thaws into something usable as cake filling.
Both are best used within about a month of freezing; any longer and the flavour noticeably fades.
How can you tell they've gone off?
Mould spots, a sharp sour smell, or a container that's bulged are all signs yoghurt has spoiled — a faint tang on its own is normal, but any mould means it goes straight in the bin. In cream, a curdled, lumpy look or a rancid taste is the tell.
In both cases, if the smell and appearance are still normal, they're often safe to use for a few days past the printed date — but mould means out, no matter what the date says.
Does homemade yoghurt need different storage than store-bought?
Homemade yoghurt has a shorter shelf life than the pasteurised, factory-made kind; it's generally best used within 5 to 7 days in the fridge. The live bacteria involved in the fermenting process keep changing the yoghurt's flavour and texture over time, so homemade yoghurt tends to turn sour faster than a store-bought tub.
Cream behaves the same way: bought homemade or unpasteurised, it spoils faster than the industrial kind — that sort of cream is best used within 2-3 days and kept in the coldest part of the fridge. Since homemade yoghurt or cream doesn't come with a printed date, noting down the day it was made makes it much easier to track how long it's been sitting.