Berries go mouldy very quickly – particularly Raspberries. Try this: Prepare a mixture of one part white vinegar (or apple cider) and ten parts water. Drain, rinse if you want (though the mixture is so diluted you can’t taste the vinegar,) and put in the fridge. Vinegar will kill any mould spores and other bacteria that might be on the surface of the fruit. Raspberries will last a week or more and strawberries go almost two weeks without getting mouldy and soft.