We found this tip online, tried it, and are excited about the results.  For most berries, this will help to keep your berries fresher, longer. The key ingredient? Vinegar!

 

Prepare a mixture of one part vinegar (white or apple cider) and ten parts water.

        1. Dump the berries into the mixture and swirl around.
        2. Drain, rinse if you want (though the mixture is so diluted you can't taste the vinegar,) and pop in the fridge.

The vinegar kills bacteria and mold spores on the surface of the fruit. After this vinegar washing, raspberries will last a week or more without getting moldy and soft.