I learned this from a friend a few years ago and have done this every single time, since, because it really DOES make a huge difference in the life of your berries (and also helps minimize bad stuff being digested by you!).
I could eat my weight in berries daily, but because that’s not healthy, I try to be more reasonable about it… but I also HATE throwing away spoiled food, and for some berries, it seems you are barely in your driveway on the way home from the store and they are spoiling! This trick helps extend their life.
I personally use Apple Cider Vinegar because it’s what we always have in the house, but any vinegar will work. The pH of Vinegar helps kill any spores, which is what makes them go bad, the spores (and time, but the spores rapidly speed the rottening process up!).
I use a 1:8 ACV to Water ratio, but honestly, people have all sorts of ratio’s – I guess find what works for you? Gently swirl the berries around to help dislodge any dirt, and this lets the vinegar do its job of killing the spores (and also any bacteria!).
I soak mine for 10-20 minutes, and then I drain them. Then I rinse them VERY thoroughly (to get rid of any lingering vinegar). (No, your berries will not take on the vinegar flavor, I promise.) Then pat them dry gently with a papertowel. Store in a container lined with papertowels, and enjoy for several more days!