Once frozen I only ever use raspberries for cooking. They become mushy. And I don't wash them before freezing.

We have frozen red raspberries for years and the flavor does not change even after a year of storage. We don't wash them either. Not sure why yours would lose sweetness after freezing.

You might just use them for juice.

They wouldn't once the sugar is there it's there. Sugar can ferment to alcohol but not in a freezer

When thawing out Raspberries some sugar separates from the berries into juice, making the berries taste more sour/tart. Frozen fruits never taste the same as fresh.

That's a good point. I never thaw just use frozen fruit from yard in a smoothie, a desert or eat straight frozen so nothing lost. Raspberries a tiny enough to put in your mouth frozen will melt quickly and get all the sugar that way.

I don't have raspberries in my area but I do have blackberries. They do the same thing. They are great fresh but they get tart after being frozen. I think some sugar is getting converted to something else during the freezing or thawing.

Maybe it's a myth that sprinkle with sugar before freezing will preserve better....for some reason this still sticks in my head and my mom also did it.

Nothing really one can find scientifically.

I do the same on mine for my breakfast cereal, freeze them in small boxes and when thawed out a box last for a week. Some I don't sugar for my daughter who doesn't or can't use sugar. Definitely, flavour is suffering allot when freezing!

Thanks everyone. I think I'll experiment when they start coming this year. I'm guessing it converts somehow. I'll also try without washing.

I was wondering whether this discussion was about reds or blacks but seems more likely you are talking about red raspberries. I freeze lots of these for fall pressing of apple/raspberry cider. The thawed berry juice may be a bit tart but the flavor dominates the apple cider even at only 20% raspberries. Since I sell to some diabetic people who keep insisting that I must be adding sugar, which I'm not, I want to keep the frozen berries as simple as possible so that the mixed juice cider will keep its appeal.

Take the hint from Ocean Spray brands and mix your fruits if you want to sweeten without sugar.

The juice I pour off of thawed red raspberries ( to drink ) is not a significant part of the whole mass of thawed berries. Maybe 5% by weight.