Differences to consider when defrosting frozen berries versus citrus fruits
Frozen berries and citrus fruits thaw differently, and this determines whether they end up as a mushy mass.
Berries thaw well if done slowly, in the refrigerator or in a cold water bath. In the refrigerator, it takes about 12 hours per half liter of fruit, while in cold water the process is much faster due to the higher thermal conductivity.
If you're in a hurry, you can place them on a plate lined with kitchen paper, in a single layer and separated, and heat them for a few seconds using the microwave's defrost function. It's best to defrost them only partially if you want to better preserve their shape.
Citrus fruits are more difficult because it's almost impossible to keep the segments intact. However, once thawed, they're very useful for getting more juice: simply heat them in the microwave for 15 to 20 seconds and squeeze them, or leave them in cold water for 15 to 20 minutes.
The key lies in how the ice crystals form. When water freezes, it expands and presses against the cell walls of the fruit. The slower the ice forms, the longer and sharper the crystals become, which can pierce those walls and leave a mushy mass when thawed. Home freezers don't freeze as quickly as commercial freezers, which is why store-bought fruit usually keeps better.
That's why it's not a good idea to defrost fruit and refreeze it. The cycles weaken the cell walls, which don't tolerate these processes well. Only defrost the amount you're going to use.
Depending on its intended use, thawed fruit has different uses. Thawed and squeezed citrus fruits make great fresh juice for lemonade, marinades, or margaritas. If you need the zest of a frozen citrus fruit, grate it before thawing. Berries for a fruit salad should be thawed gradually and used just before the last piece of ice melts. For coulis or compote, there's no need to worry, as they will liquefy anyway.
In baking, defrosting fruit rarely makes sense, unless the sudden temperature change affects the batter's composition. For pancakes, muffins, or pie fillings, it's best to use frozen fruit without thawing, as this preserves its texture and prevents its flavor from mixing with the batter.
