The lemon peel
The reason why frozen lemons taste different than lemons stored at room temperature is the level of acidity. Freezing lemons reduces this acidity, which is why they taste significantly less sour. The acidity will only return when the fruit thaws. Please be aware that the lemon peel contains 5 to 10 times (1) more vitamins than lemon juice which is why you should definitely make use of it and not just throw it away. Frozen peel tastes amazing, just make sure to wash the lemon properly before storing it in the freezer!