1, you can, but it is best to soak in warm water.

2, soak passion fruit is best to use 50-60 degrees Celsius of warm water, if the direct use of cold water will not be able to fully passion fruit and lemon in the flavor out, so that soak out of the passion fruit lemonade taste is not so good. But direct use of hot water can not, hot water will make the lemon bitter, and will also destroy the lemon in the vitamin C component. So use warm water is best, if you want to put it in the refrigerator, just wait for it to cool a little can be placed in the refrigerator.