Sometimes there is krausen but not always. Usually there will be some for the first few days but after that it’s gone. But sometimes none at all. But if you have a clear fermenter and good eyesight you can always see CO2 fizz bubbles going up – that’s a sure sign of fermentation, besides the change in specific gravity. This all makes sense because cider is very low in protein, unlike beer which has plenty of protein – protein is one of the primary building blocks of foam.
I haven’t seen foam yet with my ciders but haven’t ever used “fresh” apple juice as it is unavailable. Pectin and particulate may be a source of krausen WAG.
I got a huge cider krausen this time that refused to drop until the fermenter was cold-crashed. The yeast was US-05. I’ll rack tomorrow most likely and take it as a good sign…
I really love what US-05 does for cider. Tastes great. Unfortunately I left my US-05 cider sit for a little too long in the garage without a good seal and it turned into vinegar! Good tasting vinegar, though, that I will hang onto, maybe make some salad dressings.