This is the question that was posed to us earlier today by one of our customers in Urbana, Illinois. They are going to make to make some homemade grape wine from Catawbas this year. What a great question!
The steam juicer we offer has a see-through lid. The reason for this is so you can see the condition of the fruit as it is being steam. Through this visual inspection you can tell if the fruit has any more to give or if it has been spent.
In the case of using the steam juicer for processing grapes, you will be able to see that what were once plump grapes are now slowly becoming smaller, shriveled grapes. Eventually, all the grapes will pack to the bottom and form a flat layer of skins. This layer will only be two or three inches high depending on the volume of your steam juicer.
The story is similar for other kinds of fruits as will when using a steam juicer. They will slowly lose their size and compact together at the bottom. Once this occurs, any further steaming is just a waste of time.
Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.