North American Fruit Explorers mailing list at ibiblio

[Scott Smith <scott@cs.jhu.edu>]

Most aspects of recipes can be scaled up or down, but there are some  
steps which may not scale.  In jam recipes what cannot be scaled is  
how much you are cooking down in a given sized pot.  If you put twice  
as much in the same pot it will evaporate at half the rate and will  
likely overcook.  The rate of evaporation is based on the surface  
area, i.e. the size of the pan, not how much is in it.  When I make  
jam, I never have more than one inch thick being cooked down.  Either  
I add pans on the stove, or do it in batches so that it is under 1".

Scott