North American Fruit Explorers mailing list at ibiblio

[Sarah Kehler Ewing <skkewing@yahoo.com>]

I've enjoyed the dialog on jam-making even though I live in Canada and have 
never heard of Ball or Pumona's pectin!  Up here your choice is pretty much 
Certo, to the point that it is referred to in a generic sort of way (like 
kleenex!).

So I'm wondering if anyone has experience with doubling jam recipes made with 
Certo Light (they make pectin for jam with approx. equal sugar and fruit, 
pectin with less sugar than fruit, and sugar-free), this uses 3.5 cups of 
fruit for 5 cups of peaches.  I have 6 kids and not enough time to make jam 
by single batches!  I made some Evan's cherry jam (like a Montmorency, but 
sweeter-not Bing sweet tho'!): a strict double recipe didn't gel, but a 
double recipe with an added 1/4 cup of lemon juice plus two extra Tablespoons 
Certo pectin (works out to about two and a half a boxs per double recipe) 
gelled beautifully. Raspberry jam also worked with the same recipe: double 
everything, add 1/4 cup lemon juice and two extra Tablespoons of Certo 
pectin.  Then I tried peach jam (spiced and plain) and I am 0 for 5 double 
recipes!  The doubled recipe called for 4 Tablespoons of lemon juice already 
so I didn't add more, but did add the extra 2 Tbsp. Certo and got
 only syrup. I tried more careful measuring and boiling and 3 Tbsp. of Certo 
and still got syrup.  I tried 3 boxes of Certo and am still getting syrup!  
All fruit for all the kinds of jam was measured after being mashed to a soup 
(not chopped!) and all of my fruit was very ripe.  My altitude is about 2300 
feet.

Any advice???