Confused about lemon juice, processing time for applesauce
I'm confused about adding lemon juice to applesauce. In the Ball big book, it says "lemon juice is not an optional addition- Lemon juice is added to..assure the acidity of the finished product." This implies to me that lemon juice is a safety-related addition. However, I do see apple jam recipes that do not use lemon juice in them (as in, say apple maple jam). So, what's the deal? Is it really unsafe to can applesauce without added lemon juice?
Also, what's a safe processing time for applesauce quarts? I've seen both 15 and 20 minutes.
One last question: In Linda Lou's apple pie jam, is it okay to decrease the amount of sugar in the jam safety-wise? I'm planning to use Pomona instead of regular boxed pectin.
Thanks for your help!