jean, I'm not even going to venture to change your recipe. I'm assuming it's the one with the pineapple and raisins? If you cooked it longer it would make it thicker but it's not really safe to can pumpkin puree because of the density, and I think longer cooking is going to reduce your pumpkin to the prohibited puree consistency, so I wouldn't try that.

I don't know if the sugar is acting somewhat as a preservative in this recipe, but I don't think very much as there are two lemons with their juice, along with the pineapple.

If I were set on reducing the sugar, I'd just reduce the sugar by half then taste and add until I liked it, but I can't tell you that it is safe or tested or anything else. And since it's eaten straight from the jar, not heated, that adds another layer of risk, so I sure wouldn't play with it very much.

Annie

Rather than trying randomly modify a tested recipe and potentially making it result in poor quality (as in reducing the sugar and it won't thicken) or worse, making it unsafe (the sugar binds up some of the free water so reduces the pH slightly). The best and safest way to solve your problem is simply to can all your pumpkin plain in cubes as the guidelines say to do. That way it is all safely preserved for later use.

Then after opening the jars you can turn the plain pumpkin into whatever you wish.

https://nchfp.uga.edu/how/can_04/pumpkin_winter_squash.html

Dave