I need help! Can I open up sealed jars and re-process the contents? I didn't like the flavor

The National Center for Home Food Preservation says you can reprocess within 24 hours of the original processing. After that, it is not safe to do so. . The reason is that recooking the product, as well as adding additional ingredients, will change the density of the product (and may change the pH). Processing times are established based on the density of the product and the size of the jar — and how many minutes it will take to equalize the temperature in a water bath canner so that the product in the jar reaches 212degrees F.

With that in mind, you can always empty the jars and doctor the product in any way you wish, but you should freeze it or refrigerate for no more than a month. I hope this is helpful.

My jam is to sweet! Is it possible to recook the jam and add more fruit without any sugar?
thank you

If you jam is fine other than being not hot enough, give it as gifts and do not worry about re-processing. Your recipients may not be able to tolerate high chile heat--something to remember. And you can use this as a learning experience and make a note to add more chile in the future, or leave the chile seeds and veins in for more heat. I'd add ground red chile (cayenne) if I wanted more heat.

Also, realize that re-processing your jelly may reduce or cancel out the jell, as the effects of pectin can be reduced by heat.

If you still want to try, please read what is at these two links and then consider your decision:
Hard jam/jelly: http://nchfp.uga.edu/how/can_07/stiff_jelly.html
Soft jam/jelly: http://nchfp.uga.edu/how/can_07/remake_soft_jelly.html

It is possible to reprocess, but only within 24 hours of the original processing.

You can reprocess them. Just make sure you use new lids and bring your preserves to a boil do they are hot when you put them in the jars. You can reprocess any canned goods but the contents will be softer after the second processing, so pickles don't reprocess well but jams and sauces aren't affected.

Someone with more expertise than me should weigh in, but I think it would be fine. I recently lost my canning virginity, and - very concerned about committing murder by marmalade - I researched what to do if the seal wasn't perfect, and reprocessing was recommended everywhere. I don't see why it wouldn't be ok, even just for flavor reasons.

But, Emily, aren't the recipients going to be so touched by the effort and beauty of a gift of your homemade preserves (!) that at the end of the day the uber-precise flavouring (which is probably fabulous) will never be critiqued? Cheers, Zelda

(I realize I'm not answering the question, but I'm awfully curious why you wouldn't just chalk it up to experience and add your spice when you're going to use the preserves instead of going through all the trouble of redoing, recooking, re-canning.)