I found a similar question (about using apples from thinning) on Ask Extension and hopefully it answers your question:

How do I use thinned unripe apples? #145231

Asked August 04, 2013, 11:55 PM EDT

I would like to know if there is something I can do with my thinned apples. I could either can them or freeze them if it will be eatable. I am concerned with them being sour they will not taste good or not good for us to eat.
Just I just thought I would try to clarify my question. I am trying to use the apples I thin off my tree and not just compost them or feed them to the cows. But if I can them in the pressure cooker will they be ok and not cause a stomach ache like eating an unripe apple. Also if you know, do you have a recipe you would recommend?

Clatsop County Oregon

Expert Response

Green apples contain a higher level of acid than ripe apples, which can irritate some people’s stomachs and mouths. Cooking the apples well will tenderize the apples, but not really reduce the acidity. If they are starting to ripen, they will continue after being picked. You could lay them out to see which ones do ripen more in a few days. Some could be mixed with ripe apples to balance the tartness and flavors to make applesauce or apple butter. Most applesauce recipes recommend a mix of apples for a more interesting flavor. http://nchfp.uga.edu/how/can_02/apple_rings_spiced.html Spiced apple rings call for tart apples. They could also be substituted for crabapples in recipes. Since they may be bigger than crabapples, you might want to slice them rather than leave them whole. http://nchfp.uga.edu/how/fruit_pick.html These recipes can be safely processed in a boiling water canner. No need for a pressure canner. Hope this helps, good luck! Jeanne BrandtReplied August 12, 2013, 11:23 AM EDTThank you so much for all your information. This is very helpful and I will try doing the spiced apple rings. Thank you again for your time in responding.The Question Asker Replied August 14, 2013, 10:25 PM EDT

Thank you for this response