What can we do with large, but unripe apples?

We've been given a lot of large but unripe apples with a lot of blemishes. We've washed them and experimentally used a juice extractor to get, so far about 2 quarts of juice. The juice is starchy. We're putting it through jelly bags right now even as I type to try to separate out the "starch."--Wow, it is going from looking milky brown to perfectly clear commercial apple juice color!

I had first thought I would like to try making hard cider. Could that be done with good results, or should I add sugar since the apples are still starchy and unripe?

For now I think we will try making some jelly with this first 2 quarts and see how that goes.

Is extracting the pectin and saving for future use something we can do at home?