Yes, this is apparently why Concord grapes cannot be transported long distances without deteriorating. Witness the other table grapes you eat on a regular basis.
You’re not supposed to eat the skin, but follow my instructions as to eating a Concord grape fresh from the vine (best) or farmer’s market.
I read a wonderful story that in the early 20th century when they made grape jelly the US Army contracted for all of it in WWI. That said, it would make sense for PB&J to be the favorite US sandwich for decades.
Now that I hear they’re available in TX I’ll have to visit the source, taste and write about it. Thanks, folks!
Cooking with Dee 
grapes are icky! Peanut butter is better.
I love fresh concords – and they have muscadine grapes here down south that are similar. I like those too!