@JohnT When I went to pick these, the man that owns the small vineyard had 4
or 5 vines. Instead of picking, he laid down tarps and vigorously shook the vine, this also knocked off a tremendous amount of debris. I tried to spray all I could off the grapes. I then rolled and bounced them on a wire mesh to dry, even so, I still had a lot of little bits and pieces.
I will pick the next ones by hand. I feel the shaking technique put a lot of small unripe grapes in with the lot.