As anyone who has made elderberry wine knows, you can get a green goo that sticks to everything plastic or glass, it wont wash off with soap and water and no matter how hard you scrub it just wont come off, this stuff is a nonpolar mess. Does it come from the stems, green or unripe fruit? Nobody really knows for sure. But it can be cleaned. Several years ago in the Winemaker magazine a fellow wrote that he had cleaned the green goo off by first rubbing it with some vegetable oil. He then cleaned the vegetable oil off with soap and water. We have used this method and it works very well. Also, some people have used goo gone, but it has a lot of chemicals in it and who wants that in their primary? We also steam juice some of our berries and there is very little green goo doing it that way. Whatever the source of the dreaded green goo, dont be hesitant about making elderberry wine because that nasty looking stuff cleans off pretty easily.