There is black liquid coming out of the mincer/strainer. What is it?

There is no oil in our machines. What is happening here is that the oxygen content in some apples reacts to the metal in the strainer valve and starts to oxidize. It’s not at all harmful, but obviously it doesn’t look very nice. To prevent this, you can either sprinkle a little lemon juice over the apple segments, or if you are making a large quantity, switch everything off and rinse everything through once before continuing.