Got my grape juice for my wine using my sterile hands to break the grapes once they had had a 2 minute sulphite soak to sterilise them .
Left them c/w any stems in their juices for three days , poured off the juice into a sterile container then crushed a hand full of what was left at a time to ensure almost total juice extraction . Out of the 20 litre stainless steel bucket of black grapes I had 480 grams of waste .
So pre crush but don't crush the seeds , steep in their own juice in a covered container for three days and then put the grapes through your press to get maximum juice but don't crush the seeds for it makes the juice bitter .