I got the idea from Jeff Cox "From Vines to Wines" 22-24 days is he feels ideal. The skins break down more and release extra colour, fragrance and flavour. The short chain tannins join up to make long chains which are not as bitter. Same effect as aging. When the ferment slows the fermenter is covered with plastic sheeting or lid with an airlock. I pump a little CO2 into the fermenter every day to make sure the must is protected helps prevent oxidizing. Jeff Cox recommends getting a CO2 cylinder and setting it at a dribble. When the cap falls and all you see is liquid it is time to press. I do this with all the reds now as it has made a huge difference to the quality of the end product. I'm yet to see the effect on long term aging as I've only been doing it since 2014.
Of all the books on wine on the shelf I've found Cox to be the most practical and sensible.
As to the question on keeping yeast from a good year. My theory and it is only a theory is that whatever yeast is around in a particular year is best suited to the grapes for that year. So what was good in a wet year (here) like 2016 would not have been as ideal as those that were about in a dry year like 2014. I'm also a bit too lazy to make the effort to go that extra step and mine the yeasts for use in subsequent years. So you can see my theory is really an excuse not to create extra work.
Of all the books on wine on the shelf I've found Cox to be the most practical and sensible.
As to the question on keeping yeast from a good year. My theory and it is only a theory is that whatever yeast is around in a particular year is best suited to the grapes for that year. So what was good in a wet year (here) like 2016 would not have been as ideal as those that were about in a dry year like 2014. I'm also a bit too lazy to make the effort to go that extra step and mine the yeasts for use in subsequent years. So you can see my theory is really an excuse not to create extra work.
