If you haven’t watched Part One of The Sangiovese Project (processing the fruit), I suggest watching that first.
Part Two is all about fermentation. Two days after receiving the fruit, fermentation was under way in Bin X. It was important to plunge the cap of skins (and some berries) every day, partly for the gentle extraction of colour and tannin from the skins into the wine, but also to keep them wet to avoid spoilage.
Bin X converted the sugar into alcohol at a rapid pace. It went from 13 degrees baumé to one or two in the space of three days. By the fourth day you can see that there is a lot less activity in the ferment. With some advice I gave the bin a few more foot-stomps to squeeze more juice out of the remaining berries, which extended the ferment a few more days and extracted a bit more colour and tannin. After 10 days the ferment was finished, but daily plunging continued until pressing on the 22nd of March.
Bin Y had CO2 pumped into the bin and it was covered by cling-wrap. It was checked each day simply by smell, giving off a slightly candied fruit aroma. The weight of the berries gradually crushed the berries at the bottom of the bin, and the juice fermented dry. It was very crunchy and bright to taste.
The next part will focus on the pressing of the two bins, and their subsequent transfer into their vessels. Feel free to ask me any questions in the comments below.