A day in the life of a Winemaker during Harvest- Part 2

by Alex Rabagliatti October 01, 2018 2 Comments

A day in the life of a Winemaker during Harvest- Part 2


This is when I curse myself for agreeing to write a blog during harvest!
 
This is already our biggest ever harvest, and will be so by some distance come the beginning of next week, when most every grape will have come and gone. I’ve lifted this graph from our winery software. The y-axis is tonnage received:



 
You can see the trajectory of the 2018 harvest. It’s still in full flow, far beyond the point where the previous three vintages started to flatten out. It’s also far earlier than previous vintages. We are receiving our first Chardonnay today, 1st October, at least two weeks earlier than has been received in the previous three years – and riper too! Our main issue is keeping the presses rolling to match the speed of the grape intake, as well as juggling tank space so everything fits in but batches are kept as separate as possible to give us blending options down the line. Good problems to have!
 
The Rondo rosé I showed you a couple of weeks ago is now about half way through ferment, but today we floated some of our Pinot Noir, which we pressed yesterday.
 
Just to clarify (that’s a pun by the way - you’ll get it in a minute), flotation is a process of juice clarification (see?) whereby the raw juice straight from the press is turned into something relatively clear and ready to ferment. Grape juice as it leaves the berry is fairly cloudy and full of solids (as you can see below):

 
If we ferment in the presence of those solids you tend to get something fairly rough and tough! We remove them by pumping the juice through a high pressure chamber in the presence of very small nitrogen bubbles and a flotation aid mixed into the juice. The solids stick to these bubbles and float to the top of the tank, allowing us to draw clear, bright juice from the bottom of the tank, ready for ferment:

Alex Rabagliatti
Alex Rabagliatti


2 Responses

Alex Rabagliati
Alex Rabagliati

October 03, 2018

Hi Janette,

So if flotation is about binding grape solids to nitrogen bubbles and thus floating them out of the juice, the flotation aid is the “glue” that provides a stickiness between the bubble and the solid matter.

The principal aid we use is gelatin. We’ve tried chitin-based and potato-based alternatives but unfortunately they just don’t provide the same kind of adhesion to the bubble.

Janette MArshall
Janette MArshall

October 01, 2018

Alex great that you can write with a sense of humour, while under such pressure. Really enjoying learning along on the blog, to which end I have a question: what is a flotation aid?

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