29 June 2007
[Epi 5] TintoTV - Primary fermentation
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48 hours after crushing/mixing fruit and 24 hour after pouring the yeast-starter into our blackberry must, we check in on what should be our ongoing primary fermentation!
Primary fermentation refers to the initial and generally more “violent” fermentation soon after the yeast has been added to the must. During this time (which can last around 5 days depending on the temperature of the must), it is not unlikely to see the must have a thick layer of bubbles and foam. During these initial days, it is important to push down any layer/cap at the top of the must and to stir regularly. Generally, a lid is placed over the primary fermenter, but it is not sealed due to the vast amount of gas expelled during this process. This primary fermentation usually calms when the SG reaches about 1.030 and the bubbling appears to be more like a fizz.
Specific gravity (“SG”) indicates the density of fluid in comparison to pure water which is calibrated at a SG of 1.000. With fluids denser than water, the SG will be greater than 1.000, and, conversely, with fluids less dense than water, the SG will be less than 1.000. Our blackberry must started with a SG of 1.092. Now, as the yeast consumes the sugars, it produces alcohol; pure alcohol is less dense than pure water with a SG of about 0.785. So, during fermentation, we expect our SG to decrease, and by using a hydrometer to measure the SG, the hydrometer should slowly sink into the fluid. This reading very beneficial to help determine our fermentation’s progress.
As always, please send us any questions or feedback – we love the comments and the diggs and really appreciate your joining us for the show. Please don’t hesitate to share any pictures, processes, tips with your own winemaking – we are hoping to learn as much as we can and share what we learn.
As a side-note, we are testing technology right now to do a live episode, this will perhaps be for the blackberry bottling and we can include a chat room to make the entire experience interactive and, in the end, more fun!
Thanks again, don’t forget to comment below!
Steph was missed but Nico, you def. did a very good job on your own. Although you were not quite alone, your buddy the spray bottle was there with you … you should name him or her. As far as winemaking feedback is concerned, I can’t offer any constructive thoughts because I know much less than you guys. Go yeast go!
— Juan Carlos Jul 3 #
Great job, Nico. You don’t really need to stir as much as you did, but no harm done. One additional step I recommend is each time you take out some wine for a test, pour a little into a glass and taste it (both of you). You will learn what the wine should taste like at various stages of production, and can spot a problem early, while there might still be time to correct it.
— PeterZ Jul 10 #