partial wild ferment

[REDRUM]

I'm planning on doing a ferment of partial carbonic maceration - so I will fill about 1/3 of the fermenter with whole bunches, and add the crushed grapes on top.
The general idea of carbonic maceration is that anaerobic fermentation takes place within the intact grapes, which leads to some different & interesting flavours...
http://www.wineanorak.com/winescience/carbonic_maceration.htm

My question is whether I should stick with a commercial packet yeast from the get-go, or whether I should hold off for a few days to allow the yeasts present on the grape skins to start doing their thing before pitching the bought yeast?

I don't want the vigorous ferment of the must to drown out whatever is happening inside the whole grapes.

At the same time, I need enough alcoholic fermentation to happen from the start so as to flood the fermentation vessel with CO2 and create an anaerobic environment.

Any suggestions / thoughts? Are my concerns founded? Or should I just suck it and see?

 

[grapeman]

Not sure how to answer this for you. Ideally you would flood the fermentation vessel with C02 from the start and not rely on yeast to do it. That gives the berries longer time in an intact state for all the benefits of the carbonic maceration. As soon as alcohol levels approach 2% the grapes will likely break open. If you use a commercial strain or even wild from the start the grapes probaly won't make it even two days before they burst.

Have you made much wine before? If not you might want to begin with basic fermentation principals to avoid getting into situations you don't know how to handle.

 

[GreginND]

If you really want to mimic carbonic maceration as closely as possible, you want your fermenter to be mostly whole berries with a little bit of fermenting must in the bottom. You don't want most of your berries sitting in the juice. You want them surrounded by the CO2 and not the alcohol being produced from your fermentation. That way the berries will remain intact longer. The hard part is maintaining a strict CO2 atmosphere without oxygen. That would require maintaining a vigorous ferment in the bottom of the container throughout the maceration period and keeping it closed. Hard to do. Real carbonic maceration is done with pumped in CO2 and an airtight container without alcohol fermentation outside of the berries.

Frankly, I don't see any benefit to the effort involved unless one has the proper facilities to do a true carbonic maceration.

 

[REDRUM]

Cheers guys!
I ended up layering whole bunches at the bottom of the ferment, the crushed must on top, and pitching yeast straight away.
If the whole grapes stay intact for long enough for fermentation to take place within them, then great. If not, and it ends up being a regular ferment the whole way through, then that's fine too . ... I can compare against another batch that's all gone through the crusher anyway.

 

[GreginND]

Looking forward to learning more from your experiment. Please let us know the results.

 

[REDRUM]

I've been handstirring the must, and the whole bunches are well & truly intact sitting down the bottom of the vessels in the cooler liquid. So I have high hopes...!
I might leave them doing their thing for 10 days or so, then squish them up by hand in the buckets and let them ferment as normal from there...

 

[REDRUM]

OK, squished up the whole bunches in the must by hand last night. They were all intact - eating a few of the grapes, they had a really interesting flavour that was sort of semi-fermented but quite aromatic.

As all the juice from inside those berries has come into contact with the rest of the must the alcoholic fermentation looks to have ramped up again. The ferment temp has been relatively stable between about 24-28C, I'll let it ferment to dry on the skins - aiming to press this weekend.