Newbie Question

[whistledown]

I have been fermenting my first every batch of red wine from local grapes (Shiraz). The fermentation has been stable for the past 2 weeks at about 1.003. Unfortunately I did not take the original gravity reading. The fermentation has been controlled at a constant 24deg C. The yeast I used was Mangrove Jack BV7 with an alcohol tolerance of 14%. I have tasted the wine and there is more sweetness than I would like. Is it possible that the fermentation stopped because I have exceeded the yeast tolerance level? If so could I use a different yeast to finish off.

 

[sawineguy]

There are numerous reasons your ferment has become stuck. I don't believe it would be due to high alcohol but instead due to a lack of yeast assimilable nitrogen (YAN). Did you add any DAP or a form of nitrogen to your ferment? this could help deduce the problem of your stuck ferment. Also does your ferment have a rotten egg (H2S) smell. This is an indicator of yeast stress due to a lack of nutrients.

 

[RParker@VDV]

A simple glucose/fructose enzymatic test will confirm your suspicions. I would get a lab to run a test for (it's very cheap) and make a plan from there. Which region are you from by the way?

 

[whistledown]

I added a yeast nutrient at the rate of 1g / 5litres at the time of pitching the yeast. The only thing is I the nutrient I added is what I use for home brew beer yeast. I assumed it would be the same thing, now I am not sure. There are no off smells

 

[whistledown]

A simple glucose/fructose enzymatic test will confirm your suspicions. I would get a lab to run a test for (it's very cheap) and make a plan from there. Which region are you from by the way?

I am from VIctoria in Australia

 

[sawineguy]

Okay so if the nutrient is DAP it seems like a sufficient addition, but may require more. Does the packet of the nutrient say what it is? Otherwise reinoculating with some more yeast, or starting a rescue culture can help. Do you have a hydrometer on hand?

 

[whistledown]

The yeast nutrient says "This Yeast Nutrient is a blend of vital minerals/nutrients that aid in yeast activity during fermentation. (Zinc, Phosphorous, Potassium and Manganese)" Yes I have a hydrometer.

 

[RParker@VDV]

What temp is the wine currently sitting at? Is there any indication of fermentation at all? CO2 bubbles rising? What's your hydrometer reading (remember to account for temp if its calibrated to 20 degrees C)

 

[whistledown]

The temp is currently at 24 deg C with no sign of CO2 bubbles. My last sample looked as though the wine was starting to clear indicating fermentation has stopped. Good point about the calibration factor. When taking that into account the gravity would be 1.0005. I have been brewing beer for years and never taken the calibration factor into consideration as the odd point doesn't really matter. Having a gravity of 1.0005 is that near enough or should I strive to lower it? The wine samples actually taste quite good, a little fruity but otherwise ok. Will this fruityness mellow out as the wine ages?

 

[sawineguy]

Okay, from that reading you have a reading of 0.1 degrees Baume which is fine for many table wines, however it is not dry and this sugar can cause spoilage if enough sulphur isn't added. It is important to get your wine through Malo first but some sulphur is okay (below 60ppm total). Once complete add som sulphur to bring it up to keep the wine stable. I'm sure in your neck of the woods you don't have a problem with pH so the conversion to free SO2 will be good. Through malolactic fermentation the bacteria will impart flavours to your wine, and if you chose to age with some oak it will also add more flavours to complement the fruit.

 

[winemaker81]

The yeast could be maxed out. I purchased west coast USA grapes last fall -- all came in over 15% (not my preference, but the grapes are what they are).

I recommend 2 things:

1. Add a higher threshold yeast, such as Lalvin EC-1118 (which will ferment a rock, if given the chance). This may not help, but it won't hurt.

2. Give it time.

Last fall I did a second run wine on Malbec, Merlot, and Zinfandel pomace. It reached 1.000 and stuck. A month+ later I put the wine in a barrel, and a month after that it renewed fermentation. It blew the bung on the barrel twice.

Yeast does its own thing ......

 

[RParker@VDV]

Okay, from that reading you have a reading of 0.1 degrees Baume which is fine for many table wines, however it is not dry and this sugar can cause spoilage if enough sulphur isn't added. It is important to get your wine through Malo first but some sulphur is okay (below 60ppm total). Once complete add som sulphur to bring it up to keep the wine stable. I'm sure in your neck of the woods you don't have a problem with pH so the conversion to free SO2 will be good. Through malolactic fermentation the bacteria will impart flavours to your wine, and if you chose to age with some oak it will also add more flavours to complement the fruit.

In response to sawineguy's comments - Did you co-inoculate the wine with Malo bugs with the initial yeast addition, sequentially OR letting it do Malo naturally? If you go down the path of re-inoculating your wine with another yeast starter, I would add some malo bacteria at the same time and try and get this wine stabilized sooner than later. Again, I recommend getting some hard numbers from the lab with an enzymatic test for sugars.

 

[whistledown]

I haven't added Malo bugs but it seems like a good idea to re-inoculate with a yeast starter and add some then. I will look into getting a lab test. What type of lab would do this?

 

[sawineguy]

If you live near a wine region many small wineries should be more than happy to run a RS (residual sugar) for you. A rather reliable DIY method is to use a flintiest tablet, these were developed for diabetics to test their sugar levels in urine but works the same for wine. Adelaide university uses these for quick tests. ANPROS RESIDUAL SUGAR TEST KIT

 

[whistledown]

Thanks all there is some fantastic info in your posts. I take my beer brewing very seriously but have been doing it for a long time. This is my first foray into wine and with time and knowledge will do the same. Can you recommend a good book, beginners guide. Thanks again.

 

[sawineguy]

Glad we can help. As for a great beginner book I recommend Making Good Wine by Dr Bryce Rankine. This book is bought by most wine students where I am from and holds a special place for many winemakers. It has basic information through to the justification of processes and is in easy to read language. I've included a link for you. Making Good Wine

 

[kevinlfifer]

I agree with WineMaker81, Add a rescue yeast and wait. 1.000 sg will be really sweet, especially after some time in the bottle.

 

[whistledown]

Glad we can help. As for a great beginner book I recommend Making Good Wine by Dr Bryce Rankine. This book is bought by most wine students where I am from and holds a special place for many winemakers. It has basic information through to the justification of processes and is in easy to read language. I've included a link for you. Making Good Wine

I ordered the book today. looking forward to it.

 

[whistledown]

The Malo culture I ordered is good for 250 litres, I have 50 litres. Should I use all of the culture or just a portion of it. How do I know when it has completed.

 

[Johnd]

The Malo culture I ordered is good for 250 litres, I have 50 litres. Should I use all of the culture or just a portion of it. How do I know when it has completed.

I always use the whole thing, it doesn’t keep well. You can use Paper Chromotography or Malic Test Strips to determine your MLF completion.