Re: [Riverwoods Wineries] Wine SO2 Analysis

I forgot to include the PH measurement for the Port. It came in at 3.9, which is surprisingly high. Our initial PH measurement was 3.2, which may have been an error for such a high brix late season grape. I calibrated the PH meter twice and I verified that the PH meter is self correcting for temperature.

The PH has also come up from the fortification plus the port has likely started MLF, which raises the PH. With this high of a PH we will have to keep a close eye on it for spoilage and we will have to maintain a higher SO2 level. 30ppm is the minimum level that Angie recommended in her recent email.

Troy

Wine SO2 Analysis

We recently got some wine tested by WineWiseIdaho for SO2 and the ported tested for residual sugar.

 

• This year's 2009 Idaho Cab came in at 21ppm SO2. This is a safe level. We did not add any meta.
   
• Last year's 2008 Idaho Cab came in at 1 ppm SO2. This is a dangerously low level. We added 30ppm SO2, which will result in about 15ppm being absorbed for 16ppm total.
   
• This year's port 2009 came in at 4ppm SO2. This is a dangerous level for a wine with residual sugar. We added 50ppm SO2 which will result in a total SO2 of 29ppm.
  
• The port had a 6% residual sugar, which is slightly lower than we tried for. We estimate the alcohol level to be 20%.

 

Here is a brief history on the wines, SO2 additions and deletions (racking, etc).  We generally expect 3-5ppm SO2 loss a month from barrel storage. 7-10ppm SO2 loss from racking. In general our sulfite schedule is good. If we do an airative/splashy racking or stirring then we should add more SO2 and the reserves need a winter dose of SO2 to hold them until bottling.  I will update our "Riverwoods Guide To Sulfites" on the web site.

 

The 08 ID Cab was crushed on Oct 30, 2008 and sulfited with 1/8tsp meta per G of must, which is approx 100ppm.  It was pressed on Nov 25th. Racked off the Gross Lees on Dec 7th.  Racked off the Fine Lees in May and (I think) 15 to 20 ppm Meta added.  It has not gone through the final clarification racking. It has been in a barrel for 15 months so far.  This sulfite addition is enough to take it into May. We will want to add a little SO2 before we rack and bottle.

 

The 09 ID cab was crushed on Oct 18th with 100ppm meta and pressed on Nov 8th and racked off the gross lees a few weeks later. There have been no additions of SO2.  It has a low enough SO2 level to comfortably go through MLF. After ML we will rack it off the fine lees and add 15-20ppm meta.

 

The 09 Petite Sirah Port was crushed on Nov 17th, cold soaked for 4 days. We did fortification in 2 steps and vigorously stirred to mix the alcohol in. We pressed on Dec 2nd and again stirred vigorously.  We racked off the gross lees on Dec 10th (stirring) and again on Jan 18th because there was noticeable separation. On the last racking we added 20ppm SO2. Our PH has risen since pressing, both from the fortification and likely because ML has started. We have to maintain a higher SO2 level because of the residual sugar and higher PH. 25-30ppm

 

We follow the same sulfiting schedule for all our reds so we expect them to be about the same level as the 09 ID Cab--21ppm, which is a good level for ML.  The Malbec is going to be more like 10-12ppm because it was racked an extra time because of a scum on the surface. This is a little low, but safe enough. We'll add SO2 when we rack.