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FermFed Yeast Nutrient
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FermFed Yeast Nutrient

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Help your yeast reach the end of fermentation safely while producing amazing flavors with FermFed by CellarScience®.  Yeast that are given FermFed have a higher likelihood of fermenting without issue while producing wines with more intense flavors and aromas.  FermFed is a complex nutrient blend of diammonium phosphate, thiamin, amino acids, sterols, pantothenic acid, mannoproteins, protective microelements derived from yeast hulls, and vitamins B2, B5, B6, & B12.  FermFed also contains the organic and inorganic nitrogen (DAP) that yeast need.  

How Much Do I Add and When?
The recommendation that covers most fermentations is to add 1 gram per gallon of FermFed DAP Free at the onset of fermentation and then add 1 gram per gallon of FermFed after 1/3 sugar depletion. Mix the nutrients in a small slurry of water and add to the fermentation.  Read more below if you are interested in measuring YAN (Yeast Available Nitrogen) and adjusting your nutrient schedule accordingly.  
The Science of How it Works
The different components of FermFed work in different ways to feed and protect your yeast. 
  • Grape must/juice is often deficient in assimilable nitrogen. When yeast do not have enough nitrogen, they are more likely to produce hydrogen sulfide (rotten eggs). FermFed helps to eliminate this problem by providing enough nitrogen for most situations.   
  • Yeast get weaker as they divide and multiply. They run the risk of not being able to properly finish fermentation as the alcohol content rises. Feeding them sterols help cells maintain membrane fluidity so that the yeast can properly function as alcohol and other harmful compounds in the fermentation conspire against them.  
  • Mannoprotein molecules bind esters and terpenes and work as an anchor to keep them in solution so they are not driven off by CO2 during fermentation. 
  • Pantothenic acid is added to help reduce the production of hydrogen sulfide.  
  • Thiamine is important for yeast metabolism. 
  • Vitamins B2, B5, B6, & B12 are important for general yeast health. 
Advanced - Adjusting Your Nutrient Schedule Based on YAN (Yeast Available Nitrogen)
In addition to the nutrients provided by FermFed or FermFed DAP Free, yeast need a certain level of nitrogen to perform adequately. If deprived of nitrogen, yeast are more likely to produce off flavors, most notably hydrogen sulfide. When added at the rate of 1 gram per gallon, FermFed provides 38ppm of YAN while FermFed DAP Free adds 20ppm. 
How much YAN do you need? Acceptable levels range from 175 to 300ppm.  YAN levels in grapes vary, with grapes from warmer climates often having less. The best practice is to measure your grapes using a commercial wine lab or the Vinmetrica YAN Test Kit along with a Vinmetrica Meter. If you know your YAN the following is a good general guide:
  • 175ppm or above = FermFed DAP Free @ onset + FermFed DAP Free @ 1/3 completion (adds 40ppm YAN)
  • 150ppm or above = FermFed DAP Free @ onset + FermFed @ 1/3 completion (adds 58ppm YAN)
  • 125ppm or above = FermFed @ onset + FermFed @ 1/3 completion (adds 72ppm YAN)
  • Below 125ppm = FermFed @ onset + FermFed @ 1/3 completion + extra DAP 
The best way for to test for YAN is using a lab or a home testing solution like this YAN kit from Vinmetrica. An acceptable level for YAN is between 200 to 350ppm
  • FermFed provides 38ppm of Yan when added at the rate of 1 gram per gallon.
  • The reason we don’t automatically use FermFed for a Stage 2 is that we don’t want to introduce excessive amounts of DAP into the wine if your yeast don’t need it.  
For a full yeast nutritional plan, use FermStart when rehydrating your yeast, FermFed DAP Free at the onset of fermentation, and FermFed after 1/3 sugar depletion.