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Does yeast nutrient expire?

Discussion in 'Homebrewing' started by Ol_Johnny_Skippelwicky, Jun 26, 2013.

  1. I inherited some ancient yeast nutrient with no discernable date on it. The package says it contains urea and ammonium phosphate. Can this go bad?
     
  2. MrOH

    MrOH Savant (465) Maryland Jul 5, 2010

    Maybe? Probably? Can't hurt?

    Pitch a healthy amount and oxygenate appropriately.
     
  3. telejunkie

    telejunkie Savant (340) Vermont Sep 14, 2007

    my initial reaction is yes...but then again mainly what you're doing is boosting soluble nitrogen for the yeast to gobble up, so maybe not.
     
  4. HerbMeowing

    HerbMeowing Savant (385) Virginia Nov 10, 2010

    The best homebeer is made with fresh ingredients.

    Just sayin'.
     
  5. Thanks for the responses, everyone! My inclination was to use fresh stuff too, but I have so much old that it was a shame to let it go to waste...
     
  6. barfdiggs

    barfdiggs Savant (420) California Mar 22, 2011

    Most yeast Nutrient that you buy at the homebrew store is just food grade urea. If stored properly, its good for at least 5 years.
     
  7. pweis909

    pweis909 Advocate (715) Wisconsin Aug 13, 2005

    I would not hesitate to use old urea and ammonium phosphate. These are already broken down almost completely, making them easy for yeast to utilize. Urea could potentially break down abiotically, but even if it did, you would be adding stuff that yeast will be able to use. Don't sweat the small stuff, and this is small.
     
    billandsuz likes this.
  8. inchrisin

    inchrisin Savant (445) Indiana Sep 25, 2008


    :confused: How do you know this?
     
  9. HerbMeowing

    HerbMeowing Savant (385) Virginia Nov 10, 2010

    Yeast nutrient is cheap.
    Malt bills...hop bills...and pipeline interuptions are not.

    Why risk brewing a batch of FUBAR?
     
  10. pweis909

    pweis909 Advocate (715) Wisconsin Aug 13, 2005

    Instinct derived from a PhD in Biogeochemistry and some understanding of … soil fertility (DAP and urea are sometimes used as fertilizers).

    Sometimes in labs, chemists are concerned with abiotic transformations of reagents in jars:
    • Occasionally, the concern is for safety reason (for example, something explosive).
    • More likely, the concern is for analytical reasons, because chemists often use the ratio of atoms in molecules and reactions (stoichiometry) to deduce things, like the alkalinity of your water.
    Neither of these issues is of concern when using diammonium phosphate and urea as yeast nutrient. Although urea can be used in explosives, there are very few homebrewers who have experienced spontaneous yeast nutrient explosions:)

    And precise stoichimetry is not a concern because you are not targeting the creation of any single molecule through a specific reaction pathway. Each N and P atom added could end up in a thousand different places. And homebrewers don't measure this kind of stuff.

    Furthermore, in the absence of biological action*, DAP and urea will be pretty stable. Abiotic transformations will be trace and inconsequential. You would have to have your process dialed in more precisely than I think is realistically possible before this could be a legitimate concern.

    *In the unlikely event that you opened up your jar of yeast nutrient and found a snotty-looking biofilm growing on it, maybe adding it to your beer would not be the best decision? Even then, the nutrients held in the biofilm would benefit the yeast. But be sure to boil it!:)
     
    inchrisin likes this.
  11. For those of you who use Wyeast nutrient blend (that is what I personally use), there is a 1 year shelf life with that product.

    “Wyeast Nutrient Blend

    Product: Supplemental nutrients for propagation & brewing

    Description:

    A blend of vitamins, minerals, inorganic nitrogen, organic nitrogen, zinc, phosphates and other trace elements that will benefit yeast growth and complete fermentation. Additional nutrients are most valuable during yeast propagation and sluggish or stuck fermentations. Supplementing with nutrients will reduce lag time, improve viability and provide consistent attenuation rates.

    Usage Rate: 1/2 tsp (2.2 Grams) per 5 gallons (19 liters) of wort.

    Usage Instructions: Dissolve Wyeast Nutrient in warm water. Add solution to kettle 10-15 minutes prior to end of boil.

    Stability: 1 year if stored in airtight container in a cool environment.

    Packaging: Nutrients are available in 1.5 oz, 2lb. or 8 lbs. containers”

    Cheers!
     
    PortLargo likes this.
  12. pweis909

    pweis909 Advocate (715) Wisconsin Aug 13, 2005

    Although the ingredients of this one are a little more complicated than DAP+Urea, I feel that my earlier reasoning, based on gut instincts more than specific biochemical understanding, still stands: The amount of chemical transformation that occurs is likely very small, yeast are still likely to be able to utilize transformed products, and homebrewers don't have their systems so dialed in that subtle changes in yeast nutrient will matter.

    For me, the biggest concern about old yeast nutrient is that it means I am not brewing often enough.
     
    JackHorzempa likes this.
  13. MaineMike

    MaineMike Savant (290) Maine Jan 22, 2011

    Yeast nutrient is "expired" yeast plus some nitrogen and zinc supplements. I suppose it could become less effective over time but there's no harm in using old nutrient.
     
    pweis909 likes this.

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