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February 15
Adding Lactic Acid to the Mash


I read in Fix (1997) that lactic acid will influence the pH of the brewing water and giving Calcium lactate as a result. Does this stays in the product after brewing? I’m looking at this scenario because I get at the end of fermentation, a good attenuation with a great flocculation of the yeast, but the beer stays really hazy and I have a lot of difficulty filtering it. I do step mash at 50 Celsius for protein rest, but still get some problems. I thought it could be chill haze, but everyone told me that a rest at 50 Celsius would help, and I can see that it doesn’t. Do you have any advice?


The addition of lactic acid to the mash will help reduce the pH of the mash which assists with several aspects of good wort production:

  • Lower pH helps the diastatic enzyme action in converting starch to sugars
  • It helps reduce the amounts of astringent tannins extracted from the husk

Typically the mash starting pH should be about 5.8 and the conversion pH about 5.4-5.5. Addition of calcium either with gypsum or calcium chloride at 100-200 ppm will normally produce a mash within these pH ranges. However you can also adjust the pH downwards by adding small amounts of lactic acid either food grade, naturally produced by lactic bacteria or using sauer malt in your grist. A proper lactic acid addition should not have much, if any, effect on haze in the beer or filtration problems. For haze and filtration problems I would suggest you investigate:

  • Malt quality, particularly high protein levels and beta glucan above 100 ppm
  • Calcium additions to mash and brew kettle
  • Kettle finings efficiency
  • Trub formation/separation and proper wort clarity prior to cooling
  • Yeast settling, non-flocculent yeasts may require use of a fining agent prior to filtration
  • Chill haze finings with hydro siica agents prior to filtration


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