Lactic acid
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Lactic acid (C3H6O3) is a weak organic acid (pKa 3.86 at 20°C).
Lactic acid is produced by lactic acid bacteria and certain types of yeast. The sourness from lactic acid is a major flavor component of sour beer. Souring may also occur in beer unintentionally resulting from a microbial contamination. Some lactic acid is naturally present on malt due to bacterial activity during malting. Many types of foods also contain lactic acid such as yogurt and sauerkraut.
Brewers can use pure food-grade lactic acid as an additive to lower mash pH and/or boil pH, and similarly lactic acid is responsible for the pH-lowering effects of acidulated malt and biological acidification. When lactic acid is used for pH adjustment, the amount used is typically too low to produce sourness, although it can sometimes still be tasted. Lactic acid is reported to have a flavor threshold of about 400 ppm in beer.[1]
In winemaking, lactic acid bacteria perform malolactic fermentation, metabolizing natural malic acid (and citric acid) into lactic acid.
Where to purchase:
Sources to review:
- Free radical scavenging and antioxidant effects of lactate ion: an in vitro study
- Effect of lactic acid fermentation on antioxidant, texture, color and sensory properties of red and green smoothies
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References[edit]
- ↑ Palmer, J. and Kaminski, C. Water: A Comprehensive Guide for Brewers. Brewers Publications, 2013.