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 unintentionally in a beer with a microbial contamination. Many types of foods also contain bacterial lasting acid such as yogurt and sauerkraut.
While brewing beer, lactic acid can be used to lower mash pH and/or boil pH, by adding it as a pure product, or by using acidulated malt or biological acidification. In this case, the amount used is typically too low to produce a sour taste. Lactic acid is reported to have a flavor threshold of about 400ppm in beer.[1] Keep in mind that some lactic acid is naturally present on malt due to bacterial activity during malting.
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
References[edit]
- ↑ Palmer, J. and Kaminski, C. Water: A Comprehensive Guide for Brewers. Brewers Publications, 2013.