Kombucha Defense Mechanisms

Kombucha is a living symbiosis of bacteria and yeast that has been brewed in homes and shared with others for hundreds if not thousands of years. A living culture with such a long history must have some way of protecting itself from causing harm to those who care for it (i.e. homebrewers) or surely it would have been ditched generations ago.

While our ancestors simply had to trust their gut, modern science is discovering the important role fermented foods have played in our culinary culture since recorded history (if not longer).  The Human Microbiome Project has just begun to illuminate our understanding of the relationship between gut bacteria and health, but some of the preliminary findings are confirming what our ancestors instinctually knew: As Bacteriosapiens, fermented foods provide us with the regular influx of healthy, living bacteria our bodies need in order to boost proper functioning. The Kombucha culture evolved a few different defense mechanisms to protect itself from invasion from harmful microorganisms – low pH, ethanol and the SCOBY itself are all means that ensure the longevity of the culture. Let’s take a look at pH and the role it plays in protecting the culture.

pH & Kombucha

As you recall from the Top 5 Signs of Healthy Kombucha Brew, pH plays an important role in protecting the SCOBY from microbial invaders. Kind of like a chemical force field, the low pH creates a highly acidic environment in which our native bacteria and yeast thrive but simultaneously inhibits the growth of disruptive foreign & potentially harmful microorganisms.

pH was first conceived by Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory in 1909. Carlsberg Lab was set up by the Danish beer brewing company to advance biochemical knowledge, especially as applied to brewing beer. While studying proteins, Sørensen devised the pH scale as a means to express the concentration of hydrogen ions present in a solution.

While there are conflicting explanations for the definition, the most commonly accepted answer is that “p = potential” and the “H = hydrogen.” pH is a measurement of the acidity or alkalinity of a solution. When a substance dissolves in water, it produces charged molecules known as ions. Acidic water contains extra hydrogen ions (H+) and basic (alkaline) water contains extra hydroxyl (OH-) ions. As we can see on the chart below, the relationship from one pH level to the next is exponential.

The pH scale ranges from 0-14 with readings in the 0-7 range termed acid and readings in the 7-14 range termed alkaline. 7 is considered neutral and the ideal pH for our blood is just above 7. Without going into too many details, there is an important correlation between pH and health. While Kombucha tests on the acid side, much like lemon juice or apple cider vinegar, when it hits the digestive system it creates an alkaline ash. (See pH post part 2 which will also include how to track your own pH).

Image courtesy http://web.archive.org/web/20131216153241/http://staff.jccc.net:80/pdecell/chemistry/phscale.html

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