When food is fermented how is it ensured that the right type of fermentation occurs so that you don’t make pickles when you want alcohol and vice versa?
In: Chemistry
What about when fermentation is done with wild yeast and bacteria. How is it controlled then?
There are three different kinds of fermentation.
Lactic acid fermentation is one kind, which is when sugars and starches ferment into lactic acid. This can make pickles and saurkraut and kimchi.
Ethanol fermentation creates alcohols by breaking down sugars into glucose, using a process called glycolysis.
Acetic fermentation creates stuff like vinegar and kombucha. This works with starchy grains and fruits.
The different kinds of fermentation are caused by different kinds of yeasts, bacteria, or chemical fermenting agents. You combine those different fermenting chemicals with different kinds of organic materials to get the process you want.
This can be controlled through A) the microorganisms you use, and b) the food you give them.
Note: most pickles are not fermented, just preserved in brine. However, things like yogurt, beer, and kimchi are all fermented.
Different microbes have different metabolic pathways, meaning if you give a certain bacterium Food A, it can spit out Product B and Product C. If you gave it Food B, it could spit out Product D and Product E.
Different bacteria (and fungi like yeasts) will produce different end products (like alcohol or a variety of different acids) depending on what food they’re given.
Different types of fermentation are carried out by different bacteria. When fermenting usually one isolates the specific bacteria you want to use and inoculates whatever you’re doing be it through acetobacter off fruit flies, pitching brewers yeast into wort, introducing mother of vinegar, blooming a packet of bakers yeast in warm water, mixing with live yogurt with lactobacillus. Also picklemaking uses brining, which is just sitting in salt and acid, and does not typically involve fermentation to produce. Although the vinegar used does involve fermentation, few picklemakers also make their own vinegar as it takes many months
The two big factors are precise environment control and known good samples of the microbes you want.
For example, Yogurt. Making yogurt involves first pasteurizing the milk to remove the existing microbes, adding your own microbes, and then keeping the milk at a temperature that those germs like more than any other germ.
You can also adjust things like acidity and salinity and several lines of yeast have been maintained for centuries.
Latest Answers