Lesson One: Getting Friendly With Bacteria
I always open my discussion of fermentation with the simple fact that fermentation is the controlled rotting of food. Yummy, right?!?!
Of course many of the foods that we regularly enjoy in our society are fermented - vinegars, beers, chocolate, cheese, yoghurt, salami, wine and soy sauce are just some of the things most of us will have in our kitchen that have undergone a fermentation process. So while not everyone has thought about how fermentation is already part of their diet, must of us are regular consumers of fermented foods.
fermentation is the chemical breakdown of a substance by bacteria, yeasts, or other microorganisms, typically involving effervescence and the giving off of heat.
By harnessing those yeast, bacteria and microorganisms in our kitchen, we can open up a whole new world of food preservation and taste as well as giving our digestive systems a bit of help.
Fermentation Makes Food More Digestible
I am not going to make any wild health claims here in this course. I am not a dietitian and it has been many years since I worked as a Public Health Advisor, and even then I don’t think its useful to anyone to make miracle claims about food’s magic powers. What I can tell you, is that fermentation can be thought of as “pre-digestion” of food. Basically, those little microorganisms we harness to ferment begin to break down the foods making the nutrients within more bioavailable. As you probably know, we have a range of bacteria in our gut that do the same thing once we eat food, so these fermenting bacteria simply start that process a bit earlier and may well be different than the ones in our intestines, breaking down different elements, getting them ready for our own digestion.
It sounds complicated, but it really isn’t. For example, I am severely lactose intolerant. I can’t drink animal milk of any kind without suffering from intense stomach cramps. However, I use fermentation to my advantage - the cultures used in many aged cheeses feed off of the lactose sugar in milk, making it safe for me to eat. Many people with non-coeliac gluten sensitivity can eat sourdough bread without complaint because of a similar process. Is it a cure-all, no? But it definitely can help.
If you are interested in the health benefits of fermentation, I recommend Sandor Katz’ The Art of Fermentation
Make Food Last Longer
Going back to this idea of controlled rotting, the process of fermentation creates an environment where certain bacteria thrive and others die. This can help food last longer - as in my example above a cheddar cheese lasts a lot longer than the milk it was made from.
Much of this preservative effect is the result of lacto-fermentation. Lacto-fermentation refers to the use of lactic acid bacteria (LABs). These special tiny bacteria create lactic acid as they breakdown whatever is their preferred food. This acidification not only enhances flavour, it also produces acid that stops the growth of potentially harmful bacteria. Yeasts ferment sugars into alcohol and carbon dioxide. Both of these processes stop the availability of oxygen in the ferment and help the good bacteria thrive and stop the breakdown of foods by anything that might make the food ‘off’.
However, there are limits here. While wine may be shelf stable for many years preserved in a controlled environment, most ferments do have a shelf life. Fermented food rarely goes off in the same way as non-fermented food, but there does come a point where it is unpalatable.
Makes Food Safer
For my kids, the best part of any school castle visit is always the part where the tour guide tells them that in times past everyone (including the children) drank beer instead of water. Of course, this was a way to purify water of potentially pathogenic germs, not as my seven year old proclaimed one day “a way to get the children drunk so parents wouldn’t have to watch them”.
Through the process described above of lacto-fermentation and creation of alcohol, the fermentation process creates an environment where potentially dangerous bacteria can not grow. This means that not only does it make some foods safer.
A Note About Botulism (and how you probably aren’t going to kill your family)
We have often been scared by stories of how entire families have be en wiped out by Grandpa’s canned green beans. For many people, this has lodged in their brain to be wary of any preserved foods, especially vegetables. The good news is that the dangers here are specific to canned, and not fermented, foods. The bacteria at the root (pun intended) of the problem clostridium botulinum is natural present in soil and in its natural state it is relatively harmless. However, when the bacteria is stressed by heat (which hot water canning is one common stress), the bacteria lets off a toxin that can make people very very ill. The spore can only be destroyed by sustaining a temperature of 121 °C (250 °F) for at least 3 minutes. As heat gets nowhere near most fermented foods, the risk is essentially non-existent.
Understanding these processes is definitely useful in understanding fermentation, but don’t let it bog you down. The best thing about fermentation is that all you need to know is how to create the right environment for whatever you are fermenting and your friendly micro-organisms will do the rest.