This investigation is still fermenting.
Fermented porridge is real, and it tastes good. As to the nutrition and history, it is a little hard to discern facts from strong beliefs. There is no doubt that some folks like their porridge fermented, and that fermented porridges have roots in antiquity.
Grains are often fermented to make alcohol and other tasty things. For example, soy sauce, miso paste, and tofu are all different versions of fermented soybeans. At a basic level, fermentation means letting bacteria consume some of your food. Different bacteria eat different things, and give different results. Sound gross? The bacteria is everywhere, anyways. In the air you breath, on your hands, on vegetables and dry grains from the grocery. It is all a matter of controlling its environment.
Sourdough bread is made with a fermented “starter” culture, which begins with flour and water. After a few days, naturally occurring bacteria on the flour and in the air start to eat the sugars in the flour. Some of these bacteria are called “yeast”, but that is really a generic term for a wide range of bacteria. Dry or instant yeast from the store is a particular type of bacteria that eats sugar and releases carbon dioxide, which makes bread rise. The sourdough culture has multiple types of bacteria: some, like the commercial yeast, turn sugar into carbon dioxide. Others, mostly lactobacilli, convert sugars to lactic and acetic acids. These are the same type of bacteria that make yogurt, sour cream, sauerkraut, and some types of pickles sour.
Fermented porridge is very similar to making sourdough bread. The cultures are similar, and the flavor profiles are also similar. Fermented porridge takes on a rich, sour flavor after a few days. Unlike sourdough bread however, it doesn’t really matter how much gas is being produced, because you don’t have to worry about trapping the gas for a good end product. It also means that porridge can be fermented before or after cooking. Most folks adhere to fermenting grain first, basically as a lengthy soaking process, and then cooking them as you would for a typical bowl of porridge. However, there is some evidence of porridge fermented after cooking. The Native Americans in the American South relied on corn, particularly hominy, for much of their diet. Hominy was known as Tan fula or “Tom Fuller” to many Southern English-speakers. Tan fula hawushko was a fermented hominy, basically made by letting cooked hominy sit out until it became sour.
Fermenting grain before cooking is much more common. Soaking grain in general reduces cooking time, and fermentation can simply be a long soak. Once a culture is started, even from a different grain, it is easy to transplant or kickstart some bacteria feasting. For example, if you access to a sourdough starter, throw a spoonful into a jar of oats. Give it a day or two at room temperature and you will have sour oats.
Is this actually healthy or are people nuts?
Yes! At the very least, it is as healthy as your standard bowl of porridge, with a different flavor profile. At best, this is the solution to all of your daily problems.
Fermenting grain helps breakdown different compounds within the grain. See From Mill to Bowl for an overview of the parts of a grain. Fermenting the grain breaks down a few key components that pose an obstacle to digestion. Phytic acid, lectin, enzyme inhibitors, and gluten are all compounds (enzymes, proteins) that exist in grain, and help it with various functions. Fermentation reduces or eliminates the quantities of these substances that exist in the grain. This helps with the digestion processes that occur within the body, and in some instances makes nutrients more available.
You may say: I’ve never heard of phytic acid or lectin in my life. Some folks claim that these compounds are harmful to human health, and at least make digestion more difficult. On the other hand, millions of people eat un-fermented grain every day and seem to be getting by. If this is something important to you, it is possible to go down a rabbit hole of internet science regarding grain health. The way I see it: your body uses bacteria and enzymes to break down grain and extract energy and nutrients. Fermenting the grain starts that breakdown process and certainly helps in the digestion process. Will eating un-fermented grains kill you? Probably not. But it will make your stomach a little bit happier.
An important note: much of the fascination with fermented food, such as pickled vegetables, stems from the fact that they contain living, active bacteria cultures (“Probiotics”). Your raw, fermented porridge also contains living, active cultures. However, as soon as you boil your porridge to finish the cooking process, those bacteria are killed by heat. What’s the point if it’s not probiotic? The amount and variety of bacteria you consume from various “probiotics” such as special yogurt, is insignificant to the quantity and biodiversity of bacteria already in your gut. It is more effective to control your gut’s bacteria by feeding it well than by trying to introduce more a particular species. So, it’s not the end of the world that you’re not eating the probiotic goodness of your fermented porridge raw. The bacteria in your gut would love to continue digesting the sugars and fibers of whole grain, and fermentation assists that process.
Regardless of the health benefits of fermented grain, the unquestionable result is some sour porridge. This calls for a different approach to toppings and combinations. It could be a jumping-off point for savory porridges, with a little bit of salt and some complex flavor accompaniments. However, it does still pair nicely with yogurt, fruit, honey, or other typical oatmeal toppings.
Mix some grain (really, any grain will do) with water, so it is fully submerged and is covered by water. Let it sit for a few days. If you have sourdough starter, add a spoonful to speed up the process. Stir once a day. Once you see some bubbles and it smells faintly sour, your fermented grain is ready. Boil as you would normal porridge. Save some fermented grain if you want to continue the process (experiment) and simply add more grain and water to the mix.
When you cook your grain, don’t forget that it is acidic. If you add milk as a cooking liquid, it will curdle. No harm, but it looks gross.