Many people get tangled up in the details behind fermentation. So here is an insight to help you better understand how to manage your fermentation projects.

I find it helpful to break fermenting methods down into two broad categories: fermentation that proceeds at room temperature and fermentation that proceeds at human (mammalian) body temperature. This is a lot simpler than categorization using terms like “thermophiles,” “mesophiles,” and “psychrophiles” often used, for instance, in beer making or cheese fermentation. The distinction between room temperature and human body temperature fermentation is important because, for example, a microbe that reproduces at maximal rate at 100°F will not reproduce well at 70°F. Take our favorite microbe, Lactobacillus reuteri, as an example that, when cultivated properly at human body temperature as our L. reuteri yogurt, yields hundreds of billions of microbes per 1/2-cup serving. Larger “doses” of microbes stack the odds in favor of yielding impressive age-reversing benefits: increased dermal collagen and smoother skin, increased joint cartilage, restoration of youthful muscle and strength, increased libido, increased testosterone in males, preservation of bone density, deeper sleep. Ferment L. reuteri, however, at room temperature and it will yield far fewer microbes and you likely obtain none of these effects. For microbes like L. reuteri, human body temperature fermentation is therefore key. This applies to most species that we regard as probiotic, such as species of Lactobacillus, LimosilactobacillusLactiplantibacillus, and Bifidobacteria.

Human body temperature fermentation therefore requires use of a device that is relatively accurate in temperature regulation. Some devices that have a preset temperature are inaccurate. A temperature advertised as, say, 100°F may really be 120°F, a temperature that kills many fermenting microbes and you will therefore not obtain the microbial counts you desire nor the beneficial health effects.

This is where the advantages of room temperature-fermenting species come in. It means you can ferment species such as Pediococcus pentosaceus, Pediococcus acidilactici, Leuconostic mesenteroides, and Lactiplantibacillus plantarum to make kombucha (shown above in the photo, complete with its multi-generation, multi-layered SCOBY), kefir, sauerkraut, sopressata, or kimchi. (L. plantarum and some other of these microbes found in fermented foods, by the way, do well in both temperature environments, being unusually adaptable.) Most room temperature-fermenting species also ferment at human body temperature. Some are quite heat tolerant, surviving at temperatures such as 140°F. This means that you can ferment human body temperature-fermenting species together with room temperature-fermenting species. But you can also ferment room temperature-fermenting species without use of a device. This makes room temperature-fermenting species a good choice for travel, for instance, when you don’t have access to a device. In a hotel room, you can leave a container of commercial kefir or kefir you make from a starter culture right on a tabletop and fermentation will naturally proceed.

Recall that consumption of fermented foods, room temperature or body temperature, is the start of your effort to restore microbial species diversity to your gastrointestinal microbiome. Coupled with vigorous intake of prebiotic fibers and other microbiota-accessible carbohydrates, and you have initiated cross-feeding phenomena in which microbes help other microbes proliferate and produce beneficial metabolites to powerfully support your health.