How Elelaf sources and stabilises postbiotics differently in the lab

The first time I held a vial of fresh postbiotic ferment from our supplier I understood the category better. It was warm. It had a smell. It needed to get into a stabilized base within hours, not days. The casual way the rest of the industry treats this ingredient — as an additive you spec on a form and add at the end of formulation , was suddenly absurd.

What postbiotics actually are

The category sits next to probiotics and prebiotics but isn’t either. Probiotics are live beneficial bacteria. Prebiotics are the food those bacteria eat. Postbiotics are what beneficial bacteria produce when they are healthy and fed , short-chain fatty acids like butyrate, antimicrobial peptides, exopolysaccharides, organic acids, vitamins.

For skincare, postbiotics have an advantage over live probiotics: they don’t have to survive on the shelf, in the bottle, on the skin. They are already the finished metabolic product. The full postbiotics primer walks through the biology in detail. The catch is that the molecules themselves are sensitive , heat, oxygen, the wrong pH, the wrong preservative system can degrade them quickly.

Where postbiotic skincare quietly fails

Most brands sourcing postbiotics buy them as a dried or stabilized powder from an ingredient supplier. The powder gets shipped, stored, weighed into a formulation, blended at room temperature, bottled, and sold. From production to customer, the postbiotic has often spent eighteen months in conditions that gradually degrade the active fraction.

By the time the bottle reaches the bathroom shelf and gets opened , exposing it to air and intermittent heat , the postbiotic concentration on the INCI list may technically be accurate, but the biologically active fraction is a quarter of what it was at the lab. The label says one percent. The skin sees a fraction of that.

How we built the supply chain differently

Three changes. None of them are exotic, but together they shift the math.

First, we work with a single Korean fermentation lab that cultures the bacterial strains in-house, harvests the postbiotic fraction within 72 hours of peak metabolic activity, and ships it directly to our formulation partner under cold chain. The ingredient never sits in a warehouse for six months waiting to be sold.

Second, we formulate the base around the postbiotic, not the other way around. The pH is held at 5.2, slightly above the skin’s native pH but inside the postbiotic’s stability window. The preservative system is chosen to be microbiome-compatible but also non-reactive with short-chain fatty acids , most parabens and isothiazolinones interact unpredictably with butyrate.

Third, we test the active fraction at the bottle, not the batch. We sample every production run at week zero, week twelve, and week twenty-four post-fill. If the active fraction has dropped below 70 percent of the at-fill concentration by week twenty-four, the production run is rejected. We have rejected two runs since launch. The Microbiome Glow Serum shipping today is from a run that came back at 84 percent active at week twenty-four.

The contrarian position: most postbiotic claims are theater

Walk through the postbiotic section of any beauty retailer and read the INCI lists. Most will list “Lactobacillus ferment” somewhere in the middle of the list. Middle of the list usually means below 1 percent. Below 1 percent at the time of formulation, before any degradation, means the at-shelf concentration of biologically active postbiotic is often a trace amount marketed as a hero ingredient.

This is not specific to postbiotics. But postbiotics get hit hardest because their stability profile is the most fragile. The marketing claim and the biological reality are further apart in this category than in most.

Our position, written down: any postbiotic in our line is at minimum 2.5 percent at fill, with measured stability at twenty-four weeks. If we can’t hit that, we don’t ship it. The microbiome story only works if the postbiotic in the bottle is real.

What the literature shows about stability

A 2021 paper in the International Journal of Cosmetic Science by Lee et al. tested the stability of seven commercially available postbiotic skincare formulations stored at 25 degrees Celsius for six months. Five of the seven showed a greater than 50 percent loss of measurable short-chain fatty acid content. The other two, both from labs with cold-chain sourcing and pH-controlled bases, retained over 80 percent. The category is bimodal: most products are functionally inactive by month six, a minority are stable through year one. The labeling is identical.

FAQ

What’s the difference between postbiotic and probiotic skincare? Probiotic means live bacteria. Postbiotic means the metabolites those bacteria produce. Postbiotics are more stable as ingredients but still require careful formulation.

How can I tell if a postbiotic product is real? Look for stated percentage, not just “contains postbiotics.” Look for stability claims with a time window.

Does the Microbiome Glow Serum need refrigeration? No. The base is engineered to be shelf-stable at room temperature for twenty-four months. The cold chain is at sourcing, not at the customer.

How long until I notice effects? Microbiome shifts are measurable at four weeks, visible at eight to twelve. The 30-day resilience plan tracks the curve.

Are postbiotics safe in pregnancy? Generally yes, but check the full ingredient list. Pregnancy-safe doesn’t refer only to the postbiotic.

Where can I read more? The postbiotics tag has the rest of the science.

Sources

Lee SH et al. Stability of postbiotic cosmetic formulations: a six-month accelerated study. International Journal of Cosmetic Science, 2021. Byrd AL, Belkaid Y, Segre JA. The human skin microbiome. Nature Reviews Microbiology, 2018. Internal stability testing, Elelaf Microbiome Glow Serum production lots, 2024 to 2026.