Peptides are messenger molecules and ferments are postbiotic broths. How peptides work, the benefits of fermented skincare, and why both need care.
Peptides are messenger molecules, short chains of amino acids that signal skin toward a younger look. Ferment filtrates are the strained, metabolite-rich liquid left after microbes work on a botanical broth. Both are among the most fragile things you can put in a serum, alongside proteins like collagen and light-sensitive antioxidants like resveratrol, and that fragility is the reason a formula's design and its storage matter as much as its ingredient list. Most of these actives are in our own formulas, which means I know their trade-offs from inside the bottle, and I will point them out as we go.
What makes a skincare active fragile?
A fragile active is one whose usefulness depends on a specific molecular shape or state, and that shape can be undone by ordinary conditions: heat, water, oxygen, light, or the wrong pH. Glycerin, by contrast, is a small, sturdy molecule that hydrates whether it is warm or cool. The delicate actives are the ones that have to be built or folded a particular way to do their job, because every bit of structure a molecule needs is another thing that can come apart.
That single idea runs through this whole hub. Peptides are chains held together by chemical bonds, proteins like collagen are chains folded into precise shapes, and ferment filtrates are broths of many small, biologically active molecules. Antioxidants like resveratrol flip between forms under light. Each is powerful because of its structure, and vulnerable for the same reason [1][3].
The underlying rule, that heat and time quietly drain what is in the bottle, is the same one we cover in how temperature protects a serum's potency. This guide is about the biological actives in particular, the peptides, proteins, ferments, and barrier lipids, and what keeps them working. One thing to hold onto from the start: freshness here is about potency, about how much you get for your money.
How do peptides work, and why do formulators use them?
A peptide is a short string of amino acids, the same building blocks that make up proteins, just far shorter. In skincare, the most interesting kind are the signal peptides. Applied to skin, they act like a message the skin's own support cells recognize, and that message is associated with a firmer, plumper, springier look [11]. That is what people are after when they buy a peptide serum.
You will see several of these on our labels. Tripeptide-29 sits in 7 Winters. D.B.T. Baba Yaga carries Palmitoyl Dipeptide-5 and Dipeptide-6. Eyecicle uses Acetyl Octapeptide-3 and Pentapeptide-18 around the delicate eye area. Different peptides, one shared idea: they are messengers associated with firmer, more cushioned-looking skin, working with the skin's own machinery rather than forcing it.
Peptides are also why a lot of people choose a gentler path than retinoids, since they tend to be well tolerated and do not carry the same sun-sensitivity or flaking. If you are weighing the two, here is how peptides and retinol compare. And the eye area, where the skin is thinnest, has its own peptide story worth reading on its own, in what acetyl octapeptide-3 does around the eyes.
Why peptides are among the first things to break down
The same short structure that lets a peptide carry a signal also makes it easy to take apart. The main route is hydrolysis: water molecules break the bonds between amino acids, a reaction that is catalyzed by acids and bases, so it depends heavily on pH, and speeds up with heat [1]. A second route, deamidation, slowly alters certain amino acids over time [1]. The plain-language version is that peptides are often unstable in water, and warmth pushes the reaction along, first-order and climbing steeply as temperature rises [1][2].
Formulators have real tools against this. Attaching a fatty chain to a peptide, the reason so many ingredient names begin with "palmitoyl," improves both how well the peptide gets into skin and how stable it stays in the bottle [11]. Keeping water low where the chemistry allows, holding a gentle pH, and storing the finished product cool all slow the same hydrolysis. None of it makes a peptide permanent. It buys time.
How much time, and whether a peptide serum can shrug off a hot bathroom shelf or a summer car, is a question worth its own answer. I dug into it in do peptides survive heat.
Vegetable collagen, and why proteins fear heat
Vegetable collagen is not animal collagen. It is a plant-derived complex of proteins and amino acids chosen to give skin the cushiony, water-holding, plumped feel that collagen is associated with, without an animal source. What it shares with every protein is architecture: a protein is a long chain folded into a precise three-dimensional shape, and that shape is what makes it work.
Heat unfolds proteins. The process is called denaturation, and you have watched it happen every time an egg white turns from clear to opaque in a hot pan. The most vivid illustration in the research comes from the body's own collagen, whose triple-helix structure turns out to be thermally unstable even at body temperature: it denatures at 37 degrees Celsius over a couple of days, and only re-forms its native shape below about 30 degrees [3]. That is a laboratory finding about human collagen, not a shelf life for a serum, and I am not claiming otherwise. What it does is make the principle unforgettable. Proteins are happiest cool, and warmth is the thing that unpicks them.
How fragile is each active, side by side?
Here is the whole cast in one view, each active paired with what wears it down and the storage move that slows it.
| Active | What wears it down | The cool-storage move |
|---|---|---|
| Peptides (7 Winters, D.B.T., Eyecicle) | Water and warmth slowly cleave the bonds between amino acids | Lower water, cooler storage, and a stabilizing palmitoyl chain slow it |
| Vegetable collagen (7 Winters) | Heat unfolds a folded protein; collagen starts to come apart near 37°C, body temperature | Cooler storage keeps the structure intact longer |
| Niacinamide (across the line) | Heat and the wrong pH slowly convert it toward nicotinic acid, the flush-capable form | Near-neutral pH and cool storage keep it the gentle form |
| Ferment filtrates (Gaea's Gala, 7 Winters, Eyecicle, D.B.T.) | Little wears them down; they are cell-free postbiotic broths, not live cultures | Cool, steady storage keeps them fresh, a courtesy rather than a rescue |
| Resveratrol (7 Winters) | UV light shifts it toward a weaker form | Dark, cool, steady storage favors the active form |
The thresholds above are drawn from published stability and kinetics studies under laboratory conditions, cited through this article. They describe the direction and shape of degradation, what heat, water, light, and pH do, rather than a guaranteed shelf life for any one product. We think about it the way our Heat Age model does, as cumulative thermal exposure across a product's whole life. And throughout, degraded means less potent, never unsafe. The same table follows as a card you can save or share.
Built from Nugrahadi 2023, Qian 1993, Leikina 2002 and Finholt and Higuchi 1962; last checked 2026-09.
What are the benefits of fermented skincare?
The benefits are real, and the reason is worth understanding. Fermentation puts microbes to work on a botanical, and as they metabolize it, they break large molecules into smaller ones that skin takes to more readily, while raising the antioxidant and hydration activity of what is left [10]. A ferment filtrate is the cell-free liquid strained off at the end, rich in those small, useful molecules. It is a broth of metabolites, sometimes called postbiotics, not a jar of live culture.
For the ferment we lean on most, Galactomyces ferment filtrate (in Gaea's Gala, 7 Winters, and Eyecicle), laboratory work on human skin cells found that it nudges the genes tied to the skin barrier and its tight junctions [9]. In cosmetic terms, what that points toward is a stronger-looking, more balanced, glowier complexion. There is a fuller walk through the star ferment in what galactomyces does for your skin.
Here is the honest part that a lot of fermented-skincare marketing gets wrong. Because ferment filtrates are cell-free metabolite broths rather than living things, they do not need cold to stay alive [10]. Cool, steady storage is a general freshness good, the same courtesy you would extend to any fresh-made formula, and not a survival requirement. Some ferments even pull double duty: the white willow bark ferment in D.B.T. is a gentle, natural source of salicin, which is a softer route than straight salicylic acid, covered in white willow bark for skin.
Niacinamide has a fresh form and a flushing form
Niacinamide, or vitamin B3, is one of the best-tolerated actives in all of skincare, associated with a more even-looking tone and a more comfortable-feeling barrier [6]. It shows up across most of our line. It also carries a quirk worth knowing about, because it is a small window into why freshness matters.
Over time, and faster with heat and the wrong pH, niacinamide can slowly hydrolyze toward a close cousin called nicotinic acid [4]. Nicotinic acid is the form that can trigger a brief, harmless flush, the redness and warmth that come from prostaglandin-driven widening of the small blood vessels near the surface, sometimes with a little tingle [5]. Fresh niacinamide does not do this [6][7]. So a niacinamide product kept cool and near-neutral is more likely to stay the gentle amide form you want on your face.
To be clear, this is a tolerability-and-freshness point, not a safety scare. The independent Cosmetic Ingredient Review panel rates niacinamide and niacin as safe as used in cosmetics [8]. If your niacinamide has ever left you a bit pink, the full explanation lives in why niacinamide makes some faces flush.
Resveratrol and the light problem
Resveratrol is a plant polyphenol, the antioxidant grapes are famous for, and a tidy example of a light-sensitive active. The useful form, called trans-resveratrol, shifts to a weaker cis form under UV light and high pH [14]. It does not disappear so much as change into a shape that does less for skin, and it has genuine stability challenges even dissolved in solvents [14]. The practical takeaway is simple: resveratrol keeps best dark, cool, and steady, which is one more reason a formula that carries it, like 7 Winters, is made and stored the way it is.
Why a barrier needs three lipids working together
Your skin barrier, the outer layer that holds water in and irritants out, is held together largely by three families of fats: ceramides, cholesterol, and free fatty acids. Count the molecules and the three sit in a roughly equal, one-to-one-to-one balance, an approximately 1:1:1 ratio, even though ceramides take up the most room by weight [15]. The lesson from decades of barrier research is that this even mixture is the point. Applying just one or two of the three can slow the barrier's recovery, while a complete, balanced set of all three supports it, and getting that balance right matters most in mature skin [12][13].
This is why a serious barrier cream carries all three lipid classes rather than a single fashionable ceramide. D.B.T. Baba Yaga is built around the full set, Ceramide NP, AP, and EOP, together with cholesterol and phytosphingosine, which supports the look and feel of the skin barrier. The fatty-acid side of that recipe arrives partly as rich plant butters, murumuru and shea, the sturdy counterpart to everything fragile on this page; what murumuru butter does for dry, tight-feeling skin has its own guide. Like the other biological actives here, these lipids do best kept cool and steady. If your barrier feels stripped or reactive right now, the recovery guide has the barrier lipid ratio, drawn out.
So what keeps fragile actives working?
Two levers, and good skincare pulls both. The first is the formula. A thoughtful formulator keeps water low where the active resists water, holds a gentle pH, pairs delicate actives with protective antioxidants like vitamin E, and reaches for stabilized forms such as palmitoyl peptides where they help [1][11]. The second is storage. Cool, dark, and steady slows every reaction on the fact-asset card above: hydrolysis, denaturation, isomerization [2][3][14].
That second lever is the whole idea behind preserving skincare with cold. We make fresh in small weekly batches and keep everything refrigerated at about 4 degrees Celsius in the studio, from the day a formula is made until it ships. Cold does not make an active stronger. It slows the wear that heat and time would otherwise inflict, so what reaches your skin is closer to what left the batch. Peptides also do best beside a compatible antioxidant partner, which is part of why an oil-soluble vitamin C sits so well next to them, the vitamin C side of the story.
If you want the single clearest example of all of this in one bottle, it is 7 Winters, our collagen and tripeptide serum. In one short, essential-oil-free formula it carries a signal peptide (Tripeptide-29), vegetable collagen, galactomyces and radish-root ferments, resveratrol, and niacinamide, nearly every fragile active this guide describes, which is exactly why it is made fresh and kept cold rather than left to sit. About 43% of our written 7 Winters reviews (24 of 56) describe seeing it work. New to all of this? Our Start Here guide is a calm place to begin.
my skin hasn’t looked or felt this good in many years
What are peptides in skincare, and do they work?
Peptides are short chains of amino acids. The signal peptides used in skincare act as messengers associated with a firmer, plumper, more cushioned look [11]. They tend to be well tolerated, which is part of why many people choose them over retinoids. Because they are held together by breakable bonds, they work best in a well-designed, well-stored formula [1].
Do fermented skincare products need to be refrigerated?
They benefit from cool, steady storage the way any fresh-made formula does, but they do not require it to stay usable. Ferment filtrates are cell-free broths of postbiotic molecules, not live cultures, so they do not depend on cold to stay alive [10]. Cold is a freshness courtesy here, not a survival requirement.
Is vegetable collagen the same as animal collagen?
No. Vegetable collagen is a plant-derived complex of proteins and amino acids chosen to give skin the cushioned, hydrated, plumped feel associated with collagen, without an animal source. What it shares with all proteins is a folded structure that heat can unfold, which is why protein-based actives favor cool storage [3].
Why does niacinamide sometimes make my face flush?
Fresh niacinamide does not cause flushing. Over time, and faster with heat and the wrong pH, it can slowly convert to nicotinic acid, which can trigger a brief, harmless flush through prostaglandin-driven vasodilation [4][5]. A product kept cool and near-neutral is more likely to stay the gentle form [6]. There is more in why niacinamide makes some faces flush.
Do peptides really break down in a serum?
They can, mainly through hydrolysis, where water breaks the bonds between amino acids, sped up by heat and governed by pH [1][2]. Good formulas slow this with low water, a gentle pH, stabilized (palmitoyl) peptides, and cool storage. How far it goes in a real bottle is covered in do peptides survive heat.
Keep exploring the fragile actives
Every active on this page has its own deeper guide, and each links back here:
- Do peptides survive heat? (how fragile peptides really are, and whether a serum survives a hot shelf).
- Peptide eye serums and acetyl octapeptide-3 (what the peptides in Eyecicle do around the delicate eye area).
- Peptides or retinol? (choosing when you would rather skip retinoids).
- What galactomyces does for your skin (the star ferment, up close).
- Why niacinamide makes some faces flush (the fresh form, the flushing form, and how to tell them apart).
- How to help a stressed skin barrier recover (the ceramide, cholesterol, and fatty-acid team, put to work).
- Murumuru butter for dry, tight-feeling skin (the sturdy, saturated butter that cushions the fragile actives in D.B.T., and who it suits).
- White willow bark for skin (a gentler, ferment-derived route to a salicin glow).
References
- Nugrahadi, P.P., Hinrichs, W.L.J., Frijlink, H.W., Schöneich, C., & Avanti, C. — "Designing Formulation Strategies for Enhanced Stability of Therapeutic Peptides in Aqueous Solutions: A Review" — Pharmaceutics, 15(3):935, 2023 — https://pmc.ncbi.nlm.nih.gov/articles/PMC10056213/ «verified 2026-07-19» ↑
- Qian, Y., Engel, M.H., Macko, S.A., Carpenter, S., & Deming, J.W. — "Kinetics of peptide hydrolysis and amino acid decomposition at high temperature" — Geochimica et Cosmochimica Acta, 57(14):3281–3293, 1993 — https://pubmed.ncbi.nlm.nih.gov/11538300/ «verified 2026-07-19» ↑
- Leikina, E., Mertts, M.V., Kuznetsova, N., & Leikin, S. — "Type I collagen is thermally unstable at body temperature" — Proceedings of the National Academy of Sciences (PNAS), 99(3):1314–1318, 2002 — https://pubmed.ncbi.nlm.nih.gov/11805290/ «verified 2026-07-19» ↑
- Finholt, P., & Higuchi, T. — "Rate studies on the hydrolysis of niacinamide" — Journal of Pharmaceutical Sciences, 51:655–661, 1962 — https://pubmed.ncbi.nlm.nih.gov/13892959/ «verified 2026-07-19» ↑
- Kamanna, V.S., Ganji, S.H., & Kashyap, M.L. — "The mechanism and mitigation of niacin-induced flushing" — International Journal of Clinical Practice, 63(9):1369–1377, 2009 — https://pmc.ncbi.nlm.nih.gov/articles/PMC2779993/ «verified 2026-07-19» ↑
- Boo, Y.C. — "Mechanistic Basis and Clinical Evidence for the Applications of Nicotinamide (Niacinamide) to Control Skin Aging and Pigmentation" — Antioxidants (Basel), 10(8):1315, 2021 — https://pmc.ncbi.nlm.nih.gov/articles/PMC8389214/ «verified 2026-07-19» ↑
- Marques, C., Hadjab, F., Porcello, A., Lourenço, K., Scaletta, C., Abdel-Sayed, P., Hirt-Burri, N., Applegate, L.A., & Laurent, A. — "Mechanistic Insights into the Multiple Functions of Niacinamide: Therapeutic Implications and Cosmeceutical Applications in Functional Skincare Products" — Antioxidants (Basel), 13(4):425, 2024 — https://pmc.ncbi.nlm.nih.gov/articles/PMC11047333/ «verified 2026-07-19» ↑
- Cosmetic Ingredient Review Expert Panel — "Final report of the safety assessment of niacinamide and niacin" — International Journal of Toxicology, 24(Suppl 5):1–31, 2005 — https://pubmed.ncbi.nlm.nih.gov/16596767/ «verified 2026-07-19» ↑
- Nakajima, A., Sakae, N., Yan, X., Hakozaki, T., Zhao, W., Laughlin, T., & Furue, M. — "Transcriptomic Analysis of Human Keratinocytes Treated with Galactomyces Ferment Filtrate, a Beneficial Cosmetic Ingredient" — Journal of Clinical Medicine, 11(16):4645, 2022 — https://pmc.ncbi.nlm.nih.gov/articles/PMC9409768/ «verified 2026-07-19» ↑
- Majchrzak, W., Motyl, I., & Śmigielski, K. — "Biological and Cosmetical Importance of Fermented Raw Materials: An Overview" — Molecules, 27(15):4845, 2022 — https://pmc.ncbi.nlm.nih.gov/articles/PMC9369470/ «verified 2026-07-19» ↑
- Badilli, U., & Inal, O. — "Current Approaches in Cosmeceuticals: Peptides, Biotics and Marine Biopolymers" — Polymers (Basel), 17(6):798, 2025 — https://pmc.ncbi.nlm.nih.gov/articles/PMC11946782/ «verified 2026-07-19» ↑
- Man, M.Q., Feingold, K.R., Thornfeldt, C.R., & Elias, P.M. — "Optimization of physiological lipid mixtures for barrier repair" — Journal of Investigative Dermatology, 106(5):1096–1101, 1996 — https://pubmed.ncbi.nlm.nih.gov/8618046/ «verified 2026-07-19» ↑
- Zettersten, E.M., Ghadially, R., Feingold, K.R., Crumrine, D., & Elias, P.M. — "Optimal ratios of topical stratum corneum lipids improve barrier recovery in chronologically aged skin" — Journal of the American Academy of Dermatology, 37(3 Pt 1):403–408, 1997 — https://pubmed.ncbi.nlm.nih.gov/9308554/ «verified 2026-07-19» ↑
- Pentek, T., Newenhouse, E., O'Brien, B., & Chauhan, A.S. — "Development of a Topical Resveratrol Formulation for Commercial Applications Using Dendrimer Nanotechnology" — Molecules, 22(1):137, 2017 — https://pmc.ncbi.nlm.nih.gov/articles/PMC6155877/ «verified 2026-07-19» ↑
- Shamaprasad, P., Nădăban, A., Iacovella, C.R., Gooris, G.S., Bunge, A.L., Bouwstra, J.A., & McCabe, C. — "The phase behavior of skin-barrier lipids: A combined approach of experiments and simulations" — Biophysical Journal, 123(18):3188–3204, 2024 — https://pmc.ncbi.nlm.nih.gov/articles/PMC11447553/ «verified 2026-07-19» ↑
