Sericin in Cosmetics: The Silk Protein in Your Shampoo

From Wastewater to Cosmetics

Sericin — the gummy protein coating silk fibre — was discarded by the textile industry for centuries. Roughly 400,000 tonnes of dry cocoons a year yield around 50,000 tonnes of it, and historically most went down the drain during degumming.

It is now an ingredient.

What It Is Used For

Sericin appears in creams and shampoos, and the reported effects are specific rather than vague:

• Increased hydration and elasticity in skin
• Cleaning with lower irritancy — useful in a shampoo, where the usual trade-off is between cleaning power and harshness
• Anti-ageing and anti-wrinkle effects
• Antioxidant activity, and inhibition of tyrosinase — the enzyme central to pigment production — which is why it is investigated for skin-brightening

Hair, Specifically

The clearest result is protective rather than cosmetic. Hair treatments based on silk proteins have been shown to protect against the damage caused by bleaching and colouring — a real, measurable form of damage rather than a marketing claim.

Why This Is a Good Story

Not because silk protein in a shampoo is remarkable, but because of where it came from. An industry spent centuries treating a protein as an unwanted by-product, washing away tens of thousands of tonnes a year, and it turned out to be worth more than the wastewater treatment it required.

The same reversal shows up in the pupae and in the frass. Almost nothing about a silkworm is actually waste; it was just easier to throw away than to find a use for.

Related: what silk is made of · inside the silk gland