Drop the word “style”
Almost every bakery in Britain writes San Francisco style on the board. Not because they want to — because they cannot prove the other thing. Style is the word you use when you have bought a culture from a supplier who cannot tell you what is in it.
Our starter is different in one specific, boring, commercially useful way: we had it sequenced, and we can show you the certificate. It contains Lactobacillus sanfranciscensis — the bacterium the bread is named after. So when you bake with it, you are not baking something in the style of San Francisco sourdough. You are baking San Francisco sourdough, and you have the paperwork to say so.
What the certificate actually says
The work was done by NCIMB in Aberdeen, one of the UK’s national culture collections, under job reference NC029365, reported on 19 June 2026. They sequenced the culture and matched it at 99.73% to Fructilactobacillus sanfranciscensis — the current name for the organism most bakers still know as Lactobacillus sanfranciscensis. It was reclassified in 2020; it is the same bacterium.
That number matters more than it looks. Most starters sold as San Francisco have never been tested at all. The name is a description of a flavour, applied hopefully. Ours is a description of an organism, applied accurately, and we will send you the report to keep on file.
If a customer asks, a buyer asks, or an environmental health officer asks, you have an answer that is a document rather than an opinion.
What it does on the bench
L. sanfranciscensis is a heterofermentative bacterium: alongside lactic acid it produces acetic acid, and that is where the sharpness in a proper San Francisco loaf comes from. It is also unusually tolerant of a stiff, cool, long-fermented culture — which is exactly how a bakery runs a levain overnight.
In practice that means a rounder sourness than a straight lactic culture gives you, a crust that blisters, and a crumb that holds its structure at high hydration. It is a flavour your customers can tell apart from an ordinary sourdough, which is the whole point of putting it on a menu.
How it arrives, and how it scales
It arrives live and never dehydrated, held dormant rather than dried. A dried culture has to be resurrected over five to seven days and you find out at the end of that week whether it worked. Ours wakes on contact with flour and water and is bubbling in about two hours.
From one sachet you build to bakery volume the way you would with any levain: feed, let it peak, double the build each time. A single unit will carry you to a working mother culture inside two or three builds, and from then on it is your culture — there is nothing to re-buy, no licence and no subscription. Most bakeries order once.
- Shelf life — eighteen months sealed
- Storage — ambient, no refrigeration needed before opening
- Allergens — contains wheat (gluten). Produced in a kitchen that handles wheat and rye.
- Origin — grown, fed and packed by us in Bristol
- Documentation — NCIMB sequencing report supplied with trade orders
Who this suits
Craft bakeries and micro-bakeries who want a defensible provenance claim on a signature loaf. Delis, farm shops and food halls stocking a starter as a retail line. Cookery schools running sourdough courses, where students ask what the culture actually is and deserve a real answer. Restaurants baking their own bread and putting it on the menu by name.
Trade enquiries
Tell us roughly what you bake and how much, and we will come back with case quantities, trade pricing and a lead time. Pricing goes out with a free sample, and the sequencing report comes with the quote rather than after the order.
