Why is sourdough less processed than regular bread?

Sourdough uses a long fermentation process with wild yeast and bacteria, which naturally develops flavour and texture. This eliminates the need for emulsifiers (E471, E472e), preservatives (calcium propionate), and flour treatment agents (E920) that mass-market bread relies on. The fermentation itself acts as a natural preservative.

Is supermarket sourdough real sourdough?

At Tesco, most products labelled 'sourdough' from Jason's, Hovis, and Tesco Finest contain genuine sourdough culture and have short ingredient lists. However, some 'bake at home' and 'with sourdough' products contain additional additives like rapeseed oil and dextrose. Check the ingredients — real sourdough should list sourdough culture or starter as an ingredient.

Is gluten-free sourdough ultra-processed?

Unfortunately, yes. Warburtons Gluten Free White Sourdough Bloomer contains 18 ingredients and 6 UPF markers including flavourings, glycerine, calcium propionate, and potassium sorbate. Gluten-free baking requires additional additives to replicate the structure and texture that gluten naturally provides, making it difficult to avoid NOVA 4.

What is the glycemic index of sourdough?

Sourdough has a glycemic index of 54, which is classified as Medium GI. Sourdough bread has a medium GI of around 54, lower than regular white bread (75) because the fermentation process creates organic acids that slow starch digestion.

NOVA 3

Is Sourdough Ultra-Processed?

No — most sourdough bread is not ultra-processed

Most sourdough bread is not ultra-processed. Across 30+ sourdough products at Tesco, the majority score NOVA 3 (processed) with zero UPF markers. Genuine sourdough uses flour, water, sourdough culture, and salt — no emulsifiers or preservatives needed. The exceptions are 'sourdough-style' products from mass-market brands and gluten-free sourdough, which may contain additives like calcium propionate and glycerine that push them to NOVA 4.

Why Sourdough scores NOVA 3 — Processed

Sourdough is one of the safest bread choices if you want to avoid ultra-processed food. The traditional sourdough process — long fermentation with a live culture — naturally produces a bread that keeps better without preservatives and has good texture without emulsifiers. This means genuine sourdough inherently avoids the additives that make most sliced bread NOVA 4.

At Tesco, the Jason's sourdough range is the gold standard: products like the Great White (5 ingredients, 0 UPF markers), Wholemeal Ciabattin (5 ingredients, 0 UPF markers), and Grains & Seeds Ciabattin (6 ingredients, 0 UPF markers) all score clean NOVA 3. Hovis Sourdough White and Seeded also score NOVA 3 with just 6 ingredients each. Tesco Finest sourdough baguettes and loaves score similarly well.

The products that break this pattern fall into two categories. First, 'sourdough with' products from mass-market brands: several Tesco Finest bake-at-home items contain rapeseed oil (a seed oil UPF marker) and score "Likely NOVA 4", though with only 1 marker they sit on the borderline. Second, gluten-free sourdough — Warburtons Gluten Free White Sourdough Bloomer contains 18 ingredients including flavourings, glycerine, calcium propionate, potassium sorbate, and rapeseed oil, scoring a full NOVA 4 with 6 UPF markers. Gluten-free baking requires more additives to replicate the structure that gluten provides.

E-number guides mentioned in this article

E282Calcium propionate (preservative)E471Mono- & diglycerides (emulsifier)

Sourdough at Tesco — NOVA scores

Source: Tesco product page, March 2025

Jason's Recipe No 01 The Great White Straight Up Sourdough Loaf 450g

£2.20*NOVA 3 (processed)

Hovis Sourdough White 450g

£2.10*NOVA 3 (processed)

Tesco Finest White Sourdough Baguette 400g

£2.00*NOVA 3 (processed)

Warburtons Seeds & Grains Bread with Sourdough 400g

£1.50*NOVA 3 (processed)

Warburtons Gluten Free White Sourdough Bloomer 400g

6 UPF markers

£3.50*NOVA 4 (ultra-processed)

*Prices were correct at the time of collection and may have since changed. Check Tesco.com for current pricing.

What to look for when shopping

Genuine sourdough should have a very short ingredient list — ideally under 8 items. The key ingredients are flour, water, sourdough culture (or sourdough starter), and salt. Be cautious of 'sourdough style' or 'with sourdough' products that add emulsifiers or preservatives. If you need gluten-free sourdough, be aware it will almost certainly contain more additives. Jason's and Hovis Sourdough are the most reliable mainstream choices for clean sourdough at Tesco.

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