Vol. XXVI · Doughs of the World Plate 9 of 10gluten-free, coeliac disease, celiac, 20 ppm, cross-contact, xanthan gum, psyllium, rice flour, buckwheat, sorghum, oats, gluten-free bread, binder, 无麸质, 乳糜泻SM

Gluten-Free Baking.

A gram of wheat flour stirred into a kilo of gluten-free batter puts it at about four times the legal "gluten-free" limit.

Coeliac disease is an immune reaction to gluten proteins that damages the lining of the small intestine; about 1 % of people have it, many undiagnosed, and the only treatment is to avoid gluten for life. Wheat, rye and barley contain it; oats are naturally free but often contaminated in milling. The internationally agreed limit for a food labelled "gluten-free" is 20 mg of gluten per kilogram — 20 parts per million — because studies found that 50 mg a day damaged the gut of people with coeliac disease while 10 mg did not. Wheat flour is about 8 % gluten, so a single gram of it in a kilogram of food is already about 80 ppm. In a shared kitchen that means separate flour, sieves, toasters and boards, cleaned surfaces, and gluten-free dishes made first (XII.10).

The cooking problem is structure. Without gluten (VI.10) a dough cannot form an elastic network to trap yeast gas or hold a shape, so gluten-free flour blends — rice, sorghum, buckwheat, millet, teff, with tapioca or potato starch for lightness — need a binder: xanthan gum (about 1 % of the flour), psyllium husk (3–5 %, which also gives a bread-like chew), eggs, or a gelatinised starch paste (XXVI.1). Gluten-free bread doughs are wetter, more like thick batters, baked in tins, and stale faster. Many dishes need no substitution at all: risotto, polenta, rice noodles, 汤圆 (XXVI.8), corn tortillas. The workshop measures contamination and structure.

Below: the gluten in a kilogram of gluten-free food after the stray wheat flour you choose gets in (exact: flour × 8 % gluten), against the 20 ppm limit; and a teaching index of how well a gluten-free bread holds its gas for the xanthan gum you add, rising then turning gummy.

What you will learn
Workshop
Gluten: wheat flour about 10–12 % protein of which about three-quarters is gluten, so about 8 % (teaching round figure), and ppm = mg per kg. Limit: Codex CXS 118-1979, EU 828/2014 and US FDA, 20 ppm. Structure index (teaching): 1 − e^(−x ÷ 0.5) for x % xanthan of flour, with a gumminess penalty above 1.5 %.

Keep wheat out; put structure in

One gram of wheat flour in a kilogram of food carries about 80 ppm of gluten, four times the limit; the limit is crossed at about 0.25 g per kilogram — a light dusting from a shared sieve. Flour in the air settles on everything for hours, so in a mixed kitchen bake gluten-free first, from sealed packs, with dedicated or thoroughly washed tools, and never fry gluten-free food in oil used for battered food. In the teaching index a bread with no binder scores 0, with 1 % xanthan about 0.86, and with 3 % only 0.47, gummy and heavy.

Gluten-free sandwich loaf: whisk 300 g gluten-free flour blend (for example 150 g brown rice flour, 75 g sorghum, 75 g tapioca starch), 15 g psyllium husk powder, 3 g xanthan gum, 7 g instant yeast, 7 g salt and 15 g sugar; add 360 g warm water, 2 eggs and 30 g oil; beat 3 minutes into a thick, sticky batter-dough; spread in an oiled 900 g tin, smooth the top with a wet spatula, prove until it reaches the rim, and bake at 200 °C for about 50 minutes to an internal 98 °C (XXIV.9). Cool completely before slicing; freeze sliced and toast from frozen.

At the stove

Bake two small gluten-free rolls, one with a binder and one without, and compare their rise and crumb.

The link between coeliac disease and wheat was made by the Dutch paediatrician Willem Dicke, who noticed during the 1944–45 Dutch famine, when bread was scarce, that his young coeliac patients improved — and relapsed when Allied planes dropped bread after liberation.

Terms

Coeliac disease
An immune reaction to gluten that damages the small intestine.
20 ppm
The gluten-free label limit: 20 mg gluten per kg.
Cross-contact
Gluten getting into a gluten-free food from tools, air or oil.
Binder
Xanthan, psyllium, egg or starch paste replacing gluten's structure.
About 1 % of people have coeliac disease. "Gluten-free" means ≤ 20 ppm; a gram of wheat flour per kilo is about 80 ppm. Keep tools, flour and oil separate. Replace gluten with binders: xanthan about 1 %, psyllium 3–5 %, eggs.

Sources

  1. Codex Alimentarius, Standard for Foods for Special Dietary Use for Persons Intolerant to Gluten (CXS 118-1979, revised 2008): "gluten-free" foods contain no more than 20 mg of gluten per kg; the EU (Regulation 828/2014) and US FDA (2013) use the same 20 ppm limit.
  2. P. Singh et al., "Global Prevalence of Celiac Disease: Systematic Review and Meta-analysis", Clinical Gastroenterology and Hepatology 16 (2018) 823–836: about 1.4 % of people by blood tests, 0.7 % by biopsy. C. Catassi et al., American Journal of Clinical Nutrition 85 (2007) 160–166: 50 mg of gluten a day for three months damaged the gut lining of people with coeliac disease; 10 mg did not measurably.
  3. A teaching value chosen for the course: the right order of magnitude and shape, not a measurement of a particular food.