Northern and Eastern Europe.
A rye loaf made with yeast alone comes out of the oven with a sticky, gummy crumb. The same dough made sour holds together — the acid has disarmed an enzyme.
From Germany and Scandinavia across Poland, the Baltic and Russia, the climate shaped the kitchen. Rye, barley, oats and buckwheat grow where wheat struggles; root vegetables and cabbages store through winter; fish was salted, pickled, smoked or dried (XIII.5, XIII.9) — pickled herring, Swedish gravlax cured with salt, sugar and dill, smoked mackerel; cabbage became sauerkraut and cucumbers were lacto-fermented in brine (XIV.4); milk became butter, curd cheese, kefir, skyr and smetana. The flavours are sour, smoky, salty and earthy, with dill, caraway and horseradish, and the dishes — borscht, pierogi, goulash, smørrebrød — are built to warm and to keep.
Rye bread shows the science. Rye has little gluten-forming protein; its dough holds together by gummy pentosans and starch instead (XXIV.1). And rye flour carries a lot of amylase, an enzyme that breaks starch down, which in the warmth of the oven, before the starch has set, attacks the starch gel and leaves the crumb wet and sticky — "starch attack". Amylase works poorly in acid, so rye bakers add a large share of sour starter (XXIV.7): the dough's pH falls to about 4.2–4.5, the enzyme is held back, and the crumb sets moist but firm, with the sour, deep flavour of Nordic and German rye breads. The workshop sours a rye dough.
Below: the pH of a rye dough with the share of its flour you choose coming from a ripe sour starter (teaching curve), and the relative activity of rye amylase at that pH (teaching curve, after the enzyme's known inhibition below about pH 4.5), with how the crumb will set.
- Describe the preserving cuisines of the north and east.
- Explain why rye bread needs a sour starter.
- Make lacto-fermented vegetables and cured fish.
- Use rye, dill, caraway and cultured milk.
Sour holds the enzyme back
In the teaching curves a rye dough with no sour sits near pH 6.1, where amylase is at 1.00 of its full activity — a gummy crumb; with 15 % of the flour soured, pH 4.9 and activity 0.69; with 35 %, the usual proportion for a full rye loaf, pH 4.4 and only 0.22. Long, low baking then gelatinises and sets the starch while the enzyme is subdued, which is why dense rye loaves bake for an hour or more and must rest a day before slicing.
A simple Nordic-style rye loaf: mix a sour of 150 g wholemeal rye flour, 150 g water and 30 g ripe rye starter; leave 12–16 hours at about 25–28 °C until bubbly and sour. Add 250 g more rye flour, 50 g wheat flour, 9 g salt, 1 tsp caraway and 220 g warm water; mix into a sticky paste (it will not knead); scrape into an oiled tin, smooth with a wet spatula and prove 1–3 hours until risen by a quarter and cracking on top. Bake at 240 °C for 15 minutes, then 200 °C for about 50 minutes to an internal 98 °C (XXIV.9); cool, wrap and rest 24 hours before cutting. Gravlax: cure a side of salmon (frozen first for parasites, XIX.6) under salt, sugar and dill for two days in the fridge.
Bake two small rye loaves, one leavened with yeast only and one with a sour starter. Cut both the next day and compare the crumb.
Terms
- Starch attack
- Amylase breaking down starch in the oven, leaving a gummy crumb.
- Rye sour
- A large sour starter that acidifies rye dough.
- Gravlax
- Salmon cured with salt, sugar and dill.
- Lacto-fermentation
- Souring vegetables with lactic bacteria in brine.
Sources
- A teaching value chosen for the course: the right order of magnitude and shape, not a measurement of a particular food.
- H. McGee, On Food and Cooking: The Science and Lore of the Kitchen, 2nd ed., Scribner, 2004.