Bread sommelier Martin Göttlich guides you through the world of sourdough
Part 5 – The change of rye flour and the consequences
Despite artisan perfection, breads dry out more quickly today. One of the main reasons for this is the change in rye flour quality, which has increasingly led to ‘dry-baking rye flours’. Since 1960, the falling numbers of rye flour have doubled to tripled, while the gelatinisation temperature of the rye starch has risen from approx. 59 °C to 74 °C.
Amylases, which are essential for starch degradation, have their optimum activity at around pH 5.5 and between 50 and 70 °C. They can only break down starch after it has been gelatinised. They can only break down starch after gelatinisation. As the gelatinisation temperature has risen, this happens too late in the baking process - the amylases denature beforehand and can no longer break down the starch sufficiently. As a result, the crumb remains dry and firm. At the same time, retrogradation accelerates, causing bread to stale more quickly.
These changes are due to climatic conditions and breeding that reduced enzyme activity. The values for the 2024 harvest (falling numbers approx. 250-330 s, amylogram units approx. 680-1200, gelatinisation temperature approx. 68-76 °C (arithmetic mean for Central Germany)) show that the problem persists.
The gelatinisation temperature is now higher than the denaturation temperature of the amylases. As a result, fewer enzymes are available from the outset and the few remaining enzymes cannot do their work in time. This leads to ungelatinised starch, which favours retrogradation and therefore stale baking.
Solutions for working with dry-baking rye flour
Bakers have various options for handling ‘dry-baking rye flours’. These flours lead to reduced freshness, dry crumb and faster bread ageing. A key factor is the activity of amylase, which should not be considered undesirable. It supports the sourdough process, promotes the release of maltose for microorganisms and contributes to the Maillard reaction.
An optimally managed sourdough is essential to compensate for fluctuating rye flour qualities. Multi-stage leavening, especially full leavening, improves the bread's flavour and freshness. However, even with sourdough, many bakers do not achieve the desired result, which is why other methods are necessary.
Swelling, boiling and cooking soaker are effective measures. While swelling soaker store moisture, some of the starch in boiled soaker already gelatinises, making it easier for amylases to break it down. Cooked psoaker go even further: they completely gelatinise the rye starch, slow down retrogradation and improve freshness. The use of leftover bread (bread pudding) in bread dough production also offers advantages, but requires hygienic care and can have an uncontrolled influence on the acid content.
Ultimately, the best solution depends on the individual operating conditions. The correct use of sourdough, starter dough and cooked pieces requires specialist knowledge and an adapted recipe. However, with targeted planning, high-quality breads can also be produced with ‘dry-baking rye flours’.
