THE TRUTH The quantity of salt added to bread dough will not kill yeast; only heat – specifically above 60°C – will do this.
WHERE THE MYTH CAME FROM…
Salt plays several key roles in bread-making. It adds flavour, shortens gluten strands (strengthening the dough) and slows the rate of fermentation, giving an even texture. It’s this third role that leads to the myth. Salt competes with the yeast for water, restricting the yeast’s ability to multiply. Add too much salt and the yeast will slow to an almost inactive state, but there’s no need to keep your yeast and salt apart when making bread, especially if you’re planning on a long prove.