Current technical literature describes that when the total grain content is made up of 20% or more rye flour, the use of sourdough and/or acidifying additives is technologically necessary, i.e., to achieve an elastic and loosened bread crumb. However, it has been known for over 20 years that even 100% rye flour of average quality can be baked with a largely elastic crumb without the addition of acid. In practice, it is rightly avoided because of the poor bread aroma and taste and the lack of freshness. How much acid is required to bake rye-based products and which dough processes are important? Explanations are below.