Re: Why a 100%natural pumpernickel bread is not moldy even after 2 weeks?

Hi, Natalia.

Molds come about because of moisture content. When bread is kept out for a long period of time, it loses moisture from its cells which collect on its surface. This moisture under the right conditions will lead to mold growth. Different breads have various moisture levels. If your 100% rye bread had more water content than the pumpernickel that may be one explanation.

Also, if your rye bread was truly "100% rye", it may have included the bran and the germ. The germ of seeds are particularly susceptible to rancidity and molds. That's also why your sunflower bread developed mold. Seeds are very sensitive to spoil if not kept cool and dry.

You also mentioned that the pumpernickel bread was "100% natural." This doesn't necessarily mean that it included the germ. Also, this term is used very liberally in the marketplace, and doesn't preclude that some "natural" type of preservative wasn't used. For example, calcium proprionate is naturally produced in our bodies and can also naturally be found in cheese. So it may still be considered "natural", but include such preservatives, (which by the way is added to prevent molds).

Another factor would be the proportion of wheat starch to rye. Some is usually added even to rye breads in order to make it rise properly. The greater the ratio of rye to wheat starch, the longer its shelf life. In fact, if your pumpernickel bread went through a longer fermentation process, it would also explain its resistance to mold. The fermentation involves the use of special "starters" and undergoes a sourdough fermentation which produces acids and 'helpful' bacteria that actually have antibiotic properties, similar to penicillin! Your pumpernickel bread may have had just the right chemistry to prolong its shelf life.

Hope that helps,

Peter Bosani.

Sources: On Food and Cooking - H. McGee
The Blessings of Bread - A. Bailey - Paddington Press Ltd.