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Sliced Bread


      It is with great satisfaction that we can finally offer our breads as pre-sliced smaller packages. We have had this request form our customers for some time.  This paper offers an explanation for some the thinking and processes involved in making the decision.

      Sliced bread is a ‘New World’ innovation that Americans pride themselves in, and where the idiom ‘the best thing since sliced bread’ comes from. This convenience does come at a price however: preservatives. In the past, preservatives of one kind or another were accepted as common practice for increasing the shelf life of bread and other products, by discouraging the availability and suitability of an environment suitable for mold spores to grow. This is especially true for ‘tin’ breads – those baked in a form.

KSB Sourdough

       Some preservatives have been replaced since they were found to be not as innocent as thought earlier. Because ‘sliced bread’ cannot be done without, new inventive preservatives have been developed. Time will tell, but there is no guarantee that the new preservatives don’t also pose a health risk.  

KSB Sourdough 
At KSB, we took several years to figure out how to offer our bread sliced without preservatives, with the following knowledge in mind:


      A hearth oven loaf of bread becomes mold resistant through its crust. The crust is dry and does not facilitate easy growth for mold spores since for propagation, mold spores require moist, nourishing environments.

Once bread is sliced, the host for mold spores drastically changes, as the inner sanctuary of the bread is exposed to the air. The moist nutrient-rich inners of the bread is perfect place for the mold to start the multiplication game. Every breath of air contains millions of mold spores waiting for this chance. During warm humid weather this further radically increases mold spores in the air.


      Even though our bread has a natural preservative through our sourdough fermentation technique, it is also not entirely resistant to such an onslaught of contamination. Refusing to bow to conventional preservatives for convenience we pursued a quest to solve this dilemma, and find a practice acceptable for us, and the health standards we are dedicated to for our customers.

KSB Sourdough

      Hopefully this has shed some light on the challenge of pre-slicing our bread so it doesn't spoil prior to consumption. With proper storage we aim for a six day window in which our bread should be eaten. You can extend this in specific clay bread storage containers. However, you can also spoil the bread more quickly if it is exposed to excessive heat in a closed bread bag. As moisture/humidity rises, the local environment of the bread (inside the bag) becomes a hot-house and mold spores will quickly multiply. That is why we suggest not storing our bread in an enclosed space when it is above 20° Celsius. A simple remedy is to open the bag and let the moisture escape, or in severe cases (say in the heat of summer), take the bread right out of the bag for a short while, though in this circumstance, putting the bread in the fridge is also not a bad idea. Otherwise, the bread will also just dry out.

KSB Sourdough

      Once the whole situation is understood, a possible solution can be made. In our case, this involved controlling the air content - eliminating the mold from the air – during the slicing/packaging process. We were able to design a system using positive pressure and the right filtration systems. Admittedly, this took several years of research, considerable investment and expense with proper equipment, and installation of the new system, which is currently reflected in the higher price of the sliced products. But most importantly, we are proud to be able to provide sliced, packaged bread without any foreign preservatives.

KSB Sourdough

      I have resisted writing about this until I was sure that our system would work.  After two years including two hot summers, it has performed very well. After a round of innovation, we pioneered a means of providing a new product, much to the benefit of our customers.


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