Dried baker’s yeast production is getting importance these days.
What is baker’s yeast?
Baker’s yeast (Saccharomyces cerevisiae) is the main leavening agent in bread production. It has an enormous production quantity in the World. The moisture content of baker’s yeast is over 70% and this situation decreases the shelf life to 1-2 weeks. Additionally, baker’s yeast must be stored or transported under fridge conditions. These factors make it necessary to be dry of baker’s yeast. By drying, the moisture content is decreased to 5-10% and the stability of yeast is increased. The dried baker’s yeast can be stored at room temperatures, have a longer shelf life, and is easily activated when rehydrated.
Common techniques in dried baker’s yeast production
Commercial active dry yeast is produced by drying of baker’s yeast. For drying, several techniques can be applied such as fluidized bed, freeze-drying, spray drying, drum-drying, etc.
The most important thing in the drying of yeast is that the drying technology must be gentle as not to have a deteriorating effect on the viability and fermentative activity of yeast. Because the viability of yeast is directly correlated by leaving activity (Ahi et al. 2010). Additionally, the drying must not cause any change in the physical structure of yeast while it should have the manageable cost of installation and operation.
Spray drying is the most applied drying technique for this purpose. However, high drying temperatures cause a decrease in the cell viability of yeast. In a previous study, it was reported that during atomaziting, the viability of microoorgansims decreased nearly 4 log (Tafti vd. 2012). On the other hand, non-enzymatic reactions that occur during drying lead to deterioration of taste and aroma (Corsetti 2013).
The other technic used in the production of active baker’s yeast is freeze-drying. The disadvantages of freeze-drying technique are that it is very costly, takes a long time (2-5 days) and cannot be dried in a continuous system in the industrial sense. In addition to all these, the vacuum applied during freeze-drying also increase the aroma losses. On the other hand, even the drying temperatures is very low, in freeze drying, freezing can damage cell integrity. In a study, it was reported that freeze-drying cause 2 logoritmic reduction in yeast count (Stefanollo et al. 2018).
Is refractance window drying is solution?
Refractance window drying is an innovative technique that allows food to be dried at low temperatures and times. Recent studies have showed that refrectance window drying is affective in the protection of microorgansims during drying process.
Our in-house studies yielded very optimizing results on production of dried baker’s yeast production using refractance window drying. According to the our preliminary results, refractance window drying not only provide high yeast content but also good quality in final breads.
Need mor information about our technology, you can read Refractance Window Drying Technology post.
Interested in our dryers, get more information on our services page.
References
M. Ahi , M. S. Hatamipour & A. Goodarzi (2010) Optimization of Leavening Activity of Baker’s Yeast During the Spray-Drying Process, Drying Technology, 28:4, 490-494.
Tafti, A.G., Peighambardoust, S.Y., Hesari, J., Bahrami, A., Bonab, E.S. (2012). “Physico-chemical and functional properties of spray-dried sourdough in breadmaking”, Food Science and Technology International, 19: 271–278.
Corcetti, A. (2013). “Technology of Sourdough Fermentation and Sourdough Applications”, In: Handbook on Sourdough Biotechnology, Ed: Gobbetti, M., Gänzle, M. Springer New York Heidelberg Dordrecht London, ss:85-105.
Stefanello, R.F., Machado, A.A.R, Cavalheiro, C.P., Santos, M.L.B., Nabeshima, E.H., Copettia, M.V., Friesa, L.L.M. (2018). “Trehalose as a cryoprotectant in freeze-dried wheat sourdough production”, LWT – Food Science and Technology, 89: 510–517.