What is Compressed Yeast?
Compressed yeast is a type of baker’s yeast that comes in a solid form. It is also known as cake, wet or fresh yeast.
It is the cream yeast with most of its liquid removed. Generally it has 30-34% total solids.
Bread fermentation with yeast is an anaerobic process. Little growth of yeast occurs during dough fermentation. The oxygen of dough is rapidly consumed by the yeast as fermentation starts. The major products of yeast fermentation are carbon dioxide and ethanol. Figure 2 shows the fermentation reaction of glucose by yeast.1 Yeast can also readily ferment the non-reducing sugar sucrose because it possesses a very efficient invertase system. Sucrose is rapidly hydrolyzed into glucose and fructose and readily fermented.
Compressed yeast is prepared from yeast cream by filtration or by pressing in a filter press. Rotary continuous vacuum filters also can be used. The pressed cake is mixed with 0.1-0.2% of emulsifiers, such as monoglycerides, diglycerides, sorbitan esters, and lecithin, and then is extruded through nozzles. The extruded material, in the form of thick strands, is cut into suitable lengths and is packaged (usually in packs of about 500 g) in wax paper or polythene sheet. The compressed yeast must be cooled rapidly and stored at 5-8 oC.2
Pros and Cons
There are several different types of baker’s yeast, such as compressed yeast, dry yeast and instant dry yeast. Compared with dry yeast, compressed yeast is very perishable, requiring constant refrigeration to retain its freshness and activity. But, compressed yeast is far superior to dry active yeast in the speed at which it becomes active and the length of time it stays active. It can be frozen for several months. Its flavor tends to be milder than dry active yeast and tends to impart a sweeter taste (ideal for softer breads such as Italian or French bread).
Compressed yeast is not recommended for use in one hour or express bread machine cycles. Regular bread machine cycles are recommended.3 Yeast activity may decrease if it comes in direct contact with salt or sugar due to the high osmosis pressure for yeast cells.3
How to replace compressed yeast with instant dry yeast?
A 100g of compressed yeast can be replaced by 40g instant dry yeast and 60g water.
- Hoseney, R. Carl., and Jan A. Delcour. “Chapter 12 Yeast – Leavened Products.” Principles of Cereal Science and Technology. 3rd ed. St. Paul, MN, USA: American Association of Cereal Chemists, 2009. 188. Print.
- Batt, Carl A., and Mary Lou Tortorello. “Yeast: Production and Commercial Usages.” Encyclopedia of Food Microbiology. 2nd ed. San Diego: Academic, 2014. 828. Print.
- “Red Star® Cake (Fresh) Yeast.” Red Star Yeast. N.p., 2014.