Just like baking, proofing is a thermal unit operation in the bakery. During proofing, the dough absorbs heat from the humid, warm surroundings to reach a target internal temperature. The final proof accomplishes two major goals:
It allows more carbon dioxide to be produced through fermentation. This causes the gluten to become extensible again. After sheeting and moulding, the dough lacks extensibility and is mostly degassed with larger air cells subdivided. Proofing rectifies these “problematic” conditions in the dough.
Biochemical leavening produces the desired volume, cell structure, flavor, and eating qualities of the finished product.
The proofer establishes the best conditions for yeast to do what it does best: produce gas and make the dough rise. To readily expand, the dough needs optimum conditions of temperature, time and relative humidity (RH). These conditions are also known as proofing variables.
Proof temperature: 90–100°F (33–37.8°C). Yeast is most active at this temperature range, and its activity doubles for every 18°F (10°C) increase in temperature.
Proof time: ranges from 50 to 70 minutes
Relative humidity: 80 to 90%. Upper limit is used in white bread, while lower limit is mainly used in whole wheat, rye and multigrain bread.
Effects of temperature during proofing:
Yeast works too fast on fermentable sugars, producing excessive amounts of CO2, causing open cell structure and excessive volume in the finished product.
Dough rises too quickly.
Proof time is drastically reduced, affecting overall operations scheduling.
Insufficient production of flavors and aromas that are necessary for optimum product quality.
High risk of overproofing, if not properly balanced with a reduced proof time.
Yeast works too slowly and produces insufficient gas, causing poor volume and dense crumb grain.
Dough rises too slowly.
Proof time is drastically increased, affecting overall operations scheduling.
High risk of underproofing if not properly balanced with longer proof times.
Effects of RH during proofing:
Too high (too moist conditions)
Too low (dry conditions)
Product sticks in the pan
Small blisters on the crust
Increased pan flow
Tough or rubbery crust
Proof time needs to be reduced
Flat bottom in hearth products
Wrinkled crown (crust too soft)
Capping is highly probable
Rough crust color
Proof time needs to be increased
Achieving proofing consistency
It does not matter if you have a continuous or batch-type proofer. They all work under the same principle regardless of basic differences in operation and throughput. What matters is that you can control the variables that directly impact the production plan and quality of the finished product.
Final proofing can be profiled with a combination of RH and temperature recording device. By using this device, bakers can accurately track humidity and product temperature. This system can be used in high-speed bakeries to monitor equipment performance, minimize process variations, increase production yield and reduce waste.
Ray has worked with countless bakers and ingredients suppliers as well as electronics manufacturing; curing and heat treat customers, helping to solve conveyorized thermal processing quality issues with thermal profiling solutions, online & onsite. Ray studied Engineering and Communications at the University of Washington and has served as Technical Director and currently as BakeWATCH product manager at Electronic Controls Design, Inc. in Portland, Oregon.