As more fresh bakeries venture into the frozen arena, caution must be taken to minimize changes to product quality.
Entry into the frozen dough market offers many advantages, including extended shelf life and sales beyond a baker's immediate fresh market distribution area, and yet numerous factors impact finished product quality and consistency. Although any skilled baker has the ability to control product formulation and the manufacturing process, finishing off the product by thawing, proofing and baking often is left to the unskilled end user. Thus, much is left to chance when all is said and done.
Optimizing the performance of yeast in frozen dough is one of the most important criteria impacting bread quality. Cryoresistance, or the ability of yeast to survive the freezing process, can be accomplished with the right combination of ingredients and processing parameters. For instance, maintaining proper dough temperature is a critical step in keeping yeast dormant.
In addition, advancements in ingredient technology have resulted in improved stability for frozen product and longer shelf life, notes John Graham, regional sales manager, Red Star Yeast Co., Milwaukee.
Optimizing dough quality
Two of the most important objectives of frozen dough production are to optimize dough development during mixing, while maximizing the cryoresistance of yeast, so it remains dormant during frozen storage. Although these objectives are partially accomplished through formulation, process conditions also are key. Dough temperatures need to be in the 59°F to 68°F (15°C to 20°C) range, notes Jan van Eijk, Ph.D., Lallemand Inc., Montreal. In addition, the time between mixing and freezing needs to be short. Small batches help reduce variation between mixing and freezing.
“The temperature of your dough is achieved by the temperature in your atmosphere, the friction in your mixer and the temperature of your ingredients,” says Rick Robbins, president and owner, Pittsfield Rye and Specialty Breads Co., Pittsfield, Mass. “Some people have water chillers, as we do, although sometimes that in itself is not enough in some seasons to give you your desired dough temperatures, so ice is an option. We actually add shaved ice now. It's less friction on the mixer and better for the dough as well.”
The amount of ice needed per formulation varies depending on factors, such as the season and the amount of humidity in the air. Bakers can rely on past experience and judge the amount of ice needed based on the dough temperature of the first batch, Robbins adds. Environmentally controlled dough production rooms also are helpful. Pittsfield Rye uses evaporators to cool the dough production room — an area sealed off from the heat and humidity of the proofing and baking processes.
Colder dough is stiffer by nature, causing more wear and tear on dough processing machinery that may need to be upgraded with larger motors and more horsepower, notes Chris Bohm, senior bakery technolgist, Caravan Ingredients, Lenexa, Kan. An alternative is to find the right kind of equipment to accommodate doughs ranging from highly hydrated and sticky to those that are stiffer. Robbins feels he has done just that.
"Some people think a horizontal or a barrel mixer is better because it's stronger and more rigid,” Robbins says. “But, that being said, I'm a firm believer in spiral mixers. We have three Sancassianos. We actually tried about six different types of spiral mixers several years ago, but these mixers we chose are, I believe, the best we've seen. They have a cylindrical breaker bar in the middle, as opposed to some of the spiral mixers that have an L-like bar. The L-like breaker bar sort of slides the dry ingredients, as opposed to the cylindrical breaker bar that incorporates ingredients much quicker. It's very good for the dough and adds life to it.”
At the Robbins' bakery, once the dough is mixed, it goes through a divider; conical rounder; intermediate/overhead proofer where it rests for 12 minutes; through a final moulder, where it is degassed; then formed and placed on pans that are set onto racks and then blast frozen. The whole process takes 18 minutes. “Even though we've tried to automate and expedite our process, it still is more natural,” Robbins says. “The dough is allowed to rest for 12 minutes after it's rounded, and then it goes through a moulder. The main attribute to having the yeast remain dormant throughout the resting process is having that lower dough temperature.”
Robbins strives for a mixing temperature of 63°F (17°C) for his frozen dough versus the temperature range of 75°F to 80°F (24°C to 27°C) used for proof-and-bake bread production.
Yeast used in frozen dough has to survive frozen storage for three to six months. Typically, bakers use the same strain of yeast for proof-and-bake bread production and frozen dough, although the yeast, which is preferably the cream type, should be as fresh as possible, van Eijk notes.
The presence of trehalose, a natural disaccharide sugar with good water retention properties, is a cryoprotective compound that has been associated with yeast. Yeast with higher levels of trehalose tend have lower gassing power; therefore, the yeast tends to stay dormant longer in frozen dough, and activates more slowly, according to Lallemand.
Yeast strains specially engineered to be more cryoresistant also are available in compressed/crumbled and liquid/cream forms, Bohm notes.
Dough conditioning systems are particularly important for protecting the dough throughout freezing. “Generally, the conditioning systems are higher in oxidation, lower in reducing agents and contain high amounts of dough strengtheners and/or enzymes and hydrocolloids,” Bohm says.
High levels of antioxidants are recommended of at least 60 ppm; however, 90 ppm to 120 ppm of ascorbic acid is preferred for optimum oxidation, according to Lallemand. When reducing agents are used to reduce mixing time and speed up dough development, more oxidation is required.
Dough conditioners are very important in frozen dough. Robbins uses all natural vitamin C in all of his make-and-bake and par-baked products. Reportedly, no all-natural dough conditioners exist that work in frozen dough. The emulsifier DATEM (di-acetyl tartaric acid esters of monoglyceride) works very well in frozen dough. “Our product has a lot of tolerance, a nice shelf life and will hold up for the end user,” Robbins adds.
Other new technologies are emerging for both retarder-to-oven and freezer-to-oven processes. Caravan Ingredients has a particular range of dough conditioners that enable bakers to make yeast-raised products, such as pizza, bagels or sweetgoods that go straight from the freezer to the oven. “This is becoming increasingly important in foodservice operations where time and skills are scarce resources,” says Kerrie Medlicott, marketing director, Caravan Ingredients. “What makes this technology so special is that frozen dough manufacturers don't need to make any changes to their existing formulation or process, so their customers can have the same eating qualities, but in a more convenient format.”
Finishing the process
Frozen dough should be stored and distributed at -10°F to 0°F (-23°C to -18°C). All frozen dough needs a thawing period (retarding) for 12 hours to 16 hours at 36°F to 40°F (2°C to 4°C), notes Bohm.
“From here it is allowed to come to a temperature of around 55°F (13°C) before getting the final proof in a chamber slightly lower in temperature and humidity than what is commonly used for make-and-bake product, 90°F to 95°F (32°C to 35°C) and 80 percent to 85 percent relative humidity,” adds Bohm. “Proof time is generally about 25 percent shorter than that of conventional dough, because the dough is getting some proofing in the retarding stage.”
Freeze/thaw cycling should be avoided during storage and distribution. Thawed frozen dough should not be refrozen. Usually, there is a maximum proof time, which should not be extended indefinitely, van Eijk notes. Maintaining some semblance of control over the thawing and proofing processes is one of the biggest challenges associated with frozen dough. Many variables can fluctuate, from time and temperatures to the equipment used to product rotation by the distributor.
Robbins responded to a product complaint from a customer who “didn't understand the process.” In wanting to keep store shelves fully stocked, the store manager told his employee to place extra product in the cooler on Friday so it would be available for Sunday. Although the product was fine on Saturday, by Sunday no yeast activity was left. “As you delve further and further, hopefully you find the problem and try and correct it,” Robbins says. “Even if we're absolutely perfect on our end, there could be problems between the distributor and the end user that need to be ironed out.”
Pros and cons
Many bakers are capitalizing on the benefits frozen dough provides. Distribution can be extended beyond regional boundaries and inventory cost is reduced because of the lower volume and higher density associated with dough before it has been proofed or baked. “A typical carton of frozen dough weighing 30 lb. and containing about 240 individual rolls takes considerably less space than its fully baked and packaged counterpart,” Bohm says. In addition, because frozen dough has an extended shelf life, bakers can draw off of inventory as customer demand calls for it.
In spite of the many advantages of frozen dough, one of the major disadvantages is that finished product quality is so dependent on the finishing process used by the customer, who is more often than not, unskilled in baking. Robbins, whose customer base in Manhattan is growing, sees the industry going more toward par-baked. “Manhattan strictly does par-baked. They don't have proof boxes because there is not room for them. Space is at such a premium.” Robbins says.
Perhaps advancements in ingredient technology can remove some of the labor-intensive steps and opportunities for error that currently exist in the thawing and proofing steps required for frozen dough. A freezer-to-oven process could certainly go a long way toward maximizing quality of baked products made from frozen dough.
Advantages and disadvantages of frozen dough, par-baked and proof-and-bake breads
• Fresh-baked quality
• Labor intensive (skilled)
• Production similar to regular proof-and-bake product
• High cost for high volume of frozen storage and distribution
• Low production cost (no proof-and-bake)
• High labor cost (bake-off)