Staling, in theory, is often driven by the retrogradation of starch, a substrate that the enzyme amylase binds to and consumes.
“After baking, gelatinized starch retrogrades and becomes solid,” said Paul Bright, innovation manager, AB Mauri North America. “We perceive this as staling.”
Specifically, the starch component amylopectin, which is a collection of amylose strands, begins to recrystallize and shrink together, said Ben Reusser, senior bakery scientist, Cain Food Industries. Amylase interrupts and slows this process by breaking down those starch chains into smaller dextrins and shorter branches of amylopectin.
“This modification of amylopectin is what retards crumb firming, thus preserving the softness of the bread,” said Luc Casavant, baking applications director, Lallemand Baking Solutions.
It’s important to note, however, that there isn’t just one amylase. While each type will break down amylopectin, not all do so equally.
“Different types and amounts of amylases, like maltogenic, bacterial, fungal, G4 and others, will work at different rates and on different points of the starch chain,” said Ken Skrzypiec, vice-president of sales, Brolite Products.
Bakers need to consider how each type of enzyme will impact their finished product. For example, maltogenic amylase works at the ends of amylopectin, breaking off two units at a time, Mr. Bright said.
“Other amylases are not as discriminating in their action,” he continued. “These are the so-called endo-acting amylases because instead of working outside-in like the maltogenic enzymes, they randomly snip a part of the starch.”
Maltogenic amylase is the most effective amylase at anti-staling, said John DelCampo, division manager, Repco Bakery Solutions. Fungal amylase deactivates too quickly in the oven at 135°F, leaving nothing available to react with gelatinized starch, which is crucial to effective anti-staling. While bacterial amylase does stick around to work in gelatinized starch, its method is aggressive and can impair starch and finished loaf structure. Overdosing on bacterial amylase can also cause a loaf to collapse and a sticky and gummy crumb.
Maltogenic amylase on the other hand is more heat stable and deactivates after baking.
“Another important difference is that the action on the starch molecule is gentler, leaving the structure intact,” Mr. DelCampo said. “Finished product crumb integrity and structure is ensured regardless of the amounts used.”
Advancements in understanding enzymes and how they work has enabled food scientists to address not only staling but also adjacent issues such as softness, moistness, resilience and tenderness.
“We can customize our solutions based on desired texture and tolerance to ensure quality throughout production,” said Jesse Stinson, director, technology, Corbion. “Working side by side with bakers allows us to identify and implement the most fitting solutions for their specific application and consumer needs.”
These amylases can contribute to softness and put off staling; however, overusing them can result in a completely broken down starch molecule. This creates an overly moist, gummy crumb in the finished product.
“Used properly, however,” he said, “the endo-acting enzymes have a superior cost-in-use.”
The dextrins created by amylase also can be acted on by beta-amylase to be broken down into yeast-fermentable sugars, Mr. Reusser explained.
By using a flour’s starch as its substrate, amylases have become critical to enzyme-based softener solutions. Xylanase also can contribute to shelf life by freeing up water in the formulation.
“Xylanase enzymes can help redistribute water in the dough thereby ensuring proper hydration of the gluten during mixing, which contributes to softer baked goods,” said Deborah Waters, enzymologist, Kerry Ingredients.
Using too much xylanase, however, creates a wet and slack dough in the mixer. Instead of removing water from the formulations, Joshua Zars, regional business director, food enzymes, DuPont, suggested bakers simply lower the amount of xylanase to quickly address the issue.
Lipases also help preserve shelf life of baked foods.
“Lipases break down lipids, or fats, and complex with the starches, therefore also impeding the onset of retrogradation,” said Al Orr, vice-president of sales and marketing, J&K Ingredients.
By cleaving fatty acids from the glycerol of fat molecules, lipases create mono- and di-glycerides, Mr. Reusser explained. Mono-glycerides can then complex with amylose to hinder the retrogradation process. This process results in a softer, finer crumb structure in the finished product. Lipases also can create an emulsifying action that mimics DATEM or SSL as a side effect of its processing breaking down lipids, Mr. Reusser said.
Using too much lipase can cause problems in the final products, problems that don’t reveal themselves right away. It’s important that formulators hone in on the appropriate amount.
“A lipase overdose will appear normal during the mixing and proofing process and have great oven spring in the oven,” Mr. Zars said. “But about two-thirds of the way through the oven process, the structure weakens, and the loaves will collapse, causing very low specific volumes out of the oven.”
Whether acting on the starch or the fat, enzymes need the appropriate formulation and processing environment to activate and do their job effectively.
“Enzymes will do no work until they are hydrated and in an environment that contains the desired substrate, the molecule enzymes act on such as starch, protein or fat,”
Mr. Reusser said.
Once enzymes are mixed into the dough, which contains water, they are activated and begin acting on either the damaged starch if it’s an amylase or the lipids and polar lipids if it’s a lipase.
Once enzymes have been activated, it’s critical that the rest of the baking process supports the enzymes’ activity until it’s the appropriate time to shut them down.
This article is an excerpt from the June 2019 issue of Baking & Snack. To read the entire feature on enzymes, click here.