Problems with protein
September 20, 2016
by Charlotte Atchley
Fortifying baked goods with protein makes them popular with consumers but can bring new challenges to processing.
Protein is the scaffolding upon which bread is built. Even in baked goods that may not depend on protein for their structure — such as cookies and cakes — it still influences the texture consumers come to expect from the finished product. Being so critical to structure and final texture means protein inevitably affects the dough’s machinability as well.
“The gluten matrix in bakery products is critical to both processing and the final texture,” said Brook Carson, vice-president of product development and marketing, Manildra USA. “Adding protein to baked foods will affect dough handling by impacting the strength of the gluten matrix and overall moisture retention. Any added ingredient that may disrupt the gluten matrix or interfere with hydration, whether that is protein, fiber or a hydrocolloid, will impact dough handling.”
With protein skyrocketing in popularity and consumers thinking they need more, it’s become a preferred ingredient to bulk up foods in all categories. However, because of protein’s functionality in baked goods, it cannot be added without care and consideration. Extra protein can have serious ramifications that need formula or process adjustment to create a product that can be successfully machined and still be acceptable to consumers.
The basis of most conventional baked goods is wheat flour because of the protein found in wheat. Its functionality is so critical that it has been difficult to replicate in formulations where it is missing.
“Wheat protein has unique functionality that creates the extensibility and elasticity central to the finished product texture of most traditional baked goods,” said Vance Lamb, technical services representative, ADM Milling. This balance between extensibility and elasticity also allows the dough to be stretched and worked while still maintaining its overall structure.
This structure — and the extensibility and elasticity — happen when proteins are hydrated. In a mixing bowl, the native proteins in flour absorb water, which help them bond chemically to create the gluten that develops baked goods’ most unique structure and qualities.
As Ody Maningat, PhD, vice-president, ingredients R&D, MGP Ingredients, explained, wheat gluten is a complex binary mixture of gliadin and glutenin proteins. To form the dough systems’ protein network, gliadin and glutenin undergo sulfhydryl/disulfide interchange in the mixer. This plus hydrophobic interactions and elevated hydrogen-bonding capacity from high level of glutamine provide the basis for the formation of web-like protein network. Hydration unlocks this potential.
“Hydration is a key for functionality,” Ms. Carson said. “To optimize the functionality of gluten, it should be fully hydrated. That will allow the protein to provide the best rheological characteristics.” Those characteristics include extensibility and elasticity, directly linking a dough’s machinability to the hydration happening in the mixing bowl.
Even products that don’t depend on protein for their structure, such as cookies, can be impacted by extra protein’s need for hydration.
While wheat protein may be functional, contributing to the structure of a dough, other sources of protein used to boost a baked goods’ protein content may not be. These proteins can contribute to the overall protein per serving in a finished baked good, but they won’t contribute much in the way of structure. They can, however, interfere with the structure being created and impact a dough’s ability to run on automated equipment.
“Proteins from other sources affect the well-organized, web-like gluten protein structure in a fully developed dough and potentially have a disruptive effect on the viscoelasticity, or dough-making ability, of wheat gluten because this property is unique only to wheat gluten,” Dr. Maningat said.
While non-wheat proteins don’t necessarily contribute functionally to the dough system, they can take up some much-needed water, throwing off the all-important mixing times and viscoelasticity. “Proteins from different sources will have different amounts of solubility, water-holding capacity and hydration rates,” said Bicheng Wu, PhD, associate, global applications, Ingredion, Inc. “As a result, the water absorption rate, mixing time and elasticity are all affected.”
Not all non-wheat proteins are created equal. While proteins from many different sources share similar characteristics, such as needing hydration and interfering with the gluten matrix, each one impacts these aspects of the dough formation to a different degree. Formulators must tailor each formulation to the protein source being used. Protein from algae, a vegan source suitable for use in high-protein baked goods, has very little effect on dough. “Protein fortification can typically impact taste and texture when using proteins that interact with other ingredients in formulation,” said Mark Brooks, senior vice-president of food ingredients, Terravia. “This can often lead to an unpleasant, gritty mouthfeel. Since our protein is encapsulated within the cell wall, its impact on absorption, mix time and elasticity is minimal.”
He referred to the algae cell wall that keeps the plant protein from interacting with other ingredients. It’s what makes Terravia’s AlgaVia Protein-Rich Whole Algae suitable for baked goods applications.
Non-wheat proteins also compete for water in the dough. “Most non-wheat proteins have significant water-binding capacities, so they will increase the water absorption of bread doughs,” Dr. Maningat said. This brings everything back to the heart of the matter when it comes to protein and dough machineability — water.
When adding protein to tortillas, extensibility can become an issue.
Hydration and mixing time
At the heart of the protein “problem” is dough absorption. Protein absorbs water in a formulation, and too much protein starts to take up water needed elsewhere. “In general, dough becomes firmer and less sticky as the protein absorbs the free water in the system,” said Caleb Wagner, food technologist, food and beverage innovation group, Agropur Ingredients.
Dryer doughs make processing difficult. “Machining becomes a challenge if the water balance isn’t adjusted because it becomes very difficult to properly mix dough that is too dry,” he said.
And every protein has its own unique hydration needs. While some proteins will dry up the dough quickly, others will leave bakers with something more plasticized.
“If the protein source you are adding takes up the water instantly, that might not leave the water needed for the gluten to properly hydrate and obtain its functionality,” Ms. Carson said.
This battle for water and the dryer doughs that result reduce dough mixing tolerance and lead to longer mix times. All of this also results in reduced processing tolerances down the line.
Complicating the battle over water is the need to get enough protein into the product to justify a “good” or “excellent” source claim. “It is possible to make a good product, but it cannot be strictly based on the protein needed to make the claim,” Mr. Lamb said. “The rest of the formula and production must also be adjusted.”
An immediate way to adjust for more protein is to simply add more water and increase the mix time. There needs to be enough water in the formulation so that ingredients aren’t fighting over free moisture, and there should be plenty of time in the mixing bowl for all the ingredients to be properly hydrated, Dr. Wu explained. The changes don’t stop there, however. “Baking conditions should also be adjusted to achieve the required moisture level,” she said.
Adding extra moisture is only going to go so far into remedying extensibility and elasticity issues. Too much hydration can also cause challenges. “Overly hydrated protein going into the oven can result in hard cookies,” Mr. Wagner said. “It all comes down to controlling where your moisture is going.”
Bakers have other tools to manage water. Adding more fat or other plasticizing agents such as glycerin can control moisture migration and gel development in the oven. “These agents either inhibit or compete for the free water in the system, giving you some control over how the dough machines as well as how the structure develops upon baking,” Mr. Wagner said.
Also the type of protein being used to enrich the product can change things as well. It’s important to select the right protein source because each one has different hydration needs, not to mention the interactions that may occur with other ingredients in a formulation. “In general, baking with protein is a very trial-and-error process, as even the best-laid plans go to ruins due to unforeseen ingredient interactions and synergies,” Mr. Wagner said. Working with food scientists from a supplier such as Agropur, bakers can test their formulations with its BakiGen Bakery Ingredients line of whey and plant-based proteins to find the right balance of protein enrichment and machinable dough.
Knowledge of how these proteins work and how to optimize them with other ingredients, even other proteins operating in the formula, can go a long way in reaching formulating success.
“Understanding individual ingredient functionality will help when developing new formulas and processes to ensure the ingredients are obtaining optimal functionality,” Ms. Carson said.
Wheat protein isolate can help pastries fortified with protein achieve the sheetability they need to be machined properly.
Adding wheat protein isolates
Protein being arguably the hottest macronutrient in the food industry, fortifying baked goods with it is definitely something worth looking into. But this is not as simple as just adding extra wheat protein to the formulation or bulking up with non-wheat protein either.
“In the production of high-protein breads, addition of non-wheat protein ingredients (soy, rice, pea, etc.) that do not have the unique viscoelastic properties of wheat gluten will involve the addition of extra wheat gluten in the formula to strengthen the dough and help ‘carry’ the added non-functional protein ingredient,” Dr. Maningat said. “On the other hand, adding wheat gluten to produce high-protein bread products will make the elastic component more dominant yielding bucky doughs that are difficult to process in a normal bakery plant operation.”
Non-wheat proteins can also disrupt the gluten structure trying to be established. “Generally speaking, bakers see non-functional ingredients as not pulling their weight,” Ms. Carson said. These proteins do not contribute to structure-building and can use up water in the system; however, they contribute more to protein fortification than their functional counterparts. Formulators must discover the proper balance between the gluten functionality and other ingredients in the system.
“When customers come to us with an interest in a high-protein product, we encourage them to pay attention to the source of the protein and realize that some will be functional and some will not be beneficial to the structure,” Mr. Lamb said. “It is not likely that the strength of the original product will be able to hold the non-functional added protein; additional gluten or wheat protein isolate will be needed.”
Wheat protein isolates and vital wheat gluten (VWG) can provide that strength and address other issues associated with supporting extra protein in a formulation. According to Tess Brensing, technical products manager, ADM Milling, VWG is concentrated gluten separated from the starch and other components through washing. VWG can be further processed to concentrate its protein content as wheat protein isolate, which delivers a unique functionality.
“Certain types of wheat protein isolate, such as ADM Prolite 100, have whipping characteristics that can create foams and add tenderness to baked goods,” she said. “Other wheat protein isolates, such as ADM Prolite 200, behave more like a relaxed VWG — meaning that it provides resiliency without the chewiness of regular VWG.”
With these unique functionalities, wheat protein isolates can not only aid in giving baked goods a protein boost but also accommodate processing challenges that may arise because of the added protein. “Many formulators resolve the problem by adding a wheat protein isolate to enhance the extensibility of bucky dough, allowing the dough to be machinable in bakery plant equipment,” Dr. Maningat said.
One of MGP Ingredients’ specialty wheat protein product lines, Arise, features isolates with varying elasticity and extensibility properties, and because they are wheat-based, they are compatible with the proteins naturally present in the flour. While Arise 5000 aids in boosting the extensibility of flour tortillas and sweet goods, Arise 6000 and 8000 strengthen the structure of breads made with weak flours. In a high-protein bread, Arise helps ease the dough’s buckiness so it can be processed in conventional bakery equipment.
When formulators want to rely on non-wheat proteins for protein enrichment, VWG can help in keeping the gluten network structure. “When replacing wheat flour or adding protein for protein enrichment, the addition of other protein dilutes the wheat gluten content, which leads to changes in the dough’s viscoelastic properties and makes it difficult to process,” Dr. Wu said.
This comes from a difference in each protein’s basic composition, Dr. Wu explained. While the high cysteine amino acid composition of wheat protein enables disulfide bonds to form during kneading, a pulse protein, for example, has low cysteine content. Because of this, pulse proteins cannot form a gluten network and results in dough that is less elastic. VWG can keep that gluten structure from becoming compromised.
Manildra USA’s GemPro line of proteins can balance out this struggle by maintaining the critical gluten network but providing additional extensibility. “It allows the dough to be processed more easily and, in turn, get more kick in the oven,” Ms. Carson said.
While protein fortification can come with some caveats for baked goods, bakers can definitely take advantage of this trend. With the selection of the right protein, the balance of ingredients and the formulating expertise of ingredient suppliers, bakers can bulk up their finished products’ protein content without drying out their doughs.