How to formulate for gluten-free, part 6
When taking gluten out of bakery foods, it’s important to understand the functionality that is being replaced. Jeff Casper, R&D director, Cargill, Hopkins, MN, and Bill Atwell, PhD, retired Cargill researcher and consultant, Champlin, MN, look at the many factors involved. They recently collaborated on a new book about gluten-free product development and processing published in 2014.
Baking & Snack: The presence of gluten enables proper kneading, gas retention, finished texture and keeping quality. So, how does the formulator compensate for these functions without using gluten?
Bill Atwell: Gluten provides cohesion to doughs, and when you replace it, you need to use gums. You need a way to hold the mass together, especially with bread doughs.
When it comes to gas retention, wheat gluten is unique in its ability to inhibit the flow of gas through and out of the dough. You need something to do that in gluten-free doughs, and gums can provide that function, specifically xanthan and guar.
When dough expands, it needs to set in the oven in that expanded state to form bread. Gluten and starch provide that function in a conventional bread. When baked, the starch becomes gelatinized, pulling water away from the gluten. The gas cells in the dough expand, and the dehydrated gluten strain-hardens and becomes brittle. The cell walls eventually break and release the entrapped gas, and the gas-discontinuous dough becomes gas-continuous bread. This reaction has to occur, and both gluten and starch play key roles in setting structure. With gluten-free, starch and gum have to provide this function.
As far as texture, gluten provides the chewiness characteristic of many baked goods.
When it comes to keeping quality, there’s a different mode of staling with gluten-free foods, and starch plays a much more dominant role. You will have more issues with brittleness and chalkiness. Emulsifiers can be used to soften the crumb and delay firming, as is done in cake products.
Jeff Casper: Keeping in mind the differences between cookie and bread doughs, the function of gluten is very different in each. In cookies, the functional requirements of gluten are not as high as in bread, and so you can more easily develop structure by using a composite flour. Cookie doughs don’t need the gas-holding capabilities of bread doughs.
Among Cargill’s ingredients, which ones do you recommend for gluten-free baked foods? Why?
Mr. Casper: For Cargill, this is a broad question. Cargill offers a wide portfolio of ingredients for gluten-free products. The Cargill Texturizing Solutions business has a portfolio of hydrocolloids, blends, modified pregel and cook-up starches (tapioca, etc.) for achieving optimal texture and eating quality. All of these ingredients are tools that when combined into a composite flour system can be leveraged to the functionality of gluten.
The more you understand gluten, the more you can strategize to replace it. It is important to understand what functionality you are going after. Formulating without gluten gets down to fundamental rheology: how to create a strain-hardening material that replaces gluten. You want something that looks like and eats like bread, but there are multiple paths to achieve this.
Considering gums, guar and locust bean gum are synergistic with xanthan gum, and this synergy between hydrocolloids is used quite a bit in gluten-free products. You can blend gums for synergy to improve the rheological behavior over that of a single gum.
There are other ingredients that can be helpful. For example, inulin can be critical to quality and nutritional value. There has long been criticism of gluten-free diets that they lack fiber. Inulin has the added benefit of being multifunctional. It plasticizes the batter and provides a prebiotic fiber source. It also softens the crumb of gluten-free breads and contributes to finer grain in breads.
Another such ingredient is maltodextrin. It has similar functionalities to inulin but is not a fiber source. It has same ability to make the bread crumb finer in texture. Cargill has inulin and a range of maltodextrins that can modify the quality of gluten bread.
Gluten-free whole grain ingredients are also becoming more prominent as the nutritional profiles of starch based products are scrutinized. Cargill’s Maizewise corn flour is an example. It works well in cereals. Through Horizon Milling (now Ardent Mills), we also have gluten-free baking bases for cookies, breads, and muffins. These bases are fairly flexible so they can be used to make multiple products through simple bowl additions or process changes. These bases are great for operations that do not wish to maintain large numbers of ingredients.
What aspect of gluten-free formulating do users of your ingredients find the most difficult to navigate? Why?
Dr. Atwell: Bread is the most difficult case. And of all bread products, among the most difficult are bagels and soft pretzels. These need a good bite, which depends on the chewiness of gluten.
Gluten has a very high molecular weight, which is necessary to provide elasticity and hence the chewiness in the final product. Gums are much lower in molecular weight than gluten. Consequently, it is very difficult to provide chewiness in a gluten-free product Gluten is a huge molecule, and most other gum and protein ingredients are much smaller.
Mr. Casper: In selecting hydrocolloids and their usage level, you will be going after certain rheological properties. There are also regulatory limits to usage levels in baked foods, for example, with guar. Balancing these constraints with desired functionality can be tricky.
Among the Cargill modified starches, you can use either cook-up or pre-gelatinized styles. Determining the right modifications and starch source requires some understanding of your process and desired finished attributes, and they have an impact on costs. The expertise of the supplier is important, especially when working with gluten-free.
What advice do you have for someone attempting their first gluten-free version of a baked food or snack already in their company’s product line?
Dr. Atwell: We started working with gluten-free in 2007, and we divided the work between cookies and batters vs. bread-like products. Our advice is to work first on cookie applications. They’re the easiest. Batter-based items will need some added functionality to substitute for that of gluten, but you can still get pretty far.
The big problems are with bread. A fundamental understanding of the bread system helps, but gluten-free bread systems are even more complicated. It’s a learn-as-you-go situation.
To help move from bench to bakery, what do formulators need to know about processing gluten-free doughs made with your ingredients?
Mr. Casper: Make sure you set expectations around what you can achieve without gluten. You can have higher expectations for cookies than for batter-based and bread applications.
Gluten-free versions will process differently on equipment than standard baked foods. You should expect to work with a new process setup in developing these products. Often, equipment you’ve worked with before won’t do the job with gluten-free that it does with standard formulations.
For one thing, the dough’s degree of hydration will change. Water hydration properties of gluten should not be underestimated. Gluten-free bread dough really falls between a batter and a dough, which we outlined in our AACC handbook, “Gluten-Free Baked Products.”
When extruding gluten-free bread doughs, you will be dealing with a sticker material. Cleanout programs will also have to change.
If you’re producing cookies, you can do it on a standard processing line without too much trouble. The same can be said of batter-based items. But for breads, the dough is very different on a rheological basis from standard doughs.
We have a gluten-free cookie mix, to which you add water and shortening only, that can be run through a standard wire-cut machine. And there are similar cake and muffins mixes. But for gluten-free bread, because gluten is the structuring agent in standard products, the process will be much different. You’re looking at a more batter-like mixture, and typically, it will be extruded rather than divided.
Mixing gluten-free doughs can be simple: just hydrate and mix to ensure a uniform material. But what ends up happening is, because of the rate of hydration of the various starches, flours and hydrocolloids, you have limited working time. These doughs may stiffen over time, and the bubbles are not as stable as when gluten is present. You’ll see uneven air pockets, created during depositing. Another problem is collapse during proofing or baking.