As the predominant component of wheat flour, starch is mostly added to baked foods under this guise.
It’s seldom given the same respect that gluten receives for its performance nor the recognition that fiber gets for improving nutrition profiles. However, without starch most baked foods would not exist.
Plants produce starch, a semi-crystalline polymer, during photosynthesis. Fiber, either inherently present in flour or as an isolated food ingredient, is mostly composed of the polysaccharide amylose and amylopectin, with the former being a straight-chain polymer and the latter a branched chain. This structural difference influences behavior, namely the ability to absorb and retain water. Because plants vary in their ratio of the two polymers, the flours and starch ingredients from them will perform differently in baked food recipes.
In its rudimentary form, starch granules are insoluble in cold water. When heated, however, the crystalline structure of the amylose and amylopectin molecules is lost, and the granules begin to swell. Viscosity of the solution increases as the granules absorb more water and gelatinize, a process that involves breaking down the intermolecular bonds of amylose and amylopectin and allowing the free hydrogens to bind with water molecules. Over time and with cooling, these bonds weaken, and the linear amylose and linear segments of amylopectin rearrange themselves to be more crystalline, a process also known as retrogradation. When this occurs, water is expelled from the polymer network.
“Over time, baked goods can lose moisture,” said Kelly Belknap, applications scientist, Grain Processing Corp. “Long-term moisture management is especially needed in baked items with a longer shelf life and also frozen products.”
Suppliers may employ chemical or physical processing technologies to improve the solubility, functionality and stability of starches, offering bakers a range of ingredients. Physical processing typically involves pregelatinization of the starch followed by drying. The final starch ingredient is often considered a native starch, and suppliers will classify it as clean label. Chemically processed starches, on the other hand, undergo a structural alteration and are therefore described as modified starches.
It was not long ago that the only way to create high-performing starches was through chemical modification, said Steven Gumeny, regional products manager, Beneo. Suppliers now offer native starches designed to withstand the harshest processing conditions, including low pH, ultra-high temperature and very high shear.
“While modified starches have long served as the workhorses of the starch world, today’s label-conscious consumers are increasingly attracted to simple ingredients like basic starches,” said Shiva Elayedath, senior technical services manager, Cargill. “In response, research teams are identifying new approaches to address customers’ evolving needs.”
For example, Cargill started by looking at the botanical starch sources already available, then studying and quantifying all the attributes of each.
“By gaining greater insight into the structure and unique properties of each of our starches, we learned how to get more from them, especially when we blend two or three together,” he said. “We’re also using basic processing techniques — like controlling moisture and heat — to create more robust solutions that still appear on ingredient statements as label-friendly starches.”
Both chemically and physically processed starches are widely used by commercial bakers to improve product quality, from performance in the mixer and oven through distribution and the shelf life of the finished product. In some instances, select starch ingredients may improve the nutrition profile of a baked food. Some contribute noteworthy levels of fiber, for example, while others allow for a reduction of fat or sugar.
“Consistent texture and elasticity are important attributes when creating baked goods,” said John Mathew, senior principal scientist, ADM. “Consumers want the bite, chew and overall eating experience to be enjoyable and complementary in texture — not too hard, not too soft or chewy — and starch ingredients may assist.”
This article is an excerpt from the April 2019 issue of Baking & Snack. To read the entire feature on starches, click here.