Starch is everywhere, from the food we eat to the products we use daily. But behind this common ingredient lies a surprisingly complex and versatile world. By modifying its structure, starch can be tailored to perform in many different ways, unlocking new possibilities across industries. In this article, we take a closer look at how these modifications work and why they matter.
Starch plays a key role in nature’s energy economy. Comprised of long chains of glucose, starch serves as a stable, but easily accessible, energy source for the plants that make it and the animals that eat it. These long chains of glucose are classified as either amylose, where the glucose are linked to each other in an α configuration, or amylopectin which contains α linkages and α branch points. Although starch has this basic structure, the ratio varies from plant to plant, and as such starch sources play a huge role in its applications, from food to cosmetic sciences. Starch can also be easily modified to change its physicochemical behaviour, widening its applications. Today, we will explore the variety of applications from these modifications, exploring the wide world of starch.
Starch lends itself well to chemical modifications thanks to the presence of many hydroxyl groups found on the glucose units. In chemistry, these groups (made up of an oxygen and a hydrogen) are active sites for all kinds of new functional groups. A common chemical modification is cross-linking, which uses these hydroxyl groups to create extra linkages between the glucoses present in the starch. This often strengthens the starch, making them more tolerant to acids and heats. Cross-linking can widen the applications of the starch, allowing for a more stable use in low pH foods or cosmetic formulas, where the low pH protects against microbial spoilage, for example. Many other types and degree of modifications change starch’s gelatinization temperature, viscosity, cold-water solubility, etc., opening a wide new world of starch applications.
Starch modifying enzymes can also change the chemical structure of starch. This can be by rearranging the linkages between glucoses, which leads to a slower digestible starch, great for a slower release of energy, rather than an energy explosion that is quickly depleted. Besides the improved health effects, these modified linkages can also lead to physical changes that improve the texture and shelf-life of the modified starch, such as keeping baked bread fresh for longer.
And of course, both chemical and enzymatic modifications can be used to modify starch. This can be a bit tricky, if you first modify the starch chemically, the enzyme may no longer be able to modify it. However, having key understandings of how the chemical modifications have changed the starch structure, plus how the enzyme functions, can help maximize our experimental successes. And who knows! Often, experimentation leads to unexpected outcomes, especially when dealing with the various complexities of starch.
Starch may seem to be a relatively simple molecule, but starch science is complex and creative. That’s why we at CarbExplore love what we do: Explore carbohydrates! And that includes the complex world of starch modifications.
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