What Is Modified Starch? Functions, Types, and Applications

Introduction

Modified starch is a versatile material in food, paper, pharmaceutical, and construction industries. It is derived from native starch through modification processes. Under different modification methods, it improves performance and exceeds the properties of natural starch, and can be multifunctional. It serves as an important ingredient applied in various sectors.

What Is Starch?

Starch is widely distributed in nature and is a common component in plants, as well as the main form of carbohydrate storage. It is more than an important component of food, but also has renewability and biodegradability. That’s why starch can be used as a key raw material in pharmaceutical and industrial applications.

However, you need to make some native modifications to nature starch to meet specific performance requirements in modern formulations.

Starch Types

In real life, we usually divide types of starch into four categories:

Cereal: Corn, wheat, rice, etc.

Cereal starch has higher industrial availability and a balanced amylose ratio.

Tubers: Sweet potatoes, cassava, potatoes, etc.

Starch from Tubers can provide higher viscosity potential and a smoother texture.

Legume: Faba beans, mung beans, peas, etc.

Legumes contain high protein, which is seldom used in industry.

Others: Plant fruits, pulp, as well as some bacteria and algae.

Industrial Starch Material

For industrial use, raw starch cannot be added to formulations directly. Here are the reasons:

• Native starch is unstable under shear
• Poor freeze-thaw resistance
• Low compatibility with cementitious systems
• Retrogradation issue

And you should know that different plants vary in gelatinization temperature and viscosity behavior. So even though there are so many types of agricultural products containing starch, not all are suitable for large-scale industrial production.

As a raw material for large-scale production of starch, the following conditions must be met:

1. First is high starch content, large yield, and high utilization rate of by-products;
2. Secondly, the raw materials are easy to process, store, and sell;
3. Thirdly, the price is relatively low;
4. The fourth is not to compete with others for food.

Therefore, currently corn is generally more suitable for industrial starch sources, followed by tubers. Although rice and wheat have large yields, they are expensive and are the main staple foods for humans. Beans have high starch content, low yield, and high price.

Starch from different raw materials has different molecular weights. The proportions of amylose and amylopectin are distinct, leading to different physical and chemical properties.

Amylose Structure: from the figure below, you can see that it is a mostly linear molecular structure. It consists of glucose units with α-1,4 bonds. With the form of a straight chain, the molecules can align closely. This structure can offer amylose a stronger internal bonding and improve film-forming ability.

Amylopectin Structure: As shown in the right figure, Amylopectin has a highly branched structure with α-1,4 chains and α-1,6 branch points. This open structure allows water to penetrate more easily. So amylopectin has faster swelling and stronger viscosity development in aqueous systems.

Celotech modified starch products are made of specific starch material with targeted functionalities.

• Prestar®1027 is produced with corn: balanced viscosity & cost efficiency
• Prestar®1105 is produced with cassava: high purity & stable thickening
• Stargel®ST series is produced with potato:  high viscosity, strong water retention

What Is Modified Starch?

On the basis of the inherent properties of starch, in order to improve its performance and expand its application range, physical, chemical, or enzymatic treatments are used to change the natural properties of starch, increase its functionality, or introduce new characteristics, making it more suitable for certain application requirements. This type of product, which undergoes secondary processing and changes its properties, is collectively referred to as modified starch.

Functions of Modified Starch

Natural starch cannot meet or cannot simultaneously meet the requirements of some industrial applications, which is why we need to modify starch. Through modification, starch is no longer limited to its natural properties. Instead, you can design them into functional ingredients to meet specific performance requirements. And modified starch can open up new uses and expand its application scope. You can get benefits from modified starch with the following functions:

1. Rheology Modification

Modified starch can help adjust viscosity and flow behavior in aqueous systems. It can improve workability and ensure smoother application performance under different processing conditions.

2. Water Management

After modification, the industrial starch can enhance water retention and reduce rapid water loss in formulated systems. It can help maintain stable hydration conditions during processing and application.

3. Stabilization Effect

By preventing phase separation and improving uniform dispersion, modified starch can make the system stable.

4. Film Formation Support

With excellent firm-forming performance, it can improve surface integrity and reduce cracking and powdering issues.

5. Workability Improvement

Modified starch can improve the overall handling properties, making mixing, spreading, and application more consistent and user-friendly.

6. Compatibility Enhancement

Modified starch can improve compatibility between different raw materials. It enables multi-component systems to maintain better balance and performance consistency.

Starch Modification Methods

Modification for starch usually contains chemical modification, physical modification, biological modification, and composite modification. Each modification has different methods, and there are more than 2000 varieties and specifications of modified starch nowadays. Let’s talk about the main modification methods below.

1. Physical Modification

Physical modification refers to modifying the starch’s physical properties, including pregelatinization, heat treatment, and extrusion.

This type of starch can be directly dispersed in cold water. And it will show improved hydration and ease of use in formulation systems.

2. Chemical Modification

Chemical modifications involve processes such as etherification, esterification, oxidation, or cross-linking. By modifying the starch with chemical reactions, it can introduce new functional groups into the starch molecule.

This modification method can significantly improve stability and viscosity control. It can also make starch resistant to temperature, shear, and pH variation.

3. Enzymatic Modification

Enzymatic modification uses biological enzymes to partially break down starch molecules in a controlled way.

This biological modification can help adjust molecular weight distribution and improve consistency and processability in specific applications.

4. Composite Modification

Composite modification is to combine two or more modification methods that we have talked about above to achieve balanced performance.

This method is designed for high-demand systems with multiple performance requirements. It can improve stability, solubility, and viscosity control simultaneously.

Functional Derivative Starch

In industrial markets, modified starch is developed into functional derivatives such as starch ether or pregelatinized starch.

These products are designed for specific formulation systems such as construction materials, coatings, adhesives, and paper processing. Celotech has two brand series for your options:

Prestar® series product belongs to pregelatinized Starch, which has undergone physical modification;

Stargel®ST series product belongs to starch ether, which has undergone chemical modification.