Introduction of Modified Wheat Starch
Modified wheat starch is a significant ingredient that can be found in a variety of different industries. These industries include the food, pharmaceutical, textile, paper, and adhesive industries. Starch is a carbohydrate that can be found in wheat grains. Native starch can be found naturally in wheat grains. However, native starch can have critical defects including low acid and heat resistance, poor freeze-thaw stability, and poor texture uniformity. To ameliorate these defects, starch can be modified via physical, chemical, or enzymatic means.
Modified wheat starch can increase functionality, texture, stability, and processing ability. It can also be used to customize viscosity and shelf life, and has a wide range of applications. These include baked goods, sauces, soups, noodles, cheese, candy, frozen goods, and a variety of industrial applications.
What Is Wheat Starch?
Wheat starch is defined as the part of wheat flour that is a carbohydrate, where the gluten proteins and fiber have been removed. It is also primarily made up of two different polysaccharides, which are:
Amylose can help to create and develop some structure, while amylopectin can help to give starch a viscous and soft texture. These two can also be used to evaluate functionality of a particular wheat starch.
Wheat starch granules can be classified as two types:
- A-Type granules – large
- B-Type granules – small
These classifications can also be used to determine a starch granule’s water absorption, swelling power, and viscosity.
Natural wheat starch has gained popularity due to several benefits:
- Cost-effectiveness
- Readily accessible
- Flavor-neutral
- Thickener
- Biodegradable
Native wheat starch also has its own disadvantages:
- Instability at high temperatures
- Limited acid resistance
- Low freeze-thaw stability
- Syneresis in frozen products
- Degradation in processing
- Decreased shelf stability
Those working in food technologist areas (flour milling, baking, and industrial production) and researchers must understand the proper way to modify wheat starch. The modification of wheat starch can improve various features including water absorption, gel strength, elasticity, clarity, thickening, and resistance to heat and freezing.
This guide contains the necessary information about modified wheat starch and includes analysis of: composition, types, methods of production, benefits, applications in industry, shortcomings, and improvements to starch modification in practice
Why is Wheat Starch Modification a Widespread Practice?
When it comes to manufacturing, processing or quality concerns can often necessitate modification of wheat starch.
The Most Important Reasons for Modification:
Increased Stability to Heat
Native starch cannot withstand the processed boiled state, but modified starch can survive the boiling, baking, sterilizing, and extruding.
Increased Stability to Freeze/Thaw Cycles
Products that are frozen and thawed cannot withstand separation of water and other food products after thawing, and must be modified.
Viscosity Control
Certain viscosity is required in making sauces, soups, and filling in various cream/plastic products.
Texture Control
Modified starch can be tailored to meet the requirements of a specific application, such as firm or elastic cream.
Quality Storage Time Control
Modified starch improves the quality of products for longer storage times.
Control of Water Retention
Water binding capacity is desired in improving softness and freshness in baked goods.
Tolerance for Process Improvements
Under several particular conditions, modified starch shows improvement over unmodified starch. These include high sheer mixing, acidic environments, high pressure, and repeated heating. Modified starch retains a clear advantage over unmodified starch under these conditions.
Composition of Wheat Starch
Before stating the role of the composition of wheat starch, it is important to understand what makes up wheat starch.
Amylose
Amylose consists of a branched glucose polymer, and possesses the following characteristics:
- It forms a gel.
- It is firm.
- It retrogrades.
- It is not easily soluble.
- It can form a film.
Amylopectin
Amylopectin possesses the following characteristics:
- Branched polymers.
- It provides viscosity.
- It improves swelling.
- It gives a soft texture.
- It is stable in the absence of water.
Typical wheat starch contains:
- 25%—28% amylose.
- 72%—75% amylopectin.
Modification of starch alters the interaction of these two polymers of starch.
Classification of Modified Wheat Starch
Physical Modification
Modification of starch using heat and water (HMT)
Heat and moisture treatment modification of starch refers to a modification of starch caused by heating starch containing a small amount of water to a temperature below the boiling point of water, and thus below the point of complete gelatinization. This process alters the internal structure of starch and thus improves the functional properties of starch.
Processing Steps:
- Moisten the wheat starch.
- Allow the moisture to equilibrate.
- Heat the starch to a temperature under the boiling point.
- Cool the starch slowly.
- Dry and mill the starch.
HMT causes the following structural changes:
- Amylose and amylopectin rearrangement.
- More hydrogen bonding.
- Swelling of starch granules is easily controlled.
- Stable crystalline structure.
Modification of starch by HMT has a number of functional improvements, including:
- Increased heat stability of starch.
- Increased resistance of starch to shear.
- Starch has a higher gelatinization temperature.
- Swelling of starch is controllably reduced.
- Starch has improved stability to freeze and thaw.
- Starch has increased formation of resistant starch.
This type of wheat starch is used for the manufacture of:
- Products of baking.
- Products of noodles.
- Products of functional foods.
- Snacks.
- Extruded products.
Chemical Modification
This method can include the following:
- Cross-linking
- Acetylation
- Oxidation
- Acid modification
- Etherification
Advantages:
- Good stability
- Excellent control of properties
- Limitations
- Regulatory restrictions
- Requires controlled processing
- Some consumers avoid chemically modified ingredients
Enzymatic Modification
These enzymes can include the following:
Amylase
Breaking down starch depends on a certain family of enzymes called Amylases, which catalyze the hydrolysis of the starch molecule into smaller sugars and dextrins. During wheat starch modification, amylase hydrolyzes the chains of amylose and amylopectin. This lowers the viscosity and increases the ease of digestion of the starch. Amylases have an extensive application in the baking, brewing, and food processing industries. By supplying sugars, amylase increases yeast fermentation and hence improves the volume and texture of the bread. The texture and shelf-life of baked products are also improved. Different types of amylase, alpha and beta for example, act at different stages of the breakdown of starch and hence provide controlled modification of starch during processing.
Pullulanase
Pullulanase is a debranching enzyme that hydrolyzes the alpha-1,6 glycosidic bonds in the amylopectin molecule. Branched starch structures can be modified to more linear chains and enhanced functionality and digestibility of starch. Pullulanase is, therefore, widely used in the resistant starch and glucose syrup industries and in the starch processing industries. In the modified wheat starch industry, Pullulanase improves the formation of gels and modifies the texture and behavior of crystallization. Pullulanase also has the ability to produce low-digestible starches which support gut health and give a lower glycemic response. Pullulanase works in synergy with amylases to achieve precise and controlled modification of starch.
Glucoamylase
Glucoamylase has the ability to hydrolyze both alpha-1,4 and alpha-1,6 linkages in starch whether they be internal or terminal, fully breaking starch down into glucose. Glucoamylase acts on starch from the end of the chains. Glucoamylase has a variety of industrial uses. Within the modification of starches derived from wheat, glucoamylase has applications in the manufacture of glucose syrups, in the liquor industry as a fermentation aid, in brewing, and the processed food industry.
Glucoamylase enhances efficiency of starch conversion and adds a degree of sweetness to the products it is used in. Glucoamylase aids fermentation by providing the necessary nutrients (in this case, simple sugars) for the growth of the fermenting organisms. Glucoamylase is a valuable enzyme for the hydrolysis of starch in industry as it has the ability to produce elevated concentrations of glucose.
Benefits
- The use of enzymes improve digestibility.
- This method of modification is controllable.
- The use of enzymes require mild processing.
Reasons for Using Modified Wheat Starch
Higher Heat Resistance
Using standard wheat starch as a food thickener presents challenges due to its inability to tolerate high-processing temperatures. Wheat starch disintegrates during common food processing steps such as baking, cooking, extrusion, and sterilization. A major concern is the loss of the viscosity and textural quality of the food product. To counter the concerns of wheat starch disintegrating with the loss of textural quality, modified starch can endure the same high processing temperatures, and can continue to thicken the food. High temperature food processing is commonplace in the canning industry and many sectors of industrial food processing and bakery goods. In all of these applications, modified starch is likely to provide predictable value and functionality.
Better Freeze-Thaw Stability
With frozen food, starch can undergo a phenomenon called ‘syneresis’. During the freeze-thaw cycle, the starch can lose its ability to hold onto the freeze-bound water, causing food products to have a separated and undesirable texture. Using modified wheat starch improves freeze-thaw stability of the food product, as it can bind water in a gel structure. Such modified wheat starch can also be used for frozen bakery goods, frozen meals, and ice creams.
Stability of Viscosity
Different levels of thickness in food products can be created with different types of starch. However, standard wheat starch can create unpredictable results when processing. Modified wheat starch, on the other hand, can yield the desired thickness and can be used to improve the flow behavior of food products such as gravies, sauces, fillings, creams, and soups. Modified wheat starch can be used to yield smoother food products and can ensure the stabilized product viscosity upon cooling, heating, and even during the prolonged storage of the food product, whether it is produced on a small scale or on an industrial scale.
Improve Texture
Texture is a fundamental quality criterion in food products. Native starch may give weak, sticky, or unstable texture. Modified wheat starch is designed to produce textures of smooth, creamy, elastic, firm, or gelling structures. The ability to develop a wide range of textures makes it particularly useful in bakery, dairy, confectionery, and noodle industries. It enhances the quality of product by its sensory attributes and structural stability thus improving the mouthfeel of the product.
Increase Shelf Life
In the course of storage, starch-based products may experience retrogradation, lose moisture, and develop hard texture. Modified wheat starch slows these degradation processes, thereby maintaining the sustenance of the product. It helps reduce staleness of bakery products and preserves the quality of processed foods. Therefore, texture, flavor, and appearance, which are vital for commercial distribution and export markets, are preserved after prolonging shelf life.
Improve Water Retention
Water retention is critical in maintaining the softness and freshness of food products. Native starch may irreversibly lose moisture and lead to hardness. On the other hand, modified wheat starch has an improved water-binding capacity and retains moisture within the food matrix. This is significantly noticeable in bakery products such as bread, cakes, and pastries. Softness and freshness of these products are critical in determining consumer acceptance and overall product quality.
Improve Process Tolerance
Food processing is a challenging environment for ingredients due to high shear mixing, low and high pH, high pressure, and thermal cycling. Under these conditions, native starch may become completely unstable. On the other hand, modified wheat starch is designed to process these constraints and retain functionalities. It preserves viscosity and texture, and maintains its stability during rigorous processing operations. This makes it ideal for large volume food manufacturing that requires complex processing.
Health Benefits of Modified Wheat Starch
Aside from the functionality and processing advantages of modified wheat starch, its increasing use in the food industry may be due to its health benefits. While it is generally used as a technical ingredient, different kinds of modified wheat starch may improve the digestibility of food, glycemic response, gut health, and potentially the overall dietary system. However, the health benefits may vary depending on the modification of the starch, the final degree of the processing, and the end structure.
Better Digestibility and Energy Release
Improved digestibility and a better-controlled rate of digestion is one of the most recognized health benefits of modified wheat starch. In comparison to native starch, modified starch is better digested by humans. This preferable gut digestion of starch translates to better energy availability to the body. For some people, the rapid digestibility of starch by the gut may be beneficial, for example, people with high energetic requirements, such as athletes, or people with high metabolism. The proper use of modified starch in a food formulation may serve as a better source of carbohydrates and may improve gut comfort.
Formation of Resistant Starch for Gut Health
Heat-moisture treatment and retrogradation foster the formation of resistant starch. Resistant starch reaches the large intestine undigested, where it behaves like dietary fiber. It is fermented by gut bacteria and produces short-chain fatty acids, butyrate being one of them. These compounds help reduce inflammation and improve gut barrier function. They also promote the health of the colon and the protection of the epithelial layer lining the colon. The regular consumption of resistant starch helps maintain a healthy gut microbiome and enhances digestive health.
Lower Glycemic Response and Blood Sugar Control
The structure of modified wheat starch has been shown to lower the glycemic index of food, thus allowing slow-digesting starches to control blood sugar levels, eliminating hyperglycemic episodes, especially in individuals prone to diabetes and insulin resistance. Foods fortified with modified starch of higher resistant starch and slower digestibility, when introduced into a balanced diet, can enhance the control of blood sugar levels and improve metabolic health.
Improved Satiety and Weight Management Support
Modified wheat starch, especially resistant starch, has been shown to enhance satiety immediately after consumption and help maintain that feeling of fullness for a longer duration, thus reducing calorie intake and helping achieve weight loss goals. The fermentation of resistant starch in the gut impacts hormones that control appetite and satiety and helps reduce the urge to snack frequently.
Improved Digestive Comfort and Lower Gut Stress
Some modified starches are easier on the digestive system than the highly processed or quickly digested ones. When used correctly, they can alleviate digestive pressure, reduce bloating, and relieve irregular bowel movements. Resistant starches, which are digested at a slower rate and behave similarly to fiber, help regulate the function of the gastrointestinal tract. In functional foods, modified wheat starch can be used to improve tolerance of digestion, particularly in foods created with consumers who have digestive tract sensitivity in mind or with specialized diets.
Promote Healthy Gut Microbiota
A healthy gut microbiome is essential to maintaining a healthy immune and metabolic system and controlling inflammation. Resistant starch from modified wheat starch acts as a prebiotic and is utilized by some healthy gut bacteria, including Bifidobacteria and Lactobacilli, to maintain a balanced gut ecosystem and form healthy metabolites. A healthy gut microbiota not only promotes healthy digestion but also a healthy immune system and protects the body against unhealthy metabolic changes.
Reduced Fat Absorption in Some Formulations
Some of the modified starches are capable of changing the structure, and indirectly, the digestion and absorption of fats in the digestive tract. Some of the modified starches, by increasing the bulk of food and/or forming a gel, slow digestion and, as a result, decrease the absorption of fats in foods. This positively supports lipid metabolism and promotes heart health in the context of balanced dietary formulations. However, the effect is very formulation dependent; it depends on the type of modification and the level of modification.
Better Nutritional Stability in Processed Foods
Modified wheat starch helps protect nutritional values in processed foods during cooking, freezing, and storage. It reduces moisture loss which helps maintain the desired nutritional value of the food. By adding moisture and promoting integrity of the product, it keeps nutrients such as vitamins and minerals evenly distributed and helps improve their availability.
Is Modified Wheat Starch safe to eat?
Yes, modified wheat starch that has been approved for food use is safe to consume. Globally, food safety authorities have approved its use, and its benefits are evident in many food products. Health risks associated with its use have not been documented.
What does Modified Wheat Starch mean?
The term modified wheat starch implies that wheat starch has undergone physical/enzymatic or chemical treatments to enhance its functional properties such as stability, texture, viscosity, and its performance within food and industrial applications.
Will Modified Wheat Starch raise blood sugar?
Even with its use in processed foods, modified wheat starch is still a carbohydrate and has the potential to raise blood sugar. It is important to note, though, that the modification of the starch plays a key role in how it will impact blood sugar. Some modified starches slow digestion, and as the blood sugar response is associated with the digestion of the starch, this will result in a lower blood sugar response. Still, there are some modified starches that will still cause blood sugar elevations comparable to regular starches. Wheat starch that is resistant will enhance blood sugar responses compared to native wheat starch, but will provide a lower blood sugar response and lower glucose spikes.