Starch is widely used in the food industry for various purposes such as thickening, gelling, stabilizing, and as a replacement for expensive ingredients. Starch has been used in foods dating back to ancient times, and different types of starches such as corn starch, tapioca starch, and locust bean gum have been used in different foods such as breads, beer, baking powders, pie fillings, sauces, jellies, puddings, and salad dressings. The use of starch in the food industry has evolved over time, with developments such as the use of fluidity or thin-boiling starches in the 1830s, cross-linking with bifunctional reagents in the late 1940s, and the development of “instant” starches in the 1960s. Additionally, improvements in starch sources such as waxy corn and high-amylose starch have been made.
Functions of Starch in Food Applications
Starch is important in different types of food and its effectiveness depends on understanding how it works in each context. The changes that occur during cooking and storage affect the structure, texture, and appearance of food, and choosing the right starch depends on the desired properties and processing. Starch granules absorb water and swell during cooking, impacting the properties of the starch slurry. Overcooking can result in rubbery gels, while undercooking produces opaque and watery gels. Achieving the optimum degree of swelling can be difficult, and some food applications require cooking until all granules are disrupted to achieve gelling, emulsifying, and mouthfeel enhancement.
Read more: Functions of Starch in Food Applications
Impact of Processing and Storage on Foods Containing Cooked Starch
How processing starch affects its physical properties and distribution in food products? Optimal processing is necessary to achieve the desired texture and stability, while suboptimal processing can lead to undesired outcomes. Factors such as starch concentration, cooking time and temperature, heating and cooling rates, and shear during cooking can all affect the structure and distribution of starch in a food system. The article also discusses the effects of environmental factors and formulation on the properties of starch during storage. Retrogradation is discussed as a process that can alter the appearance, texture, and stability of starch during storage and distribution. The article provides recommendations for achieving maximum viscosity in a starch suspension, including uniform swelling, minimum granular disruption, and good dispersion.
Modified Food Starches
Starch modification improves its appearance, texture, and utility in foods during processing and distribution. Modified starches maintain their fresh appearance and eating properties longer than unmodified starches. They can also be modified to change processing properties and improve performance in various functions, such as forming a film, enhancing mouthfeel, and emulsification.
Read more: Why Starch is Modified?
The most commonly used starches in the US and Europe are corn, tapioca, potato, and wheat starches. In the US, 95% of the starch comes from corn, which represents 3.4% of the total corn crop, excluding what is used to make sweeteners and alcohol. In Europe, about 60% of the starch comes from corn, while potato and wheat each account for about 20%. Other starches like rice, sorghum, arrowroot, and sago are used in some regions. These starches differ in properties such as viscosity, stability, and gel strength, which depend on the percentage of amylose and amylopectin they contain. Starches with only amylopectin (called waxy starches) swell more, have a greater viscosity drop on prolonged cooking, and do not become opaque or gel on cooling. Waxy maize, tapioca, and high-amylose maize starches are unique and more expensive.
Read more: Starch Sources
Starch is used for many functions, like thickening, gelling, and enhancing mouthfeel. When selecting the best starch for a specific application, food product developers consider desired texture, appearance, flavor, labeling, processing, and storage conditions.
Starches like modified waxy maize, potato, and tapioca are preferred for thickening soups, sauces, and pie fillings. Granular starches don’t thicken well at low concentrations, so soluble hydrolyzates are used in thin fluids. Gelling starches like dent corn starch are used in puddings, lemon pie, and cheese products, while tapioca starch gives a softer set. Fluidity corn and potato starches are used for gel formation in high solids candy formulations, and high-amylose corn is used in candies where higher cook temperatures are possible.
Gelling and non-gelling starch blends are used for intermediate properties, like slight cuttability in products such as salad dressings. Fluidity and high-amylose starches are used to make battered and fried foods crisper, as dried gels form brittle food films.
Starch can affect mouthfeel, flavor, and labeling of food products. Different starches have different mouth coating and flavor release properties. Familiarity and regional preferences may also influence starch choice. Processing equipment and formulation also affect starch choice. For example, instant starches are used when cooking equipment is not available, and acidic formulations require more crosslinking. Stabilization may be required for frozen or refrigerated distribution.
Starches are used in various applications such as thickening, gelling, and mouthfeel enhancement. Different starches are preferred depending on the application. Granular starches like modified waxy maize, potato, and tapioca starches are preferred for thickening, while blends of gelling and non-gelling starches are used for intermediate properties. Fluidity and high-amylose starches are used for gel formation in high solids candy formulations.
Processing equipment, heat treatment, and shear affect starch choice. Instant starches are used when cooking equipment is not available, while more crosslinking is required in severe heat treatment or shear. Formulation also affects starch choice, as increased competition for water requires less crosslinked or more stabilized starch. Acidic formulations require more crosslinking. Frozen or refrigerated distribution requires greater monosubstitution for texture and appearance stabilization.
- Native Tapioca Starch in Foods
- Modified Tapioca Starch in Foods
- Pregelatinized Tapioca Starch in Foods
Interactions with Other Ingredients
Factors such as pH, salts, sugars, fats and surfactants, proteins, gums/hydrocolloids, volatiles, and amylolytic enzymes can all affect the behavior of starch in different ways, leading to changes in texture, viscosity, and other properties. It is important to consider these factors when formulating food products that contain starch to achieve the desired outcome.
Resistant starch, which is starch that is not completely digested in the small intestine, has been shown to have similar functions to dietary fiber in the large intestine. This type of starch can provide benefits such as promoting the growth of favorable bacteria and producing short chain fatty acids, which are known to be the preferred respiratory fuel of cells lining the colon. There are four types of resistant starch, which are classified based on their properties, and they can be measured as fiber via different methods. Resistant starch can be added to foods as a cost-effective ingredient with labeling benefits, but it must be able to survive food processing, distribution, and preparation for consumption as an indigestible entity. Different approaches have been used to manufacture resistant starch ingredients for various food applications, and patents describe various methods for creating different types of resistant starch.