Thickeners are essential food additives that increase the viscosity of liquids, imparting body, consistency, and stability to products ranging from sauces and soups to jams and desserts. Their composition is diverse and determines their function, nutritional value, and suitability for different dietary needs.
The primary components of food thickeners
Thickeners can be broadly classified based on their origin: natural or synthetic. The vast majority of thickeners used in food are large, water-loving molecules called hydrocolloids. These substances have numerous hydrophilic groups that bind with water molecules, forming a mesh-like network that restricts movement and creates a viscous liquid or gel.
Starch-based thickeners
Starches are among the most common and oldest types of thickeners, derived from plants like corn, potatoes, tapioca, and wheat. When heated in a liquid, starch granules swell and burst, releasing complex carbohydrates that create a thick, often opaque, texture.
- Cornstarch: Provides a clear, glossy finish and has twice the thickening power of flour. However, it loses potency in acidic conditions and can become spongy when frozen.
- Wheat Flour: A staple for thickening sauces, gravies, and stews. It is often combined with fat to make a roux, which prevents lumping. Cooking is necessary to eliminate the raw taste.
- Arrowroot and Tapioca: Excellent gluten-free alternatives derived from tropical plants. They create a clear, glossy sauce that tolerates acidic ingredients better than cornstarch.
- Potato Starch: Another gluten-free option with a low gelatinization temperature. It is effective but can lose its thickening ability if boiled for too long.
Gum-based thickeners
These are polysaccharides extracted from plants, algae, or produced by microbial fermentation. They are potent thickeners, often effective at very low concentrations. Most are not digested by the human body and act as soluble fiber.
- Xanthan Gum: A polysaccharide produced by bacterial fermentation, xanthan gum is known for its high viscosity and stability across a wide pH range. It is widely used in commercial dressings, sauces, and gluten-free baking.
- Guar Gum: Sourced from the guar bean, this gum disperses well in both hot and cold water to form highly viscous solutions. It's used in dairy products, sauces, and baked goods.
- Pectin: A natural starch found in the peels and rinds of fruits, especially citrus. It requires sugar and acid to gel effectively and is the key component in jams, jellies, and marmalades.
- Carrageenan: Extracted from red seaweed, carrageenan is used in dairy products like ice cream and chocolate milk. Its ability to interact with milk proteins allows for thickening at low concentrations.
- Agar-Agar: A vegan and vegetarian alternative to gelatin, derived from red algae. It forms a firmer, more heat-resistant gel that sets at room temperature.
Protein-based thickeners
These thickeners are derived from animal sources and are valued for their gelling properties.
- Gelatin: Made from animal collagen, gelatin forms a clear, thermo-reversible gel when cooled. It's widely used in desserts, candies, and meat products.
- Egg Yolks: Used as a traditional thickener in French sauces like hollandaise. They contain proteins that coagulate to create a rich, smooth emulsion when cooked gently.
Synthetic and modified thickeners
Some thickeners are chemically synthesized or modified from natural sources to enhance their functionality, stability, and resistance to factors like temperature or pH.
- Carboxymethyl Cellulose (CMC): A cellulose derivative that is soluble in water and functions as a thickener and stabilizer in a wide range of food products, especially beverages and dressings.
- Modified Starches: Starches that have been chemically altered to improve their stability, functionality, and resistance to industrial stresses like freezing and acidity.
Nutritional impact and health considerations
The nutritional profile of thickeners is important for managing overall diet and health, especially for individuals with specific needs or sensitivities.
Most plant-based gums, like xanthan gum and carrageenan, are largely undigested by the human body and provide minimal to no calories. They are primarily a source of soluble fiber, which can contribute to digestive health and potentially alleviate constipation. However, excessive consumption can lead to side effects such as bloating, gas, and diarrhea, particularly in sensitive individuals.
Starch-based thickeners, in contrast, contribute carbohydrates and calories to a dish. For example, a tablespoon of cornstarch can contain around 30 calories, mostly from carbohydrates. While this is a small amount, it can become significant for people requiring thickened fluids regularly, especially when compared to virtually calorie-free alternatives. This is particularly relevant for patients with dysphagia who may need to monitor their carbohydrate intake, such as those with diabetes or obesity.
Some thickeners also pose specific health risks for certain populations. The U.S. Food and Drug Administration (FDA) has noted an increased risk of necrotizing enterocolitis (NEC) in infants who have used thickeners containing xanthan gum, such as the product SimplyThick. As a result, xanthan gum is not recommended for infants under 12 months or children under 12 with a history of NEC. For this reason, selecting the appropriate thickener for a specific individual's age and health status is crucial, and medical supervision is often required for special-purpose products.
Comparison of common thickeners
| Feature | Cornstarch | Xanthan Gum | Gelatin | Pectin | Carrageenan |
|---|---|---|---|---|---|
| Source | Corn | Bacteria Fermentation | Animal Collagen | Fruit Rinds | Red Algae |
| Primary Composition | Carbohydrate (Starch) | Polysaccharide (Fiber) | Protein | Polysaccharide (Fiber) | Polysaccharide (Fiber) |
| Vegan | Yes | Yes | No | Yes | Yes |
| Thickening Trigger | Heat | Hydration (cold/hot) | Cold | Heat, Sugar, Acid | Heat (with dairy) |
| Clarity | Opaque | Clear | Clear | Opaque/Clear | Clear |
| Nutritional Impact | Adds carbohydrates/calories | Adds fiber, low calories | Adds protein, calories | Adds fiber, low calories | Adds fiber, low calories |
| Acidity Tolerance | Poor (reduced potency) | Excellent | Good | Requires acid to gel | Good |
How thickeners aid specific diets
For individuals with dysphagia, thickeners are critical for modifying fluid viscosity to reduce the risk of aspiration (inhaling food or liquid into the lungs). However, healthcare providers must carefully manage thickened fluid intake, as it can reduce overall fluid consumption and lead to dehydration. Careful consideration of taste, texture, and nutritional content is needed to ensure adequate hydration and calorie intake. Some thickeners, like those based on xanthan gum, provide soluble fiber that can also aid in bowel regularity, which can be a beneficial side effect for some patients.
Considerations for people with dysphagia
- Fluid Preferences: Don't limit beverage choices. Many thickeners can be used with a wide variety of drinks, including juice, milk, and even some carbonated beverages.
- Hydration Monitoring: It's vital to monitor hydration levels to ensure the individual is drinking enough, especially in hot weather or if taking diuretics.
- Individual Assessment: Swallowing difficulties can change over time. Regular reassessment by a speech pathologist is necessary to adjust fluid thickness as needed.
Conclusion
The question of what does thickener contain is answered by a wide range of natural and synthetic compounds, primarily long-chain polymers like polysaccharides and proteins. From familiar kitchen staples like cornstarch to versatile commercial gums like xanthan gum, the choice of thickener affects not only the physical properties of food but also its nutritional profile. While many thickeners, particularly gums, act as dietary fiber, others based on starches contribute carbohydrates and calories. For general use, thickeners are safe and effective, but understanding their specific composition and nutritional impact is crucial for individuals with dietary restrictions or health conditions. Always read ingredient lists and consult with a healthcare professional when using thickeners for medical purposes to ensure safety and proper nutrition.
A note on sustainability
As consumers become more conscious of the environmental impact of food production, the source of thickeners is also gaining importance. Many gums, like xanthan gum and guar gum, are derived from natural, often renewable, resources. Others, like agar-agar, come from sustainable seaweed cultivation. Protein-based thickeners like gelatin have implications for animal-based sourcing. Considering the origin of thickeners can be a part of making more environmentally friendly food choices.
