4.2 Functional properties of carbohydrates in foods
4 min read•august 7, 2024
Carbohydrates are crucial in shaping food's taste, texture, and appearance. From the of simple to the thickening power of , they play diverse roles in our favorite dishes. These versatile molecules can bind water, form gels, and even help create stable emulsions.
Beyond their structural functions, carbohydrates undergo fascinating transformations during cooking. They crystallize in candies, participate in browning reactions that give bread its crust, and caramelize to create rich flavors. Understanding these properties helps us appreciate the science behind our meals.
Sensory Properties
Sweetness and Flavor Enhancement
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Carbohydrates contribute sweetness to foods with simple sugars (monosaccharides and disaccharides) being the sweetest
Sweetness decreases with increasing molecular weight of the carbohydrate
Sucrose (table sugar) is often used as a reference for sweetness intensity
Fructose is perceived as sweeter than sucrose at the same concentration
Carbohydrates can enhance or modify flavors in foods by interacting with other components (proteins, fats, and flavor compounds)
Bulk, Texture, and Mouthfeel
Carbohydrates provide and texture to foods by influencing their physical structure
Starch granules swell and gelatinize when heated in the presence of water, contributing to the texture of foods (bread, pasta, and sauces)
Cellulose and other insoluble fibers provide a fibrous texture to foods (fruits, vegetables, and whole grains)
Soluble fibers (pectin and gums) can create a smooth or slimy in foods (jams, jellies, and some beverages)
The crystalline structure of sugars affects the texture of foods (granulated sugar vs. powdered sugar)
Functional Properties
Water Binding and Solubility
Carbohydrates can bind water through hydrogen bonding, influencing the water activity and stability of foods
Soluble fibers (pectin, gums, and mucilages) have a high water-binding capacity and can form viscous solutions or gels
Insoluble fibers (cellulose and lignin) have a lower water-binding capacity but can still retain water within their matrix
The of carbohydrates depends on their molecular structure and interactions with water
Monosaccharides and disaccharides are highly soluble in water, while polysaccharides have varying solubilities depending on their structure and degree of branching
Gelation and Thickening
Some carbohydrates can form gels or thicken solutions when heated and cooled
Starch occurs when starch granules are heated in the presence of water, causing them to swell, rupture, and release amylose and amylopectin
The released amylose and amylopectin form a network that traps water, creating a gel or thickened texture (puddings, sauces, and pie fillings)
Pectin forms gels in the presence of sugar and acid, which is the basis for making jams and jellies
Gums and mucilages (xanthan gum, guar gum, and carrageenan) can thicken solutions and stabilize emulsions (salad dressings and ice cream)
Emulsification and Stabilization
Certain carbohydrates can act as emulsifiers or stabilizers in food systems
Gums and mucilages (gum arabic, modified starches, and pectin) can stabilize oil-in-water emulsions by forming a protective layer around oil droplets
This protective layer prevents the coalescence of oil droplets and improves the stability of the emulsion (mayonnaise and salad dressings)
Carbohydrates can also stabilize foams by increasing the of the continuous phase and reducing the surface tension (meringues and whipped cream)
Modified starches can stabilize frozen foods by inhibiting ice crystal growth and reducing syneresis (ice cream and frozen desserts)
Physical Transformations
Crystallization and Recrystallization
Carbohydrates can undergo crystallization, which influences the texture and stability of foods
Sugars (sucrose, glucose, and fructose) can form crystals when a supersaturated solution is cooled or evaporated
The size, shape, and number of crystals depend on the cooling rate, agitation, and presence of impurities
Crystallization is important in the production of confectionery products (rock candy and fondant)
Recrystallization can occur in foods with high sugar content, leading to a grainy or sandy texture (honey and ice cream)
Controlling the crystallization process is crucial for achieving the desired texture and stability in food products
Browning Reactions
Carbohydrates participate in browning reactions, which contribute to the color, flavor, and aroma of foods
Maillard browning occurs when reducing sugars react with amino acids (proteins) in the presence of heat, producing brown pigments (melanoidins) and complex flavors
Maillard browning is responsible for the appealing color and flavor of many foods (bread crust, roasted coffee, and grilled meats)
is a non-enzymatic browning reaction that occurs when sugars are heated to high temperatures, resulting in the formation of brown pigments and characteristic flavors
Caramelization is important in the production of caramel sauces, candies, and some baked goods
Enzymatic browning occurs when enzymes (polyphenol oxidases) catalyze the oxidation of phenolic compounds in the presence of oxygen, leading to the formation of brown pigments
Enzymatic browning is a concern in fresh-cut fruits and vegetables (apples, potatoes, and avocados) and can be prevented by acidification, heating, or the use of antioxidants