Regardless of their category, a carbohydrate has carbon, hydrogen and oxygen in the form of the following saccharose structure:

Why is an understanding of structure important? It is because the molecular components, functional groups, structure and conformation will influence the functional properties of foods. It will influence the way the food behaves under different production, processing and preparation stresses.

If one looks at the following glycosyl structure, it becomes apparent that the characteristics are dependent upon the basic structure:

As noted above, each glycosyl unit has several points of hydrogen bonding. In a glucan there are five oxygens per chain unit that can form hydrogen bonds. Note also the many hydroxyl hydrogens or oxygens which can potentially bond to a water molecule. These hydroxyl groups enhance the "water solubility" of the entire unit. In polysaccharides, the solubility is decreased due to the conformation of the polymer, itself, and the decreased access of these hydrophilic groups.

Just where do we find carbohydrates?

NAME/ CLASSIFICATION	ENDPRODUCTS HYDROLYSIS	BASIC STRUCTURE OF FORMULA	SOURCE, FUNCTION OR CHARACTERISTICS
MONO- SACCHARIDES: HEXOSES
Glucose	glucose		fruits, honey, corn syrup
Fructose	fructose		fruits, honey, corn syrup
Galactose	galactose		does not occur in free form in foods
Mannose	mannose		does not occur in free form in foods
MONO- SACCHARIDES PENTOSES
Ribose	ribose		derived from pentoses of fruits and nucleic acids of meat products & seafood, does not occur in free forms in foods, is an aldose
Xylose	xylose		is an aldose
Arabinose	arabinose		is an aldose

NAME/ CLASSIFICATION	ENDPRODUCTS HYDROLYSIS	BASIC STRUCTURE OF FORMULA	SOURCE, FUNCTION OR CHARACTERISTICS
DISACCHARIDES
sucrose	glucose fructose		beet and cane sugars, molasses, maple syrup, comes in many crystal sizes and grades
lactose	glucose galactose		milk and milk products
maltose	glucose		malt products, low concentrations in plants and processed foods

NAME/ CLASSIFICATION	ENDPRODUCTS HYDROLYSIS	BASIC STRUCTURE OF FORMULA	SOURCE, FUNCTION OR CHARACTERISTICS
POLYSACCHA- RIDES
starch	glucose		branches [amylopectin] contributed viscosity; linear[amylose] contributes gelling when gelatinized; granule is important to viscosity and gel formation
dextrins	glucose		usually considered to be hydrolysis products of incompletely broken down starch fractions
glycogen	glucose	N	meat products and seafood
cellulose	glucose		comprises skeletal structure of plant cell. Indigestible stable cell structural framework of stalks and leaves of vegetables, fruits and coverings of seeds.
hemicellulose	glucose		comprises some of the plant skeletal structure; amorphous heterogeneous substance; pentose and uronic acid predominant
pectic substances	galactose		cell cementing compound; fruits and vegetables; pectin will form gel with appropriate concentration, amount of sugar and pH. Amorphous substances in the matrix of plant skeletal structure; contains minor amounts of neutral monomers such as arabinose, amylose, galactose, mannose
Malin	fructose		matrix
Galactogens	galactose		monomers such as arabinose, xylose, mannose, raffinose
Mannosans	mannose
Raffinose	glucose fructose galactose
Pentosans	pentoses	Basic monomer structure

Although the following listing indicates possible role(s) of carbohydrates, it is not easy to define these in simple systems, let alone complex food systems. For example, in lollipops the sugars, glucose and/or glucose and fructose, will control crystallization. They will also contribute to the structure due to the sugar, sucrose, and serve as a flavor enhancer and sweetener due to all three sugars. In a more complex system such as a pineapple upside down cake, carbohydrates play many roles due to the presence of all categories of carbohydrates. Following is a listing of possible roles:

agar altrose amorphous amylase anhydrous aspartame beet sugar beta-amylase calorie cane sugar caramel carmelization carbohydrate catalyst catalyze clarifier colloidal colloidal dispersion color complex carbohydrates crystalline crystallization crystallize cyclamate dextrins disaccharide enzyme enzymatic reactions ester a special linkage involving an alcohol and an organic acid.

sol a liquid like colloidal system.

synergism an interaction in which the effect of the mixture is greater than the effect of the sum of component parts.

tuber an enlarged underground stem, for example, the potato.

vapor pressure> the pressure produced over the surface of a liquid as a result of a change in some of the molecules from a liquid to a vapor or gaseous state.

vegetable gums polysaccharide substances that are derived from plants, including seaweed and various shrubs or trees, have the ability to hold water, and often act as thickeners, stabilizers, or gelling agents in various food products; for example, algin, carrageenan, and gum arabic.

What are some of the reactions, roles, functions of polysaccharides in foods?

What are the other three elements found in carbohydrates?

In which of the following products does sugar serve as yeast food?

Why is the formula representation for a carbohydrate important?

Complete the following chart using the choices indicated below:

PRIMARY CARBOHYDRATE CLASS	PRIMARY ROLE OR FUNCTION
monosaccharides	sweetness
disaccharides	influence on structural compounds
oligosaccharides	affect colligative properties
polysaccharides	dispersing agent

FOOD ITEM	PRIMARY CARBOHYDRATE CLASS	PRIMARY ROLE OR FUNCTION
cream pudding	.	.
fondant	.	.
sherbet	.	.
dietetic apple jelly	.	.
carrot
gum drop	.	.
sugar cookie	.	.

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Updated: Wednesday, October 24, 2007.