Classifications

1. Simple Carbohydrates

A. Monosaccharides – one sugar, consists of a single ring

1) Glucose (aka: dextrose) C₆H₁₂O₆

Simple single sugar known for its metabolic role as blood sugar
Found in every disaccharide and polysaccharide

2) Fructose (aka: fruit sugar / levulose) C₆H₁₂O₆

Simple sugar found mostly in fruit, honey, and saps
Same chemical formula as glucose, different structure
Sweetest natural sugar

3) Galactose C₆H₁₂O₆

Combines with glucose to form lactose
Rarely found outside of lactose

B. Disaccharides – two monosaccharides

Occurs though condensation (removal of water from two monosaccharides combining)
Breaks down into monosaccharides through hydrolysis (addition of water) during digestion

1) Maltose (malt sugar)

Two glucose units
Produced during starch digestion

2) Sucrose (table sugar)

One glucose unit and one fructose unit
Occurs in fruit, vegetables, and grains

3) Lactose (milk sugar)

One glucose unit and one galactose unit

2. Complex Carbohydrates –

Polysaccharides (many sugars): many glucose units along with a few other monosaccharides

A. Glycogen – stored glucose

Not a significant food source of carbohydrate (hydrolyzes after slaughter)
Polysaccharide composed of glucose
Created in liver, stored in liver and muscle

B. Starches – plant polysaccharides composed of glucose

Long, branched and unbranched chains of glucose molecules linked together
Found in grains (wheat, rice), legumes, and tubers (potatoes, yams, cassava)

C. Fiber – non-starch polysaccharides

Not digested by human digestive enzymes
Some digestion takes place in GI tract

Soluble vs Insoluble
Soluble – delays GI transit, delays glucose absorption, lowers blood cholesterol
- fruit (apples, citrus), oats, barley, legumes
Insoluble – Speeds GI Transit, increase fecal weight, slows starch hydrolysis, delays glucose absorption
 - wheat bran, corn bran, whole grains, cereals, vegetable

Types of Fiber

1. Cellulose – insoluble fiber

Primary constituent of plant cell walls
Many glucose molecules linked in long chains
Found in all fruits, vegetables, legumes
Resists digestion

2. Hemicelluloses – soluble and insoluble fiber

Primary constituent of cereal fibers

3. Pectins – soluble fiber

Found in vegetables and fruits (especially citrus, apples)
Used to thicken jelly, controls texture and consistency (gel effect)

4. Gums and Mucilages – soluble fiber

Gums are used as additives
Mucilages (guar, carrageenan) used as food stabilizers

5. Lignin – nonpolysaccharide fiber – insoluble fiber Found in the woody parts of vegetables: carrots, strawberry seeds
 

Type
Monosaccharide / simple carbohydrate

Other names
Dextrose

Roles
Fuel source
Simple sugar known for its metabolic role as blood sugar
Found in every disaccharide and polysaccharide

Food Sources
Abundant in carbohydrate-rich foods: grains, fruits, vegetables, milk [TOP] 
 

Type
Monosaccharide / simple carbohydrate

Other names
Fruit sugar, Levulose

Roles
Fuel source
Simple sugar found in sucrose (table sugar) and fruit
Sweetest natural sugar

Food Sources
Abundant in fruit, honey, and saps [TOP]
 

Type
Monosaccharide / simple carbohydrate

Roles
Combines with glucose to form lactose

Food Sources
Rarely found outside of lactose [TOP]
 

Maltose

Type
Disaccharide / simple carbohydrate

Other names
Malt sugar

Roles / Structure
Fuel Source
Made up of two glucose molecules

Food Sources
Produced during starch digestion in the body [TOP]
 

Type
Disaccharide / simple carbohydrate

Other names
Table sugar

Roles / Structure
Fuel Source
Made up of one glucose molecule and one fructose molecule

Food Sources
Table sugar, fruit, vegetables, and grains [TOP]
 

Type
Disaccharide / simple carbohydrate

Other names
Milk sugar

Roles / Structure
Fuel Source
Made up of one glucose molecule and one galactose molecule

Food Sources
Milk, dairy products [TOP]
 

Type
Polysaccharide / complex carbohydrate

Roles / Structure
Fuel Source
Stored glucose created by the liver
Liver stores 1/3 of the body's total glycogen and releases as needed
Other 2/3 stored in muscle cells: used mostly in exercise

Food Sources
Found in liver and muscle tissue
Not a significant food source of carbohydrate (hydrolyzes after slaughter)  [TOP]
 

Type
Polysaccharide / complex carbohydrate

Roles / Structure
Fuel Source
Long, branched and unbranched chains of glucose molecules linked together

Food Sources
Found in grains (wheat, rice), legumes, and tubers (potatoes, yams, cassava) [TOP]
 

Type
Polysaccharide / complex carbohydrate

Structure
Long chains of glucose molecules not digested by human enzymes

Roles
Soluble – delays GI transit, delays glucose absorption, lowers blood cholesterol
Insoluble – speeds GI transit, increases fecal weight, slows starch hydrolysis, delays glucose absorption
 

Sources of Fiber

1. Cellulose – insoluble fiber

Primary constituent of plant cell walls
Many glucose molecules linked in long chains
Found in all fruits, vegetables, legumes
Resists digestion

2. Hemicelluloses – soluble and insoluble fiber

Primary constituent of cereal fibers

3. Pectins – soluble fiber

Found in vegetables and fruits (especially citrus, apples)
Used to thicken jelly, controls texture and consistency (gel effect)

4. Gums and Mucilages – soluble fiber

Gums are used as additives
Mucilages (guar, carrageenan) used as food stabilizers

5. Lignin – nonpolysaccharide fiber – insoluble fiber Found in the woody parts of vegetables: carrots, strawberry seeds [TOP]