Carbohydrates Flashcards
are compounds composed
of carbon, oxygen, andhydrogen arranged as monosaccharides.
Originally called saccharides (a Greek
word, meaning sugars)
Organic compounds abundant in plants
and widespread in nature
Carbohydrates
General formula of carbohydrates
CnH2nOn
The Food and Agriculture Organization
(FAO) and World Health Organization
(WHO) recommend classifying dietary
carbohydrates by their degree of
saccharide units, which is called
Polymerization
The Institute of Medicine’s Dietary Reference Intakes (DRI) Report subdivides carbohydrates
into:
- monosaccharides (one sugar unit)
- disaccharides (2 sugar units)
- oligosaccharides (3 to 10 sugar units)
- polysaccharides (more than 10 sugar
units)
According to digestibility, carbohydrates are
simply grouped into:
- Digestible: sugar, starches, dextrin and glycogen
- Partially digestible: galactogens,
mannosans, inulin and pentosans - Indigestible: cellulose and hemicellulose
are simple sugar units that compromise
the general formula in a single ring. In this case, they form the structure. It is
divided by their arrangements of atoms that may counter the level of sweetness: glucose, fructose, and galactose.
MONOSACCHARIDES
- also known as dextrose or grape sugar or physiologic sugar or blood sugar
- body’s major fuel in all activities and
serves as the simplest sugar to form disaccharides and complex
carbohydrates - most important sugar in human
metabolism
GLUCOSE
principal product of hydrolysis from
starch and cane sugar
Glucose
sweetest natural sugar that is found in fruits, sodas, cereals, and desserts that have been sweetened with high-
fructose corn syrup; end produce of sucrose
FRUCTOSE
changed to glucose in human
metabolism and the action is reversible
(glucose can be converted to galactose
to form lactose in breast milk)
component of some compound lipids called the cerebrosides, which are found in the brain and nerve tissues
GALACTOSE
=five-carbon chains of monosaccharides found in nucleic
acids of meat and seafoods in bound
form
- in the body, they are important
components of nucleic acids and some co-enzymes
PENTOSE (RIBOSE AND RIBULOSE)
are pairs of
monosaccharides linked together.
DISACCHARIDES
Types of disaccharides are
maltose, sucrose, and lactose.
- does not occur free in nature but can be hydrolyzed by amylases from starches of cereal grains
- yields 2
molecules of glucose
-in the intestines, is not readily
fermented by bacteria and this is
beneficial for infant feeding
Maltose
also called table sugar, cane sugar and beet sugar
Sucrose
equal amounts of glucose and fructose are a mixture known as
Sucrose
contributes half of the energy
Glucose + Galactose
Limited fermentation effect in Lactose
Laxative
Excessive fermentation effect in lactose
Diarrhea
linking two
monosaccharides as evident with the
formation of water molecule from OH
group and H atom
Condensation
breaking of the disaccharide
through splitting the water molecule into
OH group and H atom; common in
digestion
Hydrolosis
three important sugar alcohols
(sorbitol, xylitol and mannitol)
general formula(CSH14O6)
also known as sugar alcohols
- group of low-digestible carbohydrates,
derived from the hydrogenation of their sugar or syrup source - do not contribute to tooth decay
Polyols
- made from high maltose corn syrup
- yields 2.1 kcal/g
- poorly absorbed in the intestines
- used more as a food ingredient as
drying ingredient - some individuals experience increased
urination, nausea and vomiting
SUGAR ALCOHOL: Mannitol
- derived from glucose
- absorbed more slowly than other
monosaccharides - has been used to delay the onset of hunger
- excessive consumption causes diarrhea
- yields 2.6 kcal/g
SUGAR ALCOHOL: Sorbitol
- found in fibers of many fruits and
vegetables - has about the same sweetness as sucrose, but yields less calories (2.4 kcal/g)
- excessive consumption can cause flatulence and diarrhea
SUGAR ALCOHOL: XYLITOL
Known as the complex carbohydrates, they are made up of 10 or more
monosaccharides (chains of monosaccharides).
POLYSACCHARIDES
chains of glucose linked together; found in plants such as grains
- world’s most abundant and cheap form
of carbohydrate
STARCH
starch molecules have two components:
- amylose (a straight chain of glucose units)
- amylopectin (a branched chain)
- intermediate products in the hydrolysis of starch
- intermediate product of starch
digestion or is formed from partial hydrolysis of starch - the action of dry heat on starch (as in toasting bread or browning of cake crust in the oven) produces dextrin
DEXTRIN
storage form of carbohydrates in meal as reserved energy; not a common dietary source of carbohydrate
GLYCOGEN (Animal Starch)
- complex carbohydrate that comes from
the family of fructooligosaccharide and acts like soluble fiber - increases the production of
bifidobacteria and helps increase
resistance to infection
Inulin
- also known as neosugar
- complex carbohydrate that act like soluble fiber
FRUCTO-OLIGOSACCHARIDES
Glycogen present in the body
355 grams (1/3kg)
- also called roughage
- indigestible part of the food
- derived from plant sources and contains
polysaccharides such as cellulose,
hemicellulose, pectin, gums, mucilages and lignins
FIBER
provides bulk, acts as a broom in the
digestive tract to prevent constipation,
and recently has been shown to prevent diverticular diseases, reduce incidence of colon cancer, reduce blood cholesterol level and decrease mucosal absorption
fiber
2 classifications of fiber
insoluble
soluble
grams of fiber daily recommended
20-30 grams
recommends a daily intake of 20
to 35 grams dietary fiber comprising 5 to 7
grams of soluble fiber and 15 to 23 grams of insoluble fiber for normal adults
FNRI-DOST
natural gel-forming fibers (alter solubility or enzyme hydrolysis); B-glucans, psyllium, pectin, guar gum, oligosaccharides; ferments in the colon for lowering cholesterol, obesity risks, CVD, DM, colon cancer
Soluble fiber
cellulose, lignin,
hemicellulose; 10-15% fermented for
stool bulks and prevent constipation
Insoluble fiber
- a fiber made of galacturonic acid and other monosaccharides
- because it absorbs water and forms a gel, it is often used in jams and jellies
- sources include citrus fruits, apples, strawberries, and carrots
SOLUBLE FIBER: PECTIN
- contain galactose, mannose and other monosaccharides
- similar to gum in structure
SOLUBLE FIBER: MUCILAGES
- obtained from a seed of a plant known as genus plantago ovata
- composed of 80% dietary fiber and small amounts of protein, fat, vitamins and
minerals
SOLUBLE FIBER: PSYLLIUM
- contain galactose, glucuronic acid and other monosaccharides
- sources are include oats, legumes, guar
and barley
SOLUBLE FIBER: GUMS
- most well known dietary fiber
- a nonstarch carbohydrate polymermade of a
straight chain of glucose molecules linked by beta bonds - found in whole-wheat flour, bran and vegetables
INSOLUBLE FIBER: CELLULOSE
a nonstarch carbohydrate polymer made of
glucose, galactose, xylose and other
monosaccharides
- can be hydrolyzed by dilute acids
- found in bran and whole grains
INSOLUBLE FIBER: HEMICELLULOSE
These are carbohydrates with 3-10
monosaccharides.
Common oligosaccharides are raffinose
and stachyose. Food sources of
oligosaccharides are chicory roots,
Jerusalem artichoke, onion, garlic, legumes, wheat, jicama, and asparagus.
OLIGOSACCHARIDES
- a noncarbohydrate polymer containing
alcohols and acids - a woody fiber found in wheat bran and the seeds of fruits and vegetables
INSOLUBLE FIBER: LIGNIN
FOOD SOURCES OF CARBOHYDRATES
Sugars
Cereal grains
Root crops
Starchy vegetables
Dried legumes
Fruits
Milk
ALTERNATIVE SWEETENERS
Saccharin
Acesulfame K
Sucralose
Aspartame
Neotame
Cyclamates
Stevia
