Transcript File carbohydrates chapter 12

-polyhydroxy aldehydes or ketones
-photosynthesis vs. cellular respiration equation
-1% of human weight are Carbs but up to 75% plants
-animals eat carbs, plants make them
Photosynthesis vs. Respiration
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• Carbohydrates
– Carbohydrates are a large group of compounds that are
generally called sugars, starches, and cellulose (all of
which are sugars or polymers of sugars)
– Generally sugars are a storage source of energy.
• By breaking sugars down into carbon dioxide and water, living
organisms can release the energy that is locked up in them to
use for energy requirements.
– Glucose is the carbohydrate that animals utilize mostly
for their energy.
Classifications
• A monosaccharide is one that is made up of just one
sugar unit.
• A disaccharide is one that is made up of two sugar
units.
• A polysaccharide is one that is made up of many
sugar units.
• These plants and their flowers
are made up of a mixture of
carbohydrates that were
manufactured from carbon
dioxide and water, with the
energy of sunlight. The simplest
of the carbohydrates are the
monosaccharides, simple sugars
(fruit sugar) that the plant
synthesizes. Food is stored as
starches, which are
polysaccharides made from the
simpler monosaccharides. The
plant structure is held upright by
fibers of cellulose, another form
of a polysaccharide.
Glucose:
-Blood sugar, dextrose, our energy source
-all our carbs convert to this
-major constituent of
disaccharides/polysaccharides
-various forms (geometric) of glucose
-aldohexose/polyhydroxy aldehyde
• Glucose (blood sugar) is an aldehyde, and fructose (fruit
sugar) is a ketone. Both have a molecular formula of
C6H12O6
Structure of Glucose
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Glucose Info
• Glucose is by far the most common carbohydrate
and classified as a monosaccharide, an aldose, a
hexose, and is a reducing sugar. It is also known as
dextrose, because it is dextrorotatory (meaning
that as an optical isomer is rotates plane polarized
light to the right and also an origin for the D
designation.
• Glucose is also called blood sugar as it circulates
in the blood at a concentration of 65-110 mg/mL
of blood.
• Glucose is initially synthesized by chlorophyll in
plants using carbon dioxide from the air and
sunlight as an energy source. Glucose is further
converted to starch for storage.
Fructose Structure
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Fructose:
• -fruit sugar
• -ketohexose/polyhydroxy ketone
• -converted to glucose in body
Fructose
• Fructose information
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Structure formula of fructose
• Fructose, or levulose, is the form of sugar found
in fruit and honey. It is a laevorotatory
monosaccharide with the same empirical formula
as glucose but with a different structure. Although
fructose is a hexose (6 carbon atoms), it generally
exists as a 5-membered hemiketal ring (a
furanose).
Fructose Continued…
• All fruit naturally contains a certain amount of
fructose (often together with glucose), and it can
be extracted and concentrated to make an
alternative sugar.
• Fructose is often used in food products designed
for people with diabetes mellitus or who have
problems with hypoglycaemia, because it is
metabolised more slowly (GI 32) than cane sugar
(sucrose) and is sweeter, so it has a smaller effect
on blood-sugar levels. However, some people can
react badly to fructose so it is not an option for
those who need to restrict sucrose intake.
Fructose Continued…
• Fructose is more commonly found together with
glucose and sucrose in honey and fruit juices.
Fructose, along with glucose are the
monosaccharides found in disaccharide, sucrose.
• An older common name for fructose is levulose,
after its levorotatory property of rotating plane
polarized light to the left (in contrast to glucose
which is dextrorotatory).
• Bees gather nectar from flowers which contains
sucrose. They then use an enzyme to hydrolyze or
break apart the sucrose into its component parts of
glucose and fructose.
-lactose
-milk sugar
(galactose + glucose)
-sucrose
-table sugar
(glucose + fructose)
Lactose
What is lactose intolerance?
Lactose intolerance is the inability to digest significant amounts of
lactose, the predominant sugar of milk. This inability results from a
shortage of the enzyme lactase, which is normally produced by the
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cells that line the small intestine. Lactase breaks down milk sugar into
simpler forms that can then be absorbed into the bloodstream. When
there is not enough lactase to digest the amount of lactose consumed,
the results, although not usually dangerous, may be very distressing.
While not all persons deficient in lactase have symptoms, those who do
are considered to be lactose intolerant.
Common symptoms include nausea, cramps, bloating, gas, and
diarrhea, which begin about 30 minutes to 2 hours after eating or
drinking foods containing lactose. The severity of symptoms varies
depending on the amount of lactose each individual can tolerate.
Lactose Continued…
• Some causes of lactose intolerance are well known. For
instance, certain digestive diseases and injuries to the small
intestine can reduce the amount of enzymes produced. In rare
cases, children are born without the ability to produce lactase.
For most people, though, lactase deficiency is a condition that
develops naturally over time. After about the age of 2 years, the
body begins to produce less lactase. However, many people
may not experience symptoms until they are much older.
• Between 30 and 50 million Americans are lactose intolerant.
Certain ethnic and racial populations are more widely affected
than others. As many as 75 percent of all African Americans and
American Indians and 90 percent of Asian Americans are
lactose intolerant. The condition is least common among
persons of northern European descent.
Sucrose
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Sucrose Info
• Sucrose is a disaccharide composed of one
molecule of glucose connected via an α(1-2)
glycosidic bond to one molecule of fructose.
• Production
• Sucrose is a covalently bonded compound.
Sucrose is generally extracted from sugar cane or
sugar beet and then purified and crystallized.
Other (minor) commercial sources are sorghum
and sugar maples.
• Refining process SKIL - Sugar Refining
Sucrose Continued…
• Usage
• Pure sucrose is the most common sweetener in the modern,
industrialized ers of the cat family, will gladly accept a food sweetened
with sucrose, even if they aren't hungry. Processed food and junk food
often have sucrose added.
• [n the Human Digestive System
• Sucrose can be absorbed into the bloodstream through the stomach
walls, which means this disaccharide can offer a fast sugar boost.
• Health effects
• Sucrose has several adverse health effects. The most common is tooth
decay, in which bacteria in the mouth turn sucrose into acid that attacks
tooth enamel. Sucrose has a high calorie content and is also believed to
cause obesity. People with diabetes mellitus need to control their intake
of sucrose. A large amount of sucrose will result in heightend blood
sugar, and over time, can result in high blood pressure
Food and Calories
How many calories do you need?
• The Easy Way
If all of those calculations seem too confusing or tedious, you can
roughly estimate your daily calorie requirements using this simple
formula:
• For sedentary people: Weight x 14 = estimated cal/day
• For moderately active people: Weight x 17 = estimated cal/day
• For active people: Weight x 20 = estimated cal/day
• 3500 calories = 1 lb. Fat storage
-many more times sweeter than natural sugars so
less expensive for manufacturers to use
-societal trend to use lower calories
-have NOT proven to help in weight loss
-diabetes: cannot handle sucrose, so alternative
Saccharine:
• -Sweet 'N Low
• -cancer link in lab animals
• -actually found to decrease blood
sugar so could make person more
hungry
Saccharine Safety Issues
• Safety, particularly as it relates to cancer risk, is on many people's
mind as a result of the saccharine saga, which began in the 1970s. In
1977, the U.S. Food and Drug Administration tried to ban this
sweetener as animal studies showed that it caused cancer of the
bladder, uterus, ovaries, skin, and other organs. But the food industry
intervened, urging Congress to keep it on the market with a warning
label that (until recently) read: "Use of this product may be hazardous
to your health. This product contains saccharin, which has been
determined to cause cancer in laboratory animals."
• In the late 1990s, the Calorie Control Council stated that the main
health concern about saccharin was bladder cancer in male rats -- not
people. They stated that further research has shown that male rats have
a particular predisposition to bladder cancer and as a result the
National Institutes of Health removed saccharin from its hit list of
cancer-causing agents.
Aspartame:
http://www.fastq.com/~dwaz/nutr
swt2.html
• -Nutrasweet,Equal
• -contains phenylalanine
• -PKU genetic disorder people cannot
break this down and leads to toxic
build-up
• -neurological damage on fetuses
Sucralose
• Brand name: Splenda
• produced by chlorinating sucrose
• Animal studies have shown
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40% shrunken thymus gland
enlarged liver/kidney
atrophy of lymph tissue in spleen/thymus
decrease in red blood cell count
aborted pregnancy
decrease in placental weights
Sucralose continued...
• No long-term studies on humans
• 11-27% of sucralose absorbed in humans
• breaks down to 1,6-dichlorofructose…a
chemical that has not been studied
regarding human physiological effects
• no clear-cut proof that it helps in weight
loss
Stevia
• Stevia is also used to aid digestion, lose weight and even stimulate the
appetite. It is also reported that Stevia powder heals external skin sores
while drinking Stevia tea reduces mouth sores and improve oral health.
And if that wasn't enough, Stevia cooks, bakes, sprinkles, and tastes,
amazingly like real sugar, maybe even better
• With all this good news about Stevia, is there a down side? That
depends on whom you ask. To date, the United States' FDA has
not approved it as a "sweetener" although they have approved it
as "dietary supplement". In contrast, Canada, South America,
Japan and China use Stevia extensively as a sweetener in
everything from soft drinks to candy, to desserts. The Coca-Cola
company manufactures Diet Coke in Canada and Japan
sweetened with Stevia and not aspartame/NutraSweet like its
American Diet Coke counterpart.
Stevia continued...
• Why won't the FDA approve Stevia as a sweetener? Citing
preliminary research studies performed in 1985-1987 which
apparently showed some ability of the active ingredients in
Stevia to be "mutagenic", i.e. capable of turning into, Salmonella
bacteria, the FDA ruled that Stevia can only be used as a
"supplement" rather than a food additive. However, further
studies of Stevia cast doubt on those original studies as whether
the results were applicable to human consumption, and
therefore flawed research. Despite the latest research findings
that contradict those earlier research findings on Stevia, the
FDA's original ruling still stands. An ironic ruling, as research
studies had long-since established the cancer-causing
properties of saccharin and the neurological and renal disease
causing properties of aspartame, studies which have been
apparently ignored in light of the fact that both artificial
sweeteners are sanctioned by the FDA for public consumption.
In addition, the ban against calcium and sodium cyclamates
Xylitol
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What is xylitol?
Xylitol is a natural sweetener derived from natural sources. It is also produced in the human body as
a by-product of a normal metabolism. Our xylitol is of the highest quality possible. It is a
pharmaceutical grade, meaning it must be more that 99.95% pure, and is made from non-GMO (nongenetically modified organism) corn fibers. It does not contain any of the corn grain and it is tested to
ensure that no corn allergens, mycotoxins, or corn proteins of any type are in the product.
Top How does xylitol differ from other sweeteners?
Chemically speaking, xylitol is not actually a sugar, but a sugar alcohol. It differs from other
sweeteners such as sorbitol, fructose and glucose because its molecule has five, instead of six, carbon
atoms. Most bacteria and yeast in the mouth are unable to make use of xylitol. It is much sweeter
than sorbitol, for instance. Assessed in terms of calories, xylitol’s sweetening power is the same as
that of sucrose (table sugar), but with 40% fewer calories. Xylitol is important because it may help to
reduce the risk of tooth decay, and everyone interested in healthy teeth should be familiar with its
properties and effects.
Top Where does xylitol occur in nature?
Xylitol occurs in small amounts in natural form, especially in fruit, berries, vegetables and
mushrooms. For example raspberry, strawberry, yellow plum and endive contain xylitol. Xylitol is
also found in human tissues.
Top Is xylitol safe for sugar-controlled diets?
Yes. Classified on labels as a carbohydrate, it has been used in foods since the 1960’s and is approved
in the U.S. as a food additive in unlimited quantity for foods with special dietary purposes and is safe
for use in any sugar-controlled diet.
Top Where was xylitol discovered?
Xylitol was discovered almost simultaneously by German and French chemists in the late 19th
century. In the Soviet Union it has been used for decades as a sweetener for diabetics, and in
Germany in solutions for intravenous feeding. Its dental significance was researched in Finland in the
early 1970’s, when scientists at Turku University showed it had significant dental benefits.
Top Is xylitol safe?
Yes it is. In 1983, JECFA, a joint expert committee of WHO and FAO, confirmed the fact, already
known by scientists that it is a safe sweetener for foods. The FDA also confirmed this fact in 1986
Sorbitol
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Sorbitol, a polyol (sugar alcohol), is a bulk sweetener found in numerous food products.
In addition to providing sweetness, it is an excellent humectant and texturizing agent.
Sorbitol is about 60 percent as sweet as sucrose with one-third fewer calories. It has a
smooth mouthfeel with a sweet, cool and pleasant taste. It is non-cariogenic and may be
useful to people with diabetes. Sorbitol has been safely used in processed foods for
almost half a century. It is also used in other products, such as pharmaceuticals and
cosmetics.
A French chemist first discovered sorbitol in the berries of the mountain ash in 1872. It
occurs naturally in a wide variety of fruits and berries. Today it is commercially
produced by the hydrogenation of glucose and is available in both liquid and crystalline
form.
Sorbitol has been affirmed as GRAS (Generally Recognized As Safe) by the U.S. Food
and Drug Administration and is approved for use by the European Union and numerous
countries around the world, including Australia, Canada and Japan.
In the United States, sorbitol is provided by a number of manufacturers, including
Archer Daniels Midland, Cargill Inc., Roquette America, Inc. and SPI Polyols, Inc
Sorbitol Safety
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Safety
Sorbitol’s safety is supported by numerous studies reported in the scientific literature. In developing
the current U.S. food and drug regulation which affirms sorbitol as GRAS, the safety data were
carefully evaluated by qualified scientists of the Select Committee on GRAS Substances selected by
the Life Sciences Office of the Federation of American Societies for Experimental Biology (FASEB).
In the opinion of the Select Committee, there was no evidence demonstrating a hazard where sorbitol
was used at current levels or at levels that might be expected in the future. The U.S. Food and Drug
Administration’s regulation for sorbitol requires the following label statement for foods whose
reasonably foreseeable consumption may result in the daily ingestion of 50 grams of sorbitol:
“Excess consumption may have a laxative effect.”
The Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food
Additives (JECFA) has reviewed the safety data and concluded that sorbitol is safe. JECFA has
established an acceptable daily intake (ADI) for sorbitol of “not specified,” meaning no limits are
placed on its use. An ADI “not specified” is the safest category in which JECFA can place a food
ingredient. JECFA’s decisions are often adopted by many small countries which do not have their
own agencies to review food additive safety.
The Scientific Committee for Food of the European Union (EU) published a comprehensive
assessment of sweeteners in 1985, concluding that sorbitol is acceptable for use, also without setting
a limit on its use
Mannitol
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Chemistry
Mannitol is a sugar alcohol; that is, it is derived from a sugar by reduction, with a molecular weight
of 182.17 g/mol,[3] and a density of 1.52 g/mL.[4] Other sugar alcohols include xylitol and sorbitol.
Mannitol and sorbitol are isomers, the only difference being the orientation of the hydroxyl group on
carbon 2.[5] Aqueous solutions of mannitol are mildly acidic and sometimes such solutions are
treated to lower the pH. Chemical Abstracts Registry Numbers for mannitol are 123897-58-5, 69-658 (D-Mannitol), 75398-80-0, 85085-15-0, and 87-78-5 (mannitol with unspecified stereochemistry).
D-Mannitol (CAS# 69-65-8) has a solubility of 22g mannitol/ 100mL water (25°C), and a relative
sweetness of 50 (sucrose=100).[3] It melts between 165°-169°C (7.6 torr), and boils at 295°C at 3.5
torr, indicating a greater boiling point at STP conditions.[4]
[edit] Obtaining mannitol
[edit] Industrial synthesis
Mannitol is commonly formed via the hydrogenation of fructose, which is formed from either starch
or sugar. Although starch is cheaper than sucrose, the transformation of starch is much more
complicated. Eventually, it yields a syrup containing about 42% fructose, 52% dextrose, and 6%
maltose. Sucrose is simply hydrolyzed into an invert sugar syrup, which contains about 50% fructose.
In both cases, the syrups are chromatographically purified to contain 90-95% fructose. The fructose
is then hydrogenated over a nickel catalyst into mixture of isomers sorbitol and mannitol. Yield is
typically 50%:50%, although slightly alkaline reaction conditions can slightly increase mannitol
yields.[5]
-glucose units linked together
-Glycogen:
Human storage of glucose in liver and
muscle cells
-Diabetes: "Type 1" cannot produce Insulin
so cannot use glucose, fats used, health
problems results, such as: atherosclerosis;
eye problems, circulation, etc.
What is the Glycemic Index?
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The Glycemic Index is a numerical Index that ranks carbohydrates based on their rate of
glycemic response (i.e. their conversion to glucose within the human body). Glycemic
Index uses a scale of 0 to 100, with higher values given to foods that cause the most
rapid rise in blood sugar. Pure glucose serves as a reference point, and is given a
Glycemic Index (GI) of 100.
Why is the Glycemic Index Important?
Your body performs best when your blood sugar is kept relatively constant. If your
blood sugar drops too low, you become lethargic and/or experience increased hunger.
And if it goes too high, your brain signals your pancreas to secrete more insulin. Insulin
brings your blood sugar back down, but primarily by converting the excess sugar to
stored fat. Also, the greater the rate of increase in your blood sugar, the more chance that
your body will release an excess amount of insulin, and drive your blood sugar back
down too low
– Starch is a storage carbohydrate used by plants.
• When plants photosynthesize the use the energy from
sunlight to convert carbon dioxide and water into
sugars and oxygen.
– Glycogen is a storage carbohydrate used by animals.
– Cellulose is a polysaccharide that is used in plant cell
walls to maintain their structure.
• Starch and cellulose are both polymers of glucose, but
humans cannot digest cellulose. The difference in the
bonding arrangement might seem minor, but enzymes must
fit a molecule very precisely. Thus, enzymes that break
down starch do nothing to cellulose.
Diabetes and Blood Sugar
• Use the below link when in ppt.
presentation mode to learn more about
diabetes and blood sugar
• Link to diabetes and blood sugar video
Glycogen
• Glycogen is the principal storage form of glucose
in animal cells. In humans and other vertebrates,
most glycogen is found in the liver (10% of the
liver mass), giving it a distinctive, "starchy" taste.
Muscles contain a relatively low amount of
glycogen (1% of the muscle mass). In addition,
small amounts of glycogen are found in the
kidneys, and even smaller amounts in certain glial
cells in the brain and white blood cells.
Glycogen Continued…
• Function and regulation of liver glycogen
• As a carbohydrate meal is eaten and digested, blood glucose levels
rise, and the pancreas secretes insulin. Glucose from the portal vein
enters the liver cells (hepatocytes). Insulin acts on the hepatocytes to
stimulate the action of several enzymes, including glycogen synthase.
Glucose molecules are added to the chains of glycogen as long as both
insulin and glucose remain plentiful. In this post-prandial or "fed"
state, the liver takes in more glucose from the blood than it releases.
• After a meal has been digested and glucose levels begin to fall, insulin
secretion is reduced, and glycogen synthesis stops. About 4 hours after
a meal, glycogen begins to be broken down to be converted again to
glucose. Glycogen phosphorylase is the primary enzyme of glycogen
breakdown. For the next 8-12 hours, glucose derived from liver
glycogen will be the primary source of blood glucose to be used by the
rest of the body for fuel.
Glycogen Continued…
• Glucagon is another hormone produced by the pancreas and in many
respects serves as a counter-signal to insulin. When the blood sugar
begins to fall below normal, glucagon is secreted in increasing
amounts. It stimulates glycogen breakdown into glucose even when
insulin levels are abnormally high.
• Glycogen in muscle and other cells
• Muscle cell glycogen appears to function as an immediate reserve
source of available glucose for muscle cells. Other cells that contain
small amounts use it locally as well. Muscle cells lack the ability to
pass glucose into the blood, so the glycogen they store internally is
destined for internal use and is not shared with other cells, unlike liver
cells.
Starch: Plant energy storage form. Alpha
linkage of glucose molecules can be broken
down by humans, so we eat starch foods
Cellulose: Most abundant molecule in living
tissue. Plant structural polysaccharide. Humans
cannot break down this Beta linkage so we
cannot access glucose, but good for fiber and
cleaning colon. Animals (herbivores) an insects
(termites) with symbiotic organism can utilize
cellulose. Wood is 50% cellulose and cotton is
95% cellulose.
• Starch is the major storage carbohydrate (polysaccharide)
in higher plants, being the end product of photosynthesis.
Starch is composed of a mixture of two polymers, an
essentially linear polysaccharide -amylose, and a highly
branched polysaccharide - amylopectin. Starch is unique
among carbohydrates because it occurs naturally as discrete
granules (or grains). Starch granules are relatively dense,
insoluble and hydrate only slightly in cold water.
• Amylose - The constituent of starch in which anhydroglucose
units are linked by a-D-1,4 glucosidic bonds to form linear
chains. The level of amylose and its molecular weight vary
between different starch types. Amylose molecules are
typically made from 200-2000 anhydroglucose units.
Aqueous solutions of amylose are very unstable due to
intermolecular attraction and association of neighboring
amylose molecules. This leads to viscosity increase,
retrogradation and, under specific conditions, precipitation
of amylose particles. Amylose forms a helical complex with
iodine giving a characteristic blue color.
Starch Stucture
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Cellulose
• Cellulose (C6H10O5)n is a long-chain polymer polysaccharide
carbohydrate, of beta-glucose. It forms the primary structural
component of plants and is not digestible by humans.
• History and Applications
• Cellulose is a common material in plant cell walls and was first noted
as such in 1838. It occurs naturally in almost pure form only in cotton
fibre; in combination with lignin and any hemicellulose, it is found in
all plant material. Cellulose is the most abundant form of living
terrestrial biomass (Crawford, R. L. 1981. Lignin biodegradation and
transformation, John Wiley and Sons, New York.) Cellulose, especially
cotton linters, is used in the manufacture of nitrocellulose, historically
used in smokeless gunpowder.
• Some animals, particularly ruminants and termites, can digest cellulose
with the help of symbiotic micro-organisms - see methanogen.
• Cellulose is processed to make cellophane and rayon.
• Cellulose is also used within the laboratory as a solid-state substrate
Cellulose Structure
Cellulose
• Cellulose is one of many polymers found in
nature. Wood, paper, and cotton all contain
cellulose. Cellulose is an excellent fiber. Wood,
cotton, and hemp rope are all made of fibrous
cellulose. Cellulose is made of repeat units of
the monomer glucose. This is the same glucose
which your body metabolizes in order to live,
but you can't digest it in the form of cellulose.
Because cellulose is built out of a sugar
monomer, it is called a polysaccharide.
Termite Mounds
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