Transcript Chapter 3

Chapter 3
Carbohydrates
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Photosynthesis
 Plants can make their
own carbohydrates from
the carbon dioxide in
the air and water taken
from the soil.
 Photosynthesis
converts energy from
sunlight into energy
stored in carbohydrates,
which the plants uses to
grow and be healthy.
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Categories of Carbohydrate
 Simple carbohydrates
 Natural sugars
 Added (Refined)
sugars
 Complex
carbohydrates
(polysaccharides)
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Starch
Fiber
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Functions of Carbohydrate
 Functions as primary source of body’s energy
 Central nervous system and red blood cells
rely almost exclusively on glucose.
 Glucose is stored in liver and muscles as
glycogen.
 Spares protein from being burned for energy
 Helps body use fat efficiently
 Part of various materials in body, such as
connective tissue, some hormones &
enzymes, and genetic material
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Monosaccharides and Disaccharides
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Relative Sweetness of Sugars and
Artificial Sweeteners
Sweetener
Rating
Sugars
Lactose
20
Glucose
70 – 80
Sucrose
100
High-fructose corn syrup
Fructose
120 – 160
140
Artificial Sweeteners
Aspartame (Nutrasweet, Equal)
Acesulfame-K (Sunette)
Saccharin (Sweet ’N Low)
Sucralose (Splenda)
160–220
200
200 – 700
600
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Neotame
7,000–13,000
Added Sugars
 Added sugars:
 Sugars added to a
food for sweetening or
other purposes, do not
include natural sugars
 Examples: Granulated
white sugar, high
fructose corn syrup
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Sugars on the Nutrition Facts Label
 The number of grams of
“Sugars” includes both
natural and added
sugars.
 To find out if a food
contains added sugar,
look at the ingredient
list.
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Examples of Added Sugars
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White sugar (sucrose)
High-fructose corn syrup or corn syrup
Invert sugar
Brown sugar
Molasses
Honey
Powdered sugar
Raw sugar
Demerara sugar
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Added Sugars and Health
 Dental caries (sugar &
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starch)
Obesity
Diabetes
Heart Disease
Hypoglycemia
Hyperactivity in
Children
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Glycemic Response
 How quickly and how high your blood sugar
rises after eating.
 Eating mainly foods with a low glycemic
response is important for people with
diabetes and seems to decrease the risk of
heart disease, type 2 diabetes, and colon
cancer, as well as enhancing weight
management.
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Glycemic Index
Glucose
Corn flakes
Waffles, French-fried potatoes, jelly beans
Bagel, white bread
White sugar, cantaloupe
Raisins, tortilla chips, cola soda, ice cream, pizza
Rye bread
Orange juice
Fresh orange, peas, carrots
Fresh peach, old-fashioned oatmeal, apple juice
White rice, spaghetti, apple, pear, tomato soup
Skim milk, low-fat yogurt
Kidney beans
Grapefruit
Soybeans
Peanuts
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Lactose Intolerance
 An intolerance to milk and most milk products
due to a deficiency of the enzyme lactase.
 Symptoms often include flatulence and
diarrhea within 30 minutes to 2 hours.
 Especially prevalent among Asian Americans,
Native Americans, African Americans,
Latinos, and other groups.
 Treatment requires a diet limited in lactose.
 Most people can drink small amounts of milk
especially if taken with food.
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Complex Carbohydrate: Starch
 Made of a long chain of glucoses linked
together.
 The glucose chains may be straight
(amylose) or branched (amylopectin).
 Found only in plant foods: grains, legumes,
vegetables, some fruits.
 Most starchy foods are cooked to make them
flavorful and able to be digested.
 Gelatinization – When starches are heated,
they absorb water and swell in size.
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Structures of Starch and Glycogen
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Fibers
 Polysaccharides found in plant foods that the
body can’t digest or absorb.
 Some fiber is digested by bacteria in the large
intestine.
 Two types: soluble or viscous fiber
insoluble or nonviscous fiber
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Food Sources of Fiber
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Soluble fiber
1.
2.
3.
4.
Fruits
Legumes
Oats, barley, and rye
Also seeds and
vegetables
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Insoluble fiber
1.
2.
3.
4.
Wheat bran, brown
rice, whole grains
Vegetables (cabbage,
carrots)
Fruits
Legumes
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Health Effects of Fiber
 Soluble, viscous fiber
 Lowers risk of heart
disease & stroke by:
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Binding bile
 Lowers risk of diabetes
and controls diabetes
by:
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Slowing glucose
absorption
 Also holds moisture in
stools, softening them
 Insoluble, nonviscous
fiber
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Alleviates constipation
and lowers risk of
hemorrhoids and
diverticulosis by:
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Increasing fecal
weight and speeding
fecal passage
through the colon
May help with weight
management
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If you decide to eat more fiber…..
 Do so slowly and
 Drinks lots of fluids
to give time for your intestine to adapt.
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Whole Grains
 Examples:
 Whole wheat
 Whole rye
 Oatmeal
 Whole oats
 Whole hulled barley
 Popcorn
 Brown rice
 Whole grains offer:
 More nutrients
 Phytochemicals
 More fiber
Dietary Guidelines for Americans recommends 3+ servings of
whole grains each day.
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Digestion, Absorption, & Metabolism
of Carbohydrates
 Starch digestion begins in mouth. (enzyme-
salivary amylase)
 Before being absorbed, carbohydrates must
be broken down into monosaccharides.
 Enzymes in small intestine (sucrase, lactase,
maltase, and pancreatic amylase) ensure that
single sugars are absorbed.
 In the liver, fructose and galactose are
converted to glucose or further metabolized
to make glycogen or fat.
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Dietary Reference Intakes
 RDA for carbohydrate – 1 year old +
130 grams daily
(minimal amount – you really need 2x)
 AMDR – 1 year old +
45-65% of kcalories
 AI for total fiber 14 g/1000 kcal
 Men 19 – 50 years old
38 g
 Men over 50 years old
30 g
 Women 19 – 50 years old
 Women over 50 years old
25 g
21 g
 DRIs – added sugars < 25% of total kcalories
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Low-Carb Foods
 To reduce carbohydrates, manufacturers:
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Substitute soy flour, soy protein, or wheat
gluten (all higher in protein) for refined flour
Substitute artificial sweeteners and/or sugar
replacers (also called polyols) for sugars
Add fiber such as wheat bran
Add high-fat ingredients such as nuts to
improve flavor and/or add bulk
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5. Sugar Replacers or Polyols
 A group of
carbohydrates that are
sweet and occur
naturally in plants.
 Examples: sorbitol,
xylitol found in sugarfree gums and candy.
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5. Sugar Replacers or Polyols
 Benefits:
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Don’t provide as many kcalories as sugar –
only about 2 kcal/gram.
Don’t promote tooth decay.
Taste sweet – though not as sweet as sugar.
Add bulk and texture to foods.
Cause smaller increases in blood sugar and
insulin than sugar.
 Side effects
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Sugar Replacers or Polyols
Sugar
Replacer
Kcal/gram
Uses
Description*
Mannitol
1.6
Chewing gum,
powdered foods,
chocolate
coatings
•50 to 70% as sweet as sugar.
Candies,
chewing gum,
baked goods,
frozen desserts
•60% as sweet as sugar. gum,
Sorbitol
2.6
•May causes a laxative effect
when 20 grams or more are
consumed
•Does not absorb moisture so it
works well as a dusting powder
for chewing gum so the gum
doesn’t stick to the wrapper.
baked goods,
•May cause a laxative effect
when 50 frozen desserts grams
or more are consumed.
•Cool, pleasant taste.
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Sugar Replacers or Polyols (cont’d)
Xylitol
Erythritol
Isomalt
2.4
0.2
2.0
Chewing gum,
candy
•As sweet as sugar.
Beverages,
chewing gum,
candy, baked
goods
•Newest polyol.
Candies, toffee,
fudge, wafers
•45 to 60% as sweet as sugar.
•Pleasant taste.
•Very heat stable.
•Much less of a laxative effect than
other polyols.
•Works well with other sweeteners
to improve flavor and body.
•Used to add bulk and sweetness
to foods.
•Very heat stable.
•Works well with other sweeteners
to improve flavor.
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Sugar Replacers or Polyols (cont’d)
Lactitol
Maltitol
2.0
2.1
Chocolate,
candies, cookies
and cakes, frozen
dairy desserts.
•30 to 40% as sweet as sugar.
No-sugar added
ice cream, lowcarb bagels,
candy, chewing
gum, chocolate,
baked goods.
•90% as sweet as sugar.
•Mild sweetness with no aftertaste.
•Used to add bulk and sweetness
to foods.
•Works well with artificial
sweeteners.
•Used to add bulk and sweetness
to foods.
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Sugar Replacers or Polyols (cont’d)
Hydrogenated
Starch
Hydrolysates
3.0
Candy, baked
goods
•25 to 50% as sweet as sugar.
•Used as bulk sweetener in low
calorie foods. Performs other
functions in foods as well.
•Can mask unpleasant off-flavors.
•Blends well with flavors.
•Works well with other sweeteners.
*All sugar replacers have the following characteristics:
• Occur naturally.
• Don’t provide as many kcalories as sugar. The average
kcalories per gram is 2, compared with 4 kcalories/gram from
sugar.
• Don’t promote tooth decay.
• Cause smaller increases in blood glucose and insulin levels
than sugar.
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Nutrition facts and ingredients for
sugar-free chocolate bar
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Artificial Sweeteners
 Approved
 Possibilities
 Saccharin
 Alitame
 Aspartame
 Cyclamate
 Acesulfame-K
 Stevioside
 Sucralose
 Neotame
 Reduced-Kcal
Sweetener
 Tagatose
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