Transcript Chapter 3 - Fernando Haro

Chapter 3
Carbohydrates
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Learning Objectives
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2.
3.
4.
5.
6.
Identify the functions of carbohydrates
List important monosaccharides and disaccharides
and give examples of foods in which each is found
Identify foods high in natural sugars, added sugars,
and fiber
List the potential health risks of consuming too
much added sugar
Identify food sources of starch and list the uses of
starch in cooking
Distinguish between the two types of dietary fiber
and list examples of food containing each one
Learning Objectives (cont’d)
7.
8.
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12.
Describe the health benefits of a high-fiber diet
Describe how carbohydrates are digested,
absorbed, and metabolized by the body
State the dietary recommendations for
carbohydrates
Identify foods as being made from whole grains or
refined grains
Discuss the nutritional value and use of grains and
legumes on a menu
Recognize alternatives to sugar in foods
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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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 burn fat efficiently
 Part of various materials in body, such as
connective tissue, some hormones &
enzymes, and genetic material
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Functions of Carbohydrate (cont’d)
 Fiber
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Promotes normal functioning of intestinal tract
Lowers blood cholesterol
You need at least 100 – 150 grams of
carbohydrate daily to spare protein and fat
from being burned for fuel and to provide
glucose to the central nervous system and
red blood cells
Categories of Carbohydrate
 Simple carbohydrates
 Natural sugars
 Added (Refined)
sugars
 Complex
carbohydrates
(polysaccharides)
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Starch
Fiber
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Monosaccharides and Disaccharides
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Relative Sweetness of Sugars and
Artificial Sweeteners
Sweetener
Rating
Sugars
Lactose
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Glucose
70 – 80
Sucrose
100
High-fructose corn syrup
Fructose
120 – 160
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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, brown
sugar, high fructose
corn syrup
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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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Foods with Added Sugars in US Diet
 Soft drinks
 Candy
 Tabletop sugars
 Baked goods
 Fruit drinks
 Ice cream
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
 4 grams sugar = 1
teaspoon
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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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Lactose Intolerance
 An intolerance to milk and most milk products
due to a deficiency of the enzyme lactase
 Symptoms often include flatulence &
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:
1. soluble or viscous fiber
2. insoluble or nonviscous fiber
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Food Sources of Fiber
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Soluble fiber
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2.
3.
4.
Beans and peas
Some cereal grains
(barley, oats)
Many fruits (apples,
pears, grapes, citrus)
Many vegetables
(carrots)
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Insoluble fiber
1.
2.
3.
4.
5.
Wheat bran, brown
rice, whole grains
Many vegetables
(cabbage, carrots)
Many fruits
Beans and peas
Seeds
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Health Effects of Fiber
 Soluble, viscous fiber
 Traps carbohydrates to
slow digestion and
absorption of glucose
 Binds to cholesterol in
GI tract
 Reduces risk of
diabetes and heart
disease
 Insoluble, nonviscous fiber
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Increases fecal weight so
that feces travels quickly
through the colon
Provides feeling of
fullness
Helps prevent and treat
constipation,
diverticulosis, and
hemorrhoids
Helpful in weight
management
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Health Effects of Fiber
 Reduces risk of type 2 diabetes and helps
control diabetes
 A diet high in fruits, vegetables, beans, and
grains that contain soluble fiber can lower
blood cholesterol levels and therefore lower
the risk of heart disease
 More research needs to be done on whether
fiber helps prevent colon cancer
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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Nutrition Science Focus:
Regulation of Blood Glucose
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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A Kernel of Wheat
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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Culinary Science
 Gelatinization
 Starchy thickeners
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Flour
Cornstarch
Arrowroot
Potato starch
Rice flour
Artificial Sweeteners
 Approved
 Possibilities
 Saccharin
 Alitame
 Aspartame
 Cyclamate
 Acesulfame-K
 Sucralose
 Reduced-Kcal
 Neotame
Sweetener
 Tagatose
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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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Stevioside
 A naturally sweet extract from the leaves of
the stevia bush found in South America
 Approved as GRAS substance – 2008
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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