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Chapter 4. Nutritive Aspects of Food Constituents. FOOD SUPPLIES:. Energy for all functions Building blocks for growth & maintenance. A Food Scientist Must Consider:. What nutrients do foods contain and what do we need?

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Chapter 4 l.jpg

Chapter 4

Nutritive Aspects of Food Constituents


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FOOD SUPPLIES:

  • Energy for all functions

  • Building blocks for growth & maintenance


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A Food ScientistMust Consider:

  • What nutrients do foods contain and what do we need?

  • What is the stability of these nutrients and how does food processing affect stability?


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Food as Fuel

The major sources of energy are:

  • Carbohydrates

  • Fats

  • Proteins


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CALORIE

  • Amount of energy required to raise the temperature of one gram of water by 1oC

    KILOCALORIE

  • Unit used to express the energy value of foods

  • Equal to 1000 Calories


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Carbohydrates

Fats

Proteins

4 kcal/g

9 kcal/g

4 kcal/g

ENERGY VALUETO HUMANS:


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ENERGY COSTS

  • Cheapest - Carbohydrates

  • Intermediate - Fats

  • Most Expensive - Proteins


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CARBOHYDRATES

  • Provide energy

  • Spare proteins

  • Help burn fats

  • Provide fiber


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PROTEINS

  • Provide essential amino acids

  • Can be used as energy

  • A complete protein contains all essential amino acids

  • Red meat, poultry, fish, milk & eggs are complete proteins

  • Vegetable sources are usually not complete


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FATS

  • Supply energy

  • Supply polyunsaturated fatty acids

  • One essential fatty acid = linoleic acid

  • Supply vitamins A,D,E & K

  • Insulate body from rapid temperature change


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Energy

Carbohydrates

Fats

Glucose

Fats

Proteins

Proteins

Stored or

Utilized

as

Consumed

as



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VITAMIN A

  • Naturally occurs only in animals

  • Plants contain the precursor,

    B-carotene

  • Deficiency leads to blindness, abnormal bones, and membrane diseases of the nose, throat & eyes

  • Sources: liver, fish oils, dairy foods w/ fat, carrots, squash, sweet potatoes, spinach


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VITAMIN D

  • Formed in skin by conversion of cholesterol and other sterols by UV radiation

  • Increases absorption of Ca & P in intestine

  • Deficiency results in bone defects (rickets)

  • Most foods are low in Vitamin D

  • Milk is fortified


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VITAMIN E

  • Essential, but specific role unknown

  • May serve primarily as an antioxidant

  • Aids in Fe absorption

  • Stabilizes biological membranes

  • Sources: vegetable oils

  • Deficiencies are rare


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VITAMIN K

  • Essential for blood clotting

  • Sources: leafy vegetables

  • Bacteria in intestine synthesize K


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VITAMIN C

  • AKA Ascorbic Acid

  • deficiency causes fragile capillary walls, gum bleeding, loose teeth, bone joint disease

  • Easily destroyed by high temperatures

  • Sources: citrus fruit, tomatoes, green vegetables, potatoes due to high consumption rate


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VITAMIN B Complex Group

  • Thiamin (B1)

  • Riboflavin (B2)

  • Niacin (Nicotinic Acid)

  • B6

  • Pantothenic Acid

  • B12

  • Folacin

  • Biotin

  • Choline


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Thiamin (B1)

  • First of B vitamins to be discovered

  • Causes the disease known as “beriberi”

  • Necessary to utilize carbohydrates for energy

  • Sources: wheat germ, whole cereals w/ bran, liver, pork, egg yolk

  • Stable to heat in acid foods, but not in alkaline foods


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RIBOFLAVIN (B2)

  • Is the yellowish pigment in skim milk

  • Essential for oxidative cell processes

  • Deficiency results in skin disorders, cracking

  • Resistant to heat, but sensitive to light

  • Paper cartons are better for milk than clear plastic or glass


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NIACIN

  • Deficiency causes skin and mucous membrane disorders

  • Necessary for the respiration and oxidation of glucose

  • Sources: meat, fish, poultry, peanuts, legumes, whole grain cereals

  • Stable to heat, light and oxidation, but will leach from foods during processing


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VITAMIN B6

  • AKA pyridoxine

  • Required for normal metabolism

  • Deficiency symptoms not well defined

  • Source: meat, liver, green vegetables, whole grain cereals


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PANTOTHENIC ACID

  • Deficiency symptoms not well defined

  • Available from a wide source of foods


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VITAMIN B12

  • Required for RNA, DNA, fat and carbohydrate metabolism

  • Helps prevent anemias

  • Contains cobalt in its structure

  • Sources: liver, meats, seafoods

  • Not present in vegetables


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FOLACIN

  • Helps prevent anemias

  • Involved in synthesis of nucleic acids

  • Sources: animal and plant tissues


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BIOTIN

  • Active in metabolism of fatty acids and amino acids

  • Seldom in short supply

  • Synthesized by intestinal microbes


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CHOLINE

  • Component of cell membranes

  • Present in brain tissue

  • Involved in nerve impulse transmission

  • Seldom in short supply

  • Synthesized by intestinal microbes



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Ca

P

Mg

Fe

Cu

Co

Zn

Na

Cl

K

I

Fl

MINERALS

Plus Others


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FIBER

  • Maintains intestinal health

  • Lowers plasma cholesterol

  • Reduces incidence of colon cancer

  • Lowers insulin requirements of diabetics

  • Sources: cereal grains, fruits, vegetables


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WATER

  • 60% of human body is water

  • Is the primary solvent of biological systems

  • Removes wastes from body

  • Cools the body through evaporation

  • We drink 400 liters per year

  • Obtain 400 liters per year from food items