Constituents of Foods

1
Chapter 3

• Constituents of Foods

2
Constituents of Foods(all edible biochemicals)

• Primary
• Carbohydrates
• Proteins
• Fats

• Secondary
• Vitamins
• Enzymes
• Pigments
• Flavors

Plus Water
3
Types of Carbohydrates

• Sugars
• Starches
• Cellulose
• Pectins
• Gums

4
Simple Carbohydrates Sugars

• Monosaccharides
• Glucose
• Mannose
• Galactose
• Disaccharides
• Sucrose (glucosefructose)
• Maltose (glucoseglucose)
• Lactose (glucosegalactose)

5
Monosaccharides
6
Disaccharide
7
Complex Carbohydrates

• Polysaccharides many simple sugars connected
  together
• Examples starch, cellulose

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Starch
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Properties of Sugars

• Are sweet
• Soluble in water
• Form crystals when dehydrated
• Supply energy when consumed
• Readily fermented
• Preservative in high concentration
• Darken upon heating (caramelize)
• Give body mouth feel to solutions

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Properties of Starches

• Are not sweet
• Limited in water solubility
• Form pastes in hot water
• Energy storage in plant tissues
• Supply energy when consumed

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Cellulose, Pectin, Gums

• Structural components of plants
• Low digestibility by humans
• Contribute to toughness, viscosity, consistency

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Proteins

• Long chain linkage of amino acids
• In skin, nails, hair, muscle of animals
• In enzymes, hormones, blood milk
• Made up of C, H, O, N (sometimes S)
• Over 20 amino acids, 8 are essential

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Amino Acid Structure
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Fats and Oils

• Serves as an energy storage material in the
  originating organism
• An energy source when consumed
• High calorie compounds
• Associated with vitamins A, D, E, K
  (fat-soluble vitamins)

15
Fat Molecule

• Composed of a molecule of glycerol and three
  fatty acids to form a triglyceride.

O
H2C-OH HOC-CH2(n)-CH3
O
HC-OH HOC-CH2(n)-CH3
O
H2C-OH HOC-CH2(n)-CH3
Glycerol
Fatty Acids
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Condensation Reaction
O
H2C-OH HOC-CH2(n)-CH3
O
HC-OH HOC-CH2(n)-CH3
O
H2C-OH HOC-CH2(n)-CH3
Glycerol
Fatty Acids
H2O
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O
H2C-O-C-CH2(n)-CH3
O
HC-O-C-CH2(n)-CH3
O
H2C-O-C-CH2(n)-CH3
Triglyceride
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Water

• Present in natural foods at 70 or greater
• 90-95 in fruits and vegetables
• Must be present for microorganisms to destroy
  foods
• Affects the texture and consistency of foods