Food Science 9/30/2025

Atoms

• Basic building blocks of matter. Individual elements

Molecule

• A unit composed of 2 or more atoms, held together by chemical bonds

Compound

• Substance whose molecules consist of unlike atoms

Ionic Bonds

• A metal loses an electron to a non metal atom

• Sodium loses an electron to oxygen or chlorine

  • Oxygen or chlorine are negative

  • Sodium is positive

  • Sodium hangs around the atom that took its electron (opposites attract)

What are characteristics of Ionic bonds?

• Characteristics

  • Dissolve easily in water

  • Form crystals at high temperatures

  • Conduct electricity in solution

• Examples

  • Table salt (NaCl)

  • Salt substitute (KCl)

Covalent bonds

• Electrons shared between two non metal atoms

• Energy is released and system becomes more stable

• Atoms make as many bonds as possible

• Stay stuck together until energy is added to pull them apart

Hydrogen bonds

• Some atoms (Flourine, oxygen nitrogen) have strong affinities for electrons, when covalently bonded to hydrogen, the electrons hang out closer to the heavier atom than near the hydrogen

• Polar molecules

  • One end sl + and the other sl -

• Electrostatic attractions

Methane

Ammonia

Water

What is a polar molecule? 

One end sl + and the other sl - 

Oxygen Atom

Larger, red ball

Slightly negative charge

Hydrogen atom

Smaller, white ball

Slightly positive charge

Hydrogen bond

Dotted line is an attraction

Dotted line with arrows is a repulsion

• The H atoms and O atom within a molecule are held by covalent bonds

• The electrostatic attraction between molecules are hydrogen bonds

Nutrients

• Food components that nourish the body to provide growth, maintenance and repair

Macro nutrients

• Protein

• Lipid

• Carbohydrates

• Water

Micro Nutrients

• Minerals and vitamins

Proteins

• Nitrogen, carbon, hydrogen, oxygen and sometimes sulfur and phosphorous

• Composed of amino acids

  • Active machinery of life

  • Muscle and other tissue

  • Enzymes

  • Hormones and antibodies

  • Shape and behavior drastically changed by heat, acid, salt and air

  • 4kcal/gram

How can we tell something is a protein

It contains hydrogens and nitrogen

Lipids (fats and oils)

• Carbon, hydrogen, oxygen

• Provide energy

• Components of living things

• Cooking medium and ingredient

• Does not mix with water

• 9 kcal/gram

Carbohydrates

• Carbon, oxygen, hydrogen

• Specialty of plants

  • Sugars, starch, dextrin, pectin, fiber

• Mix freely with water

• Flavor, bulk and texture

• 4 kcal/gram

Water

• Hydrogen, oxygen

• Major components of nearly all foods

• Medium to heat foods

• Important influence on other food molecules

• Solvent

• Hydrates

Vitamins and minerals

• Essential for nutrition

  • Vitamins

    • Sustain life and good health

  • Minerals

    • Growth and reproduction