Biology: Classification and Food Content

Study Notes

Essential atoms include Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur (CHNOPS).
These elements are fundamental in forming organic materials and carbon-containing compounds.

According to source:
- Plant-based: Includes grains, cereals, pulses, fruits, vegetables, nuts, and fungi.
- Animal-based: Comprises muscle, milk, poultry, eggs, fish, and shellfish.
Based on manufacturing methods:
- Primary processed foods: Derived from basic commodities through operations like milling or oil extraction.
- Preserved foods: Maintain natural forms but treated to extend shelf life.
- Manufactured foods: Altered significantly from original sources.

Water is the most abundant nutrient in many foods, comprising up to 95% of their composition.
Fruits and vegetables contain between 70-95% water; whole milk exceeds 80%, while most meats hover around 70%.

Boiling point drops at higher elevations; at Mt. Everest, it is 69°C.
Water's molecular composition consists of 2 hydrogen atoms and 1 oxygen atom (H2O).

Free water: Easily separable, abundant in foods, e.g., found in fruits.
Bound water: Integrated into nutrient structure, not easily removed, e.g., found in bread.

Serves as a medium for dissolving various substances (salts, acids, sugars).
Essential for heat transfer in cooking using moist-heat methods (boiling, simmering, steaming).

Water's high specific heat requires more energy to increase its temperature than most substances.
This enables high-water-content organisms to endure extreme temperatures.

Water has significant surface tension, causing molecules to form drops rather than spreading.
This trait is evident when water is placed in a cylinder, causing a concave meniscus.

Solutions: Homogeneous mixtures where solute particles dissolve fully in the solvent (e.g., sugar in water).
Colloidal dispersions: Particles (like starches and gums) do not fully dissolve due to their size.
Coarse dispersions: Larger particles remain suspended but visible.

Phospholipids emphasize emulsification, allowing hydrophobic and hydrophilic substances to mix.
Common in food products such as mayonnaise, baked goods, and beverages.
Lecithin, found in egg yolks, is a notable phospholipid.

Composed of Carbon, Hydrogen, and Oxygen (CHO).
Synthesized in green plants via photosynthesis and structured in basic units called saccharides.
Common food sources include grains, legumes, and various fruits and vegetables.

Sterols are complex molecules composed of interlinked carbon rings with diverse side chains.
Include substances like cholesterol and hormones (testosterone, estrogen) critical for various biological functions.