Microscopic size, ubiquity, simple cells with diverse metabolism, and the dual role of microbes in food production and spoilage.

How the three main food microbes differ in cell type, structure, reproduction, and food roles.

pH, water activity, oxidation-reduction potential, nutrients, and natural barriers that decide where microbes thrive.

Soil, water, air, humans, sewage, pests, equipment, and raw foods as contamination reservoirs.

Souring, proteolysis, lipolysis, ropiness, gas, and the role of hygiene, pasteurization, and refrigeration.

Surface slime, souring, putrefaction, rancidity, molds, and the module-wide control levers for food safety.

Hygiene and environmental control keep food safe.