Food Preservation, Safety and Adulteration
Food Preservation, Safety and Adulteration deals with keeping food safe and usable and detecting dishonest food practices. The exam tests preservation principles, common methods, safe-handling rules and simple adulteration tests.
Preservation principles
Microbial growth is controlled by asepsis, low or high temperature, reduced moisture, acidity, absence of oxygen, added preservatives and irradiation where permitted. Drying, salting, sugaring, pickling, canning, freezing and refrigeration use different combinations of these principles. Refrigeration slows growth; it does not kill all microbes. Canning relies on heat processing and a vacuum seal; an improperly canned low-acid food can support dangerous anaerobic growth.
Safety and adulteration
Follow safe handling: clean hands and surfaces, separate raw and cooked foods, cook thoroughly, keep food at safe temperatures and use safe water and raw materials. Adulteration is the addition of inferior, harmful or undeclared substances; contamination is unintended entry of microbes, chemicals or foreign matter. Simple screening tests include iodine for starch in milk (blue-black colour) and visual sorting for stones or ergot in grains.
Worked example
A milk sample turns blue-black with iodine. Reasoning: iodine detects starch, so the result suggests starch has been added or starchy material is present. This is a screening indication, not a complete laboratory proof; a confirmatory test is needed before legal action. The same sample should also be checked for smell, colour and sediment.
Traps
Do not say freezing sterilises food. Do not confuse preservation with flavour enhancement. A positive simple test is presumptive evidence, not a final court finding. Never taste a suspected adulterated sample.