Short answers, pulled from the story.
Food preservation includes processes that make food more resistant to microorganism growth and slow the oxidation of fats, which slows decomposition and rancidification. It can also inhibit visual deterioration, such as the enzymatic browning of cut apples. Many processes combine more than one method, such as making jam through boiling, sugaring, and sealing.
Canning was invented by the French confectioner Nicolas Appert. By 1806 the process was used by the French Navy to preserve meat, fruit, vegetables, and even milk. The reason it worked was not understood until 1864, when Louis Pasteur found the relationship between microorganisms, food spoilage, and illness.
In 2015, the International Agency for Research on Cancer of the World Health Organization classified processed meat as carcinogenic to humans. Processed meat means meat that has undergone salting, curing, and smoking. Curing can also involve nitrites, which contribute a characteristic pink color to the meat.
Hurdle technology ensures that pathogens in food are eliminated or controlled by combining more than one approach, treated as hurdles a pathogen must overcome. Leistner defined it in 2000 as an intelligent combination of hurdles that secures microbial safety, stability, organoleptic and nutritional quality, and economic viability. Examples include high temperature, low temperature, increased acidity, and lowered water activity.
Food irradiation exposes food to ionizing radiation such as beta particles or gamma rays from sources like cobalt-60 or cesium-137, killing bacteria, molds, and insect pests. Irradiated food does not and cannot become radioactive. Approximately 500,000 tons of food are irradiated per year worldwide in over 40 countries, mainly spices and condiments.
Kangina are disc-shaped vessels made of mud and straw used in rural Afghanistan to preserve grapes. The vessels can preserve fresh grapes for up to six months by passively controlling their internal environments to restrict gas exchange and water loss. This prolongs the lives of late-harvested grapes stored within them.
Pasteurization is a process for preserving liquid food, invented by Louis Pasteur in 1862, and was originally applied to combat the souring of young local wines. Today it is mainly applied to dairy products. Milk is heated to about 70 C for 15 to 30 seconds to kill bacteria, then cooled quickly to 10 C and stored in sterilized bottles or pouches in cold places.