Food preservation
Although Appert had discovered a new way of preservation, it was not understood until 1864 when Louis Pasteur found the relationship between microorganisms, food spoilage, and illness.
[5] Foods have varying degrees of natural protection against spoilage and may require that the final step occurs in a pressure cooker.
The introduction of commercial and domestic refrigerators drastically improved the diets of many in the Western world by allowing food such as fresh fruit, salads and dairy products to be stored safely for longer periods, particularly during warm weather.
Before the era of mechanical refrigeration, cooling for food storage occurred in the forms of root cellars and iceboxes.
In the recent years such PEF techniques are utilised in the artificial aging of red wines, i.e. by utising wood chips.
Smoking and salting techniques improve on the drying process and add antimicrobial agents that aid in preservation.
Smoke deposits a number of pyrolysis products onto the food, including the phenols syringol, guaiacol and catechol.
[9] Salt accelerates the drying process using osmosis and also inhibits the growth of several common strains of bacteria.
[10] In 2015, the International Agency for Research on Cancer of the World Health Organization classified processed meat—i.e., meat that has undergone salting, curing, and smoking—as "carcinogenic to humans".
These methods are used to create the specific controlled conditions that will support the desirable organisms that produce food fit for human consumption.
The barley and other ingredients also infuse the drink with nutrients, and the microorganisms can also produce vitamins as they ferment.
Cold stores provide large-volume, long-term storage for strategic food stocks held in case of national emergency in many countries.
Heating to temperatures which are sufficient to kill microorganisms inside the food is a method used with perpetual stews.
In rural Afghanistan, grapes are preserved in disc-shaped vessels made of mud and straw, called kangina.
In chemical pickling, the food is placed in an edible liquid that inhibits or kills bacteria and other microorganisms.
Typical pickling agents include brine (high in salt), vinegar, alcohol, and vegetable oil.
Common chemically pickled foods include cucumbers, peppers, corned beef, herring, and eggs, as well as mixed vegetables such as piccalilli.
[citation needed] In northern climates without sufficient sun to dry foods, preserves are made by heating the fruit with sugar.
"[9] Sugar is used to preserve fruits, either in an antimicrobial syrup with fruit such as apples, pears, peaches, apricots, and plums, or in crystallized form where the preserved material is cooked in sugar to the point of crystallization and the resultant product is then stored dry.
Multiple types of ionizing radiation can be used, including beta particles (high-energy electrons) and gamma rays (emitted from radioactive sources such as cobalt-60 or cesium-137).
Irradiation can kill bacteria, molds, and insect pests, reduce the ripening and spoiling of fruits, and at higher doses induce sterility.
PEF holds potential as a type of low-temperature alternative pasteurization process for sterilizing food products.
For cell disintegration purposes especially potato processors show great interest in PEF technology as an efficient alternative for their preheaters.
It is often used to package: This process subjects the surface of food to a "flame" of ionized gas molecules, such as helium or nitrogen.
[34] High pressure can be used to disable harmful microorganisms and spoilage enzymes while retaining the food's fresh appearance, flavor, texture and nutrients.
By 2005, the process was being used for products ranging from orange juice to guacamole to deli meats and widely sold.
[36] Biopreservation is the use of natural or controlled microbiota or antimicrobials as a way of preserving food and extending its shelf life.
[37] Hurdle technology is a method of ensuring that pathogens in food products can be eliminated or controlled by combining more than one approach.
The right combination of hurdles can ensure all pathogens are eliminated or rendered harmless in the final product.
According to the type of pathogens and how risky they are, the intensity of the hurdles can be adjusted individually to meet consumer preferences in an economical way, without sacrificing the safety of the product.
