Preservation of food

Content

Food preservation methods

Microorganisms are the main spoilage factor in foodstuffs, therefore maintenance procedures are aimed at preventing their growth and development in the preserved material and such a change in the chemical properties of foodstuffs or such packaging and closure that would limit their further development, and thereby increase safety. food. How it was done in prehistoric times and in antiquity, and how today you will learn from the following article.

prehistory Probably the oldest way to extend the shelf life of foods was to smoke them and dry them over a fire or in the sun and wind. Thus, meat and fish could, for example, survive the winter (1). Drying already 12 thousand. years ago, it was widely used in the Middle East and Central Asia. What was probably not understood at the time, however, was the fact that removing water from a product extended its useful life.

1. Smoking fish on a fire

Antiquity Salt has played an invaluable role in humanity's fight against microbes that cause food spoilage, which limits the vital activity of microorganisms. It was already widely used in ancient Greece, where the use of brine was used to extend the useful life of fish. The Romans, in turn, marinated meat. Apicius, the author of the famous cookbook from the time of Augustus and Tiberius, "De re coquinaria libri X" ("On the art of preparing books 10"), advised the product preserved in this way to soften by boiling it in milk.

Contrary to appearances, the history of chemical food additives is also very long. The ancient Egyptians used cochineal (today E 120) and curcumin (E 100) to color meat, sodium nitrite (E 250) was used to salt meat, and sulfur dioxide (E 220) and acetic acid (E 260) were used as dyes. preservatives. . These substances were also used for similar purposes in ancient Greece and Rome.

Ok. 1000 pennies As the French journalist Magelon Toussaint-Samat points out in her book The History of Food, frozen food was known in China by 3 people. many years ago.

1000-500 tenge In Auvergne, France, more than a thousand granaries from the Gallic era have been discovered during archaeological excavations. Scientists believe that the Gauls knew the secrets of vacuum food storage. When storing grain, they first tried to destroy bacteria and other microbes with fire, and then filled their granaries in such a way that the access of air to the lower layers was blocked. Thanks to this, the grain could be stored for many years.

IV-II vpne Attempts have also been made to preserve foods by pickling, using vinegar in particular. Notable examples come from ancient Rome. A popular vegetable marinade was then made from vinegar, honey and mustard. According to Apichush, honey was also suitable for marinades, as it kept the meat fresh for several days, even in hot weather.

In Greece, quince and a mixture of honey with a small amount of dried honey were used for this purpose - all this and products were tightly packed in jars. The Romans used the same technique, but instead boiled a mixture of honey and quince to a solid consistency. Indian and Eastern traders, in turn, brought sugar cane to Europe - now housewives could learn how to make "canned food" by heating the fruits with cane.

1794-1809 The era of modern canning dates back to the Napoleonic campaigns in 1794, when Napoleon began looking for ways to store perishable food for his troops fighting overseas, on land and at sea.

In 1795, the French government offered a bonus of 12. francs for those who come up with a way to extend the shelf life of products. In the year 1809, it was received by the Frenchman Nicolas Appert (3). He invented and developed the evaluation method. It consisted of long-term cooking of foodstuffs in boiling water or steam, in hermetically sealed vessels, such as jugs (4) or metal cans. Although valuation was established in France and tin can production began in England, it was only in America that the method was developed in practice.

XIX century. Salting food has long been known. Over time, people began to experiment, and in the 20th century it was discovered that certain salts gave the meat an attractive red color instead of gray. During experiments carried out in the XNUMXs, scientists realized that a mixture of salt (nitrate) prevents the development of botulinum bacilli.

1821 The first positive effects of applying a modified atmosphere to food were observed. Jacques-Étienne Berard, professor at the School of Pharmacy in Montpellier, France, discovered and announced to the world that storing fruits in low oxygen conditions slows down their ripening and increases their shelf life. However, controlled atmosphere storage (CAS) was not used until the 30s, when apples and pears were stored on ships in rooms with high CO levels.₂ - prolong their freshness.

5. Ludwik Pasteur - portrait of Albert Edelfelt

1862-1871 The first refrigerator was designed by Australian inventor James Harrison, a printer by trade. Even its production was started and it hit the market, but in most sources the inventor of this type of device is the Bavarian engineer Carl von Linde. In 1871, he used a refrigeration system at the Spaten brewery in Munich that allowed beer to be produced in the summer. The coolant was either dimethyl ether or ammonia (Harrison also used methyl ether). The ice obtained by this method was formed into blocks and transported to homes, where it fell into heat-insulated cabinets where food was cooled.

1863 Ludwik Pasteur (5) scientifically explains the pasteurization process, which inactivates microorganisms while preserving the taste of food. The classic method of pasteurization involves heating the product to a temperature above 72°C, but not more than 100°C. For example, it consists in heating it to 100°C in a minute or to 85°C in 30 minutes in a closed device called a pasteurizer.

1899 The destructive effect of high pressures on microorganisms was demonstrated by Bert Holmes Hite. For 10 minutes at room temperature, he subjected the milk to a pressure of 680 MPa, noting that as a result of this, the number of live microorganisms contained in the milk decreased. In turn, meat subjected to a pressure of 540 MPa at a temperature of 52°C for an hour showed no microbiological changes during three weeks of storage.

In subsequent years, fundamental studies were carried out on the influence of high pressure, i.e. on proteins, enzymes, structural elements of the cell and whole microorganisms. This process is called pascalization, after the great French scientist Blaise Pascal, and it is still being developed. In 1990, high-pressure jam was released to the Japanese market, and the following year, more food products such as fruit yoghurts and jellies, mayonnaise salad dressings, etc. appeared.

1905 Offered by British chemists J. Appleby and A. J. Banks. The practical application of food irradiation began in 1921, when an American scientist discovered that X-rays could kill Trichinella, a parasite found in pork.

Food was treated with radioactive isotopes of cesium 137 or cobalt 60 in lead insulators - isotopes of these elements emit electromagnetic ionizing radiation in the form of gamma rays. Further work on these methods began in England after 1930, and then in the United States after 1940. From about 1955, research into the radiation preservation of foodstuffs began in many countries. Soon, products were preserved using ionizing radiation, which made it possible to extend the shelf life, for example, of poultry, but did not ensure complete sterility of the product. They are successfully used to suppress the germination of potatoes and onions.

1906 The official birth of the freeze drying process (6). In their work presented at the Academy of Sciences in Paris, the biologist Frédéric Bordas and the physician and physicist Jacques-Arsène d'Arsonval proved that it is possible to dry frozen and temperature-sensitive blood serum. The whey dried in this way remained stable for a long time at room temperature. The inventors in their subsequent studies have described that their method can be used to fix and maintain sera and vaccines in good condition. The removal of water from a frozen product also occurs in natural conditions - this has long been used by the Eskimos. Industrial freeze-drying was used in the second half of the XNUMXth century.

6. Sublimated products

1913 DOMELRE (DOMestic ELectric REfrigerator), the first electric household refrigerator, went on sale in Chicago. In the same year, refrigerators appeared in Germany. The American model had a wooden body and a cooling mechanism on top. It was not actually a refrigerator as we understand it today, but rather a refrigeration unit designed to be installed on top of an existing refrigerator.

The coolant was toxic sulfur dioxide. German refrigerators (manufactured by AEG) were covered with ceramic tiles. However, almost only German restaurateurs could afford these devices, because they cost 1750 modern marks, which is the same as a country estate.

7. Clarence Birdseye in the Far North

1922 Clarence Birdseye, while on a freezing Labrador (7), found that at -40°C, caught fish freezes almost immediately, and when thawed, has a fresh taste, completely different from the frozen fish that could be bought in New York. He soon developed a technique for rapidly freezing food.

Rapid freezing is now known to form smaller ice crystals that damage tissue structures to a lesser extent than other methods. Birdseye experimented with freezing fish at the Clothel Refrigerator Company and later founded his own Birdseye Seafoods Inc. It specialized in freezing fish fillets in chilled air at a temperature of -43 ° C, but in 1924 it went bankrupt due to a lack of consumer interest.

However, in the same year, Birdseye developed a completely new process for commercial quick freezing - packaging fish in cartons and then freezing the contents between two refrigerated surfaces under pressure; and created a new company, General Seafood Corporation.

8. 1939 Electrolux fridge ad

1935-1939 Thanks to Electrolux, refrigerators are beginning to appear en masse in ordinary Kowalski homes (8).

60-s years. Antibiotics are beginning to be used to preserve food. However, the rapid increase in bacterial resistance to these compounds has led to their use being banned. It was soon discovered that lactic acid bacteria produce an effective natural antibiotic nisin, which is not related to medical antibiotics. Nisin is preserved, in particular, in smoked meats and cheeses.

90-s years. In the second half of the last decade of the last century, research began on the use of plasma for microbial inactivation, although the cold plasma deactivation method was patented back in the 60s. Currently, the use of low-temperature plasma in food production is considered as a first generation technology, which means that during the initial period of development.

9. Book cover by Lothar Leistner and Graham Gould on hurdling technique.

2000 Lothar Leistner (9) defines barrier technology, i.e. a method to accurately eliminate pathogens from foods. It sets up certain "obstacles" that the pathogen must overcome in order to survive. We are talking about a judicious combination of methods that ensure food safety and microbiological stability, as well as optimal taste and nutritional qualities and economic feasibility. Examples of barriers in the food system are high processing temperatures, low storage temperatures, increased acidity, reduced water activity, or the presence of preservatives.

Taking into account the nature of the product and the microflora present on it, a complex of the above factors is selected in order to remove microorganisms from food products or render them harmless. Each factor is another obstacle. By jumping over them one by one, the microbes weaken, eventually reaching a point where they no longer have the strength to keep jumping. Then their growth stops, and their number stabilizes at a safe level - or they die. The final step in this approach is chemical preservatives, which are used only when other barriers do not sufficiently inhibit microbial activity or when the barrier removes most of the nutrients from the food.

Food preservation methods

Physical

Thermal - consisting in the use of high or low temperatures:
- cooling,
- freezing,
– sterilization,
– pasteurization,
- blanching
- tyndalization (fractionated pasteurization - a method of preserving canned food, which consists in two or three times pasteurization with an interval of one to three days; the term comes from the name of the Irish scientist John Tyndall).
Decreased water activity temperature change or the addition of substances that change the osmotic pressure:
- drying,
– thickening (evaporation, cryoconcentration, osmosis, dialysis, reverse osmosis),
– addition of osmoactive substances.
The use of protective gases in storage chambers (modified or controlled atmosphere) or in food packaging:
- nitrogen,
- carbon dioxide,
– vacuum.
Radiation:
- UVC,
- ionizing.
Electromagnetic interaction, which consists in applying the properties of the electromagnetic field:
– pulsating electric fields,
– magnetic electric fields.
Application pressure:
- ultra high (UHP),
– high (GDP).

chemical

To add chemicals to a preservative solution:
- marinating
– addition of inorganic acids,
- marinating
– use of other chemical preservatives (antiseptics, antibiotics).
Adding chemicals to the process atmosphere:
- smoking.