Without refrigerators, how did the ancients preserve food? They came up with 7 ways

Some people ask, since there was no such thing as adding preservatives to food in ancient times, how did they prevent food from spoiling? Others ask, can't food be guaranteed to be healthy if preservatives are not added?

To answer this question, we must start with the principles of food spoilage and spoilage inhibition.

Sources of food spoilage

microorganism

More than 100 years ago, French microbiologist Pasteur discovered that food spoilage is caused by microorganisms. After these microorganisms have consumed the nutrients in food, they will multiply in large numbers, not only causing adverse changes in the color, aroma, taste and texture of the food, but some of these microorganisms will also bring the risk of bacterial food poisoning. Therefore, in order to preserve food for a long time, it is necessary to solve the problem of controlling the reproduction of microorganisms.

There are three conditions for the growth and reproduction of microorganisms: suitable temperature, sufficient free water and adequate nutrient supply. If food is placed in the refrigerator, the proliferation rate of microorganisms will slow down and the shelf life will be extended. If food is placed in the freezer, microorganisms can no longer reproduce and the food can be kept for several months or even longer without spoiling. Therefore, at -18℃, the shelf life of frozen food in the supermarket can be up to 12 months.

After all, storage under refrigeration conditions consumes a lot of energy, is very costly, and is not very convenient to transport and carry. If food is not placed in a refrigerator but stored at room temperature, other conditions for microbial reproduction must be controlled: appropriate temperature and sufficient free water.

Ancient Wisdom

Seven Methods to Inhibit Microorganisms

Ancient people had no refrigerators or food additive regulations, but they came up with several ways to prevent food from spoiling and extend its shelf life, effectively inhibiting the reproduction of microorganisms.

One is drying. High-moisture natural foods can be dried in the sun or by baking to remove moisture. Without sufficient moisture, bacteria cannot reproduce and mold cannot produce toxins. The ancients learned to make dried meat, dried fish, dried shrimp, dried fruit, etc. so that the food harvested once would not be wasted due to corruption and could be stored for consumption throughout the year.

The second is to add salt. Salt is an ancient preservative, but people are so familiar with it that they don't consider it an additive in the legal sense. As long as enough salt is added, most of the water will be "bound" by the salt and cannot move freely. The osmotic pressure is high, and there is very little water left for microorganisms to reproduce. The ancients learned to make salted fish, salted meat, salted eggs, salted dried tofu, pickled vegetables... As long as enough salt is added, the food can be stored at room temperature for several months or even longer.

The third is to add sugar. The principle of adding sugar is the same as that of adding salt, but the effect of sugar in binding water and increasing osmotic pressure is not as strong as that of salt. Therefore, the sugar concentration needs to be increased to more than 60% to keep the food at room temperature for a long time. For example, jam, preserved fruit, candied fruit, honey and sugar osmanthus are all preserved by a large amount of sugar.

The fourth is to add wine. High concentrations of alcohol have antibacterial and even bactericidal effects, and can also bind water molecules. For example, foods such as wine-soaked bayberry use this method and can be stored at room temperature for several months.

The fifth is smoking. Smoke contains volatile organic compounds such as phenol, aldehyde, alcohol, acid, etc. that can inhibit bacteria. They are attached to the surface of food and help inhibit bacterial proliferation. At the same time, the high temperature of smoking will also dehydrate and dry the surface of food, thereby reducing the rate of microbial reproduction. For example, smoked meat, smoked fish, smoked sausage, etc., all use the method of smoking to inhibit bacteria. However, smoked smoke contains polycyclic aromatic hydrocarbons, such as benzopyrene, etc., but the average life expectancy of ancient people was originally short, and ordinary people could not eat smoked meat several times a year. The health level depends more on whether they can have enough food. Occasionally eating smoked food has little effect on health.

The sixth is fermentation. Fermentation is to use the action of beneficial microorganisms to inhibit harmful microorganisms. For example, fermented bean curd, cheese, bean paste, sauerkraut, etc. are all fermented delicacies. Since beneficial microorganisms help decompose the undigestible components in food and produce more B vitamins, fermented food is both nutritious and easy to digest. However, fermentation alone is not enough to achieve the goal of long-term preservation at room temperature, and it is usually necessary to add a large amount of salt and other preservative measures.

Seventh, use other preservative ingredients. In addition to salt, sugar and alcohol, there are also a lot of acids, alkalis, and nitrites. For example, preserved eggs are made by adding a lot of caustic soda; the acetic acid and lactic acid in vinegar and pickles can help inhibit harmful microorganisms. Hundreds of years ago, the ancients used sodium nitrite and sodium nitrate to color and preserve meat, but at that time, because there were no food safety regulations, they added as much as they wanted. It was not until the 1990s that my country had food safety regulations, and it was discovered that the "traditional production process" of some local specialty meat products often exceeded the nitrite standard.

Traditional experience

Adopted by modern industry

Using the above ancient methods, many foods that can be preserved at room temperature can be produced. For example, when making cured food, salt is first used, and then air-dried, smoked, and roasted for dehydration, so that bacon, cured goose and other delicacies can be preserved for a long time. When making Chinese ham, a large amount of salt and nitrite are added, and the surface of the ham is dehydrated and fermented by microorganisms. The combined effect of these measures can make the ham be preserved for a long time at room temperature. When making fermented foods such as fermented eggs, sugar, salt, and alcohol are used together to inhibit bacteria.

In the modern food industry, these principles are also used to preserve food, but the equipment used is more advanced and the quality indicators are more scientific. For example, in addition to sun drying, baking and frying dehydration, there are also hot air drying, infrared drying, microwave drying and other equipment, which improve the drying efficiency and can preserve more nutrients.

However, as people's consumption level increases, consumers dislike the large amount of salt and sugar in traditional processes, and the dry and hard taste is also unpopular. However, if you want to reduce the amount of sugar and salt, you can't fully inhibit the proliferation of microorganisms, so you have to rely on food preservatives to help.

Preservatives permitted by law have all undergone a large number of toxicological tests, proving that they will not cause noticeable health damage to the human body if used within the limit. On the contrary, consuming too much salt, sugar, or a large number of pathogenic bacteria will be more harmful to human health than using only a few thousandths or even a few ten-thousandths of preservatives.

Source: Popular Science Times

Author: Fan Zhihong is a member of the Chinese Nutrition Society, a registered dietitian, and a professor at the Department of Nutrition and Health at China Agricultural University.