Author: Dr. S. Mladenov
Pchelarstvo Magazine, issue12/ 1967
For quite some time honey has been known for its preservative effect on foodstuffs of animal and vegetable nature, as well as on other organic objects. In their writings, a lot of scientists note that in Egypt, Assyria and ancient Greece honey was used for embalming dead bodies and preserving valuable seeds. In the Pyramids in Giza (Egypt) a child's corpse was found preserved in a honey container. According to the historical data, the dead body of Alexander of Macedonia, who had died of malaria in Babylon (Asia), was transported to Macedonia in a coffin filled with honey to prevent its decomposition during the long travel.
Similarly prevented from being decomposed were the corpses of Emperor Justinian and the ancient Spartan kings Agesipolis and Agesilaus. Based on data from N. Yoyrish (1949), in his dissertation Solntsev notes that for the Roman patricians’ lavish celebrations, rare game and fruit from distant areas were delivered in fresh condition and with unchanged taste qualities due to their transportation in honey containers.
It has been observed that bees embalm and capsulate the dead bodies of bigger enemies killed in the beehive, thus preventing their decomposition.
In more recent times, the Soviet scientists А.Levina and B.Tsairlin (1947) reported that they managed to preserve living human tissue in honey solution for 4-6 months.
It is generally accepted that the preservative effect of honey is due to the high percentage of sugar in it. So we decided to conduct research on the preservative effect of honey trying to analyze the nature of that effect apart from the influence of sugar concentration.
We experimented with floral honey taken from different parts of the country - from high mountain, low mountain and field regions. We used the following types of honey: linden honey, acacia honey, and honey from field, meadow and balkan flowers, that have been kept in store from one to five years. The experiments were carried out with crop seeds (beans, barley, wheat, rye and maize) and animal products (kidney, muscle, liver, fish, chicken eggs, frogs, snakes).
We would pour honey into sterile glass dishes, adding thereto fresh seeds or animal organs from freshly slaughtered animals. Then we would close tightly the dishes with glass lids and leave them for a certain period of time in the office under ambient conditions.
Besides, control tests were conducted with artificial honey, consisting of 40% glucose and 30% fructose in saline. We carried out those control tests in order to eliminate the effect of sugar as the only preserving honey component (factor).
After a certain amount of time, we would analyze the characteristics of the respective products – to what extent their typical properties were preserved. For the seeds, our conclusions were based on their color, smell, size, and for the animal products – on the texture, smell, color, etc., as well as on the results of the laboratory and bacteriological tests.
We made laboratory tests with the seeds, monitoring the germination energy and germination which give the most accurate idea of seed preservation. We carried out those experiments in the Regional Seed Testing Station in Kyustendil. After gentle and careful wipe and examination, we would place the seeds in special cardboard plates and put in a thermostat at 26°C for six days. On the third day, we would determine the germination energy taking into consideration the number of seeds with long shoots, and on the sixth day we would determine the overall germination. Likewise, we would examine the control seeds kept in honey. By bacteriological studies of the animal products, we observed the growth of microorganisms in them.
The seeds that were kept for one year in floral honey, had preserved their freshness, had normal color and texture, normal size and smell. The high germination and germination energy percentage shown by the test results proved their preservation, while the control ones had low percentage of germination and germination energy.
We would determine the preservative effect of honey on animal products on the 2nd and 4th year. The test results showed that the animal products, kept in nectar honey for four years, had retained their freshness.
Upon outward examination of the kidney that had been kept in honey for four years, we ascertained that it had retained its texture, within the normal, as well as its freshness, and a knife cut revealed preserved structure typical of a normal kidney. The color was close to normal. The kidney cells cultured on special nutrient media did not show microorganism growth.
In the control samples, where the kidney had been kept in artificial honey, there were signs of decomposition on the tenth day after the test start, which put an end to our experiments with them.
The liver kept in honey had normal texture, a color almost close to normal and normal smell. Upon liver cut, the liver structure could be distinctly seen. Bacteriological studies showed that there were no microorganisms. Control samples with artificial honey indicated some signs of liver decomposition no more than five days later.
The chicken eggs kept in nectar honey for two years had retained their freshness. When inspected under some light, the eggs appeared to have normally preserved yellow hue, with a normal air chamber. In breaking, they had a fresh look, normal smell, yolk and white clearly separated from each other, with normal color and smell. The cells cultured on nutrient media to search for microorganisms showed negative results.
The results of the studies on the preservative effect of honey showed that it has a markedly preservative effect on plant and animal products.
As has been said, the control experiments with artificial honey after the method of Yoyrish showed that the preservative effect can not be solely attributed to the suragrs in honey that, with their hygroscopic action, dеhydrate animal and plant cells. Quite indicative in this regard were the experiments with honey that had been previously heated to boiling. Such honey has no preservative effect on the test organisms, which undergo quck decomposition therein. Besides, this type of honey turns sour within a very short period.
Acids found in honey in small amounts could not explain its preservative effect either. It is ascertained that honey contains the following acids: formic, acetic, tartaric, citric, oxalic, phosphoric and the like. Its pH is 3,7. If we neutralize the acids by connecting them with a carbonate radical (sodium bicarbonate) and cause alkali or neutral (pH - 7) rection in honey, it will retain its preservative properties. This demonstrates that its preservative effect is not due to the acids.
Neither can the preservative effect of nectar honey be explained by the ferments and the albuminoidal compounds in it. Honey contains the following ferments: invertase, catalase, diastase, oxidase, peroxidase and proteolytic enzymes. Literature makes it known that when heating honey above 60 ° C, ferments (enzymes) are destroyed and proteins coagulate. We heated honey at a temperature above 80 °C, whereby enzymes and proteins were destroyed. Such honey has lost its preservative properties, as the food placed in it undergoes fast decomposition and decay processes occur.
According to our studies, the preservative effect of honey is firstly due to the antibiotic substances of plant origin (phytoncides) in it and secondly, due to the sugars. Phytoncides have bacteriostatic (inhibiting the growth of microorganisms) and bactericidal (destroying microorganisms) effect on the microorganisms found in honey and products, thus preventing the processes of decomposition.
Studying in depth the properties of phytoncides in plants, the Soviet biologist B.Tokin (1954) reported that one of their properties, along with the antimicrobial action, is that they have a preservative effect. The same author also gave scientific justification for the use of phytoncides of higher plants to preserve foodstuffs. In 1954, in his work " Губители микробов фитонциди " B.Tokin makes known the results of his experiments and observations on the preservation of fresh food, such as meat, fish, fruits, etc., by placing it at room temperature in an environment where phytoncides of garlic, onion, radish, mustard and the like are in action. According to the same author, the preservative effect of plant phytoncides had been ascertained and studied by Ravich Shtebro, Yu. Dubarova, G.Rogacheva and A.Suhacheva.
Hence, our experiments with different types of honey show that its preserving effect on animal, vegetable and other products subject to spoilage is due to the presence of antibiotic substances (phytoncides) in honey, not just because of the high concentration of sugars therein.