Healthy, healthier – fermented vegetables

image image
image

Why do we ferment food at all?

Fermentation allows us to protect food from decay, extend its expiry date and improve taste and quality. One of the ways of preventing the growth of undesirable microorganisms found on vegetables and ensuring the growth of the desired lactic acid bacteria that will ferment is to add a salt solution to the vegetables.

Unlike other microorganisms, which are more sensitive to salt in large quantities, lactic acid bacteria can well tolerate high concentrations of salt. The salt solution causes swelling and bursting of the plant cells, so the sugars and other nutrients that the lactic acid bacteria use as food are released from the cells.

Vegetable acidification is based on the rapid increase in the number of lactic acid bacteria. They increase the acidity by producing lactic acid from the sugars present in the vegetables through the lactic acid fermentation process, which gives a specific taste to the fermented vegetables.

The more acidic the content becomes, the more unfavorable the conditions become for the life of other microorganisms. Lactic acid bacteria produce hydrogen peroxide and bacteriocins. This prevents food spoilage caused by other microorganisms. The vegetable acidification not only improves its nutritional value but also benefit a large number of "good" bacteria.

image

Approximately 3kg of salt is needed for 100kg of vegetables.

image

An example of the antimicrobial activity of lactic acid bacteria against bacteria whose presence in the fermented product is undesirable.

Explanation: the white colony in the middle of the Petri dish means that the accumulated cells of lactic acid bacteria are visible. The clear zone around the colony means that unwanted bacteria can’t grow in its vicinity, while other parts of the Petri dish are opaque because the unwanted bacteria has grown and blurred the nutrient media.

The addition of starter cultures to the already present lactic acid bacteria on the vegetables enhances fermentation success. By providing the required number of bacteria, fermentation is faster and the quality of the finished product is guaranteed.

image
image

Sauerkraut, chef's delight

Sauerkraut is produced to prevent spoilage of fresh cabbage. Acidification of the fresh cabbage is popular in the western world, but also in China and Korea. Fermentation of cabbage increases its digestibility and preserves the vitamin C that cabbage has in abundance.

Cabbage can be acidified shredded or in heads. During acidification, a salt solution is added to the cabbage and anaerobic conditions are provided to prevent the growth of undesirable bacteria present on the cabbage and to ensure the growth of lactic acid bacteria that produce lactic acid and other metabolites responsible for the specific taste of sauerkraut. The optimum temperature for cabbage fermentation is 18 ° C and the process lasts about three weeks. Other vegetables can be fermented in the same way, for example, carrots, onions, garlic and beetroot.

Other metabolites are acetic acid, ethanol, diacetyl, acetaldehyde, hydrogen peroxide, carbon dioxide, bacteriocins and others. Many of these metabolites have antimicrobial activity. The activity of certain metabolites produced by lactic acid bacteria:

Acetic acid and lactic acid - They lower the intracellular pH.
Hydrogen peroxide - Oxidizing agent
CO2 - It creates anaerobic conditions and affects some enzymes.
Acetaldehyde - It affects the growth of other microbes.
Diacetyl - It gives the aroma of butter.

In the 18th century, many sailors survived a long voyage thanks to sauerkraut because it is extremely rich in Vitamin C, which prevented them from becoming ill with scurvy. People who do not consume enough vitamin C get scurvy which causes pain in the muscles, bones and joints and leads to tooth decay. One ship had up to 10 tonnes of fermented food rich in vitamin C, which was regularly consumed by sailors so that they wouldn’t become ill.
Sauerkraut is rich in fiber that is essential for good digestion and bowel health, for lowering cholesterol in the blood and controlling blood sugar levels.

image

Scurvy

A disease caused by a vitamin C deficiency, which is required for the production of collagen. Collagen is one of the proteins that make up connective tissue. If the collagen is not properly synthesized, the connective tissue does not have the necessary strength, therefore, the symptoms of the disease appear.

image
image

Cucumbers

Acidification of fresh cucumber requires the right amount of salt and anaerobic conditions. A sufficient amount of salt allows the growth of lactic acid bacteria while preventing the growth of undesirable bacteria. Adding too little salt favors the other microorganisms, so we would easily get spoiled cucumbers because the bacteria, molds and yeasts that cause the spoilage would grow. If there is too much salt in the water, the lactic acid bacteria will not be able to multiply, so again we would not get acidic but only salty cucumbers.

Unlike cabbage, a greater amount of salt is used to pickle cucumbers, up to 5 kg of salt per 100 kg of cucumbers. By adding salt, the fermentation time is shortened and the whole process can take from one to two weeks.

The high concentration of salt in the solution, besides undesirable bacteria, prevents the growth of desirable bacteria as the salt binds water to itself. The microbes need water for growth and reproduction and the water is involved in many metabolic reactions.

image

June 14th is World Cucumber Day.

image

The crunching of a good pickle can be heard up to seven meters away.

image

In the USA, on Christmas mornings children traditionally search for hidden pickles under the Christmas tree. The first child to find it receives a gift from Santa.

image
image
image image

Olives

Olives can be fermented with a naturally present microbiota, or by adding starter cultures. Freshly picked olives are not edible and must be processed first.

To make them tastier, it is first necessary to remove the bitterness in the sodium hydroxide solution. Removal of bitterness occurs due to the separation and breakdown of oleuropein, a bitter chemical compound. The olives are then rinsed with water and brine (salt solution) is added, which allows the extraction of sugars and other nutrients from the olives, necessary to grow the starter culture.

By fermentation, the bacteria present in sugar produce acetic and lactic acid, as well as substances that give aroma and acidify the olives. The following substances give the aroma to olives: esters, propionic acid, aldehydes, alcohols, phenols, terpenes and ketones.

image

The first true harvest of olives, regarding traditional varieties, could be expected only 15 years after planting the olive tree. Newer varieties yield much faster. The unripe fruit of the olive is green. During ripping, they range in color from reddish, then dark red and finally to bluish-black or black. The olive fruit can develop up to 180 days!

The olive tree has an average life span of 300 - 600 years.

image

During the first Olympic Games, olive oil was burning as an "eternal flame".