Pasteurization - preserving food or destroying nutrients?

In primeval times, people in Europe mainly ate raw plant parts, wild vegetables, and fruit. With the advent of hunting and fishing, meat, fish, and seafood enriched their diet. Methods such as salting, smoking, or drying helped preserve food, i.e., to conserve it and build up supplies for leaner times. It was only in modern times that many ways of preserving food were developed, including pasteurization. For foods such as dairy products or beverages, the pasteurization process is most well-known. 

What happens during this process? And what are the advantages and disadvantages of pasteurization? How does pasteurization affect kombucha? You will find the answers to these questions in this article.

These methods preserve food

Pasteurization

The simplest method to extend the shelf life of food is heat treatment. This kills harmful microorganisms or pathogenic bacteria, such as salmonella. This way, products are gently preserved. However, pasteurized foods do not have an unlimited shelf life, as they are not germ-free, but only low in germs. This method extends shelf life, but it also removes nutrients that we need for our health.

During pasteurization, food is heated for a short time (from a few seconds to a few minutes) to a temperature of at least 60 °C. The core temperature of pasteurization varies depending on the process - but never reaches 100 °C. The pasteurization process was named after its developer, the French chemist Louis Pasteur. In the mid-19th century, he realized that short-term heating could neutralize germs and thus extend the shelf life of food.

Many types of cheese, for example, are made from pasteurized milk; others from raw milk.

Sterilization and UHT treatment

Heating above 100 °C is sterilization. After this heat treatment, food can be stored for significantly longer. However, this method means a loss of taste and nutrients. The difference between "UHT treated" and "sterilized" milk lies in the heating process and thus also in the minimum shelf life of unopened packages.

UHT milk, so-called long-life milk, is briefly heated to at least 135 °C and filled aseptically. It can be stored unopened for at least six to eight weeks.

Sterilized milk is heated to about 110 °C for 20 to 30 minutes. It can be stored unopened for up to one year. This method is used much less frequently, as the vitamin loss is significantly higher than with long-life milk. It is also inferior in taste to long-life milk. Sterilization is not required to be labeled. You can only infer this from the long shelf life of pasteurized milk.

Homogenization

During homogenization, differently sized particles in a liquid are reduced – this makes them easier to combine. Homogenization prevents, for example, a cream layer from forming on milk. In this process, milk is forced through a fine nozzle under high pressure. This breaks down the milk fat into tiny globules and distributes it homogenously (evenly) in the milk liquid. Homogenization is often used in combination with pasteurization, sterilization, or UHT treatment.

Fermentation

Fermentation is a biological way to preserve food. Another advantage of the fermentation process is the formation of probiotics, healthy yeasts and acids, as well as many other nutrients.

About a third of our food is produced by fermentation. This includes, for example, bread, fermented dairy, meat and pickled vegetable products such as sauerkraut or kimchi, kombucha, or alcoholic beverages such as beer and spirits. The advantages of fermentation include the formation of aroma and flavor compounds, the breakdown of harmful ingredients, and the extension of shelf life. The principle: organic substances are converted into acid, gases, or alcohol. For this, raw material-specific enzymes and microorganisms – such as bacteria or yeasts – are used.

Which foods are pasteurized?

Pasteurization is suitable for liquid foods. This method is best known for milk and dairy products. But liquid eggs, fruit and vegetable juices, canned fruits, and prepared meals are also subjected to such heat treatment. Pasteurization is often combined with other preservation methods. In beverages, this is done, for example, by lowering the pH value and by light-protective, airtight packaging. As long as these are not opened, additional refrigeration is not necessary. Examples include fruit and vegetable juices or other beverages, such as lemonades or even kombucha.

Pasteurized Kombucha vs. Raw Kombucha

There is a significant difference in the production of kombucha. Some producers use the process of pasteurization to make kombucha last longer. In this process, the kombucha is strongly heated, and the healthy microorganisms of the kombucha culture are killed. Thus, the kombucha loses its healthy probiotic effect. 

In contrast, there is the raw production of kombucha. Pasteurization is omitted, and instead, only Scoby particles are filtered out of the finished kombucha to slow down further fermentation. The shelf life of raw kombucha is significantly shorter, but it is still alive and contains the valuable microorganisms that provide the healthy effect.

To bypass the problem of pasteurization and ensure that the kombucha you drink is alive and contains valuable microorganisms, simply make it yourself.

Conclusion: Pasteurization is largely superfluous for a healthy diet. With today's transportation economy, it is possible to buy and consume most foods fresh. 90 to 99 percent of microorganisms are killed. As described in some previous articles, many bacterial strains are essential for our gut health and thus for our immune system. Unpasteurized kombucha provides us with these bacteria and many other nutrients. Nevertheless, I do not want to demonize pasteurization. After all, it also allows for the moderate enjoyment and storage of foods that may not primarily provide us with all nutrients but are still something special for the soul. 

Good health!