Food preservation methods: types, characteristics and properties

In an increasingly inhabited world with more nutritional demands, a production chain that maximizes the number of foods generated with the best possible state of preservation is essential.

Unfortunately, not all countries have access to treated foods, and therefore it is estimated that one in 10 people all over the Earth are sick at any given time from a transmission infection food. These problems are exacerbated in certain regions of the Global South, where sanitation measures are scarce and inefficient.

Thus, knowing food preservation methods is very important. Not only to know the protocols that are followed in Western countries, but to raise awareness about the rights to a decent diet, both at the individual and population level, that every human being should be able to exercise.

Related article: "Food additives: what are they, what types are there, and health effects"

Food preservation methods: more important than they seem

In an introductory way and following a little the train of thought exposed previously, we are going to offer you a series of data reported by the World Health Organization (WHO) regarding Foodborne Diseases (ETA) refers:

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Every year 600 million people get sick from eating untreated food.
ATS can be deadly, especially in those under the age of five. They cause 420,000 deaths annually, 1/3 of them being infants.
Diarrheal symptoms represent 95% of Foodborne Diseases in the Americas.

Bacteria of the genera Salmonella, Campylobacter and Escherichia are the most common causative agents of foodborne illness.. These infections often present with symptoms such as fever, headaches, nausea, vomiting, abdominal discomfort, and diarrhea.

Despite being the most common bacterial agents when it comes to gastroenteritis, they are not the only ones. Viruses, parasites (the famous intestinal worms), prions, and various chemicals that are toxic to the body (such as heavy metals, organic toxins, and pollutants persistent).

Of course, this extensive list of potential threats and the figures cited above allow us to understand why the pursuit of food safety is a global public health priority. This is achieved both by disinfecting them prior to consumption and by keeping them during the different stages of transformation and storage until they reach the plate. Here the food preservation methods come into play, which we will explain below.

1. Pasteurization

Pasteurization is a thermal process carried out in liquid foods in order to reduce or cancel the load of pathogens that they may contain. We all know the pasteurization process of dairy products such as milk, and therefore we are not going to dwell on its methodology or its history. Better, let's explore some of its less conventional uses.

Less well known, for example, is that this process is also widely used in the fruit juice and juice industry. Several studies have quantified the effects of this process on the organoleptic properties of the liquid and its vitamin benefits.

It has been established that the general temperature that eliminates traces of peroxidase activity (POD, which reflects the presence of pathogenic microorganisms) in juices is of an average of 90 seconds at 80ºC.

Surprisingly, these same studies show that the loss of the amount of vitamin C in these liquids can exceed 80% after pasteurization. This is attributed to the fact that vitamin C can be easily degraded by exposure to heat and by oxidation. Thus, in many cases vitamins must be added artificially.

Thus, this example shows that, despite its widespread use (not only in milk, but also in juices, beer, egg products and a long etcetera) pasteurization also presents certain Bookings. Much less does this imply that it should not be done, as it will always be better to lose some properties of the food along the way than to die from a gastric infection.

You may be interested in: "Louis Pasteur: biography and contributions of the French bacteriologist"

2. Refrigeration

Despite the fact that we all have a refrigerator at home as part of the family of essential appliances, few know the conservation methods that occur in it. We get philosophical, because really cold does not exist, so cooling is based on extract heat from a body and transmit it to another place capable of absorbing that thermal energy (in most cases, water in the form of ice).

The purpose of the food refrigeration process is twofold:

That meat foods are covered by a natural "film" that acts as a barrier to both oxygen and water vapor.
Prevent the development of bacteria that are pathogenic to the human body or of agents that promote food spoilage.

Thus, it can be summarized that refrigeration (and to a greater extent freezing) are preservation processes that protect food from environmental and biological inclemency. It is worth mentioning that freezing is an even more aggressive process, as it transforms residual moisture in food tissues into ice crystals, which inhibits the growth of most bacterial species.

3. Dried or dehydrated

Food drying is one of the oldest dehydration processes used by humans. The combination of absolute conservation is observed in lyophilization, as it is a process that combines both freezing and dehydration stages.

We go further, because this method is not only reduced to food: without preservatives or chemicals, freeze-drying is the most appropriate process to preserve cells, enzymes, vaccines, viruses, yeast, serum, blood derivatives, algae, as well as fruits, vegetables, meats, fish and foods in general.

Returning to the more primitive method, it should be noted that during drying, the alimentary tissue of the food loses its moisture content, which results in a concentration of the nutrients in the remaining mass. Even so, it is expected that the water-soluble vitamins are partially oxidized, because after all the water molecules are leaving the food by evaporation. This is the case of vegetables, for example, that without human action, can lose 80% of their carotenes due to the drying process.

4. Canned

Unquestionably, it is the most widespread commercial preservation method globally, as it is used for almost any type of food and allows preservation during very large temporary spaces. Any microorganism present in the food is eliminated by this procedure, and no new one can access it due to its sterile condition with respect to the environment.

After the canning process, the food is subjected to a temperature of between 100º and 150º C for a certain time. After this period of sterilization and as long as the package is not opened, it is virtually impossible for any microorganisms to enter the food and alter its properties.

5. Other methods

While pasteurization, refrigeration, drying, and canning are some of the most popular food preservation methods extended today in western countries with a rail infrastructure, there are many others that we can not leave in the inkwell. We give you some more examples:

Salty: when treated with kitchen salt, meat and fish become dehydrated. In addition, the proliferation of germs in these tissues is prevented. Smoking: the antimicrobial properties of wood smoke are used, as well as the destruction of germs and enzymes by heat. Acidification: based on the reduction of the pH of the food that prevents the development of microorganisms, by adding acidic substances such as vinegar.

Conclusions

Despite the fact that the exposed theme may seem an anecdotal question and "of a home nature", nothing could be further from the truth. The World Health Organization lists foodborne diseases as one of the most relevant global health concerns. For this reason, there are organizations such as the Reference Group on the Epidemiology of the Burden of Transmission Disease Alimentaria (FERG), in charge of monitoring epidemiological outbreaks and morbidities associated with pathologies of nature food.

For all this, a global standardization and distribution of the above named conservation methods is essential, so that pathologies such as ascariasis (presence of helminth worms in the stool) or infections of a bacterial nature (such as salmonellosis) are a thing of the past, especially in countries of the Global South, where these types of disorders have an associated mortality at all contemptible.

Bibliographic references:

Food Safety, World Health Organization (WHO). Picked up on September 9 in https://www.who.int/es/news-room/fact-sheets/detail/food-safety
Mora, O. O., Villareal, Y., Spain, D. F. M., & Ceron, A. F. (2013). Pasteurization effect on sensory characteristics and vitamin C content in fruit juices. Biotechnology in the Agricultural and Agroindustrial Sector: BSAA, 11 (2), 66-75.
Navas, J. S. R. (2006). Food freeze drying. Reciteia Magazine: Food Science, Technology and Engineering Reviews, 6, 1.
Brennan, J. G. (2006). Food Processing Manual (No. 664 M294m). Zaragoza, ES: Acribia.