The principle of food preservation through drying is to reduce the free water content in food, thereby limiting the growth of microorganisms. This method is safe only when executed with proper techniques and careful control over temperature, humidity, and hygiene during processing.

In commercial food production, dried meat products undergo stringent processes. These include selecting standard-compliant ingredients, marinating with appropriate salt ratios, and heat treating to reduce microbial loads. To significantly minimize the risk of pathogenic bacteria, dried meat processing incorporates a heating or heat treatment step to ensure the internal temperature of the food reaches a safe level.

Conversely, an outdoor temperature of approximately 40 degrees Celsius may help food dry quickly but is insufficient to kill pathogenic bacteria. Instead, temperatures ranging from 4-60 degrees Celsius create favorable conditions for foodborne pathogens such as Salmonella, Escherichia coli (E. coli), Staphylococcus aureus, and Listeria monocytogenes to multiply rapidly.

When exposed to the sun, the food's surface may dry due to water loss, giving the impression of being "dehydrated". However, the interior often retains high moisture and stays warm, creating an ideal environment for bacterial growth. If the drying period is extended or air humidity is high, microorganisms can continue to proliferate before the food reaches the necessary dryness. Consuming such foods increases the risk of food poisoning and gastrointestinal illnesses.

The outdoor drying process also makes food susceptible to environmental contamination. Raw meat releases juices and odors that attract flies, gnats, and various other insects. In hot weather conditions, fly eggs can also develop quickly, further increasing the risk of contamination.

Outdoor air contains dust, microorganisms, and pollutants. Dust and exhaust fumes can adhere directly to the food's surface throughout the drying period, increasing the risk of food poisoning, acute diarrhea, and gastrointestinal inflammation.

In some rare instances, improperly processed and stored food increases the risk of Clostridium botulinum bacteria developing, which causes botulinum poisoning. This is a dangerous condition that can lead to muscle paralysis, respiratory failure, and be life-threatening.

Food dried outdoors is prone to environmental contamination. Photo created by AI

If you wish to prepare partially sun-dried meat at home, you should choose fresh, clean ingredients with clear origins and ensure strict hygiene. Instead of relying solely on sunlight, prioritize using a food dehydrator or an oven with a drying function to control the temperature and drying time.

Before dehydrating or drying, food must be thoroughly cleaned and marinated with an adequate amount of salt and spices according to a suitable recipe. An appropriate heat treatment step can be applied before or during the drying process to reduce the microbial load on the food's surface.

Nutritionist Nguyen Thi Quynh

Department of Nutrition

Tam Anh General Hospital Hanoi