Drying for Meat Preservation: An Ancient Technique

Drying is one of the oldest and most straightforward methods of preserving meat. Long before refrigerators, freezers, or chemical preservatives existed, people across the world discovered that removing moisture from meat could keep it safe and edible for weeks or even months. The principle is simple: take away the water that bacteria, yeasts, and moulds need to survive, and you dramatically slow down spoilage. While drying has lost some of its commercial dominance in the modern era, it remains a relevant technique – especially for specialty products like biltong, jerky, and various traditional dried meats found in cultures around the globe.

How drying preserves meat 🔗

At its core, meat drying works by reducing the amount of free water available for microbial and enzymatic activity. This free water is measured as water activity (a_w) – a value that indicates how much moisture in the food is actually accessible to micro-organisms. Pure water has an a_w of 1.0, while raw meat typically sits around 0.99. Most harmful bacteria require an a_w above 0.91 to grow. Normal yeasts need at least 0.88, and common moulds need about 0.80. Even salt-tolerant (halophilic) bacteria cannot grow below an a_w of 0.75 to 0.77.

When meat is dried, moisture migrates from the interior to the surface and evaporates into the surrounding air. As a_w drops below the thresholds listed above, micro-organisms are unable to carry out their basic metabolic functions. The result is a product that is shelf-stable at ambient temperatures without requiring refrigeration – provided it is adequately dried and properly packaged.

Inhibition of enzymatic activity 🔗

It is not just micro-organisms that need water. Enzymes – the biological catalysts naturally present in meat tissue – also require free water to function. These enzymes are responsible for breaking down proteins and fats, which leads to off-flavours, texture changes, and nutritional degradation over time. As meat dries and a_w drops, enzymatic activity slows down significantly. This is why well-dried meat can retain its quality over extended storage periods. The natural degradation processes are essentially put on pause.

The science behind water activity 🔗

Water activity is not the same as total moisture content. A piece of meat can still contain a certain percentage of moisture but have low a_w if that moisture is bound to proteins, salts, or other solutes and therefore unavailable to micro-organisms. The distinction matters because it is a_w, not total moisture, that determines whether spoilage organisms can thrive.

In practical terms, reducing a_w below critical thresholds prevents the growth of vegetative bacterial cells, inhibits spore germination, and blocks toxin production by moulds and bacteria. The lower the a_w, the greater the preservation effect. Dried meat products typically target an a_w of 0.85 or below, which is widely accepted as safe for shelf-stable storage without refrigeration.

Traditional and modern drying methods 🔗

Throughout history, people have used different approaches to remove moisture from meat. Today, a wide range of techniques exists – from ancient sun drying to advanced industrial methods. Here is a closer look at the most common ones.

Sun drying and air drying 🔗

Sun drying is the earliest known method of food dehydration, dating back to around 12,000 B.C. in parts of Asia and the Middle East. The process relies on direct sunlight, warm temperatures, and natural airflow to evaporate moisture from thin strips of meat. However, sun drying has significant limitations. It requires consistently warm, dry weather with minimal humidity, and the process can be slow – often taking several days. Slow drying is risky because micro-organisms can multiply in the early stages while moisture content is still high.

Air drying is a related method that takes place indoors or in shaded, well-ventilated spaces rather than in direct sunlight. It is commonly used in cooler climates where sun drying is impractical. Both methods benefit from salting the meat before drying, which draws out additional moisture and provides an extra antimicrobial barrier.

Oven drying and electric dehydrators 🔗

Modern home processors often use oven drying or electric food dehydrators. Utah State University Extension recommends starting the oven at around 160°F (71°C) to kill surface micro-organisms, then lowering the temperature to about 140°F (60°C) for the remainder of the process. Electric dehydrators offer more consistent results because they combine thermostat-controlled heat with fan-driven air circulation, ensuring even moisture removal across all pieces.

Freeze drying 🔗

Freeze drying (also called lyophilisation) is a more advanced and expensive technique. The meat is first flash-frozen, then placed under reduced pressure so that the frozen water sublimates directly from solid to vapour without passing through a liquid phase. According to research published in Frontiers in Nutrition, freeze drying produces meat with lower moisture content compared to air-dried equivalents and causes minimal changes to flavour, texture, and nutritional value. Rehydration of freeze-dried products is also more rapid and complete than with other drying methods.

Other industrial methods 🔗

Beyond these common approaches, the food industry employs several other drying technologies including vacuum drying, microwave drying, heat pump drying, and pulsed electric field drying. Each has specific advantages. For example, vacuum drying operates at low temperatures in the absence of oxygen, making it suitable for heat-sensitive and easily oxidised foods. However, it takes longer. The choice of method depends on the balance between drying speed, product quality, energy costs, and the specific characteristics of the meat being processed.

The role of salt and heat treatments 🔗

In practice, meat drying rarely relies on dehydration alone. Salt is almost always used as a complementary treatment, and for good reason. When salt is applied to meat surfaces, it creates a hypertonic environment that draws moisture out of both the meat and any bacteria present through osmosis. This dehydrating effect works alongside the mechanical drying process to lower a_w even faster. Salt also has direct antimicrobial properties – high sodium concentrations can disrupt bacterial cell membranes and interfere with their enzyme function.

Heat treatments are equally important, particularly for destroying parasitic cysts that may be present in certain types of meat. For instance, pork and bear meat can harbour Trichinella parasites. A thermal step during or before the drying process ensures that these parasites are killed. The USDA recommends that bear meat and pork be frozen for at least a month before making into jerky to destroy any trichinae present. Alternatively, heating meat to an internal temperature of at least 71°C (160°F) before or during drying effectively eliminates parasitic cysts.

Dried meat products: less commercially important, but still relevant 🔗

In developed countries, traditional meat drying has largely given way to refrigeration, freezing, vacuum packaging, and chemical preservatives. These modern methods can extend shelf life while maintaining the texture and appearance that consumers expect. Fresh, neatly packaged meat simply appeals more to most shoppers than the tough, darkened strips typical of dried products.

However, drying remains important for certain niche and traditional products. The Food and Agriculture Organization (FAO) documents several traditional dried meat products across regions: biltong in South Africa, charque (jerked beef) in South America, pastirma in Turkey and Egypt, kilishi in Nigeria and West Africa, and odka in East Africa. Each product reflects local ingredients, climate, and cultural preferences, but all share the same underlying principle of moisture reduction for preservation.

In developing countries and rural communities where cold chain infrastructure is limited, drying continues to serve as a vital and cost-effective preservation method. It requires minimal equipment and no electricity, making it accessible to small-scale processors and households alike.

Biltong: a case study in dried meat 🔗

Among all traditional dried meat products, biltong from South Africa is perhaps the best-known example still widely produced and consumed today. The word comes from the Afrikaans bil (buttock) and tong (strip or tongue), referring to strips of meat cut from lean portions of beef, game, or other animals.

How biltong is made 🔗

The process begins with cutting lean meat into thick strips or slabs, typically 1-2 cm thick, following the grain of the muscle. The meat is then marinated in vinegar – traditionally grape or malt vinegar – which serves as a primary antimicrobial agent. According to the World Health Organization, Clostridium botulinum will not grow in acidic conditions with a pH below 4.6, so vinegar provides a critical safety barrier. After the vinegar treatment, the meat is coated with a spice mix that traditionally includes rock salt, toasted coriander, black pepper, and sometimes brown sugar. Salt both enhances flavour and further draws moisture from the meat. The seasoned strips are then hung in a well-ventilated area with good airflow and dried for 4 to 10 days, depending on thickness and desired dryness.

What makes biltong different from jerky 🔗

Biltong and jerky are often compared, but they differ in important ways. Biltong is air-dried at ambient or slightly elevated temperatures without a cooking or smoking step. Jerky, on the other hand, is typically dehydrated or smoked at temperatures of at least 71°C (160°F). This heat step in jerky production serves as a thermal lethality treatment to reduce pathogens like Salmonella. Since biltong lacks this heat step, it relies on the combined antimicrobial effects of salt, vinegar, and gradual drying to achieve microbial safety. This combination of preservation hurdles – reduced a_w, low pH from vinegar, and antimicrobial action of salt and spices – is a classic example of what food scientists call hurdle technology.

Nutritional profile of biltong 🔗

Dried biltong is a nutrient-dense product. A typical 100 g portion contains approximately 65 g of protein, only 1.9 g of fat, and about 11.5 g of water. This high protein-to-weight ratio is one reason why biltong has gained popularity as a convenient, high-protein snack beyond Southern Africa, with growing demand in North America, Europe, and Australasia.

Challenges and limitations of meat drying 🔗

Despite its long history and proven effectiveness, drying has certain drawbacks that limit its broader commercial application.

Fat rancidity 🔗

Only lean cuts of meat are suitable for drying. Fat does not dry well and is prone to oxidative rancidity during the drying process and subsequent storage. Rancid fat produces unpleasant off-flavours and can make the product unpalatable. This is why excess fat must always be trimmed before drying.

Texture and flavour changes 🔗

Drying inevitably alters the texture and colour of meat. The finished product tends to be tough, chewy, and darker than fresh meat – characteristics that some consumers find unappealing. There is also some loss of vitamins, particularly thiamin, during prolonged drying periods. Modern techniques like freeze drying can minimise these changes, but at significantly higher cost.

Intermediate-moisture products 🔗

To address the poor texture of fully dried meat, food scientists have developed intermediate-moisture foods. These products are partially dried to a moisture content of 15-50%, and then humectants such as glycerol or sorbitol are added to bind the remaining free water so that micro-organisms cannot use it. The result is a more succulent product than traditional dried meat, though humectants can affect palatability. This approach has found use mainly in military rations and pet food rather than mainstream consumer products.

Best practices for safe meat drying 🔗

Whether drying meat at home or on an industrial scale, a few key principles ensure both safety and quality:

Use lean cuts only. Trim all visible fat to prevent rancidity during drying and storage.

Slice uniformly and thinly. Since drying involves moisture migration from the interior to the surface, thinner and more uniform pieces dry faster and more evenly. Uneven drying creates pockets of high moisture where bacteria can survive.

Apply salt or a salt-vinegar treatment before drying. This inhibits bacterial growth during the critical early stages when moisture content is still high. Curing salts containing nitrites provide an additional safety margin, particularly for sun-dried products.

Maintain adequate airflow and temperature. Good air circulation is essential for removing moisture-laden air from around the drying meat. Temperatures should be warm enough to promote evaporation but not so high as to cause case-hardening – a condition where the outer surface dries and seals before the interior moisture can escape.

Store properly. Once dried, meat should be stored in airtight containers in a cool, dry, and dark environment. Even well-dried meat will eventually undergo chemical changes like lipid oxidation and browning, so refrigeration or freezing extends shelf life further.

The hurdle concept in dried meat preservation 🔗

Modern food science recognises that no single preservation factor works as effectively alone as multiple factors working together. This is the hurdle concept. In dried meat products, several hurdles combine to create an environment hostile to micro-organisms: low a_w from moisture removal, reduced pH from acids like vinegar, high salt concentration, antimicrobial properties of spices, and sometimes heat treatment or the addition of nitrate/nitrite. Each individual hurdle may not be sufficient on its own, but together they provide a synergistic preservation effect that is greater than the sum of its parts. This is precisely how products like biltong achieve safety without any cooking step.

Looking ahead: the future of meat drying 🔗

While drying will likely never regain the dominant position it once held in meat preservation, it continues to evolve. Emerging technologies like pulsed electric field drying, refractance window drying, and ultrasonic-assisted drying are being studied for their ability to speed up moisture removal while preserving nutritional quality. At the same time, global consumer interest in high-protein, minimally processed snacks is driving renewed demand for dried meat products. Biltong, jerky, and similar products are increasingly positioned as healthy, convenient alternatives to highly processed snacks.

In regions with limited refrigeration infrastructure, affordable drying techniques continue to play an essential role in food security by preventing waste and extending the usability of meat after slaughter.

What do you think? Given that drying is one of humanity’s oldest preservation methods, do you think emerging drying technologies could bring it back into mainstream meat processing? And how might traditional dried meat products like biltong evolve as consumer preferences shift toward cleaner, simpler ingredients?

References

1. https://en.wikipedia.org/wiki/Biltong
2. https://www.fao.org/4/T0562E/T0562E04.htm
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC9742493/
4. https://asm.org/articles/2024/january/salt,-microbes,-acid,-heat-in-food-preservation
5. https://en.wikipedia.org/wiki/Food_drying
6. https://extension.usu.edu/preserve-the-harvest/research/drying-meat
7. https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.1057366/full
8. https://pmc.ncbi.nlm.nih.gov/articles/PMC7285303/