You are here: Home / News / News / Does Bacteria Perish With Freeze Drying?

Does Bacteria Perish With Freeze Drying?

Views: 277     Author: Kaylee     Publish Time: 2023-10-12      Origin: Site


facebook sharing button
twitter sharing button
line sharing button
wechat sharing button
linkedin sharing button
pinterest sharing button
whatsapp sharing button
sharethis sharing button
Does Bacteria Perish With Freeze Drying?

A popular technique for preserving food is called freeze drying, which is using a freezer to remove water from food. Harmful bacteria are a major source of concern when it comes to food safety since they can cause food poisoning and other health problems. Does freezing dryness efficiently eliminate bacteria?

There are two basic steps in the freeze-drying process: primary drying and secondary drying. First drying involves freezing the food and gradually removing the water molecules via a process known as sublimation, in which the frozen water instantly turns from a solid to a gas. This can efficiently destroy some forms of bacteria and create an environment that is unfriendly to their growth.

Is Freeze Drying Adequate?

Freeze drying, sometimes referred to as lyophilization, is a dehydration method used to preserve different foods and other products. There are three key processes in this process: freezing, primary drying, and secondary drying.

A product's water content can be reduced through freeze drying without going through the liquid phase. The product must be frozen to an extremely low temperature in the first phase. By a process known as sublimation, the frozen water molecules are immediately transformed from solid to gas during primary drying, eschewing the liquid phase. This stage is essential for maintaining the product's heat-sensitive components, taste, appearance, and nutritional content.

The frozen product is subjected to secondary drying following first drying. This stage entails eliminating any last bits of moisture from the product to extend its shelf life and lower the possibility of bacterial contamination.

When rehydrated, freeze-dried foods maintain their same texture and structure. With this preservation technique, food items can be stored for an extended period of time without losing their flavor or quality. Producing freeze-dried goods, such as pet food, fruits, vegetables, and even dairy products, is a common usage for freeze drying.

Which Microbes Are Affected By Freeze Drying?

By eliminating water from food products, the food preservation technique known as "freeze drying" extends their shelf life and lowers their potential for bacterial infection. Many types of bacteria can be killed by freeze drying, however other bacteria have evolved defenses to the technique.

It has been noted that gram-negative bacteria with resistant cell membranes, including Salmonella, Yersinia, E. Coli, and Campylobacter, can withstand freeze drying. These bacteria are able to survive harsh environments, such as the freeze-drying process, because of their outer layer of protection.

The existence of fatty tissue is one of these variables. Because fat functions as a barrier, bacteria found in fatty tissues may be more resistant to freeze drying. Furthermore, how the bacteria react to freeze drying may depend on where they are located within the food matrix.

Let's use the Lantian Vacuum Freeze Dryer as an example to show how bacteria react to freeze drying. With this freeze drier, you may successfully extract water from a wide range of food products, such as fruits, vegetables, and even pet food. It is important to remember that although freeze drying can greatly lower the amount of bacteria present, some bacteria may still remain, particularly gram-negative bacteria with resistant cell walls.

EVA Foaming Machine

Does Bacteria Perish With Freeze Drying?

Eliminating water from food items to stop bacterial infection and spoiling is the process of using freeze dryers, a commonly used food preservation technique. In order to improve shelf life and facilitate long-term storage, it is frequently used for freeze-dried goods, including pet and dog food. Making sure food is safe and using the right food handling methods requires an understanding of how freeze drying affects bacterial viability.


To guarantee that dangerous viruses are removed from raw meat, it is essential to boil it before freeze-drying. These viruses may not be eliminated if raw meat is freeze-dried without first being cooked; instead, they may hibernate. This is concerning since the viruses can become infectious again if they get rehydrated or if they are eaten by a host.

In order to properly eliminate most known viruses, including those that might cause food poisoning, meat must be cooked before freeze drying, with temperatures over 140°F or 60°C. The end product is safe and the freeze-drying process becomes more dependable since the viruses in the raw meat are rendered inactive through cooking.

It is advised to handle food properly and to use cooking methods prior to freeze drying in order to guarantee food safety. Safe manufacture of freeze-dried goods is made possible by this substantial reduction in the danger of viral contamination.

The Parasites

In certain food categories, such as freeze-dried goods, parasites may be harmful to your health. There is no certainty that parasites will be eliminated by freeze-drying, even though low temperatures can deactivate some parasite species.

In order to remove the frozen water from food, a procedure called sublimation is used in conjunction with freeze drying, which entails freezing food at extremely low temperatures. There are parasites that can be killed by this that are cold-sensitive. Freeze drying by itself might not be sufficient to entirely remove other parasites.

Cooking foods according to the right methods is crucial to guaranteeing that parasites are removed from freeze-dried meals. The most successful way to get rid of parasites is to cook food at 140–167 degrees Fahrenheit for at least 15–30 minutes. Ensuring that any residual parasites are completely eliminated within this temperature range can enhance the safety of food.


Regarding freeze-drying and the security of processed foods, salmonella is a serious concern. Many incidences of food poisoning have been reported globally as a result of this foodborne disease. If Salmonella or other dangerous germs are present in the food throughout the freeze-drying process, there is a chance that the finished product will become contaminated.

Unsanitary food handling practices, cross-contamination during production, contaminated raw materials, and processed foods, especially freeze-dried goods, can all lead to Salmonella contamination. These microorganisms may survive the freeze-drying process if improperly handled, and consuming them could result in disease.

Contamination of freeze-dried foods with Salmonella poses serious dangers. Reactions like diarrhea, vomiting, fever, and abdominal pain might occur after consuming tainted items. If things go bad enough, it can potentially land you in the hospital or, in very rare circumstances, kill you, especially if you have compromised immune system.

Soybean Dryer

Suitability For Bacterial Removal

Killing microorganisms in food products can be achieved with success by using freeze drying. Sublimation, a technique that involves freezing food and causing frozen water molecules to instantly change from a solid to a gas without first going through a liquid phase, is how the food is dried after being frozen. Food poisoning and bacterial contamination are considerably decreased by this dehydration procedure, which also stops the growth of dangerous germs.

Some bacteria may be more resistant to freeze drying than others, even though it is a usually efficient preservation technique against most types of bacteria. The efficacy of freeze-drying food can be affected by various factors, including the type of bacteria present and the food being dried. Due to the protective spore shells they have, certain bacteria, such as spore-forming species of Bacillus and Clostridium, are more resistant to freeze drying.

To freeze-dry food items, such as raw and frozen foods, pet foods, and even dairy and egg goods, one common option is the Lantian freeze drier. With this freeze dryer, you may safely and permanently store a variety of food products since it guarantees that dangerous bacteria are efficiently eliminated throughout the freeze-drying process.

Is It Possible To Lower The Bacterial Population?

By removing water from food products, the food preservation technique known as "freeze drying" extends the shelf life of the product. Hazardous bacterial contamination is one of the main issues with food safety and preservation.

Learn To Wash Your Hands

When it comes to freeze drying food, hand hygiene must be practised properly. By doing this, food products can have their shelf life and nutritional value extended while maintaining their water content. Nonetheless, the risk of bacterial contamination rises sharply in the absence of good handwashing practises.

The transmission of dangerous bacteria and other pathogens must be stopped by frequent hand washing. Eliminating bacteria on hands is beneficial in preventing potential contamination of the freeze-dried items. The procedure is lathering the hands for at least 20 seconds with warm water and soap, then completely washing and drying them.

Stop Cross-Contamination

In order to avoid cross-contamination when handling raw food during the freeze-drying process, appropriate precautions must be taken. Follow these procedures and safety measures:

1. Maintain food separation: Throughout the whole freeze-drying process, maintain food separation between raw and cooked ingredients. Preventing the spread of hazardous germs involves handling, storing, and processing.

2. Spotlessly clean hands and workspace: Make sure you wash your hands well—at least for 20 seconds—with soap and warm water before handling raw food. Use disinfectants intended for use in food preparation areas to thoroughly clean and sanitise the workspace.

3. Wash all utensils, trays, and surfaces that come into touch with raw food both before and after each use. To eliminate any lingering bacteria, clean them with hot, soapy water.

4. Use distinct chopping boards: To prevent cross-contamination, use different cutting boards for raw and cooked meals. Both meat and non-meat products fall under this category.

5. Properly store raw food storage: To avoid bacterial infection, raw food should be enveloped and kept in sealed containers. To avoid any possibility of cross contamination, store it in the freezer apart from cooked or ready-to-eat items.

These procedures will lessen the chance of cross-contamination-related foodborne diseases and help preserve food safety throughout the freeze-drying process.

Maintain A Consistent Storage Temperature

Food that has been freeze-dried must be stored at a constant temperature to maintain its best quality. Food can be dried out (freeze-dried) to remove water while maintaining nutrients, texture, and flavour. This is a great way to store food for a long time. However, in order to stop microbiological growth and maintain food safety, proper storage conditions must be maintained.

For optimal quality and shelf life, freeze-dried food should be stored between 0°F (-18°C) and 20°F (-7°C). The likelihood of microbial growth and pathogen proliferation is much decreased at these temperatures.

Higher temperatures have the potential to cause bacterial contamination in freeze-dried food, which could result in foodborne illness. Warmer temperatures can encourage the growth of harmful bacteria, jeopardising food safety and raising the possibility of food poisoning.

Table of Content list

Related Products