Food safety

Biological contaminants & 4 sources of biological contamination

Contamination of food items by other living organisms is known as biological contamination. Foodborne illnesses arise ...

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  • Contamination of food items by other living organisms is known as biological contamination.
  • Foodborne illnesses arise from the consumption of foods affected by biological contamination.
  • The most common examples of biological contamination include bacteria, viruses, parasites, and fungi.

Food is the main source of energy and nutrition for human beings. Despite this, humans are not the only organisms that benefit from all kinds of foods. Similar to how people use food and convert it into energy, microorganisms do so. They break down complex food structures into simpler components and use these for reproduction and biological functions.

Although microorganisms can be readily found in nature decomposing organic matter, they can quickly work their way into the food industry. When microorganisms are unintentionally present in food, they are considered biological contamination. This type of contamination is responsible for most reported foodborne illness cases globally.

Of the approximately 600 million cases of foodborne illnesses all over the world, a majority of this portion is caused by biological contamination. The Centers for Disease Control and Prevention has reported that there are at least 250 identified foodborne illnesses known to the food industry; the majority of these illnesses are attributed to biological contamination.

Every year, restaurants and other food chains are subject to public scrutiny because of the attention it gets from foodborne illness cases. This is because almost half of the reported cases of foodborne illnesses in the US are related to eating cooked foods from restaurants and deli stores. As a food business owner, you are responsible for training your team in food safety and orienting them with these potential biological contaminations for the protection of public health.

To help you control biological contamination in your food business, read this full and detailed article.


biological contamination of food


What is the biological contamination definition?

Biological contamination refers to the event wherein any other living organism, mostly microorganisms, contaminate a food product. Additionally, the term biological contamination expands to the context of contamination caused by the organic compounds or by-products of these microorganisms. The foodborne illness-causing microorganisms are collectively known as pathogens.

Even though some microorganisms such as beneficial bacteria can be used to enhance the characteristics and shelf-life of foods, pathogens can cause life-threatening effects. The premise of biological contamination refers to the unwanted presence of these microorganisms. 

Once pathogens contaminate food and grow to unsafe levels, they can cause foodborne illnesses that may have mild to life-threatening effects. Depending on the type and initial load of the biological contamination, the consequences can be very serious. 

For example, cases involving biological contamination of botulin, which is the toxin produced by Clostridium botulinum, can warrant a foodborne illness outbreak warning with just 1 or 2 cases. The effects of some biological contamination can mean life or death, especially for individuals with weak immune systems.


apple biological contamination


What are the main types of biological contamination?

Biological contamination in food generally refers to the unwanted presence of disease-causing microorganisms. We consider them unwanted as pathogenic microorganisms can cause a wide range of illnesses and spoil food, leading to food waste. Some biological contamination can produce observable spoilage characteristics.

A biologically contaminated food may show signs such as the production of foul smell, discoloration, loss of structural integrity of food, visible presence of a pathogen or bacterial communities, and drastic change in flavor. Despite this fact, some types of biological contamination can go undetected, such as when a bacterial toxin or virus causes the contamination. 

In the food industry, the main types of biological contamination are caused by the following:

  • Bacteria. Food bacteria are some of the most common biological contaminants. They are present in almost any type of food, on food handlers, and can even thrive on food contact surfaces. Bacteria such as Staphylococcus aureus are commensal to the body of food handlers. This means that they live on human skin or respiratory tract without harming them. The potential risk that this microorganism can cause lies if cross-contamination or human exposure to foods occurs, which could then spread to other points in the kitchen. Other common bacteria are soil-borne, which means they can be very present in raw foods such as vegetables, fruits, crops, and even livestock. One of the fastest ways for biological contamination to spread is through contaminated water. Most pathogens are transmitted through the water system close to the ground and sewage. Water is a major source of most pathogens.

  • Fungi (molds and yeasts). When you buy oranges in the supermarket, you may sometimes see patches of green and white circles. Sometimes on slices of bread, you may observe cottony substances that are white or black. Both observations indicate the biological contamination by fungi. This type of contamination is mainly seen in challenging conditions for bacteria, such as in acidic food, as molds and yeasts can tolerate acidic conditions and the competition for nutrients is less since other pathogens do not like this condition. Molds can produce microbial communities that vary in color, making them easy to detect. Unlike bacteria, molds can be transferred through spores floating in the air. Although their mode of transmission is faster, they are less likely to cause foodborne illnesses since you can readily observe them and exclude the contaminated food.

  • Viruses. Viruses mainly infect living organisms such as humans and animals, but they can also be transferred through food. In fact, one of the most common foodborne illness-causing pathogens is a virus, which is the Norovirus. Other viruses can also travel through water and contaminate food such as seafood, fruits, and vegetables. Since these types of food require less heating or can be eaten raw, the chances of causing foodborne illness are high. Foodborne viruses commonly cause gastroenteritis in children and adults.

  • Parasites. This type of biological contamination is common in raw meats. Parasites, although very motile, are tiny and cannot be seen by the naked eye. As their name suggests, parasites are not commensal and can harm the host that serves as their source of nutrition. Parasites are transmitted from host to host or through consuming foods contaminated by a parasite. A common example would be the presence of Trichinella spiralis, a common parasite in contaminated pork meat. This parasite could cause mild to severe gastroenteritis, especially if the contaminated meat was consumed raw or undercooked. To ensure safety, pork must be properly cooked to the correct internal temperature.

  • Toxins. In some cases, toxins associated with the mentioned biological contaminants are also considered to be under this category. Pathogens such as molds and bacteria can release toxins in foods which can then affect the consumers. These toxins can cause acute symptoms typical of food intoxication. In this type of food poisoning, it is the toxin that causes the symptoms rather than the pathogen. Toxin-producing pathogens can cause serious damage as the toxin that they produce are not detectable by the human eye. Additionally, they are far more resistant to processing such as cooking and other environmental conditions than the pathogens themselves.

In the food industry, there are other types of biological contamination. Most contaminations under this category are transmitted through fecal routes and contaminated water systems. This is why having a clean water supply and regular monitoring of this route is important. In addition, proper monitoring and control features must always be in place for proper detection and prevention.

Most, if not all, biological contaminations are sensitive to environmental factors such as extreme temperatures. That is why cooking and storage are very important food safety operations for any food business. Cooked foods and properly stored ingredients significantly reduce the potential risk of foodborne illness to human health. To help you control these operations consistently, use our digital solutions at FoodDocs.

With our digital Food Safety Management System, you can get automatically generated monitoring logs for cooking, cooling, and cold storage in just an average of 15 minutes. In addition, our system can also help you remind food handlers of when to perform the monitoring tasks by sending them intuitive notifications. Time is always an important factor in controlling biological contamination. When left uncontrolled, the growth of bacteria can double in just 20 minutes. As such, constant and consistent monitoring are crucial.


FoodDocs food safety system-1


What are examples of biological food contamination?

Bacterial contamination may be caused by pathogens such as Salmonella, Listeria, and E.coli. These examples are just some of the most well-known foodborne bacteria that cause food poisoning around the world. Food bacteria commonly contaminate foods through the water system and with poor food handling practices.

Biological food contamination may be caused by the previously mentioned pathogens. The severity and range of their effects depend on their type, initial load, and human health. Any food can be affected by biological contamination. Merely forgetting to properly wash your hands can contaminate the foods being prepared.


What is the best example of biological contamination?

The biological contamination by Norovirus has been estimated to cause approximately 685 million cases worldwide, of which 200 million affect children under 5. It is part of the Big 6 foodborne illness-causing pathogens.

Norovirus biological contamination is commonly spread through contaminated cooked food and water. In addition, as per its characteristic of being a virus, it can also be spread from human to human. It can cause symptoms such as excessive vomiting, abdominal cramps, diarrhea, fever, and muscle pain.

As you could deduce, Norovirus is the most common cause of gastric outbreaks worldwide. In fact, the World Health Organization Foodborne Disease Burden Epidemiology Reference Group (WHO FERG) ranked norovirus as the top cause of foodborne illness, the fourth main cause of foodborne deaths, and 5th main cause of disability-adjusted life years.


5 Biological contaminants in food

Biological contaminants are very common in the food industry. Some are even a natural part of the raw foods and would only become a contaminant if the process is unable to remove them. Of the 250 known causes of biological contaminations and in addition to Norovirus, the following are ranked to cause the most numbers of foodborne illnesses every year:

  • Listeria monocytogenes. The causative agent of Listeriosis is L. monocytogenes. This biological contaminant is commonly liked in dairy products including ice cream and cheeses for its ability to withstand low-temperature storage. Other high-risk foods when it comes to Listeria contamination include deli meats, processed meats, and raw poultry.

  • E. coli. Popularly known as the main cause of traveler's diarrhea, pathogenic strains of E.coli can cause foodborne illnesses even with very small amounts. E. coli is most commonly transmitted through dirty water as it comes from stools. It can also contaminate meat and persist if raw materials are not properly cooked to the correct internal temperature. Some strains that are most commonly known to cause foodborne illnesses include enteroinvasive E. coli (EIEC), enterohemorrhagic E. coli (EHEC; 0157: H7), and enterotoxigenic E.coli (ETEC).

  • Campylobacter. This pathogen causes at least 1 million food infections in the US each year. It is most commonly implicated in consuming raw or undercooked meats., especially poultry. 

  • Salmonella. Most commonly implicated in poultry meat and poultry products, Salmonella causes at least 1.35 million cases of foodborne illnesses in the US alone. This biological contaminant can also affect other foods such as vegetables, peanut butter, and other raw meats. 

  • Clostridium perfringens. Commonly found in the intestines of humans, this pathogen infects food through contaminated water. It can contaminate foods such as raw vegetables, poultry, pork, and even dried foods including dehydrated soups. C. perfringens can cause watery diarrhea and severe abdominal cramps when left untreated.

The mentioned examples in this section are only representative of some of the most widely known biological contaminations and relevant organisms. There are other examples that can potentially contaminate your food production. Some biological contaminations are more likely to occur in your operations depending on the type of food products you are producing.

Food handlers must always be aware of which major challenges from biological contaminations must be addressed and how to control them. Handling any high-risk food in your food business means a high level of food safety standards is a must.

Most types of biological contamination are caused by mesophilic organisms or those that prefer room temperature. This fact is why any high-risk food must always be stored at the right temperature and away from the temperature danger zone


What are the 4 sources of biological contamination? 

Four main sources of biological contamination include soil and water, cross-contamination, raw materials, and pests. Any type of biological contamination can be introduced at any point in the food processing system. Some pathogens have a natural affinity toward a particular food. Depending on your food products, you may need to assess and tailor control procedures for particular biological contamination. You can then use the identified type of contamination in setting critical limits for your food safety operations.

One major factor in controlling biological contamination is identifying its potential sources. Here are 4 major sources from which some of the major biological contamination may come:

  • Soil and water. The agricultural practices applied in producing raw materials such as vegetables, fruits, crops, and even livestock can heavily affect the products and affect environmental safety with an ecological risk. Since most foodborne illness-causing pathogens come from the fecal route, the use of manure as fertilizer can significantly increase the risk of biological contamination. Additionally, pathogens can be transported throughout a farm field by irrigation. Biological contaminants in water can contaminate almost everything in your kitchen since water is a universal ingredient in any food business. This also applies to preventing chemical contamination such as any heavy metal pollution and toxic chemical. Consumption of food crops affected by biological contamination can significantly put human health in danger.

water is one of the 4 sources of biological contamination


  • Cross-contamination. Biological food contamination can come from food handlers and the equipment used in the indoor spaces of your kitchen. Aside from the fact that humans naturally have pathogens on their skins, improper food handling is the fastest route for spreading biological contamination. Without proper control such as proper handwashing in-between handling food and equipment, contamination can occur and spread throughout your kitchen.

  • Raw materials. As mentioned, almost all raw materials naturally have microorganisms on their surface. What you want as a food business owner is to get a supply of materials from a supplier that applies good manufacturing and agricultural practices. This ensures that the raw materials that you use are free or have less biological as well as physical contamination. 

  • Pests. Although generally regarded as physical contamination, pests carry several different pathogens that have risks to human health. When pests leave behind droppings, hair, nails, severed body parts, or merely have slight contact with food, the pathogens that they carry can be transmitted. 

Understanding the sources of biological contamination allows your food safety team to create a more efficient monitoring system by focusing on the correct aspects of your food business. It also allows you to note which parameters must be measured, the critical limits, and how to verify appropriate control. 

To help you get all of these monitoring procedures and forms set up in just an average of 15 minutes, just start using our digital Food Safety Management System at FoodDocs. Using artificial intelligence, our system can automatically create the most significant digital monitoring forms based on your food safety operations. All you have to do is to answer a few basic questions to describe your food business.


What are the effects of biological contamination on public health?

Biological contamination carries the risk of causing foodborne illness outbreaks. When contaminated food is consumed, customers may become ill and suffer different symptoms depending on the involved biological contaminant. In more severe cases, biological contamination can even cause death. Every year, at least 3,000 consumers die in the US, whereas 420,000 deaths occur worldwide due to foodborne illnesses.

Biological contamination can significantly affect the community. When affected by foodborne illness, the members of the community become unable to connect and perform their daily tasks. As such, the economy suffers as well. Hospitalization and medical care uncontrollably grow in demand when biological contamination occurs and attention to other medical cases becomes divided.


What symptoms may biological contamination cause?

Biological contamination may show different symptoms depending on the involved pathogen, the load of contamination, and even human health. Individuals who are considered to be under the high-risk group are more likely to suffer more severe symptoms when compared with health consumers. Children under the age of 5, pregnant women, the elderly, and those with immune deficiency problems may suffer greater.

Some of the most common symptoms caused by biological contamination may include the following:

  •  Nausea
  • Vomiting
  • Diarrhea
  • Fatigue
  • Abdominal cramps
  • Fever

In more serious cases, regular diarrhea can become bloody or very watery. When blood is involved, even with vomiting, the affected consumer must immediately seek medical attention. The onset of symptoms usually shows signs from 6 to 24 hours after consuming contaminated foods. A mild foodborne illness usually takes 1 to 2 days to subside and needs constant rehydration to help the body fight the infection. 


How to detect biological contamination?

The hard part about biological contamination is that you cannot see them until they produce significant changes in the food products. With the exception of molds, most pathogens are not visible to the naked eye. That is why detection methods using test kits and more advanced machines are used in larger food businesses. 

Here are some basic and more advanced procedures used to detect biological contamination:

  • Through observation of food products and raw materials. When biological contaminants grow to a significant number, they can cause significant changes in the surface and appearance of food. At times, they can cause discoloration, unwanted softness, and even the formation of film or slime on the surface. A more obvious sign would be a change in the smell and taste of foods. 
  • Traditional microbial plating methods. Although the results of this detection method may take time, this method is fairly reliable. Samples are diluted and plated in a growing medium to detect if there are any present pathogens such as coliforms in water. This method can be used to quantify the contaminants whether their number can cause a significant negative effect or if they are up to standards. Traditional plating methods are commonly used for counterchecking the results of more advanced detection methods for bacteriological contamination.
  • Advanced test kits. This type of detection method offers a more accurate and more rapid result. Test kits are built to detect very specific targets and give you results within minutes or hours. Despite this, they can be costlier than most conventional methods. Different test kits can also be used to detect toxins, such as endotoxin contamination, which is normally undetectable under the eye of a food handler.


test kit for food contamination


There is currently a wide range of efficient detection methods in the industry. The type of detection methods used in a food establishment may vary depending on the urgency of the results as well as their specificity. Some tests only require a yes or no answer, whereas some need more detailed information. In general, the important bit for every food business is to know which biological contamination is most likely to contaminate their materials and put any consumer in danger. The efficiency of a detection method is very useful for making decisions such as in food recalls.

Food safety teams are responsible for detecting and identifying biological hazards in their production process. Biological hazard identification is a critical component of developing a food safety plan. At FoodDocs, we have created a smart, free CCP tool to help your team identify the appropriate level of action for biological hazards in your food operations. 


How to avoid biological contamination?

As the focus of the US food safety industry promotes, prevention of foodborne illnesses by focusing on the source is more effective. This approach significantly reduces the occurrences of foodborne illnesses as well as food waste. To do this, every food safety team must be aware of how to properly avoid any type of contamination. At FoodDocs, we have created a digital solution that will help every food business maintain food safety compliance.

In this section, we have highlighted some of the most important ways how you can avoid biological contamination and how our digital solution at FoodDocs can help you.

  • Raw material inspection. When selecting a supplier, always ensure that their raw material supplies will come with proof of high food safety standards such as a certificate of analysis for present pathogens. This will help you decide whether the goods are safe for food production or not. Additionally, you must also monitor the conditions in which these goods are delivered. Using our digital solution, our system can automatically create a Receiving Temperature Log for your food safety team.

  • Storage conditions. The growth of bacteria and other foodborne pathogens on any high-risk food can be significantly controlled by using controlled temperature storage. Storing foods at the temperature danger zone would speed up the spoilage process as it favors the growth of pathogens. In our system, you can get automatically generated monitoring forms for monitoring your storage conditions. Our Fridge and Freezer Temperature Logfeatures an auto-fill function that can help your team save time and would only require verification. 

  • Ensure proper cooking process. The majority of biological contaminants are sensitive to heat. Foods must be properly cooked to the correct internal temperature all the time to ensure that any existing biological contamination will be controlled to an acceptable level. Properly cooked foods are less likely to cause any foodborne illness. Use our Cooking Temperature log to automatically record all readings of your cooking processes.

  • Cool food products properly. As important as low-temperature storage, cooling products must be properly done to prevent biological contamination. To help you record temperature readings while performing the 2-step cooling process, you can use our Cooling Temperature Log at FoodDocs.


Temperature log FoodDocs

FoodDocs Temperature Log


What is even more efficient with our digital solution is that our system features a smart notification system. This feature automatically alerts food handlers whenever a task needs to be done so that no food safety operation is forgotten.You can customize the frequency of these alerts to fit your specific food safety routines.

Food safety compliance can even become more efficient through our auto-fill system. All mentioned monitoring logs feature a system that prefills the logs based on your previous data entries. This can save your team's time and would only require verification. Find out more about this digital solution below.


Digital Food Safety Management System from FoodDocs

In addition to the mentioned food safety tasks above, there are other operations required to maintain food safety in a food establishment's day-to-day operation. Every task is important to keep your customers safe while serving quality food. Using our digital Food Safety Management System, you can monitor all food safety tasks in the palm of your hand.

Using artificial intelligence our system will use the information you have provided to create a tailored digital FSMS for you. What is even more impressive is that you can further customize every monitoring form to fit your specific operations. In addition, you can convert your paper-based monitoring logs into our digital platform such as for water supply monitoring. Create a digital checklist where you can also attach the official results of your partner testing laboratories as supporting documents.

Water testing log FoodDocs

FoodDocs Water Testing Log


In addition to automatically generated monitoring logs, our digital FSMS can provide you with the following features:

  • Smart notification features that will help remind your food employees of food safety tasks, This feature will send intuitive notifications to food handlers whenever a task is due.
  • A real-time dashboard that offers an overview of your daily operations. Use this feature so you can save at least 20% of your time supervising your team. Identify areas that need more improvement and attention with this dashboard.
  • Digital cloud storage where you can store all of your digital documents. Access and organize all digital documents with ease using this dedicated cloud storage for you.

Our team of food safety and technology experts knows how hard it may be to maintain food safety compliance on a daily basis. That is why we have come up with this digital solution to help every food business make compliance an easy task.

You can try our extensive features yourself when you avail of our free, 14-day trial. Experience how our digital FSMS can help you in maintaining food safety compliance effortlessly and join our family of more than 20,000 customers worldwide.



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