When must a knife be cleaned

June 4, 2023
when must a knife be cleaned

Knives are essential to every kitchen and are used for preparing various foods. Every time a knife cuts into food, it retains the particles from that food. So if you use the same knife to cut multiple foods without cleaning the blade in between, you run the risk of transferring particles and chemicals among foods. 

If you let a knife collect residue from food, it will dry up on the blade and be challenging to remove. Therefore, cleaning and sanitizing a knife blade regularly is essential to prepping and cooking food. With that said, many knife owners aren’t sure when a knife must be cleaned and sanitized to keep it clean and germ-free. 

The rule of thumb is to clean your knife after each use and wash it properly if you use it to cut meat. However, there is much more to knife hygiene than just knowing when to clean it. You must understand the risks involved with using an unclean knife and the importance of a clean knife. This article will explain knife hygiene and tell you when and how often you should clean it. 

Issues associated with using an unclean knife

A knife makes contact with multiple foods since most people use the same knife to cut different food items. When an unclean knife comes into contact with different kinds of food, it transfers some residue from the previous food to the next. Some serious risks are associated with the cross-contamination of foods through unclean knives. Here is a list of some critical issues associated with using an unclean blade:

Bad taste and odor: Foods such as garlic and coriander are notorious for leaving their flavor on the knife when you cut them. If you use the same knife to cut another food without cleaning it, the odor and taste of the previously cut food may get transferred to the next. 

The flavor and taste transfer becomes especially apparent when you cut fruit directly after cutting food with a strong flavor. Since fruits are eaten raw, an unclean knife can affect their flavor the most.

Similarly, some fruits also leave their strong flavor on the knife’s blade, and cutting another food, such as a cake, can ruin the cake’s taste after cutting certain fruits. You wouldn’t run into this issue if you cleaned your knife, especially after cutting foods with a strong flavor. 

problems with using an unclean knife

Risk of allergies: If you or one of your family members is allergic to a particular substance, contact with the allergen should be avoided at all costs. Lactose intolerance is a common form of allergy, and knives can expose allergic individuals to lactose if the knife is not cleaned regularly. 

Think of a scenario where a knife cuts or spreads butter. The knife will have come in contact with lactose from butter, and when the same knife is used to spread lactose-free butter, for a lactose intolerant person, it transfers some of the allergens to the lactose-free product. 

The transfer of potential allergens is a significant risk associated with not cleaning your blade regularly.

Cross-contamination: As mentioned earlier, when prepping a meal, a single knife may be used to cut meats, and the same knife may also cut a loaf of bread. While something like a fresh loaf of bread is not a source of potentially harmful bacteria, raw meat contains pathogens that can sometimes put your life at risk.

So whenever you cut meat or fish, you should consider the knife contaminated and a potential source of cross-contamination. A contaminated knife shouldn’t be reused until washed and sanitized correctly. 

clean knife after cutting fish

When must a knife be cleaned and sanitized?

Whether cooking in your home kitchen or a commercial setting, you must know your knives’ proper cleaning and sanitization schedule. 

Here is how you can tell when it’s time to clean and sanitize your knife:

After cutting raw meat: As you would have probably guessed by now, raw meat is a significant source of bacteria for your knife. So naturally, whenever your blade comes in contact with any type of meat, it requires cleaning and sanitization before cutting other foods. Salmonella and E. coli are just two of the deadly pathogens your knife may come in contact with after cutting raw meat. Exposure to these pathogens can result in diarrhea, stomachache, and vomiting; in severe cases, they can even cause death. 

The pathogens from raw meat can also end up on the knife’s handle, so cleaning the whole knife and not just the blade is essential.  

clean knife after cutting raw meat

After sharpening a knife: While most stainless steel knives rarely require resharpening, traditional carbon steel knives must be sharpened often. When you sharpen a knife, small pieces of steel are removed, and some may get stuck on the blade itself. 

If the knife isn’t washed right after the sharpening process and is used instead to cut food, the small metal pieces can be transferred to the food item. As a result, you may end up ingesting the metal pieces, which can be bad for your health. Therefore, washing your blade thoroughly after sharpening it is essential to remove all the leftover metal pieces. 

clean knife after sharpening

After cutting yourself: Getting cut when using a knife is an inherent risk of cooking food. However, a knife that has made contact with human blood becomes a source of blood borne diseases. 

So once you have applied an antibiotic and cared for your wound, you should wash the knife to remove any leftover blood. 

clean knife after cutting yourself

After cutting sticky food: Some foods are inherently sticky and can stick to your knife, making them unusable. So cleaning your knife’s blade is essential if it has made contact with sticky food. 

It can be difficult to remove if a sticky substance dries up on the blade, so washing the knife before it dries up on it is essential. 

These are just some of the situations that warrant a thorough knife cleaning. You may need to clean your knife if it simply gets too dirty. 

clean knife after cutting sticky food

How to clean and sanitize a knife?

Now that you know when to clean and sanitize a knife, it is time to answer another critical question. How exactly do you clean and sanitize a blade properly? Here are some steps to follow in cleaning a knife thoroughly:

how to clean knife

Step 1. Remove any loose food debris from the knife before you start the deep cleaning process. You can use a clean cloth or paper towel to wipe the knife to prepare it for deep cleaning. 

Step 2. Now prepare some hot water and you can either pour the hot water onto the knife or briefly submerge the knife into hot water. Hot water treatment is a great way to kill bacteria and other pathogens from your knife. 

Step 3. Take a sponge and add dishwashing soap to it, then scrub the whole knife with it 

Step 4. Run warm water through the tap and rinse away all the soap. 

Step 5. Wipe the knife with a clean cloth or paper towel to dry it up thoroughly if you simply want to clean the knife. 

Note: If you want to sanitize the knife, however, you don’t have to dry the knife. 

Step 6. Pour some sanitization liquid into a tray and briefly submerge the knife in the liquid. This step will remove any leftover pathogens and make the knife germ-free.


A clean knife will not only be more hygienic but also remain sharp and durable for longer. Now that you know when and how to clean your knife, you can better care for this essential kitchen utensil. 

That being said, you should ensure you are using the correct type of soap and sanitization liquids to avoid damaging your blade. 

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