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Do you know what is cross contamination in food?

Eating safely is vitally important and many of the habits we normally incorporate into our routine are an obstacle to doing so. With the help of Noelia López, Nestlé nutritionist, we enter the world of culinary health. How we should cook to avoid the call cross contamination?

Cross contamination in the kitchen

Cross-contamination is a process in which microorganisms or other substances, such as allergens, pass from one food to another without us really knowing. It is one of the main causes of toxo-infection and is very dangerous for celiac or allergic people.

It can be caused by:

  • Direct contact: occurs because there is direct contact between raw and cooked food
  • Indirect contact: occurs when allergens pass from one food to another through hands, cloths, knives, tables, etc. that we use to cook.

To talk about nutritional well-being, Noelia López points out that we must take into account that the foods we take are insurance, that is to say, that they are free of contamination. In other words, they do not contain bacteria, parasites, chemicals or physical agents.

“Most of this type of pollution occurs in the homes themselves,” the expert points out.

How to avoid it

To avoid this contamination, the nutritionist insists that we must be meticulous in the kitchen. Following good practices to avoid cross-contamination prevents us from suffering the consequences.

The basic food safety standard specified by Noelia López is based on:

  • Clean up: both hands and utensils, with soap and water
  • Split up: separate and protect raw food from cooked food
  • copper: cook food such as meat, ensuring the reach of at least 75ºC in the center of the food
  • cool down: once cold, we must consume them after a short time or we can refrigerate them at least at 4ºC.

wash our hands

Washing your hands is a basic step, the first barrier against cross-contamination. Of course, it is often underrated. And it’s not just that, but we’re also doing it wrong.

Do you wash your hands well?

Either we forget or we do it too quickly. Because, as the nutritionist points out, washing your hands must be quite a ritual: this one rinsed three seconds with water is not enough. The estimated wash time must last at least 50 seconds!

These are the steps we must follow to wash our hands properly:

  • Scrub your palms and the top and bottom of your hands with soap and water.
  • Interlacing your fingers is important for thorough hand washing.
  • Rub your fingertips, as this is where bacteria accumulate most easily.
  • Rinse with plenty of water and dry your hands with a clean cloth.

Clean utensils and suitable material

To ensure that our kitchen is safe we ​​must take into account the cleanliness and the material of our utensils. We distinguish by groups:

Baites and scouring pads

We have to change them very frequently or disinfect them often. Because these are products with continuous daily use, something we always turn to.

Cutting boards

You cannot use the same table for cooked food as for raw food. Bacteria present in one food would pass to the other. But beyond that, we can also talk about the material ideal for cutting boards.

And although wood may seem like the best option (due to its durability or sustainability), in the kitchen it is not: its porous surface tends to absorb water, so microorganisms have an ideal environment to grow . Added to this is the possibility that it will crack from use, which can mean that our food becomes contaminated.

Noelia López recommends plastic or silicone, which can also be washed in the dishwasher. Silicone, for your comfort, easy cleaning and versatility will be the perfect choice.


Borosilicate glass is, in terms of food, the best choice for corks.

But if what interests us is plastic, we must take into account its typology to know how we can use it and with which type of food. At the bottom of these containers we will find a number that specifies the type of plastic we are dealing with. Based on that, we will use it for one thing or another.

Cutlery and knives

EFE/Barbara Walton

The same thing happens with the table, both in use and in material. In other words, we cannot use it simultaneously on raw and cooked food, nor is wood a good choice for this type of utensil.

Stainless steel, in these cases, is essential: in the kitchen, for easy cleaning, maintenance and durability, it is a material that we often turn to.

When we talk about cutlery, we must not overlook the fact that if they are in one piece, the better: they are easier to clean than those that are made up of two pieces. Since there are no spaces for food scraps to remain, the chances of food contamination are drastically reduced.

Washing food is not always a good idea

There are bad habits that pass for good and that is precisely why they are the most dangerous. And so it goes with the issue of washing food. Because, although we believe that it should always be done, the truth is that there are some foods whose washing is, in addition to being unnecessary, a possible cause of cross-contamination.

Do not wash the chicken or fish

This is the case with chicken or fish. Placing chicken or fish under water causes the resulting splashes to contaminate counters or any nearby utensils with bacteria from the food itself. The ideal and logical way to eliminate these bacteria is by cooking them. The heat would be enough.

In addition, it is also important to note that the handling of these foods must be just before cooking, so as not to make the exposure to air excessive and therefore increase the chances of contamination.

Neither do the eggs!

But, as pointed out the danger involved in washing meat and fish, Noelia López also affects the case of the egg: washing the surface facilitates the entry of microorganisms from the inside, due to the porosity of its shell.

You do have to wash it

However, the products noted above are the exceptions. In general, we will have to worry about rinsing the food. They are an example fruits and vegetables. Of course, water is not enough.

Only water removes impurities, but not microorganisms. That’s why the expert talks about a mixture of bleach suitable for food use and water (1 tablespoon for every three liters), which would guarantee the elimination of these microorganisms. Let’s not forget that after using this mixture you will need to pass them through water again, to remove any residue.

But fruits and vegetables are the classic examples… What other foods should we wash?

Rice and quinoa

Washing rice or quinoa is not a simple whim. Rinsing the rice, for example, will help us remove some of the arsenic it contains. In the case of quinoa, we are talking about a substance found naturally in it, saponin, which is easily removed with water.

Dried legumes

Other foods that we should rinse are dry legumes. It helps us to remove the impurities and the remains of dust that they may contain.

The role of order

The Nestlé nutritionist talks about the role of space in the kitchen: having different spaces that make it possible to put a barrier to a possible case of cross-contamination. It is clear that this will depend on the space of our kitchen. The ideal is to have an area for raw food and another for cooked food.

This separation is vital to have a safe kitchen and, therefore, free of contaminants.

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