3. Contamination of Food
Safety in the kitchen requires us to become expert observers. We must be able to detect both risks that are visible to the naked eye and those invisible enemies that do not alter the flavor or aroma of dishes.
In this module, we learn to classify physical, chemical, and biological hazards, identifying their origins in the environment, in animals, or in our own daily activity.
3.1. Food Hazards
A food hazard is any physical, chemical, or biological agent that may be naturally present or contaminate food with the potential to cause an adverse effect. The estimation of the probability and severity of the adverse effects of hazards associated with food is food risk (AESAN, 2024).
Food can be contaminated at any of the stages of the food chain, that is, between production and consumption. The identification of hazards must be based on the collection of the different sources of information available at the time: which will serve as a framework of reference for the subsequent determination of risk (Madrid Salud, 2025).
3.1.1. Biological Hazards
Those pathogenic microorganisms (bacteria, viruses, parasites, fungi...) and/or their toxins that cause illness in the consumer. In many food groups, they are the greatest danger for consumers, as they are often imperceptible. Food can be contaminated with these microorganisms and not appear so because there are no modifications in its appearance (Food and Agriculture Organization of the United Nations (s.f.)).
When a foodborne illness attacks a large number of people, it can become an epidemic with serious consequences for the health and lives of people and, furthermore, affect the country's economy.
3.1.2. Physical Hazards
Those foreign bodies that can contaminate food at any time during production (bones, fishbones, glass, etc.). Unlike biological or chemical hazards, they are visible or palpable (Madrid Salud, 2025).
3.1.3. Chemical Hazards
Those substances that have not been intentionally added to food or feed. These substances may be present in food as a consequence of the various stages of its production, processing, or transport. They may also be due to environmental contamination (AESAN, 2025).
3.2. Sources of Food Contamination
Regulation 852/2004 defines contamination as the introduction or presence of a hazard (DOUE-L-2004-81035). There are several forms of contamination:
- Direct contamination: The contaminant passes directly from the source of contamination to the food. For example: a handler with dirty hands touches the food or sneezes on food.
- Indirect contamination: The contaminant reaches the food through an intermediate object/medium. For example: using a dirty knife or washing with contaminated water.
- Cross-contamination: The contaminant is transferred from one food to another, usually from raw to cooked. For example: cutting raw chicken and then a ready-to-eat salad or dripping from meat thawing over ready-to-eat ham.