Microorganisms (bacteria, fungi and yeasts) are usually involved in the spoilage of food. These microorganisms decompose the food until it is inedible. Sometimes dangerous pathogens can also multiply in food, leading to dangerous food infections, such as salmonella. Microorganisms, which include bacteria, fungi and yeasts, are microorganisms that accompany us everywhere in everyday life. There are those with very positive effects that we make use of in food production. These include, for example, lactic acid bacteria for the production of yogurt, yeasts for beer production and for loosening yeast dough, and molds used in the production of blue cheese and Camembert. However, there are also microorganisms that are undesirable in food because they can lead to spoilage and produce pathogenic substances. We will now take a closer look at these.
Bacteria
Bacterial food infections are an often underestimated health risk for consumers. Bacteria produce metabolic substances that can be hazardous to human health. Most commonly, they cause diarrhea and vomiting. This can have serious consequences, especially for small children, sick and elderly people. If food is contaminated with bacteria, they often multiply explosively under good growth conditions. They particularly like water and heat. They grow less rapidly at lower temperatures, but are only killed by heating. Heat-sensitive bacteria usually die at a core food temperature of 70-80°C. Less heat-labile bacteria are not killed until temperatures exceed 100°C.
- Preventive measures against foodborne infections lie primarily in maintaining personal and food hygiene. This includes thorough and regular hand washing before and during food preparation.
- In particular, when preparing food that may be more frequently contaminated with bacteria such as poultry, eggs, meat, seafood and raw dairy products, should be worked hygienically and thoroughly clean all work equipment afterwards.
- High-risk products such as minced meat and poultry completely cooked, ie for at least 10 minutes at 80°C.
- Food after preparation either consume quickly or store refrigerated. Dishes containing raw egg, consume on the day of preparation.
Salmonella
Salmonellosis (= Salmonella disease) is the most common foodborne infection. In particular, poultry, eggs, meat, fish and food made from these foods can be contaminated with salmonella if they are not heated or not heated sufficiently. Typical signs of salmonellosis are fever, headache, diarrhea and vomiting. These occur about 12 to 36 hours after consumption of the infected food and may last for several days. In adults and individuals with intact immune systems, salmonellosis usually heals without complications after treatment. If elderly and immunodeficient people are affected, infection with salmonella can also be fatal.
Campylobacter bacteria
In addition to salmonellosis, foodborne infection caused by Campylobacter bacteria is significant. These occur predominantly in poultry meat and offal. However, raw milk and drinking water may also be contaminated. The symptoms and course of infection are similar to those of salmonellosis.
EHEC bacteria
The transmission of enterohemorrhagic Escheria coli (EHEC) to humans occurs firstly through the consumption of contaminated food. Here, ground meat, meat products (e.g., Mettwurst, Teewurst, salami), nonpasteurized milk, and dairy products play a special role. Secondly, the bacterium is transmitted from person to person through poor hygiene after visiting the toilet. Infection manifests as watery diarrhea, colicky abdominal pain, cramps, and vomiting.
Staph
Contamination of food with staphylococci usually occurs through humans. Staphylococci are found in the nose and throat, but also in wounds. Especially through improperly covered wounds on the hands, the bacteria get into the food. After eating these foods, diarrhea, vomiting and abdominal cramps can then occur.
- Special care in food preparation is required for wounds, rashes, sore throats and other upper respiratory infections.
Listeria
Listeria can be found primarily in raw products such as ground meat, raw milk and raw milk cheese. In addition, soft cheeses with red smear or noble mold, shrimp, mussels, oysters, lobster and fish may be affected. A health risk due to listeria exists mainly for pregnant women. Infection (= listeriosis) can lead to premature labor, miscarriage and damage to the unborn child. However, listeriosis can also occur in children, immunocompromised and elderly people. It manifests itself in flu-like symptoms and may be accompanied by high fever and meningitis.
- Pregnant women should avoid eating raw milk, raw milk products, soft cheeses with red smear or noble mold, raw ground meat (e.g., tartar). Meat, fish and other seafood should be sufficiently cooked before consumption.
Clostridia
The bacterium Clostridium botulinum produces a neurotoxin that is one of the most dangerous poisons found in nature. The disease caused by this toxin is called botulism. It can be fatal because it is a nerve toxin. Approximately 4 to 36 hours after ingestion, double vision, paralysis of the tongue and pharyngeal muscles, and even respiratory paralysis occur. Clostridia are heat-resistant and toxin formation occurs preferentially in the absence of air. Therefore, a hazard is primarily posed by canned, vacuumed, and boiled foods that have not been properly sterilized. Cases of poisoning have been reported mainly from home-made, inadequately heated canned foods. The most commonly affected are weakly acidic canned vegetables, canned sausages, cured meats, and raw hams.
- The best prophylaxis against botulism is proper preservation of canned or jarred foods and adequate heating of food before serving.
- Canned foods that show any indication of being unsafe, such as cans with bombage or canning jars that are no longer properly sealed, must be discarded.
Molds
Molds are widely known as spoilers of food. Molds often affect foods such as bread and baked goods, fruits, jams, nuts, cheese, meat and sausage. Some molds produce harmful toxins (= mycotoxins). For some mycotoxins a carcinogenic effect was proven. Molds form a network of threads in the food that cannot be seen with the naked eye. Usually only the white or colored spots on the outer part of the food are visible.
- Mold-infested food should therefore usually be thrown away completely.
- Exceptions are, for example, hard cheese with superficial beginning mold colonization and jam, which was made with more than half sugar. In these foods, it is sufficient if the mold is removed over a large area.