When you open the refrigerator to find a wedge of cheese speckled with green mold or a package of chicken that smells slightly sour, it can be tempting to risk your stomach rather than waste food.
But the line between harmless fermentation and dangerous spoilage is sharp. Eating spoiled foods exposes the body to various microbial toxins and biochemical byproducts, many of which can interfere with essential biological processes. Health effects can range from mild gastrointestinal discomfort to serious conditions such as liver cancer.
I am a toxicologist and researcher, specializing in how foreign chemicals, such as those released during food spoilage, affect the body. Many spoiled foods contain specific microorganisms that produce toxins.
Because individual sensitivity to these chemicals varies, and the amount present in spoiled foods can also vary considerably, there are no absolute guidelines for what is safe to eat. However, it is always advisable to know our enemies in order to take measures to avoid them.
Nuts and cereals
In foods of plant origin, such as cereals and nuts, fungi are mainly responsible for deterioration, forming diffuse spots of mold in green, yellow, black or white tones, which usually give off a musty smell. Although colorful, many of these molds produce toxic chemicals called mycotoxins.
Two common fungi found on grains and nuts such as corn, sorghum, rice, and peanuts are Aspergillus flavus y A. parasiticus. These fungi can produce mycotoxins known as aflatoxins, which form molecules called epoxides that can cause mutations by binding to DNA. Repeated exposure to aflatoxins can damage the liver and has been linked to liver cancer, especially in people who already have other risk factors, such as hepatitis B infection.
He Fusarium is another group of pathogenic fungi that can grow as mold on grains such as wheat, barley, and corn, especially at high humidity. Infected kernels may appear discolored, pinkish or reddish, and have a musty odor.
The mushrooms Fusarium They produce mycotoxins called trichothecenes, which can damage cells and irritate the digestive tract. They also produce another toxin, fumonisin B1, which disrupts the formation and maintenance of the outer membranes of cells. Over time, these effects can damage the liver and kidneys.
If the grains or nuts look moldy, discolored, or wrinkled, or if they give off an unusual odor, it is best to err on the side of caution and throw them away. Aflatoxins, in particular, are known to be potent carcinogens, so there is no safe level of exposure.
Fruits
Fruits can also harbor mycotoxins. When they are bruised, overripe, or stored in humid conditions, mold can easily grow and begin producing these harmful substances. A very common fungus is blue mold called An expanded brushknown to infect apples, but also attacks pears, cherries, peaches and other fruits.
This fungus produces patulin, a toxin that interferes with key enzymes in cells, disrupting their normal functioning and generating unstable molecules called reactive oxygen species, which can damage DNA, proteins and fats. In large amounts, patulin can damage important organs such as the kidneys, liver, digestive tract, and immune system.
The blue and green cousins of P. expandedhe An Italian pencil and the Fingered pencilare common in oranges, lemons and other citrus fruits. It is not known for sure whether they produce dangerous toxins, but they taste horrible.
It’s tempting to just cut off the moldy parts of a fruit and eat the rest. However, mold can release hyphae, microscopic root-like structures that penetrate deep into food and can release toxins even into seemingly healthy parts. Especially for soft fruits, where hyphae grow more easily, it is safest to discard moldy specimens. Do this at your own risk, but for hard fruits, sometimes you can simply cut off the moldy parts.
Also read: Is it really possible to be addicted to food? Researchers are discovering compelling similarities with drug addiction
Queso
Cheese shows the benefits of controlled microbial growth. In fact, mold is a crucial component in many of the cheeses we know and love. Blue cheeses, such as Roquefort and Stilton, get their distinctive tart flavor from chemicals produced by a fungus called Roquefort brush. And the soft, white rind of cheeses like Brie or Camembert contributes to their flavor and texture.
On the other hand, unwanted molds have a fuzzy or powdery appearance and can take on unusual colors. Greenish or reddish molds, sometimes caused by species of Aspergilluscan be toxic and should be discarded. Furthermore, species such as Common brush They produce cyclopiazonic acid, a mycotoxin that alters the flow of calcium through cell membranes, which could affect muscle and nerve function. At high enough levels, it can cause tremors or other nervous system symptoms.
Fortunately, these cases are rare, and spoiled dairy products are usually revealed by their acrid, sour and foul smell. As a general rule, throw away soft cheeses like ricotta, cream cheese, and cottage cheese at the first sign of mold. Since these cheeses contain more moisture, mold filaments can spread easily.
Hard cheeses, such as cheddar, parmesan, and Swiss, are less porous. Therefore, cutting at least 2.5 cm around the moldy area is a safer option; just be careful not to touch the mold with the knife.
Carne
While molds are the main cause of plant and dairy spoilage, bacteria are the main spoilage agents of meat. Telltale signs of meat spoilage include a slimy texture, discoloration that is usually greenish or brown, and a sour or putrid odor.
Some harmful bacteria produce no noticeable changes in odor, appearance, or texture, making it difficult to assess meat safety based on sensory cues alone. However, this bad smell is caused by chemicals such as cadaverine and putrescine, which are formed during the decomposition of meat and can cause nausea, vomiting and abdominal cramps, as well as headaches, hot flashes or drops in blood pressure.
Spoiled meats are rife with bacterial dangers. Escherichia colia common contaminant in beef, produces Shiga toxin, which inhibits the ability of some cells to make protein and can cause a dangerous kidney disease called hemolytic uremic syndrome.
Poultry often carries the bacteria Campylobacter jejuniwhich produces a toxin that invades gastrointestinal cells, often causing diarrhea, abdominal cramps, and fever. It can also cause the immune system to attack its own nerves, triggering a rare condition called Guillain-Barré syndrome, which can cause temporary paralysis.
Salmonella, found in eggs and undercooked chicken, is one of the most common types of food poisoning, causing diarrhea, nausea and abdominal cramps. It releases toxins into the lining of the small and large intestine, causing extensive inflammation. He Clostridium perfringens also attacks the intestine, but its toxins damage cell membranes. He Clostridium botulinum, which can be present in poorly stored or canned meat, produces botulinum toxin, one of the most powerful biological poisons, lethal even in minimal quantities.
It’s impossible for meat to be completely bacteria-free, but the longer it sits in the refrigerator—or worse, in the grocery bag—the more it will multiply. And you can’t eliminate all bacteria by cooking. Most die at meat-safe temperatures—between 63 and 74°C—but many bacterial toxins are heat-stable and survive cooking.
*Brad Rice Field is Professor Emeritus of Chemical and Biological Engineering, Biomedical Engineering and Public Health at Colorado State University
This article was originally published in The Conversation
Continue reading: HIV rates are higher in the southern US, despite effective treatments: a clash between culture and public health
Do you use Facebook more? Leave us a like to be informed
