Myths and legends about packaged food and drink

Food is a field full of myths because of its relevance to human health. Explore some topics about food packaging commonly found in science and fiction.

Myths and legends about packaged food and drink
Facts and legends about packaged foods and beverages. Photo by Arshad Pooloo / Unsplash

We are witnessing an unprecedented moment in human history when a single click transports us through the vast dimension of the so-called "information age". However, the growing popularization of digital media has also brought with it negative implications where "disinformation" is also an element to take into account when surfing the internet and is assumed as unscientific beliefs.

Food is a field full of myths because of its relevance to human health. Next, Herlinda Soto Valdez, professor-researcher in charge of the Packaging Laboratory of the Food and Development Research Center (CIAD), explains some topics about food packaging that are popularly moved between science and fiction:

Does glass packaging affect the taste of the food or drink?

Indeed, glass containers are the most inert and keep the contents free of oxygen and substances that migrate from the material. In contrast, plastics, even with an oxygen barrier, allow the passage of this gas, which is responsible for oxidizing and decomposing components of the taste and odor of the food or beverage. Plastics can also release components that could affect the taste. On the other hand, metal containers, although impermeable to oxygen, contain an internal coating based on epoxy or organic resins that can release compounds that affect the taste.

Is bottled water harmful when exposed to the sun?

Increasing the temperature of a beverage or bottled water increases the migration of plastic components. However, PET is one of the materials with the lowest migration levels. There is an urban legend regarding the migration of bisphenol A, a compound used to produce polycarbonate. In the Mexican market, there are polycarbonate bottles that could release bisphenol A and do so in low concentrations. But it must be clarified that PET bottles do not release bisphenol-A. The caps can release compounds that give the water a "plastic" taste and smell.

Will food break down faster if it is left in the can once it is opened?

No. The recommendation not to leave food in the can after it has been opened comes from decades ago when lead solder was used in the manufacture of steel or tin cans. Nowadays, due to the toxicity of this heavy metal, lead solder is no longer used, it has been replaced by electric solder. On the other hand, aluminum cans do not require any soldering at all. However, the recommendation is to store the food in a covered container to avoid any external contamination.

Can it be harmful to consume food from a dented can?

Indeed, cans are made up of several layers of metallic materials and organic coatings on the inside. A can that has been knocked over may have had the inner layers ruptured so that it loses its ability to protect and preserve the food. It is more advisable not to buy it and not to consume it.

Is there a risk of contracting leptospirosis by not disinfecting the cans before consuming the food they contain?

Leptospirosis is a bacterium present in the urine of rodents and other animals. This bacterium can be transmitted to humans through direct contact with urine. There are currently no studies that prove that the bacteria survive on the outside surface of a can that was in contact with rodent urine. A person is more likely to get the disease from contact with contaminated water in the event of flooding. Regardless of the disease, it is advisable to wash the cans to avoid any contamination.

How long after the expiration date is it safe to eat canned food?

The expiration date of food indicates that its shelf life is over. In the case of perishable foods (with a shelf life of fourteen days or less), it is a risk to consume one that is already expired, since its main cause of deterioration is the development of microorganisms. For semi-perishable foods (with a shelf life of approximately six months) there may be a margin of safety of a few weeks, but it is better not to take the risk.

In the case of stable foods, such as canned or dehydrated foods (with a shelf life longer than six months up to approximately two years), the main cause of spoilage is not microbial growth, but others such as rancidity, changes in taste, color, etc. These may have a safety margin of a few months, but surely the food will not have the organoleptic quality expected by the consumer.

On this issue, it is important to clarify that although food-producing companies give a safety margin to canned food, these have been reduced to avoid food waste. This has been discussed in countries of the European Union and applies to all in matters of food security, that is, not wasting food so that it reaches all the population that needs it.

Is canned food less nutritious than fresh food?

No. Heat treatments of food to keep it stable for long periods can degrade vitamins and other compounds important for good nutrition. But each case must be analyzed because there are foods that are enriched or fortified with vitamins and minerals. Definitely fresh and freshly cooked foods are better, but canned foods make it easier for us to eat foods that are not in season.