We have all heard at some point that spinach has much more iron than other vegetables. And perhaps you are also familiar with the famous idea that this is due to a misplaced comma in a work on the amounts of this nutrient in vegetables published in 1870 by Emil Wolff.
Interestingly, Popeye was created because of that mistaken belief and contributed to spinach consumption increasing by a third in the United States. They are myths upon myths, proof that sometimes what we know “all our lives” rests on feet of clay.
Wolff’s study, which was accepted as good until the 1930s, contained an error in a table, but this affected equally all the foods for which he reported their nutritional value. Thus, the history of the decimal point is a simplification from 1981 that reinterprets other errors when dealing with a few data.
For his part, Popeye did not start eating spinach until 1932, three years after the comic’s creation. But not because of iron but because of vitamin A, the same one that was later used – this time deliberately – in the carrot myth.
By then, spinach consumption had already increased because the iron fallacy had become popular, although many children continued to “suffer” from a diet rich in spinach thanks to the recommendations of the strict vegetarian sailor.
Another example of a rocky decision based on tenuous data concerns a belief that has an entire industry regulated by law: that frozen foods should be kept at -18°C or colder.
Why precisely this temperature? It would be expected that, as a result of scientific studies or experience in the sector. After all, if this were not the case and a few degrees up or down mattered little, why is it set so rigidly?
First of all, Microbiology tells us that the microorganisms that spoil food stop their growth when cold. But as was demonstrated years ago, keeping products at -12 °C is enough for bacterial growth and activity to stop.
Another scientific discipline, nutrition, explains that some vitamins remain stable at -18 °C for a year, but others can degrade significantly even at -60 °C after a few months without a few degrees above or below changing much. the result.
So, why was the temperature of -18 °C chosen as a reference to achieve the necessary food safety? According to a recent study signed by the director general of the International Institute of Refrigeration (an independent intergovernmental organization that gathers scientific and technical evidence on cooling) and five co-authors, it appears that it was selected in the mid-20th century because within the temperatures considered safe it corresponds precisely at 0 degrees Fahrenheit.
So it would have been a case of easy-to-remember rounding. Engineers would have picked up the gauntlet, routinely designing equipment and processes based on that mythical 0°F temperature, and legislation would have done the rest.
However, if we introduce Ecology into our narrative, we could consider that refrigeration involves heating the sink to which the removed heat goes, which is the environment, as well as consuming energy resources to do so. Although Engineering constantly increases the efficiency of equipment, there are insurmountable physical limits.
All energy consumption translates into an impact on the environment that, today, can very frequently be measured in carbon footprint. But what if it didn’t need to cool so much? Would it be possible to keep frozen foods safely at a higher temperature and, in the process, reduce energy consumption? The answer seems to be yes, and it is proposed that it be with the reference of -15 °C so that, in the event of a problem, it takes time to reach the still safe (microbiologically) limit of -12 °C.
The aforementioned report shows that this simple measure would mean almost a 5% reduction in what is consumed to maintain the cold chain at the current temperature. We would save 25 terawatt hours (TWh) per year (one terawatt hour is equivalent to the annual electricity consumption of 150,000 people living in the EU), equivalent to 10 million tons (Mt) of greenhouse gases, or what three million cars, as many as circulate in all of Denmark. It would, therefore, be another reasonable step on the path that takes us in the direction of reducing the human footprint on the environment.
Living sustainably costs, but it will cost more to do so in an unsustainable way. The more the different branches of science help each other to dismantle legends, the sooner we will achieve the objectives of sustainable development that are more necessary than ever.
This article was originally published on The Conversation. Enrique Baquero, researcher at the Institute of Biodiversity and Environment (BIOMA) and professor at the Faculty of Sciences of the University of Navarra. Arturo H. Ariño is a professor of Ecology, a researcher at the Institute of Biodiversity and Environment (BIOMA) and research manager at the Science Museum, University of Navarra.
