Autumn has given way to winter. And with it, the colors of the season that we have fired are gone: the green that covered the deciduous trees becomes a fan of colors, ranging from ocher to orange.
The pigments responsible for these colors are essential for human health. In addition, the quality of food is related to the preservation of these compounds and, therefore, knowing how they work helps reduce food waste .
Through new technologies we can achieve substantial improvements in two aspects: nutritional quality and the preservation of vegetable vegetables.
The pigments of plants, our vitamins
Both the green color and the range of typically autumnal colors are due to the physical-chemical properties of the leaf pigments:
- Chlorophylls are the pigments responsible for green tones.
- Carotenoids of yellow-orange colors.
These pigments are key in plant functioning and survival. They participate in such important processes as photosynthesis and tolerance to adverse conditions .
Do you remember when your grandmother told you to eat carrots to preserve your eyesight? Well, I was part of the reason. Carotenoids are essential for eyesight.
Beta carotene, the majority of carrots, is provitamin A, which is part of the retina of the eyes. Yellows such as lutein and zeaxanthin are in the macula and are responsible for dissipating reactive oxygen species from our eyes.
In addition, due to their antioxidant properties, these pigments provide other health benefits, such as improving cognitive ability and preventing degenerative diseases.
As humans are unable to synthesize carotenoids, we must incorporate them into the diet through the intake of fruits, vegetables and legumes, mainly. They are part of the vitamins.
This changes the nutritional value of vegetables
A quality that defines plants is that, although we harvest them, they are still alive. That is, they continue to perform physiological processes such as photosynthesis and breathing.
All the vegetables we see in the supermarket displays are alive. This is due to the modular characteristic of their organs and their ability to maintain physiological autonomy.
Although apparently inactive, in reality your machinery is fully active. They respond to the environmental conditions that occur since they are collected until they end up in the refrigerator of our homes.
The content of carotenoids and, therefore, of vitamins or antioxidant compounds, is very variable. It will respond to the conditions to which the products are exposed, increasing or decreasing their concentration.
In other words: the nutritional content of a vegetable (based on the carotenoid content) varies throughout the day.
For example, the carotenoid zeaxanthin – related, together with lutein, with the decrease in the risk of age-related macular degeneration – has maximum values during the day and minimum values at night.
The role of fridges
Fridges, either in our home, or in a supermarket, usually keep food under conditions of continuous darkness or continuous light.
In homes, for example, the first thing usually happens: the vegetable doesn’t see the light, except for the few seconds in which we open the door. In many supermarkets, however, the lighting is continuous and the product in the display never experiences darkness.
Our studies indicate that keeping vegetables under these extreme light conditions shortens your life.
Carotenoids and other foliar pigments degrade more rapidly under these rhythms of artificial light, which causes visual changes (color changes in the leaves from green to yellowish). It decreases the quality of food and makes it more easily wasted.
If we incorporate light / dark cycles in the refrigeration systems, so that we reproduce the day / night cycles that the vegetable experiences when it grows in the field, we will achieve substantial improvements in food preservation.
Measure carotenoid contents
To better understand the nutritional value of vegetables, and to improve their preservation, we need to quantify how many carotenoids and chlorophylls have the foods we eat.
The most precise, but at the same time expensive, technique of quantification is analysis by chromatography in a laboratory. This is an expensive and complex procedure.
A much simpler alternative is the use of techniques based on the analysis of light reflectance. They consist in evaluating the quantity of each type of light reflected by the surface of the food in question, that is, in quantifying the color. This will be proportional to its pigment content.
These methods are not as accurate, but cheaper. Only the measuring device is needed and it usually exists in portable version.
In a recent investigation , we have applied these techniques in a simulation of a supermarket environment. We have managed to determine the approximate content of the carotenoids from the measure of their optical characteristics. This fact opens an interesting line for the future and directs us to 2.0 supermarkets.
In the near future it will be possible to measure the antioxidants in our food at the push of a button. Even supermarket technology could include drones with sensors that indicate the approximate value of these compounds.
Author Bios: Rachel Esteban is Professor of Plant Physiology, José Ignacio García Plazaola is Professor of Plant Physiology both at the University of the Basque Country / Euskal Herriko Unibertsitatea and Victor Resco de Dios is Professor of Forest Fires and Global Change at the University of Lleida