Geo-Olfaction: the science behind the “scent of christmas” in the Brazilian summer

When we think of the scent of Christmas, our brains create a curious mix between fantasy and reality. There is the imagery from movies (pine and snow), but there is Brazil’s vibrant sensory reality.

Here, Christmas has the unmistakable aroma of rabanada frying with cinnamon, the sweet and fermented smell of Panettone (or Chocottone) when opening the box, mixed with sunscreen, Sunday barbecue, and that summer rain that falls in the late afternoon.

This is not random. It is the science of Geo-Olfaction in action. For us at the Olfactory Research Center, understanding these nuances goes beyond nostalgia; it means comprehending how physiology, physics, and culture shape our well-being and emotions.

1. The physics of summer: why does scent “explode” in december?

The first concept to understand the Brazilian Christmas is Smellscape (Olfactory Landscape). Research shows that the smellscape refers to the overall smell environment, acknowledging that as human beings, we perceive this partially at any one point in time.

In Brazil, the determining factor of this landscape is heat. Environmental factors, such as air temperature, have a significant impact on the detection of the odor.

High December temperatures alter the physics of odors. Heat provides energy to molecules, increasing their rate of evaporation and concentration. This means that scents in the Brazilian Christmas are physically more intense:

• The vanilla scent of Panettone expands rapidly in the kitchen.
• The smell of wet asphalt after rain rises forcefully.
• Fresh and citrus fragrances gain more prominence and volatility.

2. Olfactory heritage: from rabanada to cashew

If the smellscape is the climate, Olfactory Heritage is our culture. Scientifically, olfactory heritage concerns the smells that are meaningful to a community due to their connections with significant places, practices, objects, or traditions.

Brazil is a continental country, and our December “olfactory map” varies immensely, mixing the traditional with the regional:

• The Brazilian Classic: The smell of sugar and cinnamon from rabanada and the aroma of Panettone are temporal markers. The brain smells these and activates “party mode.”
• Northeast (The Tropical Harvest): Beyond food, the environment smells of Cashew fruit and the sea breeze.
• South (The Toast): The smell of grapes and cold sparkling wine mixes with the smokiness of the barbecue.
• Southeast/Central-West (The Rain): The smell of wet earth is omnipresent on December afternoons.

3. The science of happiness: the secret is “congruence”

Why do we feel so good smelling these scents? The answer lies not only in memory but in physiological interaction.

A recent scientific study investigated the physiological effects of olfactory and visual stimuli. The discovery was fascinating: the interaction of corresponding odors and landscapes (seeing and smelling at the same time) was able to relax and refresh the body more effectively than just smelling or seeing separately.

The Rabanada Example: When you see the golden rabanada (visual) and smell the cinnamon (olfactory), your brain processes complete and congruent information. This generates a superior physiological response of pleasure and relaxation.

On the other hand, artificial scents disconnected from the context (like a synthetic “snow” smell on a 35°C day) might not have the same positive effect. Research participants reported that artificial odors were often described as unpleasant or sharp, evoking negative emotions.

4. Well-being in the “scent of now”

Studies on nature-based interventions show that experiencing the smell of plants may facilitate stress reduction and support mental recovery. Natural scent acts as a catalyst for sensory awareness.

This Christmas, science suggests that the best olfactory experience is one that embraces our reality and creates harmony:

• Connect with nature: Enjoy the smell of seasonal fruits decorating the table.
• Value the process: Smell the food being prepared, as this is part of the multisensory experience.
• Use appropriate fragrances: Perfumes that “converse” with the heat (fresh, aquatic, or floral notes) help create this sensory congruence that our brains love.

The true “scent of Christmas” is the one that connects you to the present moment and your well-being.

Bibliographic references

Zhang X, Guo J, Zhang X, Zhang Q. Physiological Effects of a Garden Plant Smellscape from the Perspective of Perceptual Interaction. International Journal of Environmental Research and Public Health. 2023;20(6):5004. doi: 10.3390/ijerph20065004

Pálsdóttir AM, Spendrup S, Mårtensson L, Wendin K. Garden Smellscape–Experiences of Plant Scents in a Nature-Based Intervention. Frontiers in Psychology. 2021;12:667957. doi: 10.3389/fpsyg.2021.667957

Bembibre C, Strlič M. From Smelly Buildings to the Scented Past: An Overview of Olfactory Heritage. Frontiers in Psychology. 2022;12:718287. doi: 10.3389/fpsyg.2021.718287

Xiao J, Aletta F, Radicchi A, McLean K, Shiner LE, Verbeek C. Recent Advances in Smellscape Research for the Built Environment. Frontiers in Psychology. 2021;12:700514. doi: 10.3389/fpsyg.2021.700514