Our sense of smell is a fantastic conjuror of memories and the ability to link them together is known as our olfactory memory. I think that this is important to how we experience Christmas because it is a sensory overload and it got me to thinking, what is the cause of the sweet and spicy smell associated with gingerbread and that foul smell produced by your dad after one too many brussel sprouts? What is the smelly essence of Christmas to which we owe so many memories?
I love waking up in the morning with the feeling that the world outside my bedroom window has been transformed by a blanket of snow. I love snow and its crisp fresh smell although the actual component responsible for the smell of snow is a tricky thing to put your finger on. It appears not to be caused by one factor alone, instead it is thought to be a cocktail of molecules (Figure 1) which have been soaked up from the atmosphere . A fingerprint of our past and present world.
2. Musty loft
A couple of weeks before Christmas the decorations usually residing in the loft gathering dust are brought down and this is usually followed by an musty smell some would describe as being earthy, dirty, damp or even mouldy. It seems to stick to everything, the boxes containing your decorations and your clothes if you are up there for long enough. This smell is thought to originate from microbes and/or the wood in your attic that release several compounds  (Figure 2), not exactly your everyday perfume.
3. Christmas trees
Real Christmas trees smell amazing; rubbing the pine needles with your fingers activates its smell by releasing the essential oil from the needle which contains several different compounds (Figure 3) which together have been recorded as having numerous health benefits and antimicrobial effects .
A construction material for houses and the very essence of the gingerbread man. Baking gingerbread fills the house with a spicy smell that warms the nose and sparks a desire to snuggle up with a hot water bottle. The main compound responsible for this is called -gingerol (Figure 4) from stem ginger which has been reported to have anti-bacterial, anti-inflammatory and anti-tumour activities , just a few excuses to eat more gingerbread men!
5. Mulled wine
This in my opinion is the top dog of Christmas drinks, only thought of when the Christmas season begins. It is packed full of Christmas herbs, spices and fruits; clementine’s, lemon, cloves, cinnamon, nutmeg, star anise, ginger, honey and vanilla depending on the recipe. The clementine’s and lemons provide a citrusy fragrance, whilst cinnamon, cloves and ginger present a spice and warmth which together are complemented by the aniseed smell of star anise. Each component is linked to a specific compound (Figure 5) that together pack a punch with anti-microbial, anti-oxidant, anti-tumour and anti-diabetic properties as well as protection against neurodegeneration[5-8].
No Christmas meal is complete without a side of rosemary and sage stuffing to go alongside your turkey. This is another “Christmas only” appearance in our family and to me when I smell it I know that dinner is almost ready. The smell of rosemary and sage arises from their essential oils as with most herbs that contain various compounds (Figure 6) which together have anti-oxidant and anti-microbial activities [9-10].
7. Brussel sprouts
Another in the “love ‘m or hate ‘m” category, brussel sprouts are too a Christmas staple. If, like me you hate them but happen to live with others that love them, you know a thing or two about the stinky consequences that result from their consumption and this is due to the release of hydrogen sulphide gas (Figure 7). Brussel sprouts belong to a family of cruciferous vegetables which contain isothiocyanates generated from the metabolism of glucosinolates by the enzyme myrosinase. These isothiocyanates have been shown to naturally release hydrogen sulphide gas and although not conclusive it has been suggested that our gut microflora have a role to play in its release. So if you would rather this smell was not present during your Christmas festivities, I would suggest hiding the brussel sprouts somewhere they cannot be found [11-12].
So there you have it! I hope that you have enjoyed our journey behind some of the smells associated with Christmas and the potential benefits of those compounds. Enjoy the festive season, and delight in everything it has to offer. Till next time!
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