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The Science of Food Smells

The Science of Food Smells

Why do we like some aromas much more than others? And why a specific smell indicates how good the food is? The answers come from science.

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Think about what strikes you most when you come home around dinner time. What makes you think you are in for an enjoyable meal, before you even set foot in the kitchen: the aroma of food wafting through the air. In actual fact, it would be more correct to speak in generic terms of “food smells”. Whatever we choose to call it, our example perfectly describes its importance: because, very often, long before we actually see or taste the food, its smell will indicate how good it is. Furthermore, even if it were well presented and tasted wonderful, we would certainly not be tempted to eat nasty smelling food. If we consider that, on average, we breathe about 23,000 times a day, shifting over 130 cubic metres of air, we realize that the sense of smell is a particularly important issue for any fine food enthusiast!

Of the five senses, smell is the most “direct”: when we smell the aroma of a delicious dish of pasta served in tomato sauce, the odorous molecules reach the nasal cavity and are captured by the mucous which contain olfactory receptors. These consist of 5 million cells packed with “cilia” which, as soon as they come into contact with the odorous molecules, transmit a message to a specific area of our brain, through the olfactory nerve. This direct contact between nose and brain explains how a simple smell can trigger an emotion. And why, for instance, even with eyes closed, we manage to associate it with certain experiences or people. In brief, we will be remembered by the smell of the food we serve to people: let’s make sure that their recollection is a pleasant one! Furthermore, the olfactory experience influences the taste of food. Without going into tedious scientific explanations, all we need to know is that our primitive ancestors used to smell food to understand whether it was edible or not (similarly to many animals, cats being a perfect example). This is due to two processes, called “orthonasal olfaction” and “retronasal olfaction” which basically transform the olfactory signal into one of taste, thus enhancing our perception of flavour.

In the course of evolution, man has learned to classify a plethora of very intense tasting experiences. One of the most appreciated is that of caramel but, in actual fact, the real cause of a good smell in any food, is a high temperature. In simple terms, we can say that in many dishes, heat ensures that the amino acids react with some types of sugar to form dicarbonyls which, in their turn, react with other amino acids to extend the reaction. This is how pleasant smells and flavours are amplified.

The Maillard reaction - we've already talked about here -  helps create smells that are particularly welcome to the palate, on condition that the food contains as little water as possible before being cooked. If you think about it, boiled foods create some of the least appetizing cooking smells. If you are out to conjure up aromas that are sure to tempt the strongest-willed diner, bear a few simple tips in mind. First of all, choose grilled or oven-baked foods which are most likely to produce “good smells”: high temperatures in fact diffuse odorous molecules more effectively. Another trick is to use sugar-rich mixtures: for instance grilled meat or roasted chicken can be brushed with honey before cooking. And don’t be mean with the butter: this is another ingredient which, at high temperatures, releases molecules that are extremely appetizing to the nose and palate. Just think of oven-baked products such as croissant: what could possibly tempt the appetite more than that? Well, I believe you have now well and truly grasped the fact that good cooking is something you have to have a nose for.

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