The drool factor: Swetha Sivakumar on what makes food mouth-watering
Saliva plays a key role. Even though it’s 99% water, that final 1% defines how we taste, how we experience flavour, and what we can eat.
When a tragic heroine in a novel says the food “turned to ashes in her mouth”, I always wish I could tell her: “That’s the salivary glands. You have a problem with the salivary glands, dear.”
They are a highly underrated element in the eating experience, and because it is so rarely noticed, saliva is barely understood. It is 99% water, but the makeup of the rest makes all the difference. That 1% is a mix of proteins, mucus, and electrolytes such as potassium, magnesium, calcium and phosphate, among other things.
There are enzymes to break down food, proteins that fight bacteria, microbes that help repair wounds. Scientists have found over 1,000 different proteins in saliva, each with a different role.
The mucus plays an important role too. It helps keep each bite from, well, turning to ashes in the mouth. This doesn’t just contribute to delicious mouthfeel, it keeps us from choking and protects the oesophagus from damage caused by rough particles. The moistness of the mix also distributes the food evenly across taste receptors on the tongue, elevating the eating experience.
Saliva as a whole helps carry flavonoids towards the nasal passage, allowing us to experience a fuller flavour from each bite and sip. (Even wine enthusiasts who detect subtle aromas may owe some gratitude to the salivary glands.)
It is an excellent “lie detector”. Low-fat foods, no matter how well-engineered, do not feel as satisfying because fat combines with saliva to form a layer of droplets that adds a feeling of richness to the foods we eat. Low-fat foods lean heavily on carbohydrates instead. They feel drier in the mouth, and the texture of this mix gives the game away. Even if the eyes say “creamy”, the mouth will know different with the first bite. (Perhaps the tragic heroine was on a diet of crumbly, low-fat goods; that might explain the ashes too.)
Saliva is incredibly flexible. When rats were fed diets containing bitter foods, researchers found a corresponding spike in certain proteins in their saliva. Consequently, the rats became less sensitive to the bitter flavour than the control group. This is, in a sense, what we mean by “an acquired taste”. The flavour doesn’t change; the chemical makeup of the mouth does, making the once-unpleasant or unfamiliar flavour more palatable.
We never quite appreciate saliva until we have trouble manufacturing it. People with xerostomia, a condition in which glands underproduce it, often have sore mouths. Without this lubrication, they have difficulty swallowing, speaking, and eating a wide range of foods. They need to drink water often, experience pain and irritation, and a sense of distorted taste known as dysgeusia.
For a sense of what this might feel like, think back to when you last ingested an astringent food. That feeling in the mouth when one drinks masala chai or red wine is caused by the high tannin content. The tannins cause saliva proteins to precipitate or turn solid; leaving the mouth temporarily less able to lubricate itself and its food.
Stress and anxiety can affect salivation too. Whether such experiences increase or decrease the rate can vary based on genetics, overall health and the nature of the stresser. During a fight-or-flight response, for instance, the body prioritises other functions over digestion, and the mouth goes dry. Sorrow can, admittedly, cause dry mouth too.
I’d recommend, for tragic heroines, a dose of food shows or reels. Visuals of delicious meals trigger a digestion response from the body, and boost salivation -- and the appetite too.
(To reach Swetha Sivakumar with questions or feedback, email upgrademyfood@gmail.com)
