Scientists have figured out what makes Indian food so delicious

Curries, rice, naan bread, samosas and pakora. (iStock)

Indian food, with its hodgepodge of ingredients and intoxicating aromas, is coveted around the world. The labor-intensive cuisine and its mix of spices is more often than not a revelation for those who sit down to eat it for the first time. Heavy doses of cardamom, cayenne, tamarind and other flavors can overwhelm an unfamiliar palate. Together, they help form the pillars of what tastes so good to so many people.

But behind the appeal of Indian food — what makes it so novel and so delicious — is also a stranger and subtler truth. In a large new analysis of more than 2,000 popular recipes, data scientists have discovered perhaps the key reason why Indian food tastes so unique: It does something radical with flavors, something very different from what we tend to do in the United States and the rest of Western culture. And it does it at the molecular level.

Before we go further, let's take a step back and consider what flavors are and how they interact. If you were to hold a microscope to most Western dishes, you would find an interesting but not all-too-surprising trend. Popular food pairings in this part of the world combine ingredients that share like flavors, which food chemists have broken down into their molecular parts — precise chemical compounds that, when combined, give off a distinct taste.

Most of the compounds have scientific names, though one of the simpler compounds is acetal, which, as the food chemist George Burdock has written, is "refreshing, pleasant, and [has a] fruity-green odor," and can be found in whiskey, apple juice, orange juice and raw beets. On average, there are just over 50 flavor compounds in each food ingredient.

A nifty chart shared by Scientific American in 2013 shows which foods share the most flavor compounds with others and which food pairings have the most flavor compounds in common. Peanut butter and roasted peanuts have one of the most significant overlaps (no surprise there). But there are connections that are more difficult to predict: strawberries, for instance, have more in common with white wine than they do with apples, oranges or honey.

Data crunching Indian recipes

Chefs in the West like to make dishes with ingredients that have overlapping flavors. But not all cuisines adhere to the same rule. Many Asian cuisines have been shown to belie the trend by favoring dishes with ingredients that don't overlap in flavor. And Indian food, in particular, is one of the most powerful counterexamples. 

Researchers at the Indian Institute for Technology in Jodhpur crunched data on several thousand recipes from a popular online recipe site called TarlaDalal.com. They broke each dish down to its ingredients, and then compared how often and heavily ingredients share flavor compounds.

The answer? Not too often.

Here's an easy way to make sense of what they did, through the lens of a single, theoretical dish. Say you have a dish with 4 different ingredients, like the one below:

Each one of those ingredients has its own list of flavor compounds. And any two of those ingredients' lists might have some overlap. Take the coconut and onion, for instance. We can all agree that these two things are pretty different, but we can also see (in the Venn diagram below) that there's some overlap in their flavor make-up. (Ignore the math symbols.)

You could create the same diagram for all the ingredients with overlapping flavor compounds, as in this diagram. There are six that have overlap.  (Again, ignore the math.)

The researchers did this for each of the several thousand recipes, which used a total of 200 ingredients.  They examined how much the underlying flavor compounds overlapped in single dishes and discovered something very different from Western cuisines. Indian cuisine tended to mix ingredients whose flavors don't overlap at all.

"We found that average flavor sharing in Indian cuisine was significantly lesser than expected," the researchers wrote.

In other words, the more overlap two ingredients have in flavor, the less likely they are to appear in the same Indian dish.

The unique makeup of Indian cuisine can be seen in some dishes more than others, and it seems to be tied to the use of specific ingredients. Spices usually indicate dishes with flavors that have no chemical common ground.

More specifically, many Indian recipes  contain cayenne, the basis of curry powder that is in dishes like red curry, green curry, or massaman curry. And when a dish contains cayenne, the researchers found, it's unlikely to have other ingredients that share similar flavors. The same can be said of green bell pepper, coriander and garam masala, which are nearly as ubiquitous in Indian cuisine.

"Each of the spices is uniquely placed in its recipe to shape the flavor sharing pattern with rest of the ingredients," the researchers noted.

Milk, butter, bread, and rice, meanwhile—all of which are hallmarks of Western cuisine—were found to be associated with just the opposite: flavor pairings that match. When any of those ingredients appeared in an Indian dish, there was a good chance there would be a lot of flavor overlap.

A lesson for all chefs

The takeaway is that part of what makes Indian food so appealing is the way flavors rub up against each other. The cuisine is complicated, no doubt: the average Indian dish, after all, contains at least 7 ingredients, and the total number of ingredients observed by the researchers amounted to almost 200 out of the roughly 381 observed around the world. But all those ingredients — and the spices especially — are all uniquely important because in any single dish, each one brings a unique flavor.

But the upshot should also be a thought that we might be approaching food from the wrong angle. Combining ingredients with like flavors is a useful (and often delicious) strategy, but it might be a somewhat misleading rule of thumb. Indian cuisine, after all, is cherished globally, and yet hinges on a decidedly different ingredient pairing logic.

Roberto A. Ferdman is a reporter for Wonkblog covering food, economics, immigration and other things. He was previously a staff writer at Quartz.