All through my teenage life, I would head back home thinking about what was likely to have been cooked for lunch. On most days, my mind would conjure up images of cabbage, beans and other things that I used to believe was food humans were stealing from animals that go “moo”. My middle-class family unfortunately did not acquiesce to my suggestion that golden brown potatoes and puris should be on the menu every single day, for budgetary and cholesterol reasons. Thus, I decided to launch my teenage rage against the cabbage routine by spending a large part of my public transportation pocket money on pani puris from the chaatwalla who set up shop near the bus-stand. The question of how I paid for my commute is one that is best left for another day.
The pani puri experience is the sacred marriage of two culinary tricks—the ability of capsaicin in chillies to cause pleasurable pain, and the ability of deep frying to deport as many water molecules on the surface of food as possible, to create a pandimensional crunch of dehydrated, gluten-shortened wheat, inducing an endorphin rush with water flavoured with mint, chillies, cumin and black salt. The experience starts with the visual of the protean, egg-like form of the puri, filled with explosive life, and ends with flushed cheeks and sweat that can only be fixed with another pani puri. There is crispness on the outside and softness on the inside. There is the heat of the chillies and the complex sweetness of the tamarind-dates chutney. The pani puri experience is a marriage of opposites; a glorious fusion that launches a disco party in your mouth, and your soul.
But if the puri isn’t crisp enough, the entire experience is a catastrophe. I don’t have to tell you what would happen if the puri looked pasty as opposed to the perfect golden brown we have come to love. The cooking method that achieves this most crucial effect is something most experienced cooks are familiar with (and tend to use in moderation for health reasons) but something that every newbie cook is mortally afraid of—deep frying.
At a basic level, deep frying is the act of rapidly dehydrating the surface of food while ensuring that the insides cook without getting greasy. Why greasy? you ask. We use fats to deep fry our food only because water boils at 100 degrees Celsius and that temperature is simply not enough for browning to happen. And unfortunately, there are not too many liquids apart from water and fats that will not kill us when we ingest them. So, the first science lesson here is that the fats actually don’t interact with your food at all. All they are there to do is transmit heat more evenly to whatever is being fried.
So, when your puri hits the hot oil, the water molecules on its surface go, “Oh, it’s getting hot here, so I’m going to take off,” and turn into water vapour. You can see this happening as bubbles of water vapour start escaping from your puri’s surface. As long as you see bubbles, the temperature is still under 100 on the surface, because there is still liquid water left to evaporate. The moment bubbles start to cease is when the browning reaction starts. And that’s when you have to be careful, because once liquid water is out of the way, things tend to heat up really fast. Leave it for too long and the golden brown will turn into an unappetising dark brown.
So, the next obvious question is—what’s the right temperature? The answer is between 175-180 degrees Celsius. Any lower, and the outsides will dehydrate too slowly, and oil will have enough time to get into the puri and turn it greasy. Any higher, and the outsides will crisp too fast for the insides to cook fully. So, if you are a beginner, get yourself a thermometer that can measure the temperature of the oil before you drop your puris in. Experienced cooks will typically do this by dropping a small piece of whatever it is you are frying and see the rate of bubbles forming, and over time, you can build muscle memory for the right bubbling rate.
You might go, “Wait, regular puris aren’t crisp enough for pani puri,” and you would be right. To make puris for pani puri, you need to understand the science of wheat. The dough for this puri uses as little water as possible; it uses oil instead. We don’t want too much stretchy gluten formation. Fats shorten gluten. This ensures that it crisps rapidly while just having enough water inside that expands to form water vapour, which gets trapped between the crisp ball when it fries. Too little water and your puri will be a flat disc with no room for the pani puri water. Too much, and your puri will not be crisp enough on the outside.
So, the next time you eat pani puri, remember that the friendly neighbourhood chaatwalla to whom you pay a pittance to enjoy one of the galaxy’s great snacks is, in reality, a food science ninja who has walked a culinary tightrope to make the perfect pani puri experience happen.
Krish Ashok is the author of Masala Lab: The Science Of Indian Cooking.