To try a recipe for traditional mango lassi, click here.
It's the heat. Judging by the crowd outside the Jay Kishan Lassi House—a little storefront selling cool yogurt drinks opposite the railway station in Nadiad, my small town in the Western part of India—the temperature must be hovering around 118 F. As the mercury surges, the Chatwani brothers, who have been running the store for about two decades now, increase the amounts of milk they will transform into yogurt that is the main ingredient in their drinks. It does not take long, for yogurt sets fairly quickly in the summer heat.
Yogurt—the milk product teeming with bacteria, albeit good bacteria—thrives in warm temperatures. The process of making it is rather simple. A live culture, often a blend of Streptococcus thermophilus (ST) and Lactobacillus delbrueckii subspecies bulgaricus (LB) is added to warm milk and allowed to rest undisturbed. This live culture blend is easily obtained from yogurts available in U.S. supermarkets. In India, typically a small amount of yogurt from a previous batch is used to make a fresh batch of yogurt at home. If for some reason a harried homemaker runs out of yogurt from a previous batch, all she has to do is send someone over to a neighbor's house for a teaspoon of yogurt, or to the corner store. Even Mr. Chatwani says he uses the local commercial brand AMUL as a starter when they run out of yogurt. But that would be rare, given that the Chatwanis make yogurt from about 70 liters of milk every day!
It's the water. Each morning a man sits stirring a large cauldron of milk outside the Jay Kishan Lassi House. This is the first step in making the lassi—the sweet yogurt drink for which this store is justly famous. The gradual process of warming the milk evaporates a considerable amount of the water, leaving the milk creamy and ready for the bacteria to go to work. Even when the milk is rendered relatively thick, yogurt is largely water. Whey—the liquid that emerges when you first cut into any yogurt, results from the bacterial process that allows the milk solids to coagulate into their particular gel-like consistency.