On a recent visit home to Kolkata in eastern India, I made it a point to keep one afternoon free to explore Tangra, one of the two Chinatowns in the city. Once famous for its tanneries and its labyrinth lanes and bylanes, Tangra is where the locals head today for authentic Chinese food that does not cost the earth. And where else but in Tangra would one find industrial quantities of the sauces that are so vital to Chinese cuisine being made?

Having moved from Guangdong to what was then known as Calcutta after World War II, F.S.Young realized that the nearly 30,000-strong Chinese community in the city had no access to a regular supply of soy sauce. So in 1954, he set up the Sing Cheung Sauce Factory, churning out soy sauce made in the traditional manner, which much like whiskey, includes a long aging process to get the right flavor.

The ingredients were, and still are, sourced from Sikkim, North Bengal, and northeastern India. The clientele then was the local Chinese community, while today, Chinese restaurants across India use sauces made by Sing Cheung or Pou Chong, another sauce maker from Kolkata that opened shop in 1958.

Young's 69-year-old nephew Chong Hsin Wong, who runs the Sing Cheung Sauce Factory now, is understandably proud of how successful the family business has been. From soy sauce, the company now makes 15 different kinds of sauces and condiments, including the pungent mustard paste called kasundi, which is so beloved of Bengalis. The experimenting with local ingredients is obvious in flavors like the coriander chili sauce on offer.

On the other hand, the founder of Pou Chong Foods — and another Guangdong native — Lee Shih Chuan is credited with creating the green chilli sauce, without dollops of which the famous kathi rolls, or meat wraps, of Kolkata would probably not have become so famous. The Pou Chong list of products even includes a vegetarian oyster sauce made with mushrooms.

When asked if the newer multinational-backed brands have made a dent in profits, 37-year-old Janice Lee, who heads Pou Chong now, is dismissive. She says that the authentic taste that the two Chinese brands offer cannot be replicated by the newbies and therefore, there is no competition. She should know. From a single factory in Tangra, there are now two units in Kolkata producing tons of sauces every day for Pou Chong. The story is the same for Sing Cheung. People just can't seem to get enough of either.

So what is the advertising budget like, I ask? Wong of Sing Cheung laughs. Zero, he says. Publicity is entirely word-of-mouth.

Wong looks pensive when asked about the future of the business. Many of the young Chinese residents of the city have moved abroad, mainly to Canada. With the population shrinking, land sharks have moved into Tangra, taking over what is now prime property to build incongruous high-rises that are slowly erasing a unique community's way of life.