Selecting starting culture to make Yogurt Dahi

Chemistry behind making Dahi yogurt

Dry Yogurt Cultures

In India, a combination of "Lactobacillus bulgaricus" and "Streptococcus thermophilus" is used for commercial production. You can find this combination in almost any Health food stores in United States. In United States, other cultures may be added for health. Follow the instructions on the package. Normally dried cultures are prepared and added at lower temperatures and take longer incubation time.

Off the shelf pre-made Yogurts

In United States, you can buy yogurt with 'live culture' in the Grocery Stores. The major brand names are: Dannon, Columbo, Yoplait and Breyers.

These manufacturers may add other cultures and stabilizers to create milder flavors and creamier texture.

Select a plain unflavored yogurt with live culture that is not pasteurized. Always check the expiration date. The culture gets weakened with time.

I use Dannon Natural Plain yogurt with live culture as a starter.

Homemade yogurts

Homemade yogurt can be used as a starter within seven days from its making. You can repeatedly use the culture from batch to the next batch. With each new batch, the culture may weaken and not produce thick Dahi. You can not re-vitalize the weakened Dahi. You will have to restart with a dry culture or off the shelf pre-made yogurt.

There are too many variations that may occur during a incubation and storage to reliably predict the degradation. The easiest way is to just examine the texture, if it is not thick, runny or stringy, its time to stop using the batch of the yogurt to create a new batch.

Why should I save culture from new Dahi each time?

All the commercial Yogurts have stabilizers and texture enhancing compounds added. When you make Dahi, the cultures grow and the stabilizers don't. So, with each new batch you get a more pure culture than the previous batch. By the time you get to third batch, it is almost same as if you were having your homemade Dahi in India.

The dry yogurt cultures are also free of stabilizers.