How to make fermented milk

Milk and cream stored at room temperature will soon ferment and curdle because of bacterial action. This natural process, combined with careful timing, heat treatment to thoroughly sterilize the food and the use of pure cultures of desirable bacteria, yields delicious cultured milk products such as yogurt, buttermilk and sour cream. These foods are useful in cooking, are easily digested and are a good source of calcium and protein. Here are some tips for fermenting your own milk.

• Dairy thermometer
• Saucepan (preferably stainless steel)
• Sterile glass jar or wide mouth vacuum flask

• Pasteurized fresh milk or milk powder and a starter culture or fresh cultured dairy milk
• Cultured milk is made by using fresh, pasteurized whole and skim milk as well as a started culture of the proper strain of bacteria.
• When bought, cultures are inactive and must be reactivated (instructions are included with the cultures).
• Good results with less work can be obtained by using a portion of store-bought acidophilus yogurt as a starter, provided it does not contain flavouring or sweetener. The product should not have been repasteurized after culturing, since repasteurization destroys most of the desirable bacteria.
• For each new batch, fresh commercial yogurt (no older than two to three days) should be used.

• If a cultured milk product is made with a starter from a dairy supplier, it can be recultured (using a portion of the old batch to begin a new batch). It is important that the reculturing process occur within 10 days of producing the first batch as the bacteria is destroyed by long refrigeration.
• Containers should be tightly covered during culturing and refrigeration, and strict hygiene standards need to be maintained to avoid contamination.
• A starter eventually loses its vigour. If the flavour of a freshly cultured milk product is inferior or the product takes longer to thicken, it is time to buy a new starter.
• There are several methods for keeping the cultured milk mixture at the optimum temperature for fermentation. These include using a wide-mouthed vacuum flask, standing warmed jars in a container of slightly warmer water in a warm place, wrapping warmed jars in a blanket and packing them into a styrene box or insulated food carrier or surrounding them with crumpled newspaper in a food carrier.
• The flavour and texture of most milk products will improve if they are refrigerated for a few hours after being cultured.

Making your own fermented milk can appear to be a large leap of faith. But whether your making yogurt, buttermilk or sour cream, you're sure to enjoy the homemade taste that you'll be able to tailor exactly to your palate.