From whole to skim, creamed to whipped, fluid milk and related milk products have a normal pH of 6.6 to 6.9. But this neutrality stops here. In order to transform fluid milk into one of the many other dairy products in the marketplace, pH must be reduced.
Starter cultures are acid-producing microorganisms that are used in the production of dairy products such as buttermilk, cheese, sour cream and yogurt. Although they are genetically diverse, common characteristics of these bacteria include being Gram-positive, non-motile and non-sporeforming. Producing acid from lactose is their primary function; however, starter cultures can contribute to flavor, aroma and gas production; proteolytic and lipolytic activities; and inhibition of undesirable organisms.