Ecology of starter bacteria

Most starters in use to today have originated from lactic acid bacteria originally present as part of the contaminating microflora of milk. These bacteria have probably originated from vegetation in the case of lactococci (Sandine et al., 1972) or the intestinal tract in the case of Bifidobacterium spp., enterococci and Lactobacillus acidophilus.

Modern starter cultures have developed from the practice of retaining small quantities of whey or cream from the successful manufacture of a fermented product on a previous day and using this as the inoculum or starter for the preceding day’s production. This practice has been called various names but the term 'back-slopping' is used widely.

What are starter concentrates?

Traditionally 'bulk starter' in liquid form was used to inoculate the milk used in the manufacture of cheese, yoghurt, buttermilk and other fermented products. Over the past 10-15 years, the use of starter cell concentrates designated as either Direct Vat Set (DVS) or Direct Vat Inoculation (DVI) cultures have increasing being used, particularly in small plants, to replace bulk starter in cheese manufacture. Note that the terms DVI and DVS are used interchangeably although particular culture suppliers will tend to use only one term.

In addition to these high activity cell concentrates, lower activity commercial cell concentrates have been used for many years to inoculate milk for bulk starter manufacture, and in the manufacture of 'long set products' that require extended incubation. This contribution while mainly concerned with DVS cultures will also comment on concentrates use in bulk starter manufacture.

Identification of species with a biochemical key