Cheese Starter Cultures

Abstract

The use of starter cultures (often simply called starters) containing lactic acid bacteria (LAB) is an essential requirement in the manufacture of most cheeses. These cultures are called starters because they initiate or ‘start’ the production of lactic acid, their primary purpose in cheese manufacture. Acid production, combined with heating and stirring of the curd/whey mixture, causes the casein curd to synerese and expel moisture (whey) from the coagulum to produce a product—cheese—with a much lower water content (87% down to 35–60%), a lower pH (6·6 down to 4·6–5·2), and consequently a much longer shelf-life than milk. Acid production during cheese manufacture has other effects besides gel syneresis, e.g. it affects the activity, denaturation and retention of the coagulant in the cheese, curd strength, the extent of dissolution of colloidal calcium phosphate and inhibits the growth of many species of pathogenic and defect-producing bacteria. These aspects are considered in other chapters in these volumes and will not be considered further here. In this chapter, we will attempt to provide a broad understanding of the physiology, metabolism, genetics and propagation of starter cultures. It is not intended to be an exhaustive review but we would hope to indicate the likely direction of future research.