Lactic acid bacteria: starters for flavour

Changing milk into other organoleptically acceptable products by fermentation requires particular attributes of the bacteria. These include rapid acid production from lactose and development of suitable quantities of the volatile compounds, diacetyl and acetaldehyde. These compounds must not be over-produced nor should they be accompanied by off-flavours. More knowledge has accumulated concerning starter cultures for milk fermentation than for any of the other cultured foods. We are approaching the time when we can tailor-make mixed cultures of known species of bacteria to provide specific flavours because we are becoming more aware of their metabolic activity within a given foodstuff. To provide and keep a good starter for a particular fermented product it is essential to know what is expected of it in terms of flavour and aroma. This knowledge is not always available and many products are poor because of this. Knowledge of the biochemical pathways leading to flavour production can help in making the right choice of starter.