Effects of sourdough process parameters on the flavour of wheat bread

A current trend in the baking industry is to produce bread without chemical additives. This has created the interest to use wheat sourdough to improve bread texture and flavour. The influence of sourdough is mainly based on the production of acids and volatile compounds, the modification of starch and the breakdown of proteins. The characteristics of the bacterial population in combination with fermentation parameters define the changes in dough and bread properties. The aim of this work was to study systematically how the sourdough process conditions influence the formation of acids, amino acids, volatile compounds, and the subsequent flavour of the bread. Fermentations were carried out with pure lactic acid bacterial yeast and with a combination of yeast and lactic acid bacteria. Response surface methodology was utilised to study the effects of fermentation time, temperature, and ash content of flour on the fermentative activity of sourdoughs, and bread flavour. The effects of fermentation parameters on bread flavour varied with different types of sourdoughs. The total amount of amino acids increased 25-50 %, and the amount of volatile compounds increased seven to hundred fold depending on the strain and fermentation conditions. Bread flavour was enhanced by the use of sourdough fermented with lactic acid bacteria in optimised conditions. The acidity level and level of free amino acids in sourdoughs correlated strongly with the flavour of the breads.