MODELING OF THE ACTIVITY OF SELECTED STARTERS DURING SOURDOUGH FERMENTATION

In this paper, a central composite design has been applied to evaluate , by means of empirical modelling of the data, the importance of dough yield, NaCl, type of wheat flour, as well as fructose and citrate add ition, on the growth and fermentative activity of mixed sourdough star ters made by selected lactic acid bacteria and yeast. The dough yield variable was important in increasing yeast and lactic acid bacteria gr owth. The stimulating effect of NaCl on yeasts can be indirectly attri buted to a reduction in competition with lactic acid bacteria for the available sugar. The latter were in turn inhibited by NaCl above a cer tain threshold level. Citrate and fructose modification can be used to optimize the relative ratios of acetic and lactic acids. This prelimi nary work considered neither microstructural rheological features of t he dough, nor bread organoleptic properties. However, the results conf irmed the key role of some ingredients in the interaction among the so urdough starters and in the regulation of their metabolism. (C) 1997 A cademic Press Limited.