The susceptibility to mould growth of white bread produced by different processes

Abstract

Summary. Bread produced by the Chorleywood Bread Process (CBP), which is a mechanical development process, had a mean mould‐free shelf life which was 14.5‐19 hr shorter than that of bread made by a 3‐hr bulk fermentation process, following natural inoculation by controlled exposure to a low mould‐spore concentration in the air. Assessing mould susceptibility by comparing the time taken for half the exposed surfaces to show some mould growth, four‐fifths or more of the deficiency in mould resistance of the GBP bread compared with the bulk‐fermented could be made good by adding at the dough‐mixing stage a fermented‐out brew which had been started with one part of sugar for every twenty‐eight parts of flour to be used in the dough.Correlation of mould resistance with the strengths of fermented‐out sugar brews indicated that the favourable effect was due to a fermentation product. Ethanol was found to be the substance responsible, products present in trace amounts evidently not playing any important part in the observed differences in rate of mould growth on CBP bread with and without added brews. the ethanol content of the bread accounted for most but not all of the mould resistance of bulk‐fermented bread compared with CBP bread. Equilibrium relative humidity, pH, and propionic acid and moisture contents did not vary enough from one kind of bread to another to affect relative mould‐free shelf life appreciably. Evidently, therefore, an unidentified mould inhibitor is present in the bulk‐fermented bread.The commercial significance of the findings is discussed.