Preservatives are commonly used in breads because economic
losses from bread spoilage caused by bacteria or by moulds are
substantial. Ropy spoilage is caused mainly by Bacillus subtilis
and Bacillus licheniformis, the spores of which contaminate raw
materials such as flour, bread improvers, yeast, etc., and survive
baking temperatures (Rosenkvist and Hansen, 1995). Ropy spoilage
in bread is first detected by an odour similar to that of
pineapple. Later, the crumb becomes discoloured, soft and sticky
to the touch, which makes the bread inedible. The deterioration of
bread texture is due to slime being formed as a result of the
combined effect of the proteolytic and amylolytic enzymes
produced by some Bacillus strains that results in slime formation
(Viljoen and von Holy, 1997; Sorokulova et al., 2003). The full
extent of losses caused by ropy spoilage of bread is difficult to