278 BACTERIA IN OTHER FOODS 



as possible out of contact with the air. It is doubtful if such a 

 remedy is practical, as the lowering of the temperature follows the 

 removal of covers on the dough troughs and retards the whole course 

 of fermentation. 



2. Sticky, Slimy, or Viscous Bread. This affection is not nearly 

 as common as the preceding, yet the number of cases recorded is 

 quite large, and this abnormal fermentation is frequently met with 

 in country districts. As the name implies, the bread, usually the 

 crumb near the centre of the loaf, is slimy or sticky. The stringiness 

 increases with age, a proof of the living nature of the trouble. 

 Cases of sticky bread usually occur in the warm summer months, 

 the high temperature favouring the growth of the bacteria which pro- 

 duce the trouble. From this sticky bread it is comparatively easy to 

 isolate an organism which, when placed in sterilised bread, is able 

 to produce the stickiness met with under natural conditions, thus 

 proving the relation of bacteria to the trouble. The specific germ 

 causing stickiness, known as the "potato bacillus" on account of 

 the frequency with which it is met with on potatoes, is also formed 

 in yeast cake. Harrison has repeatedly found this germ present in 

 both dried and compressed yeast cake. Given favourable conditions 

 for rapid growth, this organism might produce epidemics of slimy 

 bread at any time. The bacillus forms spores able to resist un- 

 favourable conditions. This germ is occasionally met with in milk. 

 Slimy bread may be controlled by exercising absolute cleanliness 

 in the yeast tubs and kneading troughs, and by the proper sterilisa- 

 tion of the brew or ferment by the use of a certain quantity of hops. 

 In a number of experiments made with hop extracts it has been 

 found that even a small quantity of good hops (one half -ounce to 

 the gallon) has some antiseptic power and hinders the development 

 of the potato bacillus, without injuring the activity of the yeast. 

 The bread should be kept in a cool place after baking, for this 

 stickiness is most prevalent during hot weather, and a cool tempera- 

 ture prevents the rapid growth of the organism. 



3. Musty or Mouldy Bread. Musty or mouldy bread is, . as a 

 rule, only met with after the bread has been cut and allowed to 

 stand several days. Occasionally, however, we find bread only one 

 day old affected with mustiness. The specific organism is the mould 

 Mucor mucedo, which has action on bread, producing a musty odour 

 without decomposing the bread. But the chemical composition of 

 the bread is changed by the growth of mould, and this change 

 favours the subsequent growth of any bacteria that may be present. 

 Flours which have become damp, or even very low-grade flours, may 

 have this mould present in large amount, and although the organism 

 is killed by the baking process, yet the musty flavour persists and is 

 present in the baked loaf. 



