WHITE BEER, LAMHIC, GINGER-BEER 195 



chains ol Xaccharobatillus pastorianus. The latter are the cause of the aforesaid 

 optical phenomenon exhibited when the liquid is shaken. Meat-broth gelatin 

 is unsuitable for the pure cultivation of this fission fungus, and it develops but 

 imperfectly in wort gelatin, so that slightly alcoholised malt extract agar-agar, 

 in which the organism thrives, has to be employed. The re-inoculations made 

 by Yan Laer into sound beer decisively proved the agency of Saocharobacillus 

 pastorianus in the production of "turning " in that beverage. It is, however, 

 incapable of developing or becoming injurious except when the percentage 

 content of hop extract (i.e. the hop resins inimical to bacteria) in the medium 

 is small. This influence of the hop resins was, however, not further investigated 

 by Van Laer. 



As its generic name implies, Saccharobacillus pastorianus ferments sugars, 

 and especially saccharose, maltose, and dextrose, which it acts upon readily, but, 

 on the other hand, ferments lactose with difficulty. Saccharose is apparently 

 transformed without inversion, since the presence of invertin could not be 

 detected in the cultures. In media containing one of these sugars the bacillus 

 chiefly produces inactive lactic acid, in addition to ethyl-alcohol and a small 

 quantity of volatile acids (acetic and formic acids), the proportions varying with 

 the kind of sugar and the conditions of cultivation. Given a sufficiency of 

 sugar, the degree of acidity produced is then solely dependent on the composition 

 of the remainder of the medium ; in unhopped wort it amounts to as much as 

 1.26 grams (calculated to lactic acid) per 100 c.c., whilst in hopped wort it does 

 not exceed 0.27 gram. The development of the bacillus is not restricted by 

 alcohol unless more than 7 per cent, of this substance is present in the beer. It 

 thrives better in the warm, and consequently the malady is of frequent occur- 

 rence in summer in countries where the cellar accommodation is defective. 

 This explains the Flemish name " Zomerbier," applied to turned beer in general. 

 The organism cannot survive continuous exposure to 55-6o C. for a short 

 time; consequently beer intended for export to tropical countries may be 

 protected against risk of " turning " by Pasteurisation. 



153. White Beer, Lambic, Ginger-Beer. 



A low percentage of lactic acid is met with even in the best beers. It is 

 derived partly from the malt itself, which contains on an average 0.05 per cent, 

 of this acid, but is chiefly produced during the mashing process, the amount then 

 developed being nevertheless small ranging in normal beers between 0.05 and 

 0.2 per cent. The nature and amount of the acids produced during the malting 

 of barley, the kilning and mashing of the malt, and the boiling of the beer-wort, 

 have been investigated by E. PRIOR (I.). In addition to the rod-shaped species 

 already described, lactic ferments in the form of globular cells developing into 

 sheet colonies appear in the malt-mash. An acid-producing, species of this class 

 was examined by P. LINDNER (I.), who named it Pediococcus acidi lactici. Its 

 diameter is 0.6-1.0 /z, and the optimum temperature is about 40 0., but the 

 organism is killed in two minutes by a temperature of 62 C., and it does not 

 thrive either in hopped wort or beer. The spontaneous lactic fermentation 

 appearing under certain circumstances in malt-mashes has been investigated, 

 from a chemical point of view, by M. HAYDUCK (II.). The variety of the fission 

 fungi developing in these mashes is very considerable, the first in point of size 

 being the Sarcina maxima, described by P. LINDNER (II.), the individual cells of 

 the packet- colonies of this organism measuring 3-4 p. in diameter. Attempts 

 to obtain pure cultures of this, the largest species of sarcina, have hitherto proved 

 unsuccessful. 



In many instances the appearance of a vigorous lactic fermentation in beer- 



