RAW SUGAR 435 



are not an active agent in the deterioration of other sugars. In addition, 

 all these experimenters have shown by carefully controlled experiments 

 that each and all of the micro-organisms mentioned can and do cause damage 

 under favourable conditions. At one time, however, following on the opinions 

 of Greig-Smith, Lewton-Brain, Deerr, and the earlier work of Owen, there 

 was a tendency to ascribe the damage almost exclusively to bacteria, and their 

 position still remains one of great interest. As shown by Owen, all the forms 

 observed belong to the group known by the earlier bacteriologists as the 

 " potato bacilli/' or those forms that appear spontaneously on slices of potato 

 left exposed to a damp atmosphere. These bacteria are of wide distribution 

 and in the economy of nature are concerned with the destruction of organic 

 matter. Their natural habitat is the soil, and they are capable of living on 

 media very deficient in nitrogen. They are thermophilous, and many species 

 produce large quantities of gums and slime. They are continually being 

 introduced into the factory along with the cane. The torulae and the moulds 

 are also of wide and frequent distribution. Their presence in the factory is 

 probably due to air-borne infection, though torulae can also be found on the 

 rind of the cane. Owen's later work, however (with which that of Browne 

 and of Kopeloff, 18 who very recently has devoted great attention to the 

 moulds, is concordant), attributes the damage chiefly to moulds. He shows 

 that Aspergillus secretes an enzyme of great inverting power ; that it is 

 capable of functioning in greater concentration than either yeasts or bacteria, 

 and that it is less susceptible to alkalinity and acidity than are the other two 

 forms. He believes that the inversion of the cane sugar is due mainly to 

 the moulds, which also destroy the reducing sugars thus formed, this action 

 taking place in even the drier sugars. The yeasts, after some absorption 

 of water, ferment the reducing sugars originally present and those formed 

 by the moulds, but have but little invertive action. Finally the bacteria 

 come into activity only when the sugars have absorbed more water still. 

 His conclusions therefore tend to confirm the earlier observations of Shorey 

 and of Kammerling. 



The factors which influence the growth of all of these organisms are mainly 

 temperature, and the concentration of the film of molasses that forms their 

 habitat. Generally the optimum temperature for the growth of micro- 

 organisms is from 35 to 40 C., and Arrhenius 17 in particular has shown that 

 the rate of change produced by micro-organisms follows the same dynamical 

 laws as do " chemical reactions." In this connection Browne has showr 

 that deterioration is almost inhibited at 20 C., and becomes noticeable as 

 the temperature rises. Micro-organisms generally, though there are some 

 exceptions, are unable to develop in very concentrated solutions, due to the 

 phenomenon known as plasmolysis, and therefore a supersaturated film of 

 molasses will act to some degree as a preventive of deterioration. Browne 12 

 observed that certain Moniliae which he isolated from Cuban sugars were 

 active in concentrations up to 64 Brix, whilst on the other hand a bacterium 

 he studied was inactive at this concentration. Previously Ashby 18 haa 

 isolated a yeast from a Jamaican molasses that was active up to a concen- 

 tration of 80 Brix, and Owen observed that while the bacteria he studied 

 were inactive at 60 Brix, Tortulae were still active at 64 Brix, and moulds 

 at 69 Brix. 



In their study of Hawaiian sugars, Deerr and Norris 19 found that 96 

 test sugars did not deteriorate on storage when the percentage of water 

 did not rise above I per cent. ; this was found to be the case, however much 



