446 



CHAPTER XXII 



Average Composition of Molasses as correlated with Reducing Sugars 



Per Cent. 



On inspection it is at once apparent that there is a tendency for the sugar 

 to decrease as the reducing sugars increase, and that the total sugars present 

 also show a very distinct increase. It follows then that when the composition 

 of a juice is known, an idea can be obtained regarding the probable composi- 

 tion of the molasses that will result. This composition, it is evident, will 

 be determined not by the absolute quantity of reducing sugars in the juice, 

 but by the ratio of reducing sugars to non-sugars ; when this ratio is small, 

 as occurs in beet juices and occasionally in cane juices, a molasses of higher 

 purity may be anticipated ; in the presence of much reducing sugar a molasses 

 of low purity is obtained. 



In routine technical control over nearly all the cane sugar producing 



districts, a value of the ratio ^. in the neighbourhood of 



' Brix ° 



30 has come to be regarded as indicative of good work. Probably in the 

 great majority of cases this is so, but it must be remembered that the value 

 of this ratio is governed by the routine followed by the analyst, especially 

 as regards the concentration in which the degree Brix is determined, and the. 

 quantity of lead acetate which is used in the analysis. In addition, though 

 the direct polarization is indicative generally of the quantity of sugar in 

 the molasses, the ratio between sugar per cent, and polarization is by no 

 means constant, and it is quite possible to have a molasses of " 35 test " 

 contain less sugar than one of "30 test." The determination of sugar as 

 opposed to polarization affords a much more reliable criterion, and on this 

 basis a gravity purity of 40 will generally be found representative of com- 

 mercially exhausted molasses, those special cases indicated in the foregoing 

 paragraphs being excepted. 



There are, of course, many other factors besides the ratio of non-sugars 

 to reducing sugars that determine the purity of the waste molasses, and 

 indeed the statement made above has only an empirical basis. The deter- 

 mining factors have been made the subject of a classical research by Geerligs,^ 

 whose work is abstracted below. He calls attention first of aU to the differ- 

 ence between beet and cane molasses ; the higher solubility of sugar in the 

 former he attributes to the formation of a compound between the salts and 

 the sugar, the solubility of which is greater than that of sugar itself, and he 

 defines beet molasses as a hydrated syrupy liquid composed of sugar and 

 salts. In a cane molasses the presence of reducing sugars leads to a similar 

 reducing sugars-salt-water complex which abstracts water which would 



• Typical beet sugar molasses. 



