jan. i 5> 1921 Deterioration of Sugars in Storage 651 



It is interesting to note further in Table VII that in the majority of 

 cases the rank of sugars with regard to deterioration is the same for 

 the middle of the bag and for the surface. For example, the Am sugar 

 shows greatest deterioration both in the middle and at the surface, 

 while the Port and Cab sugars show least in both cases. 



It has been shown that it is possible to predict the keeping quality of 

 a sugar (from the standpoint of mold infection) by the simultaneous 

 consideration of moisture ratio and number of organisms per gram. 1 

 Evidence for a prediction based on the number of bacteria was likewise 

 advanced. 1 In Table I the plus and minus signs in the columns labeled 

 "Deterioration predicted from moisture ratio" and "Deterioration 

 predicted from number of microorganisms per gram" represent the 

 prediction of deterioration based upon these factors considered inde- 

 pendently. In this case we have taken the critical moisture ratio and 

 the number of bacteria per gram which are required to produce deteriora- 

 tion in four weeks at this temperature and humidity of incubation as 

 30 and 200, respectively. (Table VIII.) Where these conditions were 

 higher, as in the experiment of 1919, 2 less than half this number of micro- 

 organisms will produce similar effects. If attention is focused upon the 

 moisture ratio it will be seen that the factor of safety as worked out by 

 previous investigators holds true to a limited extent. In other words, 

 where the moisture ratio is above 0.30 to 0.33 deterioration usually sets 

 in, while sugars with lower moisture ratios usually resist deterioration. 

 However, there are any number of instances where this factor of safety 

 fails to function as an adequate criterion, and we may turn with some 

 confidence to the number of microorganisms per gram as a true index of 

 deterioration. In fact, a careful analysis of the data presented in Table 

 I shows that as a criterion for predicting deterioration the moisture ratio 

 or factor of safety proved to be in agreement with the analyses in 57 

 instances and failed in 86 instances; in other words, it was only 40 per 

 cent effective. On the other hand, the use of the number of micro- 

 organisms per gram as an index of deterioration resulted in 96 successful 

 predictions and 47 failures, or an efficiency of 67 per cent, which is 27 

 per cent better than the factor of safety. In the 65 cases where the 

 moisture ratio is in agreement with number of microorganisms for the 

 theoretical prediction of deterioration, there was practical confirmation 

 in the majority of instances. 



1 Kopeloff, Nicholas, and Kopeloff, Lillian, op. cit., 1920. 



2 Kopeloff, Nicholas, and Perkins, H. Z. E. op. cit., 1920. 



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