MISCELLANEOUS 



395 



Efifect of Carbon Dioxide on the Sugar Metabolism of Potatoes at Low 

 Temperatures 



Five per cent CO 2 with normal percentage of oxygen in the surrounding 

 air retards the formation of reducing sugar ^3. 25, 27 jj-^ tubers stored at 2°, 

 5°, or 7° C (36°, 41°, or 45° F). In some cases less than one-fifth as much 

 reducing sugar forms with 5 per cent CO 2 present as mth none present. 

 Even 1.1 per cent CO 2 retards the formation of reducing sugar by 20 per 



Table 43. Effect of CO2 upon the Reducing Sugar Content of Potato Tubers 

 Stored for Different Lengths of Time at Different Temperatures 



Note: (a) The reducing sugar values at the start were: 0.0, 0.1, 0.1 for Irish Cobbler, 

 Green Mountain, and Katahdin, respectively; (6) a zero value means that the sugar 

 value was less than 0.1 mg per cc of juice by the method of sugar analysis used. 



cent at 5° C (41° F). Twenty per cent CO2 at 2° C (36° F) is even more 

 effective than 5 per cent in retardmg reducing sugar formation. At 5° C 

 (41° F) it is much less effective than 5 per cent, and at 7° C (45° F) it 

 increases considerably the formation of reducing sugar. Table 43 and 

 Fig. 156 show the effect at 5 per cent and 20 per cent CO2 on the accumula- 

 tion of reducing sugar in tubers stored at 2°, 5°, and 7° C (36°, 41°, and 

 45° F). When the period of storage exceeds 60 days, both 5 and 20 per cent 

 CO 2 increase greatly the formation of cane sugar in stored tubers at all 

 three temperatures (2°, 5°, and 7° C [36°, 41°, and 45° F]). Table 44 shows 

 the effect of 5 and 20 per cent CO 2 on cane sugar concentration in tubers 

 stored at 2°, 5°, and 7° C (36°, 41°, and 45° F) for 30, 60, and 90 days. 



On the whole, the effect of variety, temperature, and CO 2 concentration 

 on the accumulation of reducing and cane sugars in potato tubers is very 

 complex. Yet with the proper selection of varieties — and there are a 

 number of good ones — three months of storage at room temperature 

 followed by storage at 7° C (45° F) and finally followed by a few days at 



