388 



GROWTH OF PLANTS 



If filter paper discs impregnated with cane sugar or chips high in cane 

 sugar and low in glucose are fried at considerably higher temperatures, 

 browning occurs; an initial frying temperature of 220° C (428° F) gave 

 some browning of such chips or discs and 240° C (464° F) starting tempera- 

 ture gave dark brown chips. If potatoes are available with high cane sugar 

 and low glucose, chips of any desired degree of brown can be produced by 

 increasing the frying temperature. In impregnated filter-paper discs the 

 monosaccharides arabinose and levulose and the disaccharide maltose 

 acted like glucose. The disaccharide lactose (milk sugar) was more resistant 

 to browning than cane sugar. In practice the fastest way to find out the 

 adaptation of any batch of potatoes for chip making is not to determine the 

 content of various sugars but actual frying of samples at standard tempera- 

 tures. 



Sugaring of Tubers in Low-temperature Storage 



Accumulation of reducing sugar. Table 39 ^^ shows the effect of three 

 different temperatures (5°, 7°, and 8.2° C [41°, 45°, and 47° F]) of storage 

 upon the accumulation of reducing sugars in 25 different varieties of pota- 



Table 39. Reducing Sugar Values Showing Responses of Tuber of Potato 

 Varieties to Conditions of Storage. Storage Started Oct. 25, 1940 



