MISCELLANEOUS 



387 



that the brovming is due to reducing sugars and not to cane (sucrose) or 

 the total sugars. 



Fig. 153 shows the evidence for this early important conclusion in the 

 solution of the potato chip problem. All the chips, including the impreg- 

 nated filter paper discs, were fried under standard conditions. The tem- 

 perature at the beginning was 195° C (383° F) and fell during frying to 



FiGTJKE 153. Chips fried under standard conditions. Top row: potato slices with 

 increasing content of reducing sugar from left to right. Middle roiv: same for cane sugar 

 but low in reducing sugar. Bottom row: filter paper discs impregnated with glucose, cane 

 sugar, and starch. Percentages of sugars are on the fresh weight basis. 



158° to 166° C (316° to 331° F). Frying was continued until all water w^as 

 driven from the chips, as indicated by cessation of bubbling. The impreg- 

 nated filter-paper discs contained less water and the water was more readily 

 driven off, so they were fried for the same length of time as the chips them- 

 selves. In the upper row it will be seen that as the chips contain more 

 glucose they become darker on frying. Those containing 1.15 per cent 

 glucose become very dark. The investigators conclude that tubers that 

 contain much more than 3 mg of reducing sugar to 1 cc of juice -^ are 

 undesirable for chips. This equals approximately 0.24 per cent of moist 

 weight of tuber. It wiW be noted that as the cane sugar content of the tubers 

 rises there is no darkening of the chips, provided the reducing sugar con- 

 tent is low. In the bottom row are filter paper discs impregnated \^ith 

 glucose, cane sugar, and starch. Only the glucose-impregnated filter paper 

 turns brown on frying. 



