A Study of Quality in Potatoes. 



221 





175. — Showing the relative size of 

 cooked starch grains at the right and 

 uncooked at the left. 



perature and moisture. Non-uniformity, with an abundance of small 

 water areas, or branches of the internal medullary area, was usually 

 observed in those tubers which grew very near the surface, or in 

 those which gave evidence of immaturity. As this portion consti- 

 tutes the bulk of the tuber 

 (34.176 per cent, of it according 

 to Coudon and Bussard, Reference 

 cited p. 220), a careful estimate 

 of its appearance and texture is 

 important. 



4. Internal medullary area — 

 Large and branching, indicating a 

 large proportion of potato sub- 

 stance which does not contain 

 enough starch grains to break 

 .down the cell walls when the tuber 

 is boiled in water. Instead of -^^^ 

 being full of starch grains, as is the 

 case with the cells of the external 

 medullary area, the cells of this portion are filled for the most part 

 with water, hence the portion has a more translucent appearance 



when held to the light (Fig. 

 177). When this portion is 

 branching the starch area is 

 permeated by these water 

 areas and is not uniform. 

 Small, indicating a diminished 

 proportion of watery sub- 

 stance and more uniformity 

 in the starch area. 



5. Texture of tuber when cut 

 with a knife— Crisp, when the 

 cut is brittle and snappy, 

 indicating maturity of starch 

 grains and a uniform cellular 

 with thin walls. 

 Leathery, when the cut is 

 soft, smooth and even,indicat- 

 cell wall, and oftentimes an 



Fig. 176. — From the external medullary area 



showing the abundance of starch in the cells Structure 

 of this part. 



ing an overgrowth in thickness of 

 inadequate supply of starch. 



A careful study of the foregoing characteristics seems very pertinent 

 because it is a matter of common knowledge that the average person 



