1905.] 



Quality in Potatoes. 



539 



Little attention has up to the present been given to the 

 conditions which influence the culinary properties of potatoes. 



Their food value is almost entirely depen- 

 Quality in c j ent U p 0n t h e starch content, and exten- 



.rOL<lL06S« . 



sive analyses have been made '.o determine 

 the amount of starch in the potato and its proportion to other 

 substances and to water. The protein, starch, and fat content, 

 and the presence of other substances which influence flavour 

 and colour, have also been investigated, and it is upon the con- 

 siderations of starch content and other chemical properties that 

 the estimation of quality has usually been made. The standard 

 of chemical composition is fairly adequate when only the utility 

 of potatoes for the manufacture of starch is considered or 

 when they are used as food for stock, and even when used for 

 human consumption the starch content must be considered, for 

 when this is deficient or falls below a certain standard (about 17 

 per cent.) the indications are that the tubers have not developed 

 properly, have not ripened, or have grown under adverse 

 conditions of soil or climate. Their culinary value, however, 

 must vary with the taste and opinion of different persons, 

 but, generally, tubers white in colour, floury and mealy when 

 cooked are preferred. The farmer, also, when growing for the 

 market, must take into account such factors as size, colour of 

 skin, shape, &c, all of which influence the sale and the price 

 obtained. 



With a view of elucidating some of the factors in the growth 

 and development of potatoes which affect their culinary quality, 

 some investigations* have been carried out by Mr. John W. 

 Gilmore, of the Cornell Agricultural Experiment Station, 

 which appear to show that the culinary and dietetic quality of 

 potatoes is not dependent upon chemical composition so much 

 as it is upon the anatomical and, perhaps, physiological 

 characteristics of the tuber and the arrangement and distribu- 

 tion of starch and water areas in its substance. Thus, in 

 general, mealiness follows upon the presence of sufficient starch 

 in the cell to rupture its walls when boiled in water. The 

 grains of potato starch expand and coalesce when boiled, and if 

 the cells are sufficiently full of these bodies the boiling will 



* Bulletin 230, June, 1905. Cornell Experiment Station. 



