Blackening of potatoes after cooking is unsightly and markedly affects their market value and consumer acceptance. Ultimately, any appraisal of a food must be based on the characteristics consumers

Blackening of potatoes after cooking is unsightly and markedly affects their market value and consumer acceptance. Ultimately, any appraisal of a food must be based on the characteristics consumers prefer (5),^ Several studies of American consumers' preferences tabulate the cooking qualities in potatoes considered most desirable. In 1,032 home interviews in the cities of Cleveland and Rochester (S), mealiness was the quality mentioned by more than three-fourths of the homemakers; whiteness was next in preference. The most common complaint of 880 retailers was the tendency of some potatoes to cook black. In a consumer study of 1,653 individuals in New Hampshire, Rinear (16) found that 71 percent stressed mealiness and 14.1 percent stressed white appearance as the cooking quality most desirable for potatoes. Spangler (19) reported that of 1,165 Chicago retailers, 25 percent listed a tendency to cook black as either the first or the second objectionable cooking defect of potatoes. In a survey of potato preferences among 1,203 household consumers by the Bureau of Agricultural Economics (27)j 16 percent mentioned '^cooked black'' as a frequent defect. Blackening after cooking is a common fault in potatoes grown in certain northern areas. This discoloration does not appear before and during cooking but develops gradually upon exposure of the potatoes to air after cooking, thus reducing their desirability for home and institutional use. The discoloration most often appears first at the stem-end as a gray or blue-gray color. The area may extend over much of the surface and through the vascular regions and even into the interior of the tuber or it may be quite localized. The color varies from a pale blue-gray to a very dark or even black discoloration. If discoloration takes place, it is more intense if the potatoes are steamed or if they are boiled before peeling.