Studies of the potato microstructure during blanching

The texture changes of potatoes (variety Desire) at different blanching tim es (0-240 s) and temperatures (85 degrees C, 95 degrees C, 100 degrees C) w ere examined within this study. After blanching the breaking forces (N) were determined with an INSTRON tex ture analyser (type 1140). The logarithm of the breaking force as a functio n of blanching time show that 3 different stages (0-40 s; 40-160 s; 160-240 s) were found at all temperatures (85 degrees C, 95 degrees C, 100 degrees C). Photographs of potato cells were taken from scanning electron microscopy st udies. Results show that the swelling and gelatinization of the potato star ch has only little influence on the texture during the first (0-40 s) of th e 3 different observed stages. In this initial stage the breaking forces in creased with time. The water uptake of the potato cells was determined gravimetrically. The re sults show that the increase of the breaking forces during the first 40 s r esults from the water uptake. The examinations with the scanning electron microscopy and the texture anal yser proved that the main reason for the changes in texture are due to soft ening and destruction of the cell walls. In the second (40-160 a) and third stage (160-240 s) of the blanching process a linear relationship was found between the logarithm of the breaking force and the blanching time.