Direct methods for potato sloughing assessment mostly consist in CPM (cooked potato mass) tests in which potato cubes are cooked, sieved and the mass of the remaining cooked potato tissue on the sieve is recorded. The characteristic time CT100 determined from the CPM cooking curve indicates the potato resistance to sloughing. The CPEM (cooked potato effective mass) method was proposed as a modification of the CPM tests. The potato mass is determined continually during cooking so that the whole cooking curve is obtained in one test. The CPEM cooking curve has two main parts (the cooking and the breaking part) from which two CPEM parameters: cooking time (CT) and slope of the breaking part (SBP) characterising the disintegration process are derived. Two potato varieties Agria and Samantana cultivated under different conditions were tested. Dependence of the CPEM parameters on the potato tuber density was observed. The CPEM parameters differed more for different cultivation conditions than for different varieties. (c) 2005 Elsevier Ltd. All rights reserved.