Ruggedness testing of the official method for rot fragments in comminuted tomato products

The official AOAC method for rot fragments in comminuted tomato products (44.224) has been revised on the basis of Youden's ruggedness testing procedures to provide better control over the sources of variability. Two sets of ruggedness tests were carried out to evaluate the type of balance used to weigh the sample, amount of stain, staining time, sieve design, technique used to transfer stained material from beaker to sieve, washing technique used to accumulate stained material at edge of sieve, diameter of eye dropper used to transfer sample from sieve to graduated tube, number of 0.5 mL portions examined, and magnification used to examine prepared slides. A 3-way analysis of variance conducted on amount of stain, transfer technique, and washing technique showed that the transfer and washing techniques were significant areas of variability.