Extraction of light filth from tofu: collaborative study

Results are reported for a collaborative study of a method for the extraction of light filth from tofu. A 100 g test portion is digested in HCl solution with Igepal CO-730 and Igepal DM-710. Hairs and insect fragments are isolated by wet-sieving on a No. 230 sieve, dispersing remaining residual product with Aerosol OT 75%, and filtering. Average recoveries by 9 collaborators for 3 spike levels of rat hairs (5, 10, 15) were 80, 78, and 84%, respectively; for 3 spike levels of insect fragments (5, 15, 30), recoveries were 97, 99, and 99%, respectively. The method was adopted first action by AOAC International.