Extraction of Light Filth from Bean Paste: Collaborative Study

Abstract

Bean paste is a popular Asian food frequently imported to the United States. The main varieties are: hot bean and blackbean, which are used in pastry fillings; and soybean paste, which is usually used as a condiment. A new method was developed for the extraction of light filth from bean pastes containing beans and flour, and from hot bean paste containing red pepper. A100 g test portion is boiled in tap water containing Igepal DM-710 and CO-730 and washed with hot tap water on a No. 230 sieve. The residue is transferred to a beaker and boiled in isopropanol in a reflux apparatus. The mixture is transferred to a No. 230 sieve. The residue is washed again, transferred to a 2 L trap flask with 40% isopropanol, boiled with magnetic stirring, cooled, and trapped off with flotation liquid [mineral oil-heptane (85 + 15, v/v)]. Ten laboratories participated in a collaborative study validating the extraction method for the detection of light filth. Average recoveries were 94.9 and 82.8% for insect fragments and rat hairs, respectively. The method has been adopted first action by AOAC INTERNATIONAL.