Extraction of light filth from canned green leafy vegetables: collaborative study

The official first action method, 44.108, for the extraction of light filth from whole or chopped canned greens specifies a water-heptane flotation that results in the flotation of an excessive amount of interfering plant material and in low recoveries. A new method has been developed using a 40% isopropanol-water-mineral oil flotation. The new method yielded a decreased amount of plant material and 84.9% recovery of the aphid spike compared with 42.5% recovery of the spike by the official method. The new method has been adopted as official first action to replace the existing method, except for broccoli.