Evaluation of microporous covers for the reduction of mushroom substrate preparation odors

Three microporous membrane covers of various weights and porosities were co mpared for their ability to impede the transmission of odor-producing compo unds released during Phase I of the mushroom substrate preparation process. Moist cotton flannel 10 cm x 10 cm (4 in. x 4 in.) fabric swatches were us ed to assess the intensity of odors above four test piles: one with no cove r and one with each of the three covers under investigation. The swatches w ere suspended above each pile (by laying them on top of 10 cm diameter x 10 cm long PVC pipe sections) for 1, 4, and 10 min durations. Upon completion of each test run, five panelists were asked to sniff swatches from all pil es and all exposure times and rate the odor intensities from zero to five, zero indicating no detectable odor and five being equivalent to the odor pr esent on a swatch exposed to an uncovered pile for 30 minutes. Additionally , a quantitative assessment of odors, using thermal absorption and gas chro matography, was conducted and the results yielded trends which were compati ble with those obtained qualitatively, thus validating the effectiveness of the olfactory procedure employed. Ten minute duration test results indicat ed that cover A was most effective, cover C was nearly as effective, and co ver B was the least effective, although a reduction in odor intensity was o bserved.