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

Three microporous membrane covers of various weights and porosities were compared for their ability to impede the transmission of odor-producing compounds released during Phase I of the mushroom substrate preparation process. Moist, cotton flannel 10 cm×10 cm (4 in.×4 in.) fabric swatches were used to assess the intensity of odors above four test piles: one with no cover and one with each of the three covers under investigation. The swatches were suspended above each pile (by laying them on top of 10 cm diameter ×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 piles 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 present on a swatch exposed to an uncovered pile for 30 minutes. Additionally, a quantitative assessment of odors, using thermal absorption and gas chromatography, was conducted and the results yielded trends which were compatible with those obtained qualitatively, thus validating the effectiveness of the olfactory procedure employed. Ten minute duration test results indicated that cover A was most effective, cover C was nearly as effective, and cover B was the least effective, although a reduction in odor intensity was observed.