Alternative Mushroom Production System Using Non-composted Grain-based Substrates
Open Access
- Author:
- Bechara, Mark Anthony
- Graduate Program:
- Agricultural and Biological Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- September 07, 2007
- Committee Members:
- Paul Heinz Heinemann, Committee Chair/Co-Chair
Paul Walker, Committee Member
Thomas Lehman Richard, Committee Member
John Michael Regan, Committee Member
Charles Peter Romaine, Committee Member - Keywords:
- non composted substrates
agaricus bisporus
cost modelling
Pleurotus eryngii
Agaricus blazei - Abstract:
- The commercial production system of Agaricus bisporus mushroom relies entirely on composting as a means to generate a mushroom-specific substrate, and all aspects of this traditional system are designed for the preparation, processing, and handling of this compost-based substrate. Furthermore, the substrate, which is a mixture of compost and delayed-release supplements, has been refined for maximum mushroom production, and although widely adopted by mushroom producers around the world, this system is environmentally problematic (odor emissions, nutrient-rich run-off, and substrate disposal limitations) and these problems will only intensify with urban sprawl. In this study, grain-based mushroom production systems were evaluated as a potential alternative to the traditional compost-based system for A. bisporus. Two types of grain-based systems were developed and called– “Satellite Mushroom Production System” (SMPS), and “Complete On-site Mushroom Production System” (COMPS). Mushroom producers adopting the SMPS, would use a substrate primarily composed of commercial grain spawn, whereas mushrooms producers adopting the COMPS would use a subsrate composed of cereal grains mixed with oilseed (grain/oilseed). Both systems were tested and refined for mushroom production and substrate bioefficiency (BE). Furthermore, the theoretical designs and the direct costs for mushroom production for each system were developed and calculated. For the SMPS, the factors influencing mushroom production were: adding a layer of water-holding materials below the commercial grain spawn substrate, heat-sterilizing casing with the addition of activated carbon, and type and level of delayed-release supplement used. Overall, the highest yield of mushrooms for a commercial grain spawn substrate was 14.28 kg/m2 with a corresponding BE of 177% and was obtained for a treatment containing 5% S41- an underlying layer of perlite (2000 ml) and cased with a heat-sterilized casing containing 25% activated carbon. The design of SMPS entails different steps that start with mixing of the substrate ingredients, transferring the substrate to trays, and subsequent steps are comparable to traditional compost-based systems. Based on the cost model developed for the SMPS, the cost of production/unit weigh of mushroom is $4.00/kg. This is much higher than the market cost of A. bisporus and mushroom producers would not make a profit. For the COMPS, the factors that were tested for mushroom production using grain/oilseed substrate were type of cereal grain used, type and rate of oilseed added, pre-conditioning the substrate with Scytalidium thermophilum (a mushroom compost thermophile), and moisture content in the grain portion of the substrate. Furthermore, two additional mushroom producing species (A. blazei and Pleurotus eryngii) were grown on the grain/oilseed substrate to determine whether the grain-based system could be extended to the production of other mushroom forming species. For A. bisporus, adding oilseeds to a basal substrate composed of millet grain increased yield and a 15% amendment of soybean gave the highest yield (16.9 kg/m2 with a corresponding BE of 205%). Furthermore, preconditioning the substrate with S. thermophilum improved yield on oat based-substrates and decreased spawn-run time for all grain/oilseed substrates. Moisture contents ranging from 50-65% seem adequate for mushroom production, whereas the peak in yield is observed between the 55% and 60% moisture levels. For A. blazei and P. eryngii mushroom production, grain/oilseed substrate successfully supported mushroom production. For A. blazei, millet with 30% niger yielded 15.9 kg/m2, whereas, an oat/oilseed substrate provided the highest yield of 106 g for P. eryngii. Overall, the highest yield for A. bisporus was observed for a millet/ 5% soybean substrate with an additional amendment of 5% delayed-release supplement (Promycel Target®) which produced 21.3 kg/m2 with a BE of 273%. The system design is composed of an aseptic processing unit that converts the raw materials into a suitable mushroom substrate, and steps following the processing of the grain/oilseed substrate are comparable to the SMPS. Based on the cost model developed for the COMPS, the cost of production/unit weight of mushrooms is $1.40/kg, and this would provide mushroom producers with a profit. Based on findings from this research, developing an alternative commercial A. bisporus mushroom production system using grain-based substrates is a highly promising alternative to commercial compost-based system and its environmental problems. Yield from grain-based substrates is still lower than compost-based substrates but further refinement of the substrate ultimately will increase mushroom yield. A pilot-scale system is needed to test scale-up of this system for mushroom production on grain-based substrates.