Comparative Efficiency and Resource Use of Atmospheric vs. Pressurized Sterilization for Sustainable Mushroom Production

Commodities

Practices

The problem this project addresses is the lack of accessible, efficient, and scalable sterilization options for small and mid-sized mushroom farms. Most commercial-scale pressure sterilizers are prohibitively expensive, require large footprints, and often present challenges with building codes and power infrastructure. They are also complex to operate and maintain, making them impractical for many farms at our scale.

At MyCo Planet, we currently use atmospheric barrel sterilization, which worked well in earlier stages but has shown increasing contamination and declining yields over the past year. This raises an important question: are atmospheric systems inherently limited for larger batch sizes or certain mushroom varieties that require true sterilization?

We have purchased a new, mid-sized pressure sterilizer model that may bridge the gap-large enough for small commercial farms yet compact, affordable, and more energy efficient than full industrial systems and atmospheric systems. By comparing both methods, this project will evaluate not only contamination and yield outcomes, but also energy, water, and labor use. Many small to mid-scale mushroom growers face the same challenge of balancing cost, code compliance, and energy efficiency while maintaining production quality. This research aims to identify a sustainable, scalable sterilization model that improves yields while reducing resource use.

This project will evaluate the comparative efficiency, resource use, and production outcomes of atmospheric barrel sterilization versus a new, compact pressure autoclave system for small to mid-sized mushroom farms. The innovative aspect lies in testing a newer autoclave design that is more affordable, space-efficient, and energy-conscious than the large industrial sterilizers traditionally available. This unit has the potential to make pressurized sterilization practical and attainable for farms that have previously relied on atmospheric methods due to cost, space, or infrastructure constraints.

The trial will be conducted at MyCo Planet, we currently use atmospheric barrel sterilization systems, which have performed well but have recently shown increased contamination rates and reduced yields as our production volume has scaled and may no longer be the most efficient solution.

We will prepare identical substrate batches consisting of organic hardwood sawdust and soy hulls, hydrated and mixed under uniform conditions. Each batch will be bagged using the same filter patch grow bags and inoculated with identical strains of Lion's Mane and Blue Oyster mushrooms, two species with differing sensitivities to sterilization quality. Half of the substrate will be sterilized in our existing atmospheric barrel system (operating at ~200°F), while the other half will be processed in the new mid-sized autoclave (operating at ~249°F and 14 psi).

This project includes two months of substrate block production followed by incubation and fruiting to collect yield and contamination data. Each month will include replicated batches under both sterilization method. This provides sufficient data for basic statistical comparison and variance analysis in on-farm research. Two months aligns with MyCo Planet's normal production turnover: approximately three to four weeks for colonization and one to two weeks for fruiting. Repeating the process ensures consistency while keeping data collection within the six-month labor and facility window supported by this grant. The approach balances rigor and feasibility, producing a robust dataset on yield, contamination, and resource efficiency while using real operating conditions that accurately represent small- to mid-scale mushroom farm production cycles.

Data will be collected for energy consumption (kWh), water use, labor time, yield per block, and contamination rate. Each treatment will be replicated across multiple production cycles to capture variation and strengthen statistical reliability. We will also document qualitative data such as ease of use, safety, and cleaning requirements to assess long-term practicality for small-farm operators.

Our hypothesis is that the compact autoclave will achieve deeper sterilization and improved yields with lower contamination losses, while demonstrating reduced overall resource use per pound of mushrooms produced. Although pressure sterilization typically involves higher upfront investment, the potential efficiency gains and waste reduction could make it a cost-effective and sustainable choice for farms of our size.

This project aligns with regenerative agriculture principles by optimizing resource efficiency, reducing energy consumption, and improving the viability of sustainable mushroom farming systems. Mushrooms are a regenerative crop that converts agricultural byproducts such as sawdust and soy hulls into nutritious food and compostable waste. By identifying an energy-efficient sterilization method, this project strengthens the circular economy model within small-scale food production.

Findings will be shared through on-farm demonstrations, workshops, and digital outreach in partnership with regional grower networks and extension educators. We will provide a comprehensive summary of performance, costs, and best practices for both systems. The expected outcome is a clear, data-backed recommendation that helps farmers choose the most efficient, sustainable, and scalable sterilization approach, empowering small to mid-sized mushroom operations to grow responsibly and profitably.