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

Commodities

• Miscellaneous: mushrooms

Practices

• Crop Production: sustainable, organic
• Education and Training: extension, farmer to farmer, mentoring
• Energy: energy conservation/efficiency, energy use
• Farm Business Management: cooperatives, e-commerce, farm-to-institution, farm-to-restaurant, farmers' markets/farm stands
• Production Systems: organic certification
• Sustainable Communities: food hubs, local and regional food systems, sustainability measures, urban agriculture

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.