Progress report for FW24-001
Project Information
Mushroom cultivation generates roughly 1-2 million tons of polypropylene (PP) and high-density polyethylene (HDPE) plastic waste per year globally, with 3 tons of plastic coming from Bridgetown Mushrooms alone. A reusable alternative to single-use plastic grow bags would significantly reduce plastic waste. This project will test the feasibility of a reusable grow bag made of silicone rubber (SR) and compare growing outcomes with current single-use PP bags.
Previously, Bridgetown Mushrooms partnered with the Oregon Applied Sustainability Experience, funded by US EPA, to investigate effective alternatives to PP bags. Solutions explored had significantly lower production rates, higher costs, or infrastructure requirements infeasible for the company. The company distributed an industry survey and interviewed nine experts, all of which expressed concern about plastic waste in the industry. Findings concluded that while there is not a simple solution, there is collective desire to reduce waste and explore reusable bags.
SR stands out as a potentially suitable material for reusable bags. SR can be used indefinitely at 300°F with minimal deterioration. This project seeks to test an initial concept of a reusable bag made of SR to determine its viability. Working with material specialists, Bridgetown Mushrooms will develop and compare a reusable bag made of SR with the current standard PP bag. Lessons learned from this project could pave the way for eliminating the majority of plastic waste in the industry. Potential outcomes would be the elimination of at least 78,000 single-use plastic bags (3 tons) per year at Bridgetown Mushrooms alone, and collaboration with the industry for broader development and adoption.
Bridgetown Mushrooms will develop a fact sheet and accompanying graphics to distribute via its social media channels and website, will share information at an industry conference, and will initiate a pledge for cultivators to reduce plastic waste in the mushroom industry.
Research Objectives:
- Assess the difference in biological efficiency between fruiting blocks cultivated in reusable silicone rubber (SR) bags and standard polypropylene (PP) bags.
- Evaluate the variance in contamination levels for the treatment (SR) and the control (PP).
- Determine the longevity of prototype reusable SR bags when subjected to continual heat exposure in an autoclave.
- Establish the financial cost and feasibility of adopting reusable silicone bags.
Educational Objectives:
- Raise awareness and promote reusable growing bags to professional mushroom cultivators and hobbyists.
- Engage with stakeholders and build community support for alternatives to single-use plastic growing bags.
- Introduce a pledge for cultivators to reduce plastic waste in the mushroom industry.
SARE_Updated Timeline_Bridgetown Mushrooms
|
Date |
Activities |
Team Members |
|
April-June 2024 |
R&D of SR bag; create first generation for testing. |
PI. TA aids in material input, PM monitors budget. |
|
June 2024 |
Begin preliminary testing on one SR bag. |
PI. RL aids in establishing standardized protocol |
|
June 2024 |
Write standardized procedures for the Production Team (PT). |
PI, PM |
|
July 2024 |
Train Production Team. |
PI, RL, PM |
|
July 1-Oct 1, 2024 |
Run bag group 1 (Objective 1&2) |
PI, RL. PT assists with initial setup of experiments. |
|
July 10-Oct 10, 2024 |
Run bag group 2 (Objective 1&2) |
PI, RL. PT follows standardized procedure for obj 1. |
|
July 20-Oct 20, 2024 |
Run bag group 3 (Objective 1&2) |
PI, RL. PT will assist. |
|
July 2023-Jan 2024 |
Conduct objective 3 experiment (16 total autoclave runs) |
PI will assist RL and PT. |
|
September 2024 |
Social media post #1: Highlight the extent of single-use plastic used to grow mushrooms and notify our audience of the Western SARE grant award |
PM, TA, RL collaborate on appropriate messaging. |
|
November 2024 |
Analyze data from Group 1-3. Determine if SR bags are able to undergo additional testing. |
PI. RL will analyze data. |
| November 2024-February 2025 |
Run bag group 1.1 (Objective 1&2) |
PI, RL. PT will assist. |
|
November 2024-February 2025 |
Run bag group 2.1 (Objective 1&2) |
PI, RL. PT will assist. |
|
December 2024 |
Social media post #2: Discuss barriers for finding alternatives to single-use plastic and proposed solutions. |
PM, TA, RL collaborate on appropriate messaging. |
|
January 2025 |
Develop a printed fact sheet outlining preliminary results of research. |
PM, RL collaborate on appropriate messaging. |
|
February 2025 |
Distribute fact sheet at North American Mushroom Conference. |
PI |
|
March 2025 |
Analyze all data for Obj. 1-4 and write final report. |
PI, PM, TA, and RL will collaborate. |
|
March 2025 |
|
PM, PI, TA, and RL collaborate on messaging. |
|
April 2025 |
|
PM, PI, TA. |
Cooperators
- - Technical Advisor
Research
Bridgetown Mushrooms will determine if single-use polypropylene (PP) bags can be replaced with a new reusable silicone rubber (SR) bag. Single-use grow bags are the industry standard and this research seeks to develop and test a first-of-its-kind reusable grow bag made of SR. The experimental phase will be completed within the 1-year period of the grant with time to repeat objectives 1 and 2 for seasonality changes.
Research Objectives
- Assess the difference in yield between fruiting blocks cultivated in reusable silicone rubber (SR) bags and standard polypropylene (PP) bags.
- Evaluate the difference in contamination levels between the treatment (SR) and the control (PP).
- Determine the longevity of reusable SR bags when subjected to continual heat exposure in an autoclave.
- Perform a cost-benefit analysis and determine feasibility of adopting reusable silicone bags.
Background and Significance
While there are ways of growing specialty mushrooms (SM) without single-use plastic bags, cultivators use single-use bags for the ease of access, affordability, consistency, and scalability. Currently, there are no other commercial methods for producing SM that meet these needs. Some push compostable bioplastics, but they are not environmentally preferable (Vendries et al., 2020). A prior SARE project validated the lack of scalability of one of the only other accessible options (FNC22-1335 Mushroom farming without single-use plastic...) The project concluded that the bucket technique is, “...ideal for home-scale production but is not feasible for market farmers.” With no other feasible options, this project seeks to test the viability of a new concept to reduce plastic waste: a reusable grow bag made of silicone rubber.
Experimental Design
Prior to testing, a first generation SR bag will be designed and produced with in-house CAD engineer and external material specialist support. We aim to produce 50 first generation bags for this experiment with:
- 30 in rotation for Objectives 1 and 2
- 10 in rotation for Objective 3
- 10 additional to be used as replacements for Objective 1 in the event of bag failure.
Objectives 1 and 2:
These one-way independent experiments will use yield (objective 1) and contamination (objective 2) to determine differences between the two types of grow bags. Three bag rotations will occur across three groups, totaling nine replications. The number of experimental units per group will be 20 (10 SR bags and 10 PP bags). Each rotation will last approximately 20 days from bagging to harvest, with 10 days in between each rotation (See Figure 1. SARE Experimental Design - Obj. 1 & 2). The total sample size will be 180 (20 experimental units over nine replications) spanning approximately 110 days. The number of experimental units allows for relevant statistical analysis.
The treatment (SR) and the control (PP) bags will both undergo the company’s standard operating procedures, as follows.
- Materials (per experimental unit):
- One bag (made of PP or SR, with a filter patch)
- 10 pounds of substrate
- 0.26 pounds of spawn
- Methods:
- Load prepared substrate into bags and sterilize at 250°F.
- Add spawn and seal to prevent contamination.
- Allow ~10 days for colonization, depending on species, and monitor for contamination.
- Move viable (non-contaminated) bags to fruiting chambers and record contamination loss data.
- Harvest fruit (mature mushrooms).
- Weigh, trim, and document the yield per bag.
- Data Analysis
Contamination and yield data will be collected from the above methods at steps (d) and (f) (respectively). Comparative average yield and contamination loss are prioritized as they reveal whether the SR bag creates an ideal, sterilized environment for growing SM similar to PP bags. Contamination data is meant to measure bag failure rate and the yield data will provide the amount of mushrooms harvested per viable bag. This data set will be directly compared to Bridgetown’s baseline average production values of 2.5lbs yield per PP bag and 5% loss due to contamination. From these baseline values, our lower limit for successful average yield per bag is 1.75lb and the upper limit for contamination is 10% loss.
Objective 3
This investigation will document deterioration of silicone rubber bags used for spawn and substrate from sterilization treatment. This qualitative experiment will be conducted 18 times over a 6 month period to determine durability of empty and filled SR bags. All bags will be numbered.
- Materials:
- 10 SR bags
- 240 lbs Spawn
- 4 lbs per bag
- 600 lbs Substrate
- 10 lbs per bag
- Autoclave
- Methods:
- Load filled and empty SR bags into the autoclave and run via standardized procedure at 250°F.
- Remove and inspect the bags for signs of deterioration and record which, if any, bags have failed.
- Repeat 1x/month over 6 months:
- Spawn: 10 EU with 6 replicates
- Substrate: 10 EU with 6 replicates
- Empty: 10 EU with 6 replicates
- Data Analysis:
Failure data will be collected from the above methods during step (b) and during any accidental damage. The two metrics recorded are (1) bag failures due to process cycling, and (2) bag failures due to accidental damage. These metrics will be used to calculate the average lifetime of the SR bags during the 6-month study and will inform the cost-benefit analysis and comparative environmental impact.
Objective 4
This phase of the project will synthesize data to perform a cost-benefit analysis and determine feasibility of adopting reusable silicone bags.
- Methods:
- Complete objectives 1-3 and analyze findings.
- Determine the number of SR bags needed annually to maintain current production levels.
- Determine total cost per unit at small-scale vs projected cost at large-scale production.
- Determine return on investment.
- Create a list of benefits for PP bags and SR bags.
- Data Analysis:
Data from the previous objectives will be used to determine the number of SR bags needed over time to maintain current production levels, and the expected total cost per year in comparison with Bridgetown’s current annual cost of $45,000 for 78,000 single-use PP bags. Two overall costs will be calculated: (1) cost calculated from the development of the first generation SR bag, and (2) cost from estimated quotes for large-scale production, if obtainable. These costs will help determine if replacing PP bags with SR bags is financially viable for Bridgetown and wide-scale adoption.
Research Outcomes
Bridgetown Mushrooms has made significant progress in research and development of a silicone rubber mushroom grow bag. To date, the company has developed a CAD design needed for obtaining manufacturer quotes and identified a manufacturing partner. During this phase, Bridgetown drew up multiple design concepts, evaluated potential part configurations, and consulted with material science advisors to ensure the bag's structural integrity and performance. Upon completion of the CAD, Bridgetown Mushrooms contacted 17 different manufacturers to asses production feasibility. Of the 17 manufacturers, seven indicated they were unable to produce the bag, two required substantial redesign, and six did not respond. One manufacturer provided a quote; however, Bridgetown determined the option was unsuitable. Ultimately, the company identified an engineering firm capable of both engineering design support and manufacturing services, which allows for adequate support and a more efficient production process.
With the unexpected difficulty of finding a manufacturer, the timeline for bag development was delayed. Progress on the research objectives and outcomes will begin once the bag has been manufactured.
Education and Outreach
Participation Summary:
The project’s education plan is centered around three primary objectives, each with specific outreach activities and methods to achieve them. These objectives aim to raise awareness, inform professionals and hobbyists in the mushroom industry, and engage with stakeholders while emphasizing diversity in outreach strategies.
Education Objectives
- Raise awareness of reusable bags to professional mushroom growers and hobbyists.
- Engage with stakeholders and build community support for alternatives to single-use plastic growing bags.
- Introduce a pledge for plastic reduction in the mushroom industry.
Objective 1: Raise Awareness of Reusable Growing Bags
Education Objective: Share the results comparing reusable silicone rubber growing bags to traditional polypropylene growing bags with mushroom professionals and hobbyists. This effort aims to raise awareness of the single-use plastic waste generated in the industry and inspire support for further development and adoption of reusable bags. Materials will highlight all research objectives.
Outreach Activities and Methods:
- Social Media Engagement
- Bridgetown Mushrooms will create four engaging social media posts on the following channels: Instagram (15,700 followers), Facebook (3,700 followers), and LinkedIn (350 followers). Our audience is comprised of local and international mushroom growers, scientists, and consumers. Through these platforms, we have engaged with a diverse range of hobbyists and small farmers with limited resources.
- Post 1 will highlight the extent of single-use plastic used locally and globally to grow mushrooms and will notify our audience of the Western SARE grant award. (Scheduled for project quarter 2)
- Post 2 will discuss the barriers for finding alternatives to single-use plastic, why biodegradable plastic is not a preferred solution, and why reusable bags are a viable option. (Scheduled for project quarter 3)
- Post 3 will discuss the results of our research comparing the performance of reusable silicone bags with single-use polypropylene bags. An Instagram and Facebook carousel will display graphics summarizing the data for each of the research objectives. The post will also be shared to Instagram and Facebook stories. A LinkedIn post will be made with the graphics. These posts will direct readers to our comprehensive website blog post, outlined below. This post will be promoted for 30 days on Instagram and Facebook to reach an extended audience of people interested in mushroom cultivation. (Scheduled for project quarter 4)
- Post 4 will be a short video showing the reusable bag in production flow and how a reusable bag could easily replace single use. The post will share cost-benefit information and direct viewers to our comprehensive blog post (below). (Scheduled for project quarter 4)
- Bridgetown Mushrooms will create four engaging social media posts on the following channels: Instagram (15,700 followers), Facebook (3,700 followers), and LinkedIn (350 followers). Our audience is comprised of local and international mushroom growers, scientists, and consumers. Through these platforms, we have engaged with a diverse range of hobbyists and small farmers with limited resources.
- Website Blog and Email Newsletter
- A comprehensive blog post will be published on our website and shared in our email newsletter to over 1,300 subscribers. The post will combine the content of the three social media post topics above and expand on the research findings. It will discuss the specific results from the project, outlining efficiency and performance comparisons, the durability of the silicone rubber bag under repeated autoclave cycles, and a cost-benefit analysis of switching from single-use polypropylene bags to reusable silicone bags. (Scheduled for project quarter 4)
- Participation at the 2025 North American Mushroom Conference
- Bridgetown Mushrooms will present or exhibit at the 2025 North American Mushroom Conference. A dedicated factsheet will be developed to distribute at the conference, effectively sharing our research findings with industry professionals. (Occurring in project quarter 4: February 2025)
Objective 2: Engage with Stakeholders and Build Community Support
Education Objective: Share results with our stakeholders and build greater community support and awareness of sustainable agriculture objectives and waste reduction opportunities.
Outreach Activities and Methods:
Activities one and two under Objective 1 will also help meet Objective 2. In addition to these activities, the following methods will be used.
- Farmers Market Outreach: The factsheet developed for the North American Mushroom Conference will be available at our three farmers market booths in 2025, including the Lake Oswego Farmers Market, the City of Tigard Farmers Market, and the South Waterfront Farmers Market.
Objective 3: Introduce a Pledge for Plastic Reduction in the Mushroom Industry
Education Objective: Measure pledge interaction, and build cultivator momentum and commitment to reduce plastic waste.
Outreach Activities and Methods:
- Develop a Pledge Form
- The pledge form will briefly outline single-use plastic waste generated in the specialty mushroom industry and will link to our comprehensive blog post summarizing project findings. It will then allow cultivators to select one or more pledge statements (e.g. “I pledge to educate others on plastic waste in the mushroom industry.” “I pledge to calculate my annual plastic waste generated.” “I pledge to investigate recycling opportunities for my plastic waste.”).
- Distribute the Pledge Form
- The pledge form will be advertised via social media near the end of the project in quarter 4.
Innovative Engagement and Diverse Media Outlets
The innovative aspect of this education plan lies in its multi-media approach. Specifically, the plan leverages various social media platforms with diverse audiences. Each of these platforms have the power to reach different segments of the mushroom-growing community, from small local hobbyists to large national cultivators. This use of social media maximizes the project’s outreach and ensures the message reaches a broad spectrum of stakeholders.
Additionally, the use of visual graphics summarizing research data on social media makes complex information digestible and engaging. This approach taps into the power of visual storytelling, making it easier for the audience to understand and remember key messages. Paid advertising will expand the reach. The website blog post will target those who prefer more in-depth information and will highlight the SARE grant funding opportunity for other mushroom growers who are interested in a research project.
In-person outreach at the North American Mushroom Conference and at farmers markets will include a factsheet with visuals, showcasing the project’s findings. Engagement at the conference will foster industry discussions and knowledge sharing. Distribution at farmers markets will engage the general public and other cultivators in the importance of sustainable agriculture and potential solutions to plastic waste. This method of education centers the importance of grassroots support in creating and driving lasting change in sustainable agriculture practices.
Educational outreach is tied to the results of our research. As our bag prototypes have not yet been tested, outreach efforts are still underway.
Education and Outreach Outcomes
The educational outreach is dependent on the findings of our completed research. As our experimental design phase has yet to begin, outreach is still in progress.
N/A