Cultivation of gourmet mushrooms using brewer’s spent grain

Project Overview

FNE14-795
Project Type: Farmer
Funds awarded in 2014: $14,997.00
Projected End Date: 12/31/2015
Region: Northeast
State: Massachusetts
Project Leader:
Mycoterra Farm
Mycoterra Farm

Annual Reports

Commodities

  • Miscellaneous: mushrooms

Practices

  • Pest Management: prevention
  • Production Systems: general crop production

    Proposal summary:

    Local cultivation and sale of gourmet mushrooms is a growing niche in the sustainable foods market. Access to commonly used substrates may be limited by geographic or economic factors. Spent brewers’ grain (SBG) is a waste product of all commercial breweries, is produced in large quantities, and has been identified as an alternative nutrient source in mushroom cultivation. The aim of this project will be to develop formulas for replacing standard substrates with SBG, and to determine the economic practically of doing so at the production scale. The effects of SBG as a substitute for rye grain in the vegetative scale-up and fruiting steps of pearl oyster, shiitake, and lion’s mane will be tested. Each experiment will be repeated 2-4 times. The ultimate benchmark for success of the project will be economic viability as determined by a cost-benefit analysis. Economic viability will be determined by measuring mushroom yields as determined by dry and wet biological efficiency.

    Project objectives from proposal:

    The objective is to characterize feasibility of brewer’s spent grain (BSG) for cultivation of three popular edibles: pearl oyster (Pleurotus ostreatus), shiitake (Lentinula edodes) and lion’s mane (Hericium erinaceus). The project will be divided into four parts, testing the effects of BSG as:
    A)a substitute for rye grain in the vegetative scale-up steps
    B) a substitution for rye grain in fruiting step of shiitake and lion’s mane
    C) a replacement for bran as nitrogen source in the fruiting step of shiitake and lion’s mane
    D) a substitution for rye grain in fruiting step of pearl oyster.  

    Figure 1 shows the experiment overview. A1 and A2 will be performed with all mushrooms. A3, B and C will be done with shiitake and lion’s mane, while D will be done using pearl oyster. After determining the best set of treatments based on colonization times, yields, and biological efficiency (BE), a cost/benefit analysis will determine the feasibility of using BSG in mushroom production. Replicates in the following methods are based on batch sizes normally produced at Mycoterra.All media will be autoclave sterilized or pasteurized prior to inoculation. Controls and treatments will incubate in identical environments.

    The experiment will start 4/1/13 and data will collected and analyzed by 12/31/13. BSG will be sourced from Brewmaster’s Tavern in Williamsburg, MA.   A will test the effects of replacing rye with BSG in the vegetative scale-up steps (rye jars, rye bags, and sawdust bags).  In A1 (rye jars) the control will consist of 18 replicates of jars containing 200 g rye grain, 200 g water, and 2 g gypsum.The treatment jars will contain identical mass of BSG. Initial moisture and pH of both groups will be measured. Both groups will be inoculated from agar culture. A1 will run 4/1–5/1. Each A1 batch will incubate 2-4 weeks until fully colonized. Any jars failing to colonize by 4 weeks will be deemed unviable. 

    Growth will be monitored daily and judged on a scale from 0 – 5, and length until full colonization in each jar will be noted. Frequency of contamination within groups will be noted. A1 will be repeated up to three times with modifications as necessary to optimize colonization time.   A2 (rye bags) methods will be modified as needed based on the results of A1, and spawn will be transferred from A1 to A2. The A2 control (rye to rye) will have 6 replicates of bags of 2200 g rye grain, 1400 g water and 8 g gypsum, and each bag inoculated with one jar of rye grain from the A1 control.  In Treatment 1 (rye to BSG) rye bags will be replaced by an amount of BSG adjusted to equal mass. Treatment 2 (BSG to BSG) will replace rye jars with BSG jars from the A1 sample groups and rye bags with BSG bags adjusted to equal mass. A2 run 6/1–7/1.  Each A2 batch will be allowed to incubate 2-4 weeks until full colonization is achieved. Data will be measured as in A1. Once results of A2 are satisfactory, lion’s mane and shiitake A2 spawn will be transferred to A3, and to D for pearl oyster. A2 will be repeated two times with modifications as necessary to optimize colonization time.   In A3, control and treatment from A2 will be transferred to sawdust bags.

    The control will be 32 sawdust bags inoculated with A2 rye at a rate of 1:5. The treatment will replace rye inoculum with the most successful A2 treatment. Moisture content will be normalized to 60-70%. Data will be measured as in A1, however colonization in individual blocks will not be tracked. A3 run 8/1–9/1. Each A3 batch will be allowed to incubate 2-4 weeks until fully colonized.  Spawn will then be used in B and C. A3 will be done in duplicate.   B will test the effects of replacing grain inoculum with BSG on BE of shiitake and lion’s mane grown on supplemented sawdust. The control will consist of 21 spawn bags with the standard combination of sawdust, bran, and gypsum inoculated at a rate of 1:7 with A3 control. The treatment will replace the inoculum with A3 treatment.

    Moisture content will be normalized to 60-65%. Bags will be observed tridaily for 8-12 until full colonization, noting growth rate, colonization time, and contamination rate for. Fruiting will then be initiated in the grow room. The first fruiting flush of each batch will be harvested over a one-week period and weighed fresh and dried. Subsequent flushes will not be evaluated. B will run 10/1-12/1. B will be done in duplicate.   C will test the effect of BSG as a bran replacement on BE in shiitake and lion’s mane. C will follow the same timeline and experimental design as part B with the following changes. The control (A3 control to sawdust + bran) will consist of standard supplemented sawdust with A3 control sawdust. Treatment 1 (A3 control to sawdust + BSG) will replace the bran with BSGin quantity to contribute an equivalent amount of nitrogen as determined by Stamets’ formula for nitrogen supplementation (Stamets 2000).

    Treatment 2 (A3 treatment to sawdust + BSG) will mirror Treatment 1 but with A3 treatment in place of A3 control. C will proceed from this point as B, with data collected in the same manner. C will be done in duplicate   D will test the effect of BSG as a nitrogen supplement on BE for growing pearl oyster. The control will be the standard production formula: A2 control used to inoculate rye straw at a 20% rate. Treatment 1 will replace A2 control with the same mass of A2 treatment. Treatment 2 will inoculate with A2 treatment at a 40% rate. Replicate numbers will depend of capabilities of the new facility, but will be comparable to B and C. Data will be collected as in B. D run 6/1–7/1.

    Data will be collected over a four-week period. Data analysis will be performed by the end of October. D will be done in quadruplicate.   The ultimate benchmark for success of the project will be economic viability.

    Mushroom yield in parts B, C, and D will be most important data for determining this. The aggregate weight of the first flush will be weighed fresh to determine yield of each treatment. Wet weight will be an effective measure of “financial efficiency” in the marketplace since mushrooms will be sold fresh. The market worth of the mushrooms produced in each treatment will be determined by multiplying batch weight by standard price per lb. In the mushroom industry biological efficiency (BE) is the standard measure of mushroom yield vs. energy input, and is considered essential to evaluating the success of fruiting parameters. The formula is: BE % = (fresh weight of mushrooms / dry weight of substrate) * 100 (Chang et al. 1981). After fresh weights are measured, aggregate dry weights will be measured in order to account for any differences in water content between treatments.

    Additional measures of success will be colonization time and evidence of contamination, which will be measured in all parts. Colonization progress will be tracked using a semi-quantitative 0 (uncolonized)-5 (fully colonized) scale. Completion of colonization on a per bag/jar basis will be tracked in A1 and A2. ANOVA will be performed for individual colonization times in A1 and A2 in order to determine effect of BSG on colonization times. Fisher’s least significant difference will be used to determine significance. Time to complete batch colonization for parts A3, B, C, and D will also be noted, but not tracked on an individual basis and therefore stats will not be performed. Contamination in parts A1-A3 will indicate failure of the jar/bag. Contamination in B, C, or D will be noted, and contamination beyond a low threshold before the first flush completes will indicate failure. During the colonization period of each step, photographs will be used for documentation of notable colonization and contamination data.  

    The final step in order to determine the economic feasibility of using BSG as a rye replacement will be a cost-benefit analysis. Cost of rye vs BSG, total colonization times of treatments vs controls, total yields, contamination rates, and biological efficiency will be taken into account. Qualitative measures such as limitations due to BSG spoilage and mushroom quality will also be considered.   Although sales of mushrooms in the U.S. have nearly tripled since 1978, the number of mushroom farms has decreased by 13% in the same period, despite a growing population and greater interest in local, sustainable food sources (usda01.library.cornell.edu).

    By establishing a workable system for utilizing BSG, this project has the potential to decrease costs associated with starting and maintaining a mushroom farm, which could result in a greater number of local sources of mushrooms. With grain being a major prohibitive cost in mushroom cultivation, finding a cheaper replacement may allow for more small-scale mushroom growers in the Northeast. In the past 30 years, the number of microbreweries has dramatically increased throughout the region. Therefore, access to BSG will only continue to increase, allowing new mushroom farms to develop in both developed and rural areas. We believe the increased availability of BSG as a replacement of rye grains will allow more mushroom farms to develop and maintain a profitable business model.   Brewers’ spent grain is the major brewing by-product. Using BSG for commercial mushroom cultivation provides an avenue for BSG recycling in addition to the major avenue currently, which is as livestock feed. This would be useful in situations where transport to livestock farms is impractical, if BSG is not desired as feed, or if BSG supply outstrips demand as feed, which is becoming more of a possibility due to increasing numbers of breweries and beer production.     

    Julia Coffey regularly gives talks on mushrooms including basic information, small scale mushroom farming, and growing mushrooms at home. She has presented locally at the Montessori School, Westhampton Library, and the North Country Garden Center through the “Grown in Westhampton” agricultural meeting group. She has a ready audience waiting for a new and interesting topic, especially on the subject of mushroom roles in local sustainability. Julia will communicate the results of this project at this locales.   Mycoterra Farm has an established network with other large and small-scale mushroom farms throughout the country. These include Fungi Perfecti, Provisions Mushroom Farm, and Cascadia Mushrooms in WA, Birch House Farm in WI, and Myriad Mycology in OR. Efforts will also be made to make new connections in Northeast to communicate results with. Project results will be shared through personal interactions regarding the utility of BSG in their operation.   Information will also be disseminated in a written form through the UMASS Amherst community through the Stockbridge School of Agriculture. Dylan Kessler will compose a poster detailing the results and implications, and offer presentations to interested students, staff, and faculty. He will also create two semi-permanent poster exhibits on the UMASS campus.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.