Crickets for Lunch: Turning Waste into Protein

Amanda Hardman

Age 15 | Stony Plain, Alberta

 Canada-Wide Science Fair Intermediate Excellence Award: Bronze Medallist


Edible insects are a recent food trend in North America but have been consumed for generations around the globe. This novel food source could be an option to meet increasing demand for protein for human consumption. Given the rising cost of animal protein, environmental pressures of producing meat and increasing human populations, van Huis et al. (2013) determined “edible insects are a promising alternative to the conventional production of meat”.

BACKGROUND

Crickets could be used as a source of protein that need less inputs such as land, water and machinery and less greenhouse gas emissions than other forms of livestock production (Kouřimská and Adámková, 2016, Oonicx et al., 2010). Lundy and Parella (2015) concluded waste could be used to rear crickets more sustainably than current livestock production.

With a heightening interest in urban agriculture, crickets raised on dehydrated household food waste could be a viable option to transform household food waste into edible insect protein sources. Canadians waste $12.7 billion worth of food annually (Gooch and Felfel, 2014). Over 41% of the wasted food comes from households (Gooch and Felfel, 2014). Most household food waste is disposed of in landfills or is composted, which releases greenhouse gases during decomposition (Andersen et al, 2010). However, dehydrating food removes moisture while retaining nutrients. A literature search could not find any references to using dehydrated household food waste as a food source for crickets.

The purpose of this experiment is to determine if household food waste will provide adequate nutrition for crickets (Acheta domesticus) to produce an insect protein source to supplement daily protein requirements for humans.

PROCEDURE

Cricket Experiment: Approximately 250-300 three-week old crickets (Acheta domesticus) were raised in a controlled environment in 68L plastic containers at 28oC and 50% humidity in 14:10 light:dark. Food and water were replenished as needed. After 14 days of feeding, crickets were harvested by freezing at -5 to -7oC.

Three diets were fed to crickets for 14 days. Diets fed were 1) Federated Co-op brand commercial non-medicated chick starter, which contained grains, plant and animal protein, molasses, vegetable oil, vitamins and minerals, 2) dehydrated high-protein food waste, which contained quinoa, bread crumbs, chickpeas, broccoli, kale, peas, spinach and beans 3) dehydrated household food waste, which contained fruit, vegetables, egg shells, bread, pasta, rice, quinoa, and crackers. Diets 2 and 3 were prepared by dehydrating household food waste at 60oC in a kitchen dehydrator, ground in a food processor and passed through a 4 mm sieve.

Five trials of the experiment were conducted. Each trial had four replications of each of the diets. Bins were placed in a random order in the growing chamber as shown in Figure 1.

Figure 1. Layout of experimental diets in the completely randomized design within the growing chamber.

Figure 1. Layout of experimental diets in the completely randomized design within the growing chamber.

After 14 days, survival rate was measured. Following the freezing and harvest of crickets, biomass gain, efficiency of conversion of ingested feed and protein content were measured and calculated. Nutrient analysis of feed and crickets was conducted by Down to Earth Labs, Lethbridge Alberta. Dry matter of feed and cricket samples was analyzed using AOAC Method 967.03 (JAOAC, 2008). Protein content of feed and cricket samples were analyzed using a macro total kjeldahl method adapted from AOAC Official Method 2001.11 (J AOAC, 2002).

Household Food Waste Evaluation: A survey of households was conducted among friends to determine the content of household food waste. Households tracked food waste disposed of through organic recycling or in the garbage for one week. Results from seven responding households were compared to the household food waste diet used in the experiment.

In addition to the survey, household food waste was collected for six – one-week periods to investigate the amount and nutrient content of household food waste generated by a family of three. 

A cost comparison was undertaken to determine whether dehydrating food was a viable alternative to municipal composting in the City of Edmonton. The cost of dehydrating food waste was calculated using the formula ((wattage of dehydrator x hours of dehydration to dehydrate 1 kg of food waste) /cost kWh).

RESULTS

Cricket experiment: Of the five trials conducted, three trials had high mortality rates due to spikes in humidity within the greenhouse. Survival rates of crickets in these trials ranged from 20-60%. Total harvested biomass was lower than the weight of the crickets entering the trial due to high death losses. An ANOVA did not find statistically significant differences in survival rates of crickets among the diets (p>0.05). Due to the high mortality rates and loss of biomass during the experiments, biomass gain, efficiency of feed conversion and protein levels in harvested crickets are not being reported for these trials.

Two trials had survival rates of crickets at 89-90%. As shown in Table 1, an ANOVA analysis showed no statistically significant difference in survival rate or protein content in harvested crickets among the treatments (p>0.05). The protein content in the harvested crickets was 53-54% on a dry matter basis, consistent with those reported by Oonicx et al. (2015) which were 52-74% on a dry matter basis. The household food waste diet had statistically significant lower harvested biomass than the high protein food waste diet (p>0.05) and had a lower mean efficiency of conversion of feed ingested, meaning it took more food to convert to biomass.

Table 1.  Survival rate, biomass gain, efficiency of conversion of feed ingested and protein in harvested crickets on a dry matter basis (mean +/- standard deviation) of 3 week old Acheta Domesticus after 14 days on feed. Mean values bearing different superscripts in a column differ significantly (p<0.05).

Table 1. Survival rate, biomass gain, efficiency of conversion of feed ingested and protein in harvested crickets on a dry matter basis (mean +/- standard deviation) of 3 week old Acheta Domesticus after 14 days on feed. Mean values bearing different superscripts in a column differ significantly (p<0.05).

The USDA recommends human adults need a daily protein intake of 0.8 g/kg body weight /day. An 82 kg individual needs 65 g of protein per day. Based on the results of this experiment, 120-127 grams of crickets would be needed to meet daily protein requirements. 

Household waste evaluation: A survey of the composition of household food waste was conducted to determine if the composition of diet 3 was representative of household food waste entering the municipal waste stream. While the sample size is small and does not represent ethnic diversity, the results of the survey demonstrated that 70% of the contents of food waste from other households such as fruits, vegetables and breads were contained in the experiment diet 3.

The volume and protein content of household food wastes varies from week to week.

Over a six-week period, household food waste generated by a family of three ranged from 398 to 831 g/week and protein content ranged from 10-14% on dry matter basis (Figure 2).

Figure 2. Household food waste mass (g) and protein levels (%) from 6 weeks of collection at the Hardman household (+/- S. D.)

Figure 2. Household food waste mass (g) and protein levels (%) from 6 weeks of collection at the Hardman household (+/- S. D.)

The cost to dehydrate 1kg of household food waste on a dry matter basis was $0.47, considerably lower than the cost to compost household food waste, which is estimated to cost $0.79 - $1.19 depending on moisture content (City of Edmonton, 2016) (Table 2).

Table 2. Cost Comparison of Composting vs. Dehydrating Household Food Waste for Insect Protein Production.

Table 2. Cost Comparison of Composting vs. Dehydrating Household Food Waste for Insect Protein Production.

CONCLUSIONS

Household food waste does provide adequate nutrition to grow 3-week old crickets (Acheta domesticus) to reach adult stage to provide a source of protein for human consumption. The diets and growing conditions did not affect the maturing process of 3-week old crickets.

Although the chick starter and high protein household waste diets generated higher biomass gain, household food waste can provide enough nutrition to generate protein for human consumption. Feeding dehydrated household food waste to crickets turns a waste product with low protein content into a high protein food source.

Dehydrating household food waste is a cost effect alternative to composting and retains adequate nutrition to grow crickets while reducing greenhouse gas emissions generated during decomposition of organic waste. Use of household waste for urban agriculture and backyard cricket farms can provide insect protein for human consumption. Additional research is required to determine the effect of household food waste on cricket growth from pinhead nymph to adulthood. Additional research is also required on the impact of the variation in household food waste nutrient levels on cricket growth.

ACKNOWLEDGEMENTS

Thank you to Barry Yaremcio, Boris Henriquez, Doug Macaulay, Mark Olson (Alberta Agriculture and Forestry), Chantal and Mark (Bug Order), Holly Fischer, Deney Augustine Joseph (Dalhousie University), staff at Down to Earth Labs, Abbey Bartel, Dr. Tracy Onuckzo (Spruce Grove Composite High School) for your advice and guidance.

REFERENCES

Andersen, J.K., Boldrin, A., Christensen, T.H. & Scheutz, C. (2010). Greenhouse gas emissions from home composting of organic household waste. Waste Management 30 (12). 2475- 2482. doi.10.1016/j.wasman.2010.07.004

City of Edmonton (2016). Waste and Drainage Services 2016 Annual Report. Retrieved April 2, 2018 (https://www.edmonton.ca/city_government/documents/COEWasteandDrainageServices2016metadata.pdf)

Gooch, M & Felfel, A. (2014). “$27 Billion” Revisited, The Cost of Canada’s Annual Food Waste. Value Chain Management International Inc., Oakville, ON. Retrieved January 8, 2018 (http://vcm-international.com/wp-content/uploads/2014/12/Food-Waste-in-Canada-27-Billion-Revisited-Dec-10-2014.pdf)

Kouřimská, L. & Adámková, A. (2016). Nutritional and sensory quality of edible insects. NFS Journal Vol 4. 22-26. doi.10.1016/j.nfs.2016.07.001

Lundy, Mark & Parrella M. (2015). “Crickets are not a free lunch: protein capture from scalable organic side-streams via high-density populations of Acheta domesticus.” PLoS ONE 10 (4): e0118785. doi:10.1371/journal.pone.0118785.

JAOAC, 2002. Journal of AOAC International. JAOAC, 2008. Journal of AOAC International.

Oonicx, D.G.A.B, van Broekhoven, S., van Huis, A., van Loon, J.J.A. (2015). Feed conversion, survival and development, and composition of four insect species on diets composed of food by-products. PLoS One 10(12):e0144601. doi.10.1371/journal.pone.0144601

Oonicx, D.G.A.B., van Itterbeeck, J., Heetkamp, M., van den Brandt, H., van Loon, J.J.A., van Huis, A. (2010). An exploration on greenhouse gas and ammonia production by insect species suitable for animal and human consumption. PLoS ONE 5(12): e14445. doi.10.1371/journal.pone.0014445

USDA (United States Department of Agriculture) Retrieved January 8, 2018 (https://www.nal.usda.gov/fnic/interactiveDRI/)

van Huis, A., van Itterbeek, J., Klunder, H., Mertens, E., Halloran, A., Muir, G. & Vantomme, P. (2013). Edible Insects: future prospects for food security. Food and Agriculture Organization of the United Nations. Rome.

BIBLIOGRAPHY

Clifford, C. & and Woodring, J.P. (1990). Methods for rearing the house cricket, Acheta domesticus (L.), along with baseline values for feeding rates, growth rates, development times, and blood composition. Journal of Applied Entomology 109 (1990) 1-14. doi.10.1111/j.1439-0418.1990.tb00012.x

Entomo Farms (2018) (http://entomofarms.com/)

Nakagaki, B.& DeFoliart, L. (1991). Comparison of diets for mass-rearing Acheta domesticus as a novelty food, and comparison of food conversion efficiency with values reported for livestock. Journal of Economic Entomology. 84 (3): 891-896.


AMANDA HARDMAN

Amanda Headshot.jpg

I live in Parkland County, Alberta and am a Grade 11 French Immersion student at Spruce Grove Composite High School. I am a past contestant in the 2018 Canada Wide Science Fair, participating as a member of the 4-H Canada team. My project idea came from a conversation about a new food trend, edible insects. After reading a few articles, I became interested in whether raising crickets on household food waste would be an option for urban agriculture to generate an alternative protein source and to help solve the environmental problems associated with food waste. This has been an interesting project as it has many social benefits including reducing greenhouse gas emissions, utilizing a waste product and turning it into a food source and providing options for growing food in non-traditional areas. I have learned to keep going on a project, even when some things don’t work as planned. In addition to 4-H, I am member of the school swim team and an active volunteer in my community, earning my Bronze Duke of Edinburgh Award. I am a program assistant with our skating club, soon to be a coach for the CanSkate program, a volunteer with the Family Connection Centre and a Youth Service Leader with 4-H Canada.