Farming BSFL - Foodborne Pathogens & Safety | What You Need to Know : The Life and Times of BSF (Black Soldier Flies)
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Farming BSFL - Foodborne Pathogens & Safety | What You Need to Know

by Terry Green on 03/03/15

Black Soldier fly larvae (BSFL) grow off biodegradable wastes and in the process provide an earth-friendly means of recycling valuable nutrients in wastes into insect biomass (see Recycling Biodegradable Wastes? | Take Your Cue from Mother Nature).  Scaled up production of BSFL could  provide an alternative sustainable high quality fish meal substitute which one day could help offset overfishing of our oceans (see Black Soldier Fly Larvae | An Earth Friendly Feedstock?).  This blog discusses some important biological safety issues concerning the farming and marketing of BSFL.

Whereas the nutritional value of BSFL (see Nutritional Composition of Black Soldier Fly Larvae (Hermetia illucens) is well-established, and byproducts in farming BSFL can be used to improve crop viability (see Amending Soil with Black Soldier Fly Processed Food Scrap Leachate and Effect of non-aerated compost teas on damping-off pathogens of tomato), safety issues concerning the potential risk of introducing enteric and foodborne pathogens into animal feedstocks, and carryover of pathogens into byproducts used, for example, as foliant sprays and soil amendments for farm crops, have received little attention.  Given the importance of safely farming foods destined for animal and human consumption, farmers growing BSFL with the intent of marketing BSFL and offshoot byproducts realized in farming BSFL should seriously consider implementing quality control monitoring programs designed to ensure that their farmed larvae and byproducts are free of foodborne pathogens at the time they are marketed.

BSFL grown off of animal manure and/or post-consumer food scrap, in particular, must be considered a rich source of foodborne pathogens where measures must be taken to ensure that any pathogens present are not passed on into the food chain. Enteric pathogens common in cow, pig and chicken manure which can cause food poisoning, and more serious life-threatening diseases, include, for example, coliforms, viruses, protozoa and multicellular parasites.  E. coli, Samonella, Shigella, Yersinia, Citrobacter and Klebsiella growing in and/or contaminating feedstocks are but a few familiar examples of coliform bacteria which left unchecked pose a serious threat to human health.

In addition, it is important to keep in mind that organic matter deemed free of coliforms, albeit rich in nutrients, added back to soil, may in certain instances still support the growth and entry of foodborne pathogens and fecal coliforms into the food chain  (see, for example, Factors Affecting Compost Tea as a Potential Source of Escherichia coli and Salmonella on Fresh Produce).

For these reasons, food safety, which includes management practices on a BSFL farm and processing site, requires action on the part of the farmer and/or processor of BSFL to put into place a sound quality control program in maintaining safety from farm to fork. Fortunately, screening BSFL and residual byproducts recovered in farming BSFL for potential pathogens can be done inexpensively using field testing kits designed for screening soils, food and water for fecal contamination (see, for example, E. coli Quantitube(TM) Test Kit - 10 Test Kit and 3M™ Petrifilm™ E.coli/Coliform Count Plates). Alternatively, testing can be done by sending out test samples periodically through a certified laboratory.

For BSFL grown off of manure, since the presence of residual pathogenic bacterial carryover in end products must be assumed, a plan must be in place to deal with this potential threat to the food chain before end products are shipped out or applied to agricultural soils. Although the negative results in testing BSFL grown off of food scrap might well be expected in monitoring BSFL grown solely on food scrap, pre- or post-consumer in origin, one should keep in mind that a negative test does not rule out contamination from an external source. Soil and other surfaces at the processing site, seeded with bacteria, could still lead to new growth of bacteria in stock products harvested and set aside for shipment.  Accordingly, regular quality control monitoring of all BSFL products sold commercially should be standard practice.

As the technology for producing BSFL on an industrial scale evolves, it is likely that sterilization during the drying stage of the larvae will ensure that end product are free of pathogenic bacteria. It should be noted that temperatures in the range of 60+ C (140+ F) must be attained and held for periods exceeding 24 hours in drying and preparing BSFL for shipment. These conditions should be sufficient to ensure die off of any residual pathogens carried over during the harvest of BSFL destined for commercial sale. Periodic and regular checks for contamination of the final end products before and after drying should further help allay the risk of passing on potential pathogens carried over during the farming of BSFL as an alternate source of high quality protein to be used in animal feedstocks or destined to be used for human consumption.

Putting in place a microbial screening program on end products should serve to furthermore help build a safety record in the farming of BSFL which in the long run through good data management and records will enable BSFL producers to establish credibility in clearing farming and harvesting processes with local, state and federal regulatory agencies in addition to gaining FDA clearance in establishing a systematic safety net in safely formulating harvested BSFL into animal feedstocks to be marketed on an industrial scale where safety of the product is paramount.

In our next blog practical steps in setting up coliform screening in farming BSFL  will be discussed– stay tuned! Check back anytime for more to follow on strategies in managing BSFL and processing biodegradable waste. Comments on this blog, or any of our other blogs, are always welcome. Follow us through our RSS feed. For additional information or follow-up questions, visit our Forums page, or Contact Us (http://www.dipterra.com/).


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