Bioremediation of Bacteria, Histamine, and Animal DNA by Black Soldier Fly Larvae for Safe Food Waste Valorisation

By 2050, the global population is expected to reach 9.8 billion, increasing pressure on agri-food systems and worsening food waste. In the EU, around 59 million tonnes of food is wasted annually, enough to feed 42 million people per year. This waste has major public health impacts. Managing it through safe, sustainable strategies is essential. Black soldier fly larvae (BSFL; Hermetia illucens) offer a promising solution by converting food waste into high-value products: protein, fat, and organic fertiliser. However, EU legislation currently prohibits using food waste as insect feed due to possible contamination with prions and other foodborne hazards such as bacteria and histamine. This study evaluates the food safety potential of BSFL by assessing their ability to reduce pathogenic bacteria and histamine, and to determine whether they bioaccumulate animal DNA (pork, beef, chicken). To test this, 2 tonnes of heterogeneous food waste was transformed into BSFL substrate and used as the test group in a bioconversion assay. Larvae in the test group showed improved performance, with higher bioconversion, growth rates, and a lower feed conversion ratio compared to the control group. Analyses were conducted on food waste substrate, larvae, BSFL meal, and frass, including controls. Bacterial enumeration followed ISO protocols; histamine was quantified using an ELISA kit; DNA was extracted and then analysed via PCR and agarose gel electrophoresis. BSFL significantly reduced Salmonella spp. and Vibrio spp. in the test group (p = 0.002), and Bacillus cereus and Vibrio spp. in the control (p = 0.015). Histamine levels decreased significantly (p = 0.029). No animal DNA was detected in larvae (p = 0.029), though traces persisted in frass, indicating excretion rather than bioaccumulation. These findings support the safe use of BSFL in food waste valorisation and their integration into circular, One Health food systems focused on safety and sustainability.