Barborakova et al. 2024 - Heavy metals in black soldier fly larvae under feed-variant trials

Barborakova et al. measured microbial hazards and heavy metals in black soldier fly larvae before and after four experimental feed treatments. The paper is directly useful for insect-protein and animal-feed safety context because it reports Cd, Pb, Ni, Cu, Mn, Mo, Zn, Co, and Cr in larvae by ICP-OES. Its Evidence Fitness is limited to feed-substrate and experimental insect-protein evidence; it is not a market survey of retail insect-protein products.

Key numbers

Feed variants: BF = larvae before experimental feeding; I = egg pasta cooked in whole milk; II = cooked rice with peas; III = poultry feed; IV = cooked couscous, boiled eggs, fresh spinach, and carrot peels. Table 6 reports concentrations as mg/kg with standard deviation.

HMTc-relevant metals, Table 6:

• Cd: BF <LOD; variant I <LOD; variant II 0.13 +/- 6.84 mg/kg; variant III 0.12 +/- 4.87 mg/kg; variant IV 0.18 +/- 1.22 mg/kg. LOD for Cd was 0.0004 mg/kg.
• Pb: BF 3.07 +/- 2.12 mg/kg; variants I-IV <LOD. LOD for Pb was 0.008 mg/kg.
• Ni: BF 9.92 +/- 0.34 mg/kg; variant I 3.89 +/- 1.06; variant II 6.63 +/- 0.54; variant III 8.86 +/- 0.64; variant IV 6.32 +/- 0.85. LOD for Ni was 0.002 mg/kg.
• Cr: all groups <LOD. LOD for Cr was 0.011 mg/kg.

Other reported elements, Table 6:

• Cu: BF 33.77 +/- 0.29 mg/kg; variant I 17.54 +/- 0.83; variant II 6.67 +/- 1.79; variant III 26.45 +/- 0.44; variant IV 6.53 +/- 0.98. LOD for Cu was 0.003 mg/kg.
• Mn: BF 123.43 +/- 0.71 mg/kg; variant I 106.01 +/- 0.69; variant II 69.51 +/- 0.58; variant III 118.71 +/- 0.21; variant IV 63.38 +/- 0.39. LOD for Mn was 0.0003 mg/kg.
• Mo: BF <LOD; variant I <LOD; variant II <LOD; variant III 2.45 +/- 5.82 mg/kg; variant IV <LOD. LOD for Mo was 0.004 mg/kg.
• Zn: BF 114.49 +/- 1.57 mg/kg; variant I 110.57 +/- 1.27; variant II 48.97 +/- 0.81; variant III 98.62 +/- 0.68; variant IV 39.42 +/- 0.54. LOD for Zn was 0.691 mg/kg.
• Co: all groups <LOD. LOD for Co was 0.002 mg/kg.

Cadmium summary from the abstract and discussion: Cd concentrations in larvae after feeding ranged from 0.12 to 0.18 mg/kg, with the highest value in variant IV.

Methods (brief)

The study reared black soldier fly larvae under laboratory conditions at 27 +/- 1 degrees C and 50-60% relative humidity. Four replicate feed treatments were run for each variant, with 100 g larvae at the start of the experiment and 380 g/day feed ration in each replicate. Larvae were frozen, lyophilized, ground, and analysed for selected metals by ICP-OES. Microbiological testing used ISO-aligned plate dilution methods and MALDI-TOF identification, but the routeable heavy-metal evidence is Table 6.

Implications

Certification: This source is useful for novel-protein and insect-protein risk review. It shows that feed substrate can shift larvae metal concentrations, with Cd detected after several feed variants and Pb detected only before experimental feeding. It should not be treated as a market benchmark for retail supplements or pet foods.

Courses: The paper demonstrates the two-sided risk of insect bioconversion: larvae can upgrade waste streams into protein, but the substrate can carry metals into edible or feed ingredients.

App: Insect-protein ingredient records should preserve substrate-dependent uncertainty and avoid assuming that all black soldier fly larvae products share one metal profile.

Microbiome: The paper includes microbial safety data, but this page only routes the heavy-metal occurrence portion.

Wiki pages this source may touch

• non-soy-protein-source
• cadmium
• lead
• nickel
• chromium
• icp-oes

Verification notes

• Evidence Fitness: routeable as experimental insect-protein/feed-substrate evidence. It is not fit for clean retail benchmark pooling because the larvae were laboratory-fed defined substrates rather than sampled from a consumer market.
• Speciation: the paper reports total elemental concentrations and does not speciate chromium, arsenic, or mercury. This page records Cr, not Cr-VI.
• Table 6 reports Cd standard deviations that are much larger than the means for variants II-IV. Values are transcribed as printed, and the anomaly should be treated as a source-level reporting issue rather than corrected by inference.
• The fetched filename suggested rice milk, but the PDF is a black soldier fly larvae paper. The source page follows the actual PDF title, DOI, byline, and matrix.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.