Muntean et al. 2024 - elemental content of alternative aquaculture protein flours
Muntean and colleagues evaluated animal- and plant-derived protein flours as alternative ingredients for fish nutrition, including spent coffee grounds and other food-industry by-products. The study reports elemental composition for each flour type, including aluminum, nickel, total arsenic, cadmium, and lead; these are feed-ingredient and supply-chain values, not finished coffee or fish occurrence values.
Key numbers
Table 2 reports animal-origin protein flours. Snail flour contained Al 21.78 +/- 2.71 mg/kg, Ni 4.18 +/- 0.42 mg/kg, As <LQ, Cd 0.06 +/- 0.001 mg/kg, and Pb 0.24 +/- 0.02 mg/kg. Slug flour contained Al 211.90 +/- 15.33 mg/kg, Ni 1.55 +/- 0.09 mg/kg, As 1.56 +/- 0.74 mg/kg, Cd 1.17 +/- 0.85 mg/kg, and Pb 0.53 +/- 0.0002 mg/kg. Hepatopancreas flour contained Al 62.50 +/- 5.91 mg/kg, Ni 1.21 +/- 0.59 mg/kg, As 0.11 +/- 0.02 mg/kg, Cd 11.45 +/- 0.93 mg/kg, and Pb 1.72 +/- 0.0003 mg/kg. The text flags hepatopancreas flour Cd as notably higher than the other animal-origin flours.
Table 3 reports plant-origin protein flours. Sunflower flour contained Al 3.03 +/- 0.05 mg/kg, Ni 6.11 +/- 0.22 mg/kg, As <LQ, Cd 0.49 +/- 0.01 mg/kg, and Pb 0.15 +/- 0.01 mg/kg. Hemp flour contained Al 5.05 +/- 0.39 mg/kg, Ni 5.95 +/- 0.14 mg/kg, As <LQ, Cd <LQ, and Pb 0.14 +/- 0.01 mg/kg. Flax flour contained Al 3.54 +/- 0.22 mg/kg, Ni 1.50 +/- 0.08 mg/kg, As <LQ, Cd 0.28 +/- 0.02 mg/kg, and Pb 0.11 +/- 0.01 mg/kg.
Pumpkin flour contained Al 15.2 +/- 1.06 mg/kg, Ni 1.67 +/- 0.09 mg/kg, As <LQ, Cd <LQ, and Pb 0.16 +/- 0.01 mg/kg. Coffee grounds flour contained Al 0.16 +/- 0.01 mg/kg, Ni 0.08 +/- 0.01 mg/kg, As <LQ, Cd <LQ, and Pb <LQ. Spent brewer’s yeast flour contained Al 6.1 +/- 0.51 mg/kg, Ni 0.12 +/- 0.01 mg/kg, As <LQ, Cd 0.01 +/- 0.001 mg/kg, and Pb 0.01 +/- 0.001 mg/kg.
The quantification limit was 0.005 mg/kg for Table 2 and 0.05 mg/kg for Table 3. Coffee grounds flour had the highest plant protein content at 71.8%; spent brewer’s yeast flour had 57.9% protein. The paper reports low PAH levels across the tested flours, with hepatopancreas flour at 0.0353 ug/kg total PAH and coffee grounds flour at 0.0252 ug/kg total PAH.
Methods (brief)
The authors used FT-NIR spectroscopy (Tango Bruker) for nutritional characterization with matrix-specific calibration correction factors derived against Kjeldahl protein and Soxhlet lipid references. Elemental concentrations were determined after microwave-assisted acid digestion (500 mg sample in 8 mL 65 % HNO3 + 2 mL 30 % H2O2) by ICP-OES (Perkin Elmer Optima 5300 DV), with trace elements quantified in the mineralised solutions by ICP-MS. PAHs were measured by HPLC with fluorescence detection after saponification and cyclohexane extraction.
The plant-origin sample frame included sunflower, hemp, flax, pumpkin, coffee grounds, and spent brewer’s yeast flours. The animal-origin sample frame included Helix pomatia snail flour, Arion spp. slug flour, and Helix pomatia hepatopancreas flour. The text reports five collection events for Helix pomatia, eight for Arion spp., and three hepatopancreas collection events, with nine sunflower-oilcake, five hemp-oilcake, three flax-oilcake, three pumpkin-seed-oilcake, twelve coffee-grounds, and seven spent brewer’s yeast samples on the plant side.
Implications
Certification: Supply-chain evidence for feed-ingredient screening. Do not route the spent-coffee-ground values into coffee occurrence pools, and do not route the feed-flour values into fish flesh occurrence pools.
Courses: Useful for explaining why circular-economy feed ingredients still need contaminant screening; hepatopancreas flour showed much higher Cd than the other tested alternatives.
App: Context only unless a downstream fish-product synthesis explicitly models feed-to-fish transfer from separate occurrence evidence.
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Verification notes
The DOI, title, author list, journal, and year were taken from the Molecules PDF. The paper reports arsenic only as As, so this page records it as total arsenic and does not infer inorganic arsenic. The auto-fetched filename is a coffee/cadmium gap hit because spent coffee grounds are one tested feed-ingredient flour; products are intentionally empty because the source does not measure finished coffee or fish products.
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.
| Commit | Date | Description |
|---|---|---|
| 4039d20 | 2026-06-10 | scope: broaden ingest to the full upstream+downstream literature (marine, atmospheric, attribution, exposure, toxicology) — inclusion is the default |