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Relationship between zinc and cadmium contents and cultivating conditions of gourmet and medicinal mushroom Agaricus subrufescens

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Overview

Jasińska and colleagues measured zinc and cadmium in the gourmet and medicinal mushroom Agaricus subrufescens and related concentrations to cultivation conditions. The study is routeable for mushroom occurrence context because it reports cadmium concentrations in fruiting bodies and substrates. It is an experimental cultivation source, not a retail-market survey.

Key numbers

All values are mg/kg dry matter (d.m.) unless otherwise noted.

  • Cd in fruiting bodies (Table 2, by substrate × flush): 2.6 mg/kg (MC10 % 5th flush) to 17.9 mg/kg (MC40 % 1st flush). Mean across all substrates and flushes 6.63 mg/kg (SD 5.08). The Results text reports an internal range of 1.2–21.6 mg/kg “data not presented in the tables,” which is wider than the per-cell range visible in Table 2 (2.6–17.9); the table-cell range is used here as the audit-defensible value.
  • Zn in fruiting bodies (Table 2): 43.9 mg/kg (MC20 % 4th flush) to 116.2 mg/kg (MC40 % 3rd flush). Mean across all substrates and flushes 81.5 mg/kg (SD 25.20). The abstract reports a slightly wider Zn range of 42.8–126.9 mg/kg without table attribution; Table 2 cells span 43.9–116.2.
  • Cd in mushroom composts at inoculation (Table 1): 0.36 mg/kg (10 % digestate) to 0.19 mg/kg (40 % digestate); Cd decreased as digestate share rose.
  • Zn in mushroom composts at inoculation (Table 1): 34.78 mg/kg (10 % digestate) to 28.75 mg/kg (40 % digestate).
  • Bioconcentration factor BCF (basidiocarp/substrate, Table 3): Zn 1.82–3.75 across MC10 %–MC40 %; Cd 20.4–29.4 across the four substrates, indicating substantially stronger Cd than Zn bioaccumulation regardless of digestate fraction.
  • EU regulation cited: Commission Regulation (EC) No. 1881/2006 sets a general Cd limit of 1 mg/kg fresh matter for mushrooms excluding Agaricus bisporus, which the authors note “roughly corresponds to 10 mg/kg dry matter.”
  • Polish legislation cited (per Results text): Zn upper limit of 100 mg/kg DW for mushrooms; the authors note their Zn values are at or just above this limit in the MC30 % and MC40 % flushes.

Methods (brief)

Cultivation: Agaricus subrufescens spawn was applied at 3 % of fresh substrate weight to four mushroom composts based on wheat straw and paper with food waste digestate from anaerobic digestion at 10, 20, 30, and 40 % of pre-processing dry matter. Cultivation bags (50 µm polypropylene, 7 L, ~3 kg compost) were incubated at 25 ± 2 °C for 15 days then 20 ± 2 °C for 5 days at 85–95 % humidity under 6000 K LED, CO₂ < 1000 ppm. Five flushes were harvested over a 110-day cropping period; experiments used a fully randomised design with four replications across two cultivation cycles.

Sample prep: caps and stipes were dried (105 ± 5 °C, 96 h), ground in a Retsch PM 200 cutting/ball mill, and 0.50 ± 0.01 g was microwave-digested in concentrated HNO₃ (Mars 5 Xpress, CEM), filtered, and diluted to 15.0 mL. Each sample was analysed in triplicate.

Determination: total Cd and total Zn by inductively coupled plasma optical emission spectrometry (Agilent 5100 ICP-OES, radial view; wavelength 214.439 nm; RF 1.2 kW). Method LOD reported at 0.0026 mg/kg d.m. (3σ); whole-procedure analytical uncertainty ~10 %. No matrix-matched mushroom CRM was available; traceability was checked against CRM S-1 (loess soil), CRM NCSDC 73349 (bush branches and leaves), CRM 2709 (soil), and CRM 405 (estuarine sediments), with recovery 80–120 %. ANOVA for randomised blocks at α = 0.05.

The work is an experimental cultivation study using A. subrufescens grown on engineered digestate-based composts. Results are not retail-market occurrence data and should retain substrate, flush, and basis (d.m.) metadata when cited.

Implications

Certification: Supports mushroom Cd context but should be treated separately from ordinary retail mushrooms.

Courses: Useful for explaining substrate-to-fruiting-body transfer.

App: Can inform mushroom ingredient risk only with the experimental-cultivation caveat.

Update history

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