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Free and bound amino acids, minerals and trace elements in matcha (Camellia sinensis L.): A nutritional evaluation

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Overview

Koláčková and colleagues analysed amino acids and 32 minerals and trace elements by ICP-MS in ten commercial matcha powders, eight from Japan and one each from China and Korea, and estimated intakes from a 5 g daily serving. Cadmium, arsenic and mercury were quantified in all ten products, while lead was not detected in four.

Key numbers

  • Lead: not detected (LOQ < 0.01 ng/g) in four products; 0.05 to 1.82 ng/g dry weight in the other six (Table 3).
  • Cadmium: 1.03 to 1.52 ng/g; mercury: 1.31 to 2.63 ng/g; arsenic (total): 14.2 to 31.5 ng/g dry weight (Table 3).
  • Aluminum: 5.42 to 113 ug/g; nickel 205 to 434 ng/g (Table 3).
  • A 5 g serving contributes under 0.1% of the cadmium PTMI and under 0.6% of the aluminum PTWI (Table 6, Section 3.4).

Methods (brief)

Microwave acid digestion and quadrupole ICP-MS with helium collision cell; five measurements per product; dry weight basis. Accuracy was checked with four certified reference materials (green algae, tea leaves, rice flour, lichen), but the CRM results are in a supplementary table that was not available.

Evidence Fitness

Direct evidence for matcha powder, but the file is the Journal Pre-proof, not the final typeset article. Ten products, each analysed as one sample in replicate. Lead values are much lower than those usually reported for tea leaves, and Table 3 repeats identical values across several product columns, which may be a transcription problem; treat the per-product values with caution. Brand names are coded as products 1 to 10.

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