Overview
Hata and colleagues developed an enzymatic plus methanol extraction method for organoarsenic species in wakame. The occurrence-relevant material is a single commercial dry wakame product from Japan; the rest of the paper tests extraction efficiency and speciation preservation. The source reports total arsenic in the dry wakame and method-dependent extractable arsenic peaks, but it does not report measured inorganic arsenic.
Key numbers
All product concentrations are reported by the source on a dry-wakame basis.
| Matrix | Result | Source-reported value |
|---|---|---|
| Commercial dry wakame | Total arsenic | 25.50 ± 1.05 mg/kg dry weight (mean ± SD, n = 3) |
| Wakame, alginate lyase + cellulase plus 100% MeOH extraction | Overall arsenic extraction rate | 88.8 ± 8.4% (n = 3, mean ± SD) |
| Wakame, alginate lyase + cellulase pre-treatment supernatant | Arsenic elution rate | 45.5 ± 2.2% (n = 5, mean ± SD) |
Enzymatic pre-treatment elution rates from Table 2:
| Treatment | Elution rate |
|---|---|
| A(-)C(-), no alginate lyase and no cellulase | 17.2 ± 3.7% |
| A(-)C(+), cellulase only | 22.6 ± 0.6% |
| A(+)C(-), alginate lyase only | 31.2 ± 0.7% |
| A(+)C(+), alginate lyase + cellulase | 45.5 ± 2.2% |
Extraction rates from Table 3:
| MeOH concentration | A(-)C(-) extraction rate | A(+)C(+) extraction rate |
|---|---|---|
| 0% | 22.5 ± 1.1% | 48.3 ± 0.5% |
| 50% | 21.8 ± 0.9% | 58.7 ± 4.1% |
| 100% | 28.1 ± 0.2% | 88.8 ± 8.4% |
Arsenic species/peak contents in wakame extracts from Table 4, reported as mg/kg dry wakame:
| Extraction condition | Peak a | Peak b (AsSug 482) | Peak c | AsSug 328 | Sum |
|---|---|---|---|---|---|
| A(-)C(-), 0% MeOH | 0.68 | 1.32 | 0.57 | 1.51 | 4.07 |
| A(-)C(-), 100% MeOH | 4.53 | 1.38 | 0.63 | 1.43 | 7.97 |
| A(+)C(+), 0% MeOH | 5.09 | 5.94 | 0.61 | 1.57 | 13.22 |
| A(+)C(+), 100% MeOH | 10.46 | 5.48 | 0.61 | 1.49 | 18.04 |
The authors identified AsSug 328 and AsSug 482 in the wakame extracts. Peak a was estimated to correspond to arsenic-hydrocarbon 388 (C21H46OAs in the results text) and arsenic-phospholipid 1012 (C49H95O14PAs in the results text); peak c was not identified. Neither AsSug 254 nor DMA was detected in this study, which the authors used as evidence that the enzymatic method did not alter the arsenic-compound composition.
Methods (brief)
A commercial dry wakame product, harvested from the Sanriku Coast and purchased from a retail market in Choshi City, was ground to powder before analysis. Total arsenic was measured by ICP-MS after microwave acid digestion of 100 mg powdered sample with 2.5 mL of HNO3:H2O2 = 5:2 and dilution to 30 mL with 5% HNO3. The total-As method was validated with NMIJ CRM 7405-a Hijiki: certified 35.8 ± 0.9 mg/kg, measured 35.5 ± 0.4 mg/kg (mean ± SD, n = 3).
For extraction testing, 100 mg dry wakame was incubated for 6 hours at 37 °C with alginate lyase, cellulase, both enzymes, or no enzyme in 0.1 M phosphate buffer (pH 6.0). Methanol extraction was then tested at 0, 50, and 100% MeOH. Arsenic species/peaks were separated by cation- and anion-exchange HPLC-ICP-MS and identified or tentatively assigned with HPLC-ESI-Q-TOF-MS.
Implications
This source should be treated as a narrow method-plus-occurrence record for dry wakame. It supports the seaweed/kelp food row by adding a Japanese retail dry-wakame total-arsenic value and showing that extraction conditions strongly affect the recovered organoarsenic profile. Because inorganic arsenic was not reported, this page should not be used as an inorganic-arsenic occurrence value.
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Verification notes
- Identity checks before writing found no existing source page for DOI
10.14252/foodsafetyfscj.2014037, raw handleMFK_hata2014, title text, or cite keyhata2014-wakame-organoarsenic-extraction. - All Key numbers were rechecked against
/tmp/hmi-seaweed-034.txt, extracted withpdftotext -layout. Tables 2, 3, and 4 were copied directly; the total-arsenic value is from Results section3-1. - Units and bases are preserved as
mg/kg dry weight,mg/kg dry wakame, and%; no unit conversion was performed. - Speciation check: the source reports total arsenic and organoarsenic/arsenosugar peaks. It does not report inorganic arsenic, so frontmatter uses
metals: [tAs]only and no AsSug/DMA value is promoted to iAs. - Brand firewall: the source does not identify a consumer brand; the page records only the retail-market dry wakame category and source-described harvest/geographic context.
- Missing-slug check: no missing product or ingredient slug blockers. Exact
wakameis retained in source text while frontmatter uses broad seaweed/kelp food slugs.
Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and 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.