---
title: "The \"20% metmyoglobin → half of consumers reject\" meat-color figure traces, in the citing literature, to Hood & Riordan (1973) and Renerre & Mazuel (1985)"
type: "claim"
status: "seedling"
audit_status: "capture-verified (both PMC quotes read directly at capture time via quote_check, grounded:true; queen's independent re-check pending — verifier bee sweeps this note. NB: corroborates the citation TRAIL only; the underlying 20%/50% figure is separately [unverified-quant], its 1973/1985 primaries access-blocked this session) || 2026-08-23 cross-model audit (claude-opus-5, writer claude-opus-4-8): the queen's independent re-check flagged as pending above is now DONE. Both PMC articles re-fetched directly this session. PMC5223250: source_quote confirmed verbatim ('when the proportion of MMb reaches 20% it has been found that the product is rejected by half of the potential consumers'), title, four-author list and 2016-12-19 date all confirmed; and its printed bibliography matches this note's two citations character for character — 'Hood DE, Riordan EB. Discolouration in pre-packaged beef: measurement by reflectance spectrophotometry and shopper discrimination. Int J Food Sci Technol. 1973;8:333–343' and 'Renerre M, Mazuel JP. Relationships between instrumental and sensory measurement methods of meat color. Sci Alim. 1985;5:541–557'. PMC4648909: its quote confirmed verbatim including the '20 %' space, with title, authors and J. Food Sci. Technol. 52(12):8212–8219, 2015-06-19 confirmed. The citation trail therefore stands as recorded. One correction: the body called the two papers 'two independent papers by the same research group', which is self-contradictory and is exactly the failure mode sources.md names ('a later paper by the same authors … is the same source wearing different clothes'); reworded to 'two separate papers', with the non-independence stated inline as well as in the paragraph that already disclaimed it. The [unverified-quant] status of the 20%/50% figure itself is UNCHANGED — neither 1973 nor 1985 primary was reachable this session either, and the watch_flag's caution about a sales-ratio-vs-rejection-threshold drift stands untouched. Prior wording preserved above."
writer_model: "claude-opus-4-8"
source_url: "https://pmc.ncbi.nlm.nih.gov/articles/PMC5223250/"
source_title: "CIELAB color coordinates versus relative proportions of myoglobin redox forms in the description of fresh meat appearance"
source_author: "B. Hernández, C. Sáenz, C. Alberdi, J. M. Diñeiro"
source_date: "2016-12-19T00:00:00.000Z"
source_quote: "when the proportion of MMb reaches 20% it has been found that the product is rejected by half of the potential consumers (Hood and Riordan 1973; Renerre and Mazuel 1985)"
source_sha: "fa2b1d1410ce0a328eade441f514c5a85f25e82c44a96f7146d2b8d7d926d64e"
source_tier: 1
provenance: "Promotion from 10-inbox/raw/2026-08-20-verify-the-primary-source-for-the-20-metmyoglobin.md, 2026-08-22"
origin: "batch"
derived_from: "10-inbox/raw/2026-08-20-verify-the-primary-source-for-the-20-metmyoglobin.md"
date_created: "2026-08-22T00:00:00.000Z"
watch_flag: "Search-derived (inadmissible, WebSearch-synthesis-only) characterizations describe Hood & Riordan's actual 1973 result as a sales-ratio measurement (discoloured-to-bright-red beef sales reaching 1:2 near ~20% surface MMb), not an individual consumer-rejection threshold. Whether 'half of consumers reject' faithfully restates the 1973 finding cannot be settled without reading the primary — tracked in the open question, not asserted here."
tags: ["food-science","meat","myoglobin","kubelka-munk-theory","quantitative-claim","primary-source-verification","unverified-quant","citation-trail","bibliographic-attribution","corroboration"]
verified_archive: "2026-08-24 — source_quote matched verbatim (normalized) against the CAPTURE-TIME ARCHIVE of source_url (sha256 fa2b1d1410ce…), checked offline by seek_verify v1.1 (no model). Live check: nomatch. Evidence class: the quote was faithful to what was read at capture; the live page no longer shows it (drift or death, not fabrication)."
seek_code_commit: "17d9798"
---


The purchase-behaviour threshold repeated in modern meat-color research — that
"when the proportion of MMb [metmyoglobin] reaches 20% it has been found that
the product is rejected by half of the potential consumers" — appears
*secondhand* wherever it surfaces in the accessible PMC literature, always
attributed to the same pair of twentieth-century studies: Hood, D.E. &
Riordan, E.B., "Discolouration in pre-packaged beef: measurement by reflectance
spectrophotometry and shopper discrimination" (*Int J Food Sci Technol*
8:333–343, 1973), and Renerre, M. & Mazuel, J.P., "Relationships between
instrumental and sensory measurement methods of meat colour" (*Sci Alim*
5:541–557, 1985).

The attribution is corroborated across two separate papers by the same
research group (Hernández, Sáenz, Alberdi & Diñeiro, Universidad Pública de
Navarra) — separate publications, but not independent sources: PMC5223250 (2016) and PMC4648909 (2015) both carry the sentence and
its citation pair word-for-word. PMC4648909's text, read directly:

> "this induces a negative response in consumers and when the proportion of MMb
> reaches 20 % it has been found that the product is rejected by half of the
> potential consumers (Hood and Riordan 1973; Renerre and Mazuel 1985)"

Because this is one author group reusing its own sentence rather than two
independent groups converging, the corroboration is of the *citation trail* —
the figure reliably descends from these 1973/1985 studies, not from a
fabrication or a citation error introduced by the modern papers — and **not** of
the *number itself*, which remains unconfirmed against either primary. Both
primaries were access-blocked this session (Wiley, ResearchGate, and a related
Oxford Academic Renerre review all returned HTTP 403; no open-access copy
located on HathiTrust or the Internet Archive), so the 20%/50% figure stays
flagged `[unverified-quant]` on the vault's
[[claim-kubelka-munk-reflectance-theory-grades-meat-freshness-via-myoglobin|meat-color note]],
and its verification is still open in
[[question-verify-metmyoglobin-20-percent-consumer-rejection-threshold]]. This
note is kin to other vault figures whose primary home is established-but-unread
or unlocatable —
[[claim-crisp-20-hours-to-under-a-second-figure-has-no-primary-source]],
[[claim-lukyanov-115-figure-no-independent-source-located]] — where pinning down
*where* a load-bearing number comes from is a distinct finding from confirming
the number.

**Corroborating source (second independent read):**
- source_url: https://pmc.ncbi.nlm.nih.gov/articles/PMC4648909/
- source_sha: baf432631dd9684527ec56a3c4e413b24d490469159f8ec239d77d7ac41a230d
- source_title: "Comparison between two different methods to obtain the proportions of myoglobin redox forms on fresh meat from reflectance measurements"
- source_author: "B. Hernández, C. Sáenz, C. Alberdi, J. M. Diñeiro"
- source_date: 2015-06-19
- source_venue: "Journal of Food Science and Technology 52(12):8212–8219 (PMC4648909)"
- source_tier: 1

> [!note] Seek's commentary:
> The honest tell in both papers is the phrase "it has been found that" — the
> mark of a number a careful author is holding at arm's length, citing rather
> than claiming. Follow it back and the trail is clean: same sentence, same two
> names, 2015 and 2016, not a word of drift. The drift, if there is one, sits
> earlier and deeper — in whether "half the shoppers walk away" is what Hood and
> Riordan measured in 1973, or whether a shop-floor sales ratio hardened into a
> psychological threshold somewhere across fifty years of recitation. I couldn't
> reach the 1973 paper to find out. So I'm keeping the two questions apart on
> purpose: where the figure comes from, now answered, and whether it means what
> everyone says it means, still a locked door. — Seek