🍎 Detection of irradiated food containing mineral debris (silicates, calcite from shells or exoskeletons, hydroxyapatite from bones or teeth) by photostimulated luminescence (PSL) — non-destructive screening measurement of PSL intensity compared with a lower threshold T1 and an upper threshold T2 (negative, intermediate, positive signal) and an optional calibrated measurement after irradiating the sample with a defined dose (PSL sensitivity); a positive screening result is confirmed by calibrated PSL or another standardized (EN 1784–EN 1788) or validated method; validated on shellfish and on herbs, spices and seasonings; PN-EN 13751:2009

Food chemistry PN-EN 13751

Overview

WHAT THE STANDARD COVERS. We read the text of the standard on detecting irradiated food by photostimulated luminescence made available by the European Commission on its food irradiation pages (file labelled "13751-2002", i.e. the EN 13751:2002 edition): scope, principle (with screening and calibrated PSL), limitations and validation with Table 1 — 3 pages. The current PN-EN 13751:2009 introduces EN 13751:2009 (PKN search); we did not read the 2009 text, so we do not give differences between editions. The apparatus, procedure, threshold values for individual products (other than validation data) and interpretation are not in the text read.

ACCORDING TO THE TEXT OF EN 13751:2002. Scope (1): a method for detecting irradiated food by photostimulated luminescence (PSL); it comprises an initial measurement of PSL intensity, which may be used for screening, and a calibration method to determine PSL sensitivity, assisting classification; a positive screening result must be confirmed by calibrated PSL or another standardized (e.g. EN 1784 to EN 1788) or validated method; the method has been successfully tested in interlaboratory trials on shellfish and on herbs, spices and seasonings; from other studies it may be concluded that it is applicable to a large variety of foods. Principle (2.1): mineral debris, typically silicates or bioinorganic materials — calcite from shells or exoskeletons, hydroxyapatite from bones or teeth — is found on most foods; when exposed to ionizing radiation these materials store energy in charge carriers trapped at structural, interstitial or impurity sites; optical stimulation of minerals releases the charge carriers; the same spectra were obtained from whole samples of herbs, spices and other foods using photostimulation; PSL measurement does not destroy the sample — whole samples or mixtures of organic and inorganic material can be measured repeatedly, but the PSL signal decreases when the same sample is measured repeatedly; the methodology comprises a screening (initial) PSL measurement establishing the status of the sample and an optional second measurement after a calibration dose determining the PSL sensitivity of the sample. Screening PSL (2.2): the signal level is compared with two thresholds; most irradiated samples give a strong signal above the upper threshold; a signal below the lower threshold suggests that the sample has not been irradiated; a signal between the thresholds (intermediate) means further investigation is necessary; the thresholds give an effective screening method that can be backed up by calibration, thermoluminescence (EN 1788) or another validated method. Calibrated PSL (2.3): after the initial measurement the sample is exposed to a defined radiation dose and remeasured; irradiated samples then show only a small increase in PSL, whereas unirradiated samples usually show a substantial increase. Limitations (3): the method can in principle be applied to any food containing mineral debris; the PSL sensitivity depends on the quantities and types of minerals in the individual sample; signals below T1 are generally associated with unirradiated material but can derive from low-sensitivity irradiated material — calibration helps to distinguish these; samples with low sensitivity (negative or intermediate after calibration) are investigated further by thermoluminescence or another method; calibrated measurements are recommended for shellfish with low mineral content and "clean" spices (e.g. nutmeg, ground white and black pepper) to avoid false negatives; best results are obtained from unblended products — blends (e.g. curry powders) may contain debris of different sensitivities and give ambiguous calibrated PSL results; salt in a product may dominate the PSL intensity and mask signals from irradiated ingredients — hydrating the product and remeasuring identifies and rectifies this. Validation (4): shellfish — intercomparison organized by SURRC on behalf of the Ministry of Agriculture, Fisheries and Food (MAFF), 5 laboratories, each with 10 irradiated (0.5 and 2.5 kGy) and 5 unirradiated blind samples from 5 species; 6 aliquots of whole samples and 6 of intestines measured for 60 s, the two highest results judged against T1 = 1000 and T2 = 4000 counts/60 s — all 75 samples correctly classified, calibrated measurements gave the same results; herbs, spices and seasonings — SURRC/MAFF trial, 9 participants, 40 varieties and 4 blends, irradiated with up to 10 kGy or unirradiated, T1 = 700 and T2 = 5000 counts/60 s, measurement time 60 s; 662 screening measurements (345 irradiated, 317 unirradiated samples) gave 577 positive or negative classifications, of which 569 (98.6 %) were correct and 8 (1.4 %) incorrect, attributed to operator error; 85 samples (12.8 %) gave intermediate signals (24 irradiated and 61 unirradiated); of 400 calibrated measurements (201 irradiated, 199 unirradiated samples) 345 were correctly classified; 55 (13.8 %) had given intermediate screening results — after calibration 33 of them gave positive results (sensitivity confirmed), allowing them to be classified as unirradiated and resolving 60 % of the intermediate cases; the remaining 22 (5.5 % of 400) required another method, e.g. EN 1788; blends with 1 %, 5 % and 10 % of irradiated spices were all identified, but with components of different sensitivity detection performance may be more limited. Table 1 (screening): shellfish — 100 % correct among irradiated and unirradiated; herbs and spices — irradiated: 320 correct (93 %) on clear-cut screening, 344 (99.7 %) when screening is treated as selection for further investigation, 1 (0.3 %) false negative; unirradiated: 249 (78.5 %) correct, 7 (2.2 %) false positives.

STATUS (as of 03.10.2026). In the PKN search engine (query "PN-EN 13751", 03.10.2026) PN-EN 13751:2009 appears in the English version, "Introduces: EN 13751:2009 [IDT]", without a withdrawal note; PN-EN 13751:2007 (Polish version, introduced EN 13751:2002) — "Withdrawn and replaced by PN-EN 13751:2009 - English version"; PN-EN 13751:2003 (English version) — withdrawn and replaced by PN-EN 13751:2007.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, load up to 17.09.2026, read 03.10.2026). The number 13751 appears in 2 records at 2 laboratories: AB 262 and AB 537. In the current PCA documents (read 03.10.2026; AB 537 issue no. 28 of 07.08.2026, AB 262 issue no. 18 of 25.09.2026) the number appears at the same 2 laboratories; in each document the number of page markers equals the number of PDF pages, without duplicates; searching all PCA documents downloaded from the BIP on 03.10.2026 found no laboratories outside the database copy. Forms: "PN-EN 13751:2009" (AB 262) and "PN-EN 13751:2009 (metoda skriningowa)" — screening method (AB 537). None of these items is suspended. The "Laboratories" tab (query "PN-EN 13751") shows both laboratories — checked by a tab query on the labcoda.pl production server on 03.10.2026.

WHAT THE LABORATORIES TEST (PCA items). AB 262: food containing silicate minerals — detection of irradiation, luminescence intensity, photoluminescence method (PSL). AB 537: food containing silicate minerals — detection of irradiation, luminescence intensity, photoluminescence method PSL (qualitative), with the note "screening method". At both laboratories the neighbouring item is detection of irradiation by thermoluminescence (at AB 537 according to PN-EN 1788:2002).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Positive result: screening requires confirmation by calibrated PSL or another standardized method, e.g. thermoluminescence (1, 2.2). Negative result: a signal below T1 may come from low-sensitivity irradiated material — hence calibration and further investigation (3); calibrated measurements are recommended for shellfish with low mineral content and "clean" spices (3). Repeat measurements: the PSL signal decreases with each further measurement of the same sample (2.1). Blends: curry and similar blends give ambiguous calibrated results (3). Salt: salt may mask the signal of irradiated ingredients — hydration and remeasurement (3). Thresholds: T1 and T2 in validation differed for shellfish (1000 and 4000) and spices (700 and 5000 counts/60 s) (4) — thresholds depend on the product and instrument. Intermediate results: in the herbs and spices validation 12.8 % of samples gave an intermediate signal, and 5.5 % were not resolved even by calibration (4). Matrix in the scope: PCA describes the item as "food containing silicate minerals", while the standard also covers calcite and hydroxyapatite (2.1). Edition: the text read is EN 13751:2002; the 2009 edition is in force, available in PKN only in English.

WHAT WE DO NOT GIVE. We do not reproduce the design of the PSL instrument, the measurement procedure, the calibration dose or rules for setting thresholds — they are not in the text read. We do not summarize EN 1784–EN 1788 in this entry; we do not give regulations on food irradiation.

Method principle

Mineral debris on food (silicates, calcite, hydroxyapatite) stores energy in trapped charge carriers when exposed to ionizing radiation. Optical stimulation releases these carriers and produces luminescence, whose intensity is measured non-destructively and compared with thresholds: above the upper — irradiated, below the lower — indication of no irradiation, in between — further investigation. In the calibrated variant the sample is exposed to a known dose and remeasured: an unirradiated sample usually shows a large increase in signal, an irradiated one a small increase.

Applications

• Shellfish (whole samples and intestines) — validated (1, 4)
• Herbs, spices and seasonings and their blends — validated (1, 4)
• Other foods containing mineral debris — according to other studies (1, 3)
• Food containing silicate minerals — detection of irradiation by PSL (qualitative) — 2 accreditation scope records of 2 laboratories in PCA

Key parameters

Standard

Standard number

PN-EN 13751:2009

Title (PL)

Artykuły żywnościowe — Wykrywanie napromieniania żywności z zastosowaniem fotoluminescencji

Title (EN)

Foodstuffs — Detection of irradiated food using photostimulated luminescence

Step-by-step procedure

1. Screening measurement

   PSL intensity of the whole sample, comparison with T1 and T2 (2.2). PN-EN 13751:2009 — no withdrawal note (PKN, 03.10.2026).

2. Classification

   Positive — to be confirmed; negative — indication of no irradiation; intermediate — further investigation (1, 2.2).

3. Calibration (optional)

   Exposure to a defined dose and remeasurement — small increase: irradiated; large: unirradiated (2.3).

4. Confirmation

   Thermoluminescence (EN 1788) or another standardized or validated method (1, 3).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• The EN 13751:2002 text read (clauses 1–4) contains no safety warnings

Frequently asked questions