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Measuring hordein (gluten) in beer--a comparison of ELISA and mass spectrometry.

Tanner GJ, Colgrave ML, Blundell MJ, Goswami HP, Howitt CA - PLoS ONE (2013)

Bottom Line: Subjects suffering from coeliac disease, gluten allergy/intolerance must adopt a lifelong avoidance of gluten.Several barley beers also contained undeclared wheat proteins.MS quantification is undertaken using peptides that are specific and unique, enabling the quantification of individual hordein isoforms.

View Article: PubMed Central - PubMed

Affiliation: Commonwealth Scientific and Industrial Research Organisation Plant Industry, Canberra, Australian Capital Territory, Australia.

ABSTRACT

Background: Subjects suffering from coeliac disease, gluten allergy/intolerance must adopt a lifelong avoidance of gluten. Beer contains trace levels of hordeins (gluten) which are too high to be safely consumed by most coeliacs. Accurate measurement of trace hordeins by ELISA is problematic.

Methods: We have compared hordein levels in sixty beers, by sandwich ELISA, with the level determined using multiple reaction monitoring mass spectrometry (MRM-MS).

Results: Hordein levels measured by ELISA varied by four orders of magnitude, from zero (for known gluten-free beers) to 47,000 µg/mL (ppm; for a wheat-based beer). Half the commercial gluten-free beers were free of hordein by MS and ELISA. Two gluten-free and two low-gluten beers had zero ELISA readings, but contained significant hordein levels (p<0.05), or near average (60-140%) hordein levels, by MS, respectively. Six beers gave false negatives, with zero ELISA readings but near average hordein content by MS. Approximately 20% of commercial beers had ELISA readings less than 1 ppm, but a near average hordein content by MS. Several barley beers also contained undeclared wheat proteins.

Conclusions: ELISA results did not correlate with the relative content of hordein peptides determined by MS, with all barley based beers containing hordein. We suggest that mass spectrometry is more reliable than ELISA, as ELISA enumerates only the concentration of particular amino-acid epitopes; this may vary between different hordeins and may not be related to the absolute hordein concentration. MS quantification is undertaken using peptides that are specific and unique, enabling the quantification of individual hordein isoforms. This outlines the problem of relying solely on ELISA determination of gluten in beverages such as beer and highlights the need for the development of new sensitive and selective quantitative assay such as MS.

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Related in: MedlinePlus

Scheduled multiple reaction monitoring (MRM) mass spectrometry revealed the presence of wheat gluten proteins in beers 5, 6, 9, 16, 30–33, 45, 55 and 56.(A) α-gliadin peptide pQQILQQQLIPCR; (B) α-gliadin peptide VPVPQLQPQNPSQQQPQEQVPL; (C) high molecular weight glutenin peptide IFWGIPALLK; and (D) low molecular weight glutenin peptide SIVLQEQQQVR. Three MRM transitions were monitored for each peptide. The summed peak areas ± S.D (n = 3) for the two most intense MRM transitions are shown, the third MRM transition was used as a qualifier (confirmation of peptide identity).
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pone-0056452-g003: Scheduled multiple reaction monitoring (MRM) mass spectrometry revealed the presence of wheat gluten proteins in beers 5, 6, 9, 16, 30–33, 45, 55 and 56.(A) α-gliadin peptide pQQILQQQLIPCR; (B) α-gliadin peptide VPVPQLQPQNPSQQQPQEQVPL; (C) high molecular weight glutenin peptide IFWGIPALLK; and (D) low molecular weight glutenin peptide SIVLQEQQQVR. Three MRM transitions were monitored for each peptide. The summed peak areas ± S.D (n = 3) for the two most intense MRM transitions are shown, the third MRM transition was used as a qualifier (confirmation of peptide identity).

Mentions: : MS analysis of beers after tryptic digestion revealed the presence (✓) or absence (✗) of wheat proteins: α-gliadin, γ-gliadin and low- and high- molecular weight glutenins indicative of the beer containing wheat (see Fig. 3).


Measuring hordein (gluten) in beer--a comparison of ELISA and mass spectrometry.

Tanner GJ, Colgrave ML, Blundell MJ, Goswami HP, Howitt CA - PLoS ONE (2013)

Scheduled multiple reaction monitoring (MRM) mass spectrometry revealed the presence of wheat gluten proteins in beers 5, 6, 9, 16, 30–33, 45, 55 and 56.(A) α-gliadin peptide pQQILQQQLIPCR; (B) α-gliadin peptide VPVPQLQPQNPSQQQPQEQVPL; (C) high molecular weight glutenin peptide IFWGIPALLK; and (D) low molecular weight glutenin peptide SIVLQEQQQVR. Three MRM transitions were monitored for each peptide. The summed peak areas ± S.D (n = 3) for the two most intense MRM transitions are shown, the third MRM transition was used as a qualifier (confirmation of peptide identity).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585340&req=5

pone-0056452-g003: Scheduled multiple reaction monitoring (MRM) mass spectrometry revealed the presence of wheat gluten proteins in beers 5, 6, 9, 16, 30–33, 45, 55 and 56.(A) α-gliadin peptide pQQILQQQLIPCR; (B) α-gliadin peptide VPVPQLQPQNPSQQQPQEQVPL; (C) high molecular weight glutenin peptide IFWGIPALLK; and (D) low molecular weight glutenin peptide SIVLQEQQQVR. Three MRM transitions were monitored for each peptide. The summed peak areas ± S.D (n = 3) for the two most intense MRM transitions are shown, the third MRM transition was used as a qualifier (confirmation of peptide identity).
Mentions: : MS analysis of beers after tryptic digestion revealed the presence (✓) or absence (✗) of wheat proteins: α-gliadin, γ-gliadin and low- and high- molecular weight glutenins indicative of the beer containing wheat (see Fig. 3).

Bottom Line: Subjects suffering from coeliac disease, gluten allergy/intolerance must adopt a lifelong avoidance of gluten.Several barley beers also contained undeclared wheat proteins.MS quantification is undertaken using peptides that are specific and unique, enabling the quantification of individual hordein isoforms.

View Article: PubMed Central - PubMed

Affiliation: Commonwealth Scientific and Industrial Research Organisation Plant Industry, Canberra, Australian Capital Territory, Australia.

ABSTRACT

Background: Subjects suffering from coeliac disease, gluten allergy/intolerance must adopt a lifelong avoidance of gluten. Beer contains trace levels of hordeins (gluten) which are too high to be safely consumed by most coeliacs. Accurate measurement of trace hordeins by ELISA is problematic.

Methods: We have compared hordein levels in sixty beers, by sandwich ELISA, with the level determined using multiple reaction monitoring mass spectrometry (MRM-MS).

Results: Hordein levels measured by ELISA varied by four orders of magnitude, from zero (for known gluten-free beers) to 47,000 µg/mL (ppm; for a wheat-based beer). Half the commercial gluten-free beers were free of hordein by MS and ELISA. Two gluten-free and two low-gluten beers had zero ELISA readings, but contained significant hordein levels (p<0.05), or near average (60-140%) hordein levels, by MS, respectively. Six beers gave false negatives, with zero ELISA readings but near average hordein content by MS. Approximately 20% of commercial beers had ELISA readings less than 1 ppm, but a near average hordein content by MS. Several barley beers also contained undeclared wheat proteins.

Conclusions: ELISA results did not correlate with the relative content of hordein peptides determined by MS, with all barley based beers containing hordein. We suggest that mass spectrometry is more reliable than ELISA, as ELISA enumerates only the concentration of particular amino-acid epitopes; this may vary between different hordeins and may not be related to the absolute hordein concentration. MS quantification is undertaken using peptides that are specific and unique, enabling the quantification of individual hordein isoforms. This outlines the problem of relying solely on ELISA determination of gluten in beverages such as beer and highlights the need for the development of new sensitive and selective quantitative assay such as MS.

Show MeSH
Related in: MedlinePlus