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Food

Gluten-Free Food Labeling - Text Version of PowerPoint Presentation by Jupiter Yeung

Slide 1 - Commercial Gluten Test Kits / Methods

Jupiter Yeung, PhD
Principal Scientist
Food Products Association

FDA Gluten Free Meeting, Aug 19, 2005

photo - FPA logo

Slide 2 - Gliadin Detection Methods

  • Immunochemical
    • ELISA
    • Lateral Flow Device
    • Immunoblotting
  • PCR
  • MS
    • MALDI-TOF
    • LC/MS/MS

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Slide 3 - Sandwhich ELISA

photo - diagram displaying how sandwich ELISA works

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Slide 4 - Gliadin Antibodies Specificity

  • Skerritt mAb
    • omega-gliadin (alpha-gliadin)
    • wheat - 100%, rye - 120%, barley - 5%
  • Mendez R5 mAb
    • QXPFP toxic epitopes of alpha, beta, gamma, omega-gliadins
    • Equally to wheat, rye and barley
  • Both Ab recognize raw and cooked prolamins

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Slide 5 - Commercial Gliadin ELISA Kits

Company Product LOD* LOQ* Range* Replicates Costs
Neogen Alert (Qualitative) 10     1 $237/20Sampl
Veratox   5 5-50 1 $465/38Sampl
R-Biopharm RidaScreen 1.5 2.5 2.5-40 2 $425/96 wells
RidaScreen Fast 5 5 5-40 1 $400/48 wells
Tepnel Gluten Assay Kit, AOAC or High sensitivity 5 50 50-1000 2 $425/96 wells
0.5 5 5-100 2
Hallmark HAVen Gluten, AOAC or High sensitivity 5 50 50-1000 2 $425/96 wells
0.5 5 5-100 2
Diffchamb Transia Plate Gluten 5 5 5-100 2 $500/96 wells
Transia Plate Prolamins 1.5  0.8 0.8-12.5 2 $500/96 wells
Morinaga Wheat Protein 0.3* 3.12 3.12-20 2 $600/96 wells

* ppm gliadin

ppm gluten = ppm gliadin x 2

blue cells = Converted to ppm from micro-g/mL

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Slide 6 - Commercial Gliadin ELISA Kits

Company Product Validation
Neogen Alert  
Veratox  
R-Biopharm RidaScreen  
RidaScreen Fast PWG ring trial
Tepnel BioKit Gluten (AOAC OM)
High Sensitivity  
Hallmark HAVen Gluten (AOAC OM)
High Sensitivity  
Diffchamb Transia Plate Gluten NFA, Sweden
Transia Plate Prolamins  
Morinaga Wheat Protein NIHS, Japan

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Slide 7 - Gliadin ELISA

photo - ELISA test tray

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Slide 8 - Lateral Flow Device (Dipstick)

Company Product LOD (ppm gluten)   Costs
R-Biopharm Rida Quick 10  $200 / 20 strips
Tepnel Gluten Rapid 100 $150 / 10 strips
Gluten Home 100 $ 75 / 5 strips

*Positive can mean less than LOD

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Slide 9 - Lateral Flow Device

photo - strip text diagram

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Slide 10 - Lateral Flow Device

photo - lateral flow diagram showing procedure and interpretation

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Slide 11 - Lateral Flow Device

photo - lateral flow device results displaying negative, positive and very high level results

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Slide 12 - Issues with Gluten Test Kits

  • Ab has different specificities to different prolamins, e.g. Skerritt Ab
  • Various results from different extraction media: 4060% EtOH, cocktails
  • Different standards used from different kits
  • False positives and negatives require a confirmatory test
  • Limited availability of confirmatory test to most food lab
  • No sampling plan

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Slide 13 - Extraction Media

  • Aq. Alcohol (4060% EtOH)
  • Cocktail (reducing agent + others)
    • interaction of Ab and Ag

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Slide 14 - Matrix Effect

  • Cocktail (reducing agent + others)
    • interference with complex food matrices, e.g. milk
    • interaction of Ab and Ag
  • Samples with high polyphenols, tannins and syrups require fish gelatin to improve recovery

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Slide 15 - Effects of Extraction Media

photo - table of effects of extraction media data

Hasselberg et al. Proceeding of the 18th Meeting, WPGAT, 2004

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Slide 16 - Effect of Partial Hydrolysis

photo - bar graph showing effect of partial hydrolysis data

Ferre et al. Proceeding of the 18th Meeting, WPGAT, 2004

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Slide 17 - Reference Materials

  • IRMM480 Wheat Gliadin
  • NIST
    • SRM 1567a Wheat Flour
    • RM 8418 Wheat Gluten
    • RM 8436, 8437, 8438, 8441a
  • Others

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Slide 18 - Confirmation Methods

  • AbWestern blot
  • PCR qualitative, quantitative
  • MS MALDITOF, LC/MS/MS

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Slide 20

photo - line graph displaying gliadin profile data

Garcia et al., Proceeding of the 18th Meeting, WPGAT, 2004

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Slide 20 - Detection & Speciation

  Wheat Gliadins Rye Scalins Barley Hordeins Oat Avenins
Ab-based + -
PCR + + + +
MS + + + +

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Page Last Updated: 01/30/2015
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