Using ELISA-Based Lateral Flow Devices to Support Allergen Cleaning Validations

Transcription

1 Using ELISA-Based Lateral Flow Devices to Support Allergen Cleaning Validations Joe Baumert, Ph.D. Associate Professor Co-Director, Food Allergy Research & Resource Program (FARRP) Department of Food Science & Technology University of Nebraska-Lincoln, USA

2 Allergen Assessment: Cleaning & Sanitation Strategies Visually clean is the standard in the food industry If residue is present on the equipment surface, a positive analytical result is likely No need to test clean again Visual inspection has been quite effective, especially with particulates Analytical methods can be used to support visual assessment, validation, verification of allergen removal Swabbing equipment surfaces (contact surfaces and hard to reach areas), testing CIP final rinse water (when possible), and push-through material are commonly sampled for allergen assessment Some companies do analyze finished product as a final step in their validation process; do so only when you would expect negative results

3 Possible Detection Methods to Support Allergen Cleaning Validations Quantitative Methods: Enzyme Linked Immunosorbent Assay (ELISA) Polymerase Chain Reaction (PCR) Mass Spec Methods (LC-MS/MS) Surface Plasmon Resonance (SPR) Qualitative Methods: Lateral Flow Devices (ELISA LFD) General Protein Tests ATP/Bioluminescence Tests PCR ELISA, LFD, MS X molecules of DNA Z g of peanut Y molecules of protein (TOTAL PROTEIN)

4 How To Decide What Test to Use in a Specific Situation? The specificity of the test method is one concern general protein, allergenic source protein, DNA, or ATP The sensitivity of the test method is a second concern; Will the method support the corporate target level? Can you correlate the method results to the corporate target level?

5 Uses of allergen analytical methods Manufacturing environment (e.g. surfaces) Cleaning validation (surfaces, rinse water, push through materials) Ingredients or raw materials Final product (often free-from claims)

6 Considerations When Selecting an Analytical Method Method should be most appropriate for use Sample type (environment, food, cleaning liquids) Aim of analysis (demonstrate removal of one allergen on a surface, or all proteins?) Time and expense / number of samples (if you determine analysis needed frequently, is your method feasible?). Choice of method is based upon identified risks; methods support allergen control and are not a substitute for good manufacturing or cleaning practices.

7 Considerations When Selecting an Analytical Method Recommended to validate removal of allergenic residue using specific ELISAs ATP and general protein tests do not detect proteins from allergenic sources specifically so the effectiveness of these tests ALONE as the sole approach must be carefully examined Surrogate testing (protein, ATP) can be helpful in some cases ATP or general protein swabs can provide a good quick check on sanitation effectiveness during routine cleaning PCR tests available for some allergen residues where ELISAs are not available

8 ELISA and ELISA-Based Technologies Many commercial kits available, some labs also offer in house ELISA methods Most used method for allergen detection Usually specific and sensitive Fast turnaround Suitable for many food-processing settings Due to the need for conditions allowing antibody binding and enzyme-linked detection, limited to a few extraction conditions Source: microscopesblog.com

9 Key Decisions When Selecting ELISA Methods (quantitative and qualitative) What do you want to measure? Select appropriate detection system according to major components in the product Example: Milk Total Milk β-lactoglobulin Casein What protein source is used as the standard in the method? What units are the results reported in? Example: ppm casein or ppm NFDM (quantitative)

10 Lateral Flow Devices (LFDs) Later flow test/ strip test / dipstick Also uses antibodies but in a different format Used primarily for cleaning assessment, but can be used for food product testing (must consider matrix effects on sensitivity) Often combined with swabbing Rapid (approx. 10 min) Sensitive Typically qualitative only Typically no lab equipment needed on site analysis

11 Lateral Flow Devices (LFDs) Sample introduced to a sample pad Fluid in sample migrates to the conjugate (or release) pad contains chemicals necessary for protein-ab binding and visualization Fluid migrates to a capillary bed which has a strip containing immobilized antibodies on a test line, and, if present, to another further on (control line) Detection by color (usually blue or red)

12 Validating a Method for Purpose Analyze a positive control to ensure your method can detect under your conditions Analyze a negative control to ensure no false positive results If quantitative, you can evaluate the recovery (the % of allergen you included in a positive sample that is detected) of a method under your use A good analytical lab can help you design a method validation plan if necessary

13 Lateral Flow Device Hook/Overload Effect Overloading a LFD can cause a false negative result (due to the hook effect ) Neogen Technical Product Information: Eliminating Hook Effect

14 Interpreting Lateral Flow Device Results: Negative Positive High Positive J.L. Baumert, D.H. Tran; 11 - Lateral flow devices for detecting allergens in food; Handbook of Food Allergen Detection and Control, 2015,

15 Be Careful of Residual Cleaning and Sanitizing Solutions General Protein Swab Total Milk LFD Casein LFD Pos control: 200 ppm NFDM protein Pos-purple Pos Pos COMMODITY CAUSTIC 1% NaOH neg-colorless/light blue neg neg 1% NaOH +200 ppm NFDM protein Pos-purple +/- faint pos 0.3% NaOH neg-light green neg neg 0.3% NaOH ppm NFDM protein Pos-purple faint pos pos 0.03% NaOH neg-light green neg neg 0.03% NaOH ppm NFDM protein Pos-purple faint pos pos COMMERCIAL CAUSTIC-ECOLAB 1% Exelerate CIP neg-light green neg neg 1% Exelerate CIP +200 ppm NFDM protein gray-lavender neg neg 0.3% Exelerate CIP neg-light green neg neg 0.3% Exelerate CIP ppm NFDM protein Pos-purple neg +/- 0.03% Exelerate CIP neg-light green neg neg 0.03% Exelerate CIP ppm NFDM protein Pos-purple pos pos COMMERCIAL ACID-ECOLAB false negative false positive 1% Envirocid Plus neg-light green neg neg 1% Envirocid Plus +200 ppm NFDM protein Pos-purple pos pos 0.3% Envirocid Plus neg-light green neg neg 0.3% Envirocid Plus ppm NFDM protein Pos-purple pos pos 0.03% Envirocid Plus neg-light green neg neg 0.03% Envirocid Plus ppm NFDM protein Pos-purple pos pos COMMERCIAL SANITIZER-ECOLAB 0.3% Vortexx pos-intense purple neg neg 0.3% Vortexx +200 ppm NFDM protein pos-intense purple faint pos pos 0.03% Vortexx pos-purple neg neg 0.03% Vortexx ppm NFDM protein pos-dark purple pos pos 0.003% Vortexx neg-colorless/light blue neg neg 0.003% Vortexx ppm NFDM protein pos-purple pos pos

16 Special Considerations What do you do when you cannot consistently get nondetect with allergen swab? - Test push through product (especially if you expect uniform distribution); be careful of particulates - Consider the use of allergen tracking tools and risk assessment tools to judge extent of risk - Use precautionary allergen labeling if risk is too high

17 Thank You for Your Attention Joe Baumert, Ph.D. Food Allergy Research & Resource Program Department of Food Science & Technology University of Nebraska farrp.org