QUANTITATIVE ELISA FOR WALNUT ALLERGENS

 

• Quantitative results in 30 minutes after sample preparation
• High specificity using monoclonal antibodies
• Uniform protocol across the Allergen‑Shield ELISA range
• Broad food matrix compatibility
• Surface swabbing kits available
• Excellent reproducibility and precision

 

For the in‑vitro quantitative determination of walnut protein residues in food matrices such as bakery products, chocolate, sauces, beverages, spreads, and processed foods. Intended for use by trained laboratory professionals engaged in food allergen monitoring and quality assurance testing.

 

The Allergen‑Shield Walnut ELISA (Cat. No. A2348/A2396) is a quantitative sandwich enzyme‑linked immunosorbent assay (ELISA) designed for the detection of walnut protein residues in foods labeled as walnut‑free. This highly specific assay provides reliable quantification of walnut proteins to ensure compliance with global food allergen labeling regulations (EU No. 1169/2011, FDA, FSANZ, and Codex Alimentarius).

General Information

Walnut (Juglans regia) is a common allergenic tree nut belonging to the Juglandaceae family. Its major allergens, Jug r 1 and Jug r 4, are heat‑stable proteins that remain active even after processing. Walnut allergy can cause severe allergic reactions including anaphylaxis, and thus requires sensitive detection for labeling and cross‑contamination prevention. The Allergen‑Shield Walnut ELISA provides accurate detection for use in food manufacturing and analytical testing laboratories.

Principle of the Test

The Allergen‑Shield Walnut ELISA is based on the sandwich enzyme immunoassay principle. Microtiter wells are coated with antibodies specific to walnut proteins. Standards and extracted samples are added to the wells, allowing binding of walnut antigens to the immobilized antibodies. After washing, an HRP‑conjugated antibody binds to the captured antigen. Upon addition of the TMB substrate, a color develops proportional to the walnut concentration. The reaction is stopped with acid and read photometrically at 450 nm.

 

 

Performance Characteristics

• Limit of Detection (LOD): 1.0 ppm walnut (0.17 ppm walnut protein)
• Limit of Quantification (LOQ): 2.5 ppm walnut (0.43 ppm walnut protein)
• Standard curve range: 0–100 ppm
• IC50: 30–56 ppm
• Recovery: 90.9% (CV = 7.2%)
• Intra‑assay CV at 7.5 ppm: 6.4% (n=16)
• Intra‑assay CV at 25 ppm: 6.2% (n=16)
• The assay exhibits strong reactivity to walnut (Juglans regia).
• Minimally reactive to pecan (0.0006%), poppy seed (0.0008%), rapeseed (0.0010%) and nutmeg (0.0003%).
• At concentrations as high as 100,000 ppm, no cross-reactivity was observed in the other matrices (including tree nuts, legumes, seeds, flour, meats and spices).

 

 

Storage and Stability

Store kit and reagents at 2–8 °C. Do not freeze. Protect standards and TMB substrate from light. Reseal unused strips with desiccant immediately after use. Expiry dates are printed on labels.

 

 

Resource

   Allergens Shield Brochure

   Allergen-Shield Walnut ELISA Kit Manual KD 8_28

 

 

Ordering Details

Stock Code        Description                                                                      Pack Size

PGB-A2396           ALLERGEN-SHIELD WALNUT KIT                                        96

PGB-A2348           ALLERGEN-SHIELD WALNUT KIT                                       48

PGB-AS1020         ALLERGEN-SHIELD SWABBING KIT                                   20