Detection of Mustard, Egg, Milk, and Gluten in Salad Dressing Using Enzyme-Linked Immunosorbent Assays (ELISAs)

• Published in: Journal of food science Vol. 74; no. 5; pp. T46 - T50
• Main Authors: Lee, Poi-Wah, Niemann, Lynn M, Lambrecht, Debra M, Nordlee, JulieA, Taylor, Steve L
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Publishing Inc 01.06.2009; Wiley; Wiley Subscription Services, Inc
• Subjects: Acetic Acid - analysis; acidity; allergenic food proteins; allergens; Animals; Biological and medical sciences; detection; Egg and egg product industries; Egg Proteins - analysis; Eggs; Eggs - analysis; ELISA; enzyme-linked immunosorbent assay; Enzyme-Linked Immunosorbent Assay - methods; food analysis; Food Analysis - methods; food composition; food contamination; Food Handling - methods; Food Hypersensitivity - prevention & control; Food industries; Food science; Fundamental and applied biological sciences. Psychology; General aspects; gluten; Glutens - analysis; Hydrogen-Ion Concentration; Immunoassay; Methods of analysis, processing and quality control, regulation, standards; Milk; Milk Proteins - analysis; mustard; Mustard Plant; Plant Oils - analysis; Proteins; salad dressing; salad dressings; Egg; Dairy product; Acidity; Enzyme immunoassay; allergenic food proteins; Salad dressing; Analysis method; Egg product; Plant protein; pH; Control method; Mustard; Detection; Gluten; ELISA assay; Food; Allergen; Milk; ELISA
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/j.1750-3841.2009.01162.x

Enzyme-linked immunosorbent assay (ELISA) is a commonly used method for the detection of trace amounts of potentially allergenic protein residues in foods. However, food matrices and processing conditions can affect the detection of protein residues. The effects of acidity on the detectability of several allergenic proteins commonly found in salad dressing using ELISAs was investigated. First, recovery experiments were performed on salad dressing formulated with 0 to 1000 ppm mustard flour (mustard). The mean percent recovery for mustard from the salad dressing was only 7.7%± 1.6%. When the pH of the salad dressing was adjusted to pH 7 prior to spiking with mustard, recovery improved to 94.1%± 7.6%. However, if the pH was adjusted to pH 7 after spiking and extraction, the recovery was only 11.1%± 1.7%. When vinegar was spiked with mustard flour at pH 3, 3.5, and 4, detectability of mustard was lowest at pH 3. Basic extraction of mustard proteins from salad dressing did not improve the mustard detection. Acidic salad dressing matrices reduced the detectability of mustard by the mustard ELISA probably because of acid precipitation of mustard proteins that renders them insoluble and nonextractable. Commercial salad dressings containing 100 ppm (mg/kg) of egg, milk, or gluten were analyzed every 2 to 4 d for 90 d using 3 commercially available ELISAs. A decrease in the detection of the egg, milk, and gluten in the salad dressing upon storage was observed. Our study highlighted the importance of evaluating the utility of various ELISAs for specific food matrices and the recovery as a function of product storage.