Mass Spectrometry for Foodomics

The accurate, sensitive, and rapid detection and quantitation of large and complex molecules, such as proteins, can be performed using LC-MS techniques. Not only can the target protein be detected, but the digested peptide fragments of the marker protein can also be detected through the utilization of their distinct molecular masses. LC-MS/MS also has the greatest potential for future improvements due to its reliability, sensitivity, and specificity, compared with conventional methodologies. In particular, its multiplexing capability is especially attractive for the simultaneous detection of multiple allergens in single samples, given the increased complexity and diversity of food matrixes.

We developed a specific, selective, and sensitive LC-MS/MS-based method for multi-allergen marker detection in a single sample injection (see Figure 1). First, it was necessary to map the peptides to identify unique and selective ones that could be used as signature markers of each allergen. The markers mapped were for the 12 allergens to which most adults and children with food allergies react. These were egg whites, milk, peanuts, soy, almonds, Brazil nuts, cashews, hazelnuts, pecans, pine nuts, pistachios, and walnuts. A targeted multiple-reaction monitoring (MRM) method using the SCIEX QTRAP 4500 system was then optimized to successfully screen for the mapped marker peptides of the 12 types of allergen in samples of bread and cookies. The bread and cookies were prepared with the allergen commodities incorporated before baking, to mimic typical manufacturing conditions more closely than spiked food matrices. Further, 16 commercial bakery products were analyzed to verify the applicability of the screen to the 12 allergen commodities mapped. To ensure the selectivity and specificity of the detection method, multiple proteins, peptides, and MRM transitions were evaluated for each allergen.

The marker peptides of the allergen commodities—the whole egg (whites and yolks), whole milk, peanut butter, and hazelnuts—were then simultaneously quantified using an MRM method performed on a QTRAP 6500 system, which incorporates the IonDrive Turbo V ion source that enables analyte quantification in the most challenging samples (see Figure 3). These four allergens were precisely quantified in 10 different food matrixes. The quantitation method demonstrated excellent sensitivity, with a quantitative limit of three parts per million (ppm) in whole egg, and 10 ppm in the milk, peanut, and hazelnut samples. There was also good recovery at 60 to 119 percent, and repeatability with an RSD of less than 20%. The analytical range was 10 to 1000 ppm for each allergen commodity.

As such, this detection and quantification methodology meets the performance criteria defined by the AOAC International Standard Method Performance Requirement (SMPR) for the detection and quantitation of selected food allergens. The developed method was therefore assessed for linearity, sensitivity, recovery, and repeatability and approved by the AOAC International Expert Review Panel on Selected Food Allergens for the Stakeholder Panel on Strategic Food Analytical.

This foodomics-based analytical method is another tool in the arsenal for food analysis. It provides an accurate and precise way of performing the analysis to detect and quantify markers of multiple allergens in single samples of diverse and complex foodstuffs. This method should contribute to improving food safety by reducing the likelihood of food products being marketed containing undeclared allergens. Not only will this potentially save lives, but it can also confer substantial cost savings by reducing the main reason for food product recalls.

Furthermore, in the long run, improved food safety should contribute to improved quality of life, as well as lower rates of morbidity and mortality attributed to food allergies. By empowering individuals with food allergies with the ability to more confidently select and consume their food, better guaranteed food safety facilitates better nutrition and health, and can help these individuals realize a lifestyle that incorporates a diet designed for personalized health.