It has been a few decades since the first “-omics” terms for various analyses were coined. Genomics sought to map and characterize the genes and genetic makeup of an organism; proteomics described the analysis and investigation of the protein profile, or proteome, of an organism. And in the years since, the “-omics” suffix has served as a convenient way to describe all the potential profiling, mapping, qualitative and quantitative analyses, and so on, that could be explored for a given biochemical compound class.
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Explore This IssueApril/May 2020
Foodomics, then, which might be the latest in this long line of “-omics” disciplines, is when food products are studied for safety, nutrition, and authenticity through the application of those same “-omics” workflows and technologies. And, among the techniques that might be employed, mass spectrometry is considered crucial to the work and applications of this growing field.
Applications of foodomics could potentially incorporate genomic, proteomic, and/or metabolomic analyses of any of an infinite variety of food products for compound or ingredient profiling, fraud detection/authenticity, or biomarker research such as those used for allergens screening or crop modification. The vast and complex global food market today presents a wide world of potential as research for food supply, production, international distribution, and nutrition reach unprecedented consumer interest and demand. Foodomics represents a field that is rooted in established analytical practices developed from related disciplines while also being on the cutting edge of analytical needs and demands of academic researchers and industry alike. Keeping up with the challenges presented by these diverse applications demands the development of advanced, powerful, and highly versatile analytical strategies.
One high-demand application for foodomics is the identification of and screening for markers of common allergens in a food commodity. Allergenic foods, such as nuts, eggs, milk, and soy, can be very dangerous for sensitive individuals to consume. There is no cure for food allergies, so sufferers must rely on food safety guarantees and correct labelling to avoid consuming allergens. Common triggers are peanuts, tree nuts (such as almonds, walnuts, cashews, hazelnuts, pecans, pistachios, Brazil nuts, pine nuts, and chestnuts), shellfish, egg whites, and, in children, milk. As such, a reliable method that can screen for the marker constituents of these has enormous implications for food safety and the global food market.
SCIEX has established methodologies that enable the simultaneous analysis of multiple allergens in food products, using high-resolution quadrupole time-of-flight (QTOF) technology to identify the marker peptides for the allergenic commodities, and then a subsequently developed triple quadrupole mass spectrometry (LC-MS/MS) method for routine screening of foods for the allergens. This routine analysis might be employed to ensure that foods processed in the same facilities have not become cross-contaminated.
The importance this issue has spurred the development of foodomics techniques aimed narrowly at the identification and detection of allergenic materials. Advanced chromatography and spectrometry technologies are now routinely employed to perform proteomic and metabolomic analyses of foodstuffs. Diverse foods, ingredients, and manufacturing methods present analytical challenges for the laboratories tasked with testing finished food products. A rapid method that can confidently confirm and identify a panel of allergens would be invaluable for the testing and screening of food.
Despite the current industry standard of using immunoassays and polymerase chain reaction (PCR) techniques in allergen screening, the rapid advancements of liquid chromatography mass spectrometry (LC-MS) technology mean that we are seeing a shift towards LC-MS/MS methods. While immunoassays, particularly enzyme-linked immunosorbent assay (ELISA), are rapid, sensitive, and easy to use, they are susceptible to cross-reacting with components of the sample matrix, leading to false positive results. False negative results can also occur, especially when the marker protein(s) being detected undergo denaturing or modification due to heat or other food processing. ELISAs are also unable to detect more than one type of allergen protein at a time in each sample. However, PCR can be multiplexed, meaning that more than one marker for allergens can be detected in a single reaction in single samples. The only drawback is that PCR detects only DNA and, as such, cannot be used to screen for proteins directly. Moreover, DNA can be destroyed by thermal or food processing, and, as such, can result in false negatives in tests using PCR methods.
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.
Dr. Hyland is global technical marketing manager for food and environmental at SCIEX.