Mass Spectrometry for Foodomics

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.

Figure 1: Peptide-selection workflow using the LC-MS/MS and database-searching software. Courtesy SCIEX.

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.

Figure 2: Extracted-ion chromatograms (XIC) from LC-MS/MS analysis of bread (top) and cookie (bottom) homogenates fortified with egg, milk, peanut, soy, and nut proteins at 100 ppm. Multiple peaks corresponding to allergenic tryptic peptides are displayed.
Courtesy SCIEX.

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.