[FOOD SAFETY & QUALITY]

by Neil H. Mermelstein

Applying Metabolomics to Food Research

etabolomics is the study of metabo- resonance (NMR) and liquid or gas chro- metabolomics to understand which com- lites, which are small molecules that matography linked with mass pounds in fruits and vegetables impart Mare produced during metabolism in spectrometry in targeted and untargeted health benefits in humans. She said that living organisms, including plants, animals, approaches. These techniques provide metabolomics aims to profile the totality of and humans. Metabolites can be amino very large amounts of data, so sophisti- chemical compounds present within a acids, lipids, sugars, phosphates, nitro- cated statistical methods are used for system, whether a plant, fruit, or vegeta- gen-containing compounds, polyols, and data analysis and interpretation and com- ble, a processed food product, or a biological fluid. Hundreds or thousands of chemicals can be monitored simultane- ously, and by using mass spectrometry or NMR spectroscopy, she and her team can determine the effect of perturbations on the system without prior knowledge of which compounds are altered. Metabolomics, she said, can be used to investigate how a food product changes with food processing, to detect adultera- tion or misbranding or changes in nutritional profile, to better understand what flavor compounds contribute to prod- uct liking, and to explore how dietary interventions with these food products alter the human metabolome. The data can also be correlated with other information, such as sensory evaluation data, genetic analyses, and microbiological data to pro- vide additional value. Cooperstone is primarily interested in understanding the factors that affect the biosynthesis of phytochemicals. By better Metabolomics involves use of high-throughput assays and analytical techniques such as nuclear magnetic resonance (NMR) and characterizing plants, utilizing diverse liquid or gas chromatography linked with mass spectrometry. © angelblue1/iStock/Getty Images Plus plant germplasm and applying plant breed- ing approaches, she and other researchers can better design studies to understand other chemicals. Profiling an organism’s puterized libraries of mass spectra are how particular components of crops affect total metabolites, or metabolome, at any used to help identify and compare metabo- health. Cooperstone and her colleagues given time provides information about its lites within a system. have used metabolomics to understand health status and other criteria and can the effects of thermal processing of black increase understanding of metabolic path- Metabolomics Applications raspberries and how different phytochem- ways and the effects of changes in the Metabolomics is used around the world in icals in the black raspberries are related to metabolome on disease and product medical and pharmaceutical research and bioactivity in vitro. They have also used characteristics. is also being applied to food, nutrition, and metabolomics to elucidate bioactive com- Metabolomics involves the use of high- agriculture. Jessica Cooperstone, assis- ponents from tomatoes in a model of throughput assays and analytical tant professor at Ohio State University, non-melanoma skin cancer. techniques such as nuclear magnetic and her colleagues are using Devin Peterson, professor at Ohio pg 74 02.19 • www.ift.org State University, is adapting untargeted chemical profiling methods of discovery Application of Nuclear Magnetic Resonance–Based Metabolomics in Food Science from the metabolomics field to advance understanding of flavor perception, refer- Question or hypothesis ➜ Study design ➜ Sample selection/collection ➜ ring to this application as “flavoromics.” His program focuses on identifying chemi- Sample documentation ➜ Raw sample storage ➜ Sample preparation ➜ cal stimuli (taste, aroma, and NMR data acquisition ➜ NMR sample storage ➜ Spectra processing ➜ Data somatosensory effect) that impart flavor to foodstuffs, investigating multi-flavor preprocessing ➜ Data analysis ➜ Data interpretation interactions on perception, and mapping pathways of flavor generation/stability Adapted with permission from “Nuclear Magnetic Resonance (NMR) Spectroscopy in Food Science: A Comprehensive Review” by and mechanisms of flavor delivery. The Emmanuel Hatzakis, Comprehensive Reviews in Food Science and Food Safety, doi: 10.1111/1541-4337.12408. characterization of compounds that drive flavor perception and reward provides a of rapid analytical methodologies that can NMR metabolomics to understand how platform for the development of sustain- be used as effective and reliable tools for food affects the human gut microbiome able, nutritious, and healthy foods that food quality control. This research is and ultimately human health by defining have high product acceptability. People expected to generate new methods for profiles of various foods and determining generally eat what they like, he said, and analysis and food safety, he said, and help the effects that nutrients in these foods nutritious food and more sustainably develop novel agronomic and processing have on gut microbial function and host sourced products have limited societal methods for increasing the nutritional health. For example, she has studied the impact if the population, as a whole, does value of foods. For example, they can be metabolomics of human milk and has iden- tified several small-molecule components Metabolomics is used around the world that may be important for infant health. in medical and pharmaceutical research and is also being She has shown that lactose is an impor- tant component of milk and that replacing applied to food, nutrition, and agriculture. lactose with maltodextrin in infant formula to create lactose-free formulas has a pro- not consume them. used to quantify the impact of key pro- found impact on infant metabolism. This Modern methods of flavor character- cessing unit operations on the composition work, she said, has important implications ization have relied on a targeted approach of certain metabolites that appear in foods in the manufacture of infant formulas. to identify flavor molecules by screening and possess important health benefits. He Slupsky is also studying the effect of compounds individually (in isolation) or out is also working to produce and character- plant pathogens on plant health, focusing of context (e.g., from the effluent at the ize products and food ingredients with on how the citrus greening disease end of a gas chromatographic column) for high commercial and nutritional value from Huanglongbing, caused by the pathogen sensory activity, he said. Methods based raw foods and/or food wastes that are Candidatus Liberibacter asiaticus, affects on singular compound evaluation can currently used as cheap feed components citrus metabolism. She is using metabolo- overlook drivers of flavor perception by or disposed of (with an additional eco- mics to determine biomarkers for early ignoring potential interactions among nomic and environmental cost). The final detection of the disease. Current methods stimuli. To overcome this analytical limita- goal, he said, will be to use these alterna- for detection of the pathogen have low tion, he and his colleagues have utilized tive value-added products or compounds sensitivity even when the tree is symptom- flavoromics to understand novel drivers of as food supplements and/or to design per- atic, she said, and her method is proving to food flavor in wheat bread, orange juice, sonalized and selective nutritional have high sensitivity even at the pre- coffee, fruit, and other products. therapies and health regimens. He is also symptomatic stage. Given that this disease Emmanuel Hatzakis, assistant profes- investigating the interaction between has decimated citrus production in Florida sor at Ohio State University, is using NMR nutrition and gut microbiota, specifically and is increasing in California, Slupsky spectroscopy and metabolomics to study focusing on prebiotics and probiotics. said that fresh citrus production in the the composition and nutritional value of Carolyn Slupsky, professor at the United States is at risk and her work could foods. He is working on the development University of California, Davis, is using result in a test that could slow or stop pro-

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Applying Metabolomics to Food Research continued...

Oils that are very spicy appear to have a represent the end products of the Metabolomics Resource Centers stronger impact on platelet aggregation Maillard reaction and lipid oxidation. function, he said; the blood metabolomic Compounds such as sugars, amino acids, he National Institutes of Health (NIH) profiles differ, and panelists’ platelet and fatty acids are precursors to volatile Common Fund provided funding for a metabo- reaction to the oil could be predicted compounds and flavor, he said, and he Tlomics program for fiscal years 2012–2021. from their metabolic profile. Newman has a working list of more than 70 volatile Among other things, the program established six said that future projects will include compounds representing lipid oxidation regional metabolomics centers, called the building targeted metabolomics for use in products such as aldehydes and ketones Regional Comprehensive Metabolomics unbiased diet pattern analysis. and some components of the Maillard Resource Cores. The centers conduct research; Oliver Fiehn, professor at University reaction such as pyrazines. provide consultation on study design, targeted of California, Davis, is using untargeted Gale Strasburg, professor at and untargeted metabolomics, and data analysis; metabolomics to study the effect of flax- Michigan State University, is using and offer metabolomics services to industry and seed oil on microbes, specifically for metabolomics to improve meat and poul- academia, including analysis and training. The understanding the effects of flaxseed try quality. He said that quality is affected centers are as follows: consumption on circulating inflamma- by the animal’s genetic background and • NIH West Coast Metabolomics Center at tion–related metabolic profiles in interactions with the environment that University of California, Davis African-American and non-Hispanic affect expression of those genes. Early • Michigan Regional Comprehensive white women. He is developing improved exposure of newly hatched poultry to Metabolomics Research Core at University of methods in analytical chemistry and bio- heat stress or cold stress can affect gene Michigan informatics to capture and utilize expression, which influences the growth • NIH Eastern Regional Comprehensive metabolomic data, to help understand and development of muscle, leading to Metabolomics Resource Core at University of which parts of larger biochemical net- problems such as altered fat deposition North Carolina works respond to genetic perturbation or and altered muscle fiber type, and pre- • Southeast Center for Integrated environmental stress. For example, he market heat stress frequently results in Metabolomics at University of Florida has used the new MassBank of North pale, soft, exudative meat. Strasburg and • Resource Center for Stable Isotope- America repository, designed for effi- his colleagues are using targeted and Resolved Metabolomics at University of Kentucky cient storage and querying of mass untargeted metabolomics to compare the • Mayo Clinic Metabolomics Resource Core spectral records, to associate more than metabolomic profile of turkey breast 160 polyphenols in red wines with taste muscle samples exposed to normal tem- sensory data. The repository, he said, perature conditions to samples exposed provides free access to more than to heat stress, looking for differences to 260,000 mass spectra, including more better understand the mechanism of for- gression of the disease. than 50,000 mass spectra of flavonoids mation of the metabolites involved. John W. Newman, research chemist and natural products. Ranjith Ramanathan, associate at the Western Human Nutrition Jerrad F. Legako, assistant professor professor at Oklahoma State University, Research Center of the U.S. Dept. of at Texas Tech University, is using metab- is using metabolomics to study the Agriculture’s Agricultural Research olomics to help make better decisions biochemical basis of meat color changes, Service and associate adjunct professor about animal production practices and specifically, the relationship between at University of California, Davis, focuses meat handling. He said that while the postmortem metabolite profile and beef on the use of targeted metabolomics to genetic makeup of animals in large part color. The oxidation of myoglobin leads to study lipids and mediators and enhance affects meat quality, specific metabolites brown color formation, he said, and understanding of how food and nutrition can also directly influence quality. Flavor postmortem muscle is biochemically can prevent and influence obesity and its perception, he said, is driven by interac- active. Various studies have shown that adverse health effects. He has done a tions of chemical compounds on the glycolytic and tricarboxylic metabolites number of food-related projects using human tongue and by volatile compounds are critical to limit discoloration of meat, metabolomics, including studies on the in the olfactory system. He is studying he said, and he is using metabolomics to U.S. Dietary Guidelines for Americans, how metabolites such as volatile com- study muscle-specific metabolite vitamin status and metabolism, almonds pounds developed through alterations of differences in economically important and skin biology, fish oil and inflamma- inherent components of meats contribute beef muscles and how mitochondrial tion, and influence of olive oil varietals on to flavor development. He is using gas function affects the bright red color of blood pressure and platelet function. He chromatography and mass spectrometry raw meat. FT said that different varieties of olives taste in a semi-targeted approach, looking at different and have different biological previously identified compounds as key Neil H. Mermelstein, IFT Fellow, components that end up in the oil and the Editor Emeritus of Food Technology markers for flavor and looking for other • [email protected] health benefits of olive oil may be partly compounds not previously targeted. He is dependent on the variety of olives used. specifically looking at metabolites that pg 76 02.19 • www.ift.org