Peanut flavor compounds from amino acid precursors

Authors: Dean, Lisa; KLEVORN, CLAIRE - North Carolina State University

Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/31/2017
Publication Date: 7/12/2017
Citation: Dean, L.L., Klevorn, C. 2017. Peanut flavor compounds from amino acid precursors. American Peanut Research and Education Society Abstracts. Vol. 49.

Interpretive Summary: U.S. peanuts are known globally for their superior flavor when roasted. Many studies have been performed to determine the chemical compounds that create the flavors to assure flavor quality and to investigate ways to increase it. In the past, most studies have concentrated on identifying the compounds that are volatile. This work takes a new approach known as metabolomics using high performance chromatography coupled with mass spectroscopy to identify compounds that extracted using various solvent systems to identify the largest number of compounds possible and then trace them back to the metabolic pathways in peanuts that create the compounds. This research will concentrate on discussing those compounds that are the result of amino acid metabolism. This new information gives insights into the types of compounds that could be increased by traditional breeding practices to create new peanut cultivars with higher roasted peanut flavor potential.

Technical Abstract: Investigations to determine the chemical compounds responsible for peanut flavor have traditionally depended on the analysis of volatile compounds. The more recent field of the study of metabolomics provides new tools and approaches for the determination of chemical compounds that are lost, created or changed by the roasting of peanuts. By concentrating on the metabolomic pathways most affected by roasting, new insights into roasted peanut flavor have been revealed. Raw runner and virginia-type peanuts were obtained from 3 different warehouses as 10 pound samples from 5 individual commercial lots (n=15 for each market-type). Samples were split into two five-pound subsamples with one subsample remaining raw while the other was roasted (Hunter L-value 48±1). A multi-platform metabolomics approach including RP/UPLC-MS/MS and HILIC/UPLC-MS/MS was utilized to analyze the samples. Employment of this metabolomics-based approach identified 383 compounds within raw and roasted runner- and virginia-type peanuts, 360 of which were confirmed against authentic standards. Utilization of pathway analysis revealed that the biochemical pathways responsible for the small-molecular weight compounds that were most changed as a result of the roasting process were all amino acid pathways. Arginine and proline metabolism, phenylalanine metabolism, alanine, aspartate, and glutamate metabolism, and glutathione metabolism were the metabolic pathways that included the compounds most impacted by the roasting treatment. Specifically, the proline derivative betonicine and 5-oxoproline, a glutathione metabolite, were found to be differentiating (fdr p-value<0.05) metabolites between the raw and roasted peanuts. Coupling of metabolomic pathway analyses provided new insight into the types of amino acid derivatives that are involved in volatile compound generating reactions that occurred during the dry-roasting process.