A metabolomics-based approach identifies changes in the small molecular weight compound composition of the peanut as a result of dry-roasting

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

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2017
Publication Date: 8/18/2017
Citation: Klevorn, C.M., Dean, L.L. 2017. A metabolomics-based approach identifies changes in the small molecular weight compound composition of the peanut as a result of dry-roasting. Food Chemistry. 240:1193-1200. https://doi.org/10.1016/j.foodchem.2017.08.058.
DOI: https://doi.org/10.1016/j.foodchem.2017.08.058

Interpretive Summary: Raw peanuts produce many small chemical compounds known as metabolites during the course of their growth and development. Some of these compounds are altered during roasting into new compounds that are responsible for the flavors of peanut such as "roast peanutty". Metabolomics is a method of analyzing products using advanced chromatography equipment that allows for large numbers of chemical compounds to be identified at one time. As a result raw peanuts can be better characterized in order to predict flavor formation by roasting. This report is the first to use a metabolomic approach to the study of peanuts and their flavors.

Technical Abstract: Peanut production in the United States is a $1.12 billion industry. United States peanut production is primarily focused on the edibles market. Peanut seeds are included in a variety of snack and confectionary products. Raw peanuts are rarely consumed in the United States. Instead, peanut seeds are typically subjected to thermal processing prior to consumption. Dry-roasting is one of the most common forms of thermal processing of peanuts. The objective of the present study was to determine how the small molecular weight composition of the peanut seed changes as a result of the dry-roasting process using a metabolomics-based approach. Runner and virginia-type peanut seeds were each sampled from five independent lots at three different warehouse locations. The raw samples were roasted to an industry standard dry-roast until they reached a Hunter L-value of 48±1. Raw and roasted peanuts were characterized using analytical platforms including (RP)/UPLC-MS/MS (positive and negative ion mode ESI) and HILIC/UPLC-MS/MS with negative ion mode ESI. Pathway analysis was performed to identify metabolic pathways most associated with the small molecular compounds present. A total of 383 compounds were confirmed identified within the samples. Sixteen compounds were found to be unique to the roasted peanuts. Compounds associated with arginine and proline metabolism were found to be most changed by the roasting process. Products of chemical degradation and compounds contained within the vesicular bodies of the peanut were found at higher levels after the roasting treatment. Dry-roasting had a large impact on the levels and types of small molecular weight compounds present within the peanut seed. Understanding how these compounds change as a result of the roasting process provides useful information about the development of peanut flavor.