Impact of Storage on Peanut Seeds: Part A–Long-Term Storage and Oxidation Product Accumulation

Peanut seeds contain approximately 50% oil, presenting a significant challenge for both short- and long-term storage due to their susceptibility to lipid peroxidation. This oxidative process can deteriorate the nutritional quality of peanut products and reduce seed viability and germination rates, posing risks for germplasm conservation, breeding programs, and the peanut industry. In an evaluation of fatty acid profiles from long-term stored seeds representing more than 8400 peanut germplasm accessions, we identified one unique (1) and two similar (2a and 2b) peaks in the GC analysis as potential chemical markers of peroxidation formed during transesterification. Subsequent analysis of 168 peanut accessions demonstrated that peaks 1 and 2b accumulated at significantly higher levels in stored seeds compared with freshly harvested seeds (0.66% vs 0.09% and 1.15% vs 0.14%, respectively). A concurrent reduction in linoleate acid content was also observed in stored seeds (29.61% vs 32.56%). Structural elucidation using NMR and GC–MS, in conjunction with comparison to authentic standards, identified peak 1 as methyl epoxystearate, derived from the epoxidation of methyl oleate, and peaks 2a and 2b as methyl coronarate and methyl vernolate, formed through epoxidation of methyl linoleate at the 9,10- and 12,13-epoxide positions, respectively. This study provides the first evidence of epoxidation products arising from oleic and linoleic acids in stored peanut seeds and establishes their potential as biochemical indicators of oxidative deterioration. In addition, we outline strategies for developing peanut cultivars with improved nutritional profiles and greater resistance to storage-related degradation. Together, these findings offer new insights into the chemical pathways underlying seed quality decline and highlight opportunities to develop peanut cultivars with enhanced nutritional stability and improved storage resilience.