Physiological, biochemical, and biophysical changes in chia seeds during accelerated aging: implications for lipid composition and seed quality.

Chia, an oilseed native to Mexico and Guatemala, is prized for its nutrition and versatile uses in food and industry. Ex situ conservation of chia seeds is vital, yet their high lipid content complicates long-term storage. This study investigates artificial aging's impact on chia seed quality, emphasizing oxidative stress effects on lipid composition, antioxidants, and physiological properties. Two chia genotypes -one with mixed seed colors (MN) and another exclusively white (WN)- were subjected to accelerated aging to analyze germination, growth, electrical conductivity, and biochemical and biophysical changes over time. Accelerated aging revealed stress tolerance in chia seeds but significantly impacted germination and biochemical composition. Germination decreased from 100 to 0% over 56 days, with reduced radicle and hypocotyl lengths, fewer normal seedlings, and more abnormal or dead seeds. Peroxide values rose significantly, from 1.81 to 6.50 meq.kg^-1 (WN) and 0.85 to 3.22 meq.kg^-1 (MN), while free fatty acids increased from 0.41 to 2.95% oleic (WN) and 0.40 to 3.18% oleic (MN). Tocopherol content decreased markedly, disrupting the antioxidant-prooxidant balance. These biochemical changes resulted in higher saturated fatty acids, reducing membrane fluidity, and increasing electrical conductivity from 129.26 to 399.25 μS.cm^-1.g^-1 (WN) and 177.06 to 500.81 μS.cm^-1.g^-1 (MN). Thermal properties analyzed by DSC highlighted transitions within -90 to 100 °C, while FTIR spectroscopy revealed viability-related changes, particularly in the 1740 cm^-1 region. These findings underscore the impact of oxidative stress on seed quality, posing challenges for conservation and commercialization and emphasizing the need for strategies to mitigate storage-related deterioration.

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