Trolox equivalent antioxidant capacity of Coffea arabica L. seeds

ABSTRACT The causes of the low desiccation tolerance and low longevity of coffee seeds have not yet been fully elucidated, and a full understanding of their complex physiology is of great interest. Among several alternatives, the loss of antioxidant capacity in seeds may be related to their rapid loss in quality during storage. The objective of this study was to determine the total antioxidant capacity of coffee harvested at different ripeness stages before and after the storage of seeds with different water contents and to relate antioxidant capacity to physiological quality. Seeds in the greenish-yellow or cherry stages, recently harvested or stored for nine months at 10 °C with 40, 30, 20 and 12% water content (wet basis - wb), were submitted to physiological and biochemical quality evaluations, and the Trolox equivalent antioxidant capacity (TEAC) was determined. The germination and root protrusion of coffee seeds from greenish-yellow and cherry fruits were not affected by drying, but seeds harvested at physiological maturity had greater vigor when the moisture content was lower. The quality of coffee seeds decreased during storage, and this decrease was greater in seeds stored with higher water contents. Coffee seeds in the greenish-yellow stage had a higher antioxidant capacity than those in the cherry stage when recently harvested, but there was a substantial reduction in this capacity during storage at both maturation stages. Coffee seed deterioration is related to a reduction in antioxidant capacity, and the isoenzymatic profiles of the antioxidant process are little affected by the seed maturation stage. The deterioration of coffee seeds during storage is related to a reduction in their total antioxidant capacity, regardless of their maturation stage, being more pronounced in the greenish-yellow stage.摘要 咖啡种子脱水耐性低下与贮藏寿命较短的成因尚未完全阐明，全面解析其复杂生理机制具有重要研究价值。在诸多潜在影响因素中，种子抗氧化能力的丧失可能与其贮藏过程中品质快速劣变密切相关。本研究旨在测定不同成熟度采收的咖啡种子，在不同含水量（湿基，wb）贮藏前后的总抗氧化能力，并分析抗氧化能力与生理品质的关联。本研究选取青黄熟期与红果熟期的咖啡种子，分别为新鲜采收样本，以及在10℃下以40%、30%、20%、12%含水量（湿基，wb）贮藏9个月的样本，对其进行生理与生化品质评价，并测定了Trolox等效抗氧化能力（Trolox equivalent antioxidant capacity, TEAC）。 青黄熟期与红果熟期咖啡种子的萌发与胚根突出过程均不受干燥处理影响，但生理成熟度采收的种子在含水量更低时活力更高。咖啡种子的品质在贮藏过程中逐渐劣变，且含水量越高的种子品质下降幅度越大。新鲜采收时，青黄熟期咖啡种子的抗氧化能力高于红果熟期种子，但两个成熟度阶段的种子在贮藏过程中其抗氧化能力均出现显著下降。咖啡种子的劣变与抗氧化能力下降相关，且抗氧化过程的同工酶谱几乎不受种子成熟度的影响。无论成熟度如何，咖啡种子贮藏期间的劣变均与总抗氧化能力下降相关，且该现象在青黄熟期种子中更为显著。