Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal; Grupo de Investigación en Polifenoles (GIP-USAL), Facultad de Farmacia, Universidad de Salamanca, Campus Miguel de Unamuno s/n, 37007 Salamanca, Spain.
Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal.
Food Chem. 2018 Mar 15;243:208-213. doi: 10.1016/j.foodchem.2017.09.137. Epub 2017 Sep 28.
The present study aims to assess the effect of different nitrogen (N) rates on the chemical composition and antioxidant properties of stevia frozen fresh and dried leaves, and to define the best growing conditions to maximize the levels of bioactive compounds. In general, processing affects more significantly the tocopherol and sugar contents than N fertilization. The most abundant sugars were xylose, arabinose + fructose and sucrose, presenting dried samples with higher contents than frozen fresh ones, while the latter better retained tocopherols than dry samples. Regarding phenolic compounds, greater levels were found in dried samples and in those fertilized with 25 kg N ha. Leaves from plants fertilized with 25 and 50 kg N ha also evidenced higher antioxidant activity, which seemed to be influenced by the phenolic composition. In general, N fertilization provides an improvement in the chemical composition and bioactive potential of stevia leaves.
本研究旨在评估不同氮（N）水平对甜叶菊冷冻鲜叶和干叶化学成分和抗氧化特性的影响，并确定最佳的生长条件以最大限度地提高生物活性化合物的含量。一般来说，加工比 N 施肥更显著地影响生育酚和糖的含量。最丰富的糖是木糖、阿拉伯糖+果糖和蔗糖，干样中的含量高于冷冻鲜样，而后者比干样更好地保留生育酚。关于酚类化合物，干样和施氮 25kg/公顷的样品中含量较高。施氮 25 和 50kg/公顷的植株叶片也表现出较高的抗氧化活性，这似乎受到酚类成分的影响。一般来说，N 施肥可改善甜叶菊叶片的化学成分和生物活性潜力。
