Department of Nutrition, Food Science, Physiology, and Toxicology, School of Pharmacy (CIFA), University of Navarra, E-31080 Pamplona, Spain.
J Agric Food Chem. 2010 Mar 10;58(5):2958-65. doi: 10.1021/jf9037375.
The antioxidant capacity of coffee brews prepared with different coffeemakers (filter, plunger, mocha, and espresso) was measured by colorimetric (total phenolic compounds and ABTS) and electron spin resonance (ESR) spectroscopy techniques (Fremy's salt and TEMPO). The mocha coffeemaker had the highest yield in coffee antioxidant extraction per gram of ground roasted coffee, but espresso coffee was richest in terms of antioxidant intake (per milliliter of coffee brew) followed by mocha, plunger, and filter. Both Folin-Ciocalteu (total phenolic compounds) and ABTS assays reacted with standard solutions of chlorogenic acids (CGA) and melanoidins (MO-Ala and MO-Gly). However, Fremy's salt was mainly scavenged by chlorogenic acids, whereas the stabilized radical TEMPO was effectively scavenged by melanoidins, but not by chlorogenic acids. Thus, ESR spectroscopy allows distinguishing between phenolic and nonphenolic antioxidants. Moreover, the addition of pH-regulator agents to coffee, such as sodium carbonate (75 ppm) and bicarbonate (75 ppm), to extend its shelf life, slightly increases the pH, modifying the antioxidant capacity in those coffee brews with the highest capacity (mocha and espresso).
用不同的咖啡机（过滤式、活塞式、摩卡式和意式浓缩式）制作的咖啡冲泡物的抗氧化能力，通过比色法（总酚类化合物和 ABTS）和电子自旋共振（ESR）光谱技术（Fremy 盐和 TEMPO）进行了测量。摩卡咖啡机每克研磨烘焙咖啡的咖啡抗氧化提取产量最高，但就每毫升咖啡冲泡物的抗氧化摄入量而言，意式浓缩咖啡最为丰富，其次是摩卡式、活塞式和过滤式。Folin-Ciocalteu（总酚类化合物）和 ABTS 测定法均与绿原酸（CGA）和类黑素（MO-Ala 和 MO-Gly）的标准溶液发生反应。然而，Fremy 盐主要被绿原酸清除，而稳定的自由基 TEMPO 则被类黑素有效清除，而不是绿原酸。因此，ESR 光谱法可区分酚类和非酚类抗氧化剂。此外，向咖啡中添加 pH 调节剂，如碳酸钠（75 ppm）和碳酸氢盐（75 ppm），以延长其保质期，会略微提高 pH 值，从而改变那些具有最高抗氧化能力的咖啡冲泡物（摩卡式和意式浓缩式）的抗氧化能力。
