Silván José Manuel, Morales Francisco J, Saura-Calixto Fulgencio
Consejo Superior de Investigaciones Científicas (CSIC), Instituto de Ciencia y Tecnología de Alimentos y Nutrición-ICTAN, José Antonio Novais 10, 28040 Madrid, Spain.
J Agric Food Chem. 2010 Dec 8;58(23):12244-9. doi: 10.1021/jf102489u. Epub 2010 Nov 10.
There is a methodological and conceptual overlap between coffee melanoidins and dietary fiber. Green Uganda coffee beans were roasted in a range from 8.1 to 21.6% of weight loss to evaluate melanoidins and dietary fiber. Samples were characterized by color, moisture, solubility, water activity, carbohydrates, polyphenols, protein, soluble dietary fiber (SDF), and melanoidins content. Hydroxymethylfurfural and chlorogenic acids were also measured as chemical markers of the extent of roasting. Melanoidins rapidly increased from 5.6 (light roasting) to 29.1 mg/100 mg soluble dry matter (dark roasting). A melanoidins-like structure was already present in green coffee that might overestimate up to 21.0% of the melanoidins content as determined by colorimetric methods. However, its contribution is variable and very likely depends on the method of drying applied to green coffee. SDF content (mg/100 mg soluble dry matter) gradually increased from 39.4 in green coffee to 64.9 at severe roasting conditions due to incorporation of neoformed colored structures and polyphenols. Then, SDF progressively turns to a maillardized structure, which increased from 11.0 to 45.0% according to the roasting conditions. It is concluded that the content of coffee melanoidins includes a substantial part of dietary fiber and also that coffee dietary fiber includes melanoidins. A conceptual discussion on a new definition of coffee melanoidins as a type of maillardized dietary fiber is conducted.
咖啡类黑素与膳食纤维在方法和概念上存在重叠。乌干达绿咖啡豆在失重8.1%至21.6%的范围内进行烘焙，以评估类黑素和膳食纤维。通过颜色、水分、溶解度、水分活度、碳水化合物、多酚、蛋白质、可溶性膳食纤维（SDF）和类黑素含量对样品进行表征。还测定了羟甲基糠醛和绿原酸作为烘焙程度的化学指标。类黑素从5.6（轻度烘焙）迅速增加到29.1毫克/100毫克可溶性干物质（深度烘焙）。绿咖啡中已经存在一种类似类黑素的结构，通过比色法测定时，其可能会高估类黑素含量的21.0%。然而，其贡献是可变的，很可能取决于应用于绿咖啡的干燥方法。由于新形成的有色结构和多酚的掺入，SDF含量（毫克/100毫克可溶性干物质）从绿咖啡中的39.4逐渐增加到重度烘焙条件下的64.9。然后，SDF逐渐转变为美拉德化结构，根据烘焙条件，其从11.0%增加到45.0%。得出的结论是，咖啡类黑素的含量包括膳食纤维的很大一部分，而且咖啡膳食纤维也包括类黑素。对将咖啡类黑素重新定义为一种美拉德化膳食纤维进行了概念性讨论。
