Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
Carbohydr Polym. 2013 Aug 14;97(1):81-9. doi: 10.1016/j.carbpol.2013.04.067. Epub 2013 Apr 30.
The coffee residue left after the preparation of the brew (spent coffee grounds - SCG) is very rich in polysaccharides, namely galactomannans and arabinogalactans, which are polymers that can be used as dietary fibre and present immunostimulatory activity. Considering the huge amount of SCG produced all over the world, the reutilisation of this by-product by its application as food ingredients is very promising. However, the yields of extraction of these polysaccharides tend to be very low, namely the galactomannans. Based on the observation that the yield of galactomannans extracted from the ground coffee to the brew increase when the coffee is roasted, in this study, with the aim of increasing the yield of these polysaccharides, the SCG was roasted and then extracted with hot water and alkali solutions. The roasting at 160°C promoted an increment of 15% in the yield of galactomannan extractions and further improvement of the yield of extraction until 56% of all galactomannans was achieved by alkali extractions at 60 and 120°C. In these samples the galactomannans still kept their characteristic structure, including the acetylation and branching, determined by sugar linkage analysis and mass spectrometry. The yield of extraction of arabinogalactans under these conditions was 54%.
冲泡后留下的咖啡渣（用过的咖啡渣-SCG）非常富含多糖，即半乳甘露聚糖和阿拉伯半乳聚糖，这些聚合物可用作膳食纤维，并具有免疫刺激活性。考虑到全球生产的 SCG 数量巨大，通过将这种副产品应用于食品成分的再利用是非常有前景的。然而，这些多糖的提取收率往往非常低，特别是半乳甘露聚糖。基于观察到从研磨咖啡到冲泡过程中提取的半乳甘露聚糖的产率随着咖啡烘焙而增加，在这项研究中，为了提高这些多糖的产率，SCG 经过烘焙，然后用热水和碱溶液进行提取。在 160°C 下烘焙可将半乳甘露聚糖提取产率提高 15%，通过在 60 和 120°C 下进行碱提取，可进一步提高提取产率，直至获得所有半乳甘露聚糖的 56%。在这些样品中，半乳甘露聚糖仍保留其特征结构，包括通过糖键分析和质谱确定的乙酰化和支化。在这些条件下，阿拉伯半乳聚糖的提取产率为 54%。
