Resumo:
A coffee crop may consist of up to 1/5 of defective beans and finding a suitable destination for this material is economically interesting. Many coffee industries collect the selections - material containing coffee defects - and blend them with non-defective coffee fruits in specific proportions to obtain a marketable product. Studies on the composition of selections are scarce. Hydro- and liposoluble bioactive compounds were determined in five types of roasted and ground selections of coffee Arabica and in healthy Arabica and Robusta coffee species throughout an optimized HPLC-UV/Vis-MS-based method. Nicotinic acid and 4-CQA were not detected. Black and sour beans seem to increase the level of caffeine (variation from 1.3 to 2.4 g 100 g-1 of sample) in the selections. The occurrence of defects decreases the level of 5-CQA, the main representative chlorogenic acid. Trigonelline content is high in Arabica coffee, and the presence of defects does not promote a clear variation in its amount. Kahweol concentration (~74.6 to 76.9 mg g-1 of oil) was practically
the same up the Arabica sample set; this diterpene was absent in Robusta coffee. Cafestol (variation between 12.4 and 16.4 mg g-1 of oil) is a good quality indicator. Kahweol and 16-O-methyl cafestol are species indicators, and caffeine can point out the species of coffee. PCA revealed that sour beans were associated with the presence of kahweol, while cafestol and trigonelline were correlated to the occurrence of coffee skin. The higher the proportion of black beans, the more balanced the contents of water-soluble and liposoluble compounds.
