# Antioxidant Activity of Coffee Components Influenced by Roast Degree and Preparation Method
###### Abstract  
Coffee is of interest to consumers and researchers, mainly due to its stimulating properties and positive effects on the human body. Properties of coffee infusions depend on many factors and the most important ones include the roasting process and the brew preparation method. In this paper, we analyzed infusions prepared with the use of pressure methods (professional: espresso and consumer: moka pot brew), obtained from beans roasted to the medium and dark degree, with the aim of determining the share of individual groups of ingredients in the antioxidative properties of coffee. Tested infusions showed various characteristics that were partly related to different parameters of their preparation. In general, a greater amount of phenolic compounds was extracted in moka brews. Espresso, on the other hand, exhibited greater antioxidant activity per portion of the brew and a greater ability to quench free radicals. The degree of roasting had an uneven effect on the antioxidant activity of the brews, depending on the method and its mechanism of antioxidant action. The share of activity of the particular groups of antioxidants in overall activity varied between all methods; the most pronounced changes were observed in the espresso brews. The results indicate, however, that the activity of phenols and melanoidins is based on a mixed mechanism of antioxidant action, but in the case of the latter, the mechanism of hydrogen atom transfer may have an advantage.  
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content during the roasting process is reduced to as little as 10% of the initial value, and the observed decrease depends on the roasting time/degree [11]. On the other hand, during this process, melanoidins are formed--high molecular weight, water-soluble products of the Maillard reaction [6; 12; 13]. Numerous studies have shown that melanoidins are responsible not only for the color of coffee but also significantly contribute to its antioxidant effect [4; 12].  
The method of preparation also affects the health and sensory quality of consumed infusions [4]. Currently, there are many methods of brewing coffee that differ in parameters and complexity. Among methods of brewing that were mostly investigated are French Press, drip/poured coffee, Turkish coffee and cold brew [11; 14; 15; 16; 17; 18; 19; 20; 21]. Much research has been performed on the influence of the brew preparation method on their characteristics, but relatively little attention has been paid to the moka pot method. During preparation, there is an increased pressure, which may explain the frequent information from producers of moka pots about the similarity of the moka infusion to the professional espresso coffee. However, the preparation of moka brew is easier and does not require the use of expensive equipment. Taking into account the above information, the aim of this study was to assess the impact of the bean roasting degree and the method of brew preparation on the characteristics and antioxidant activity with particular emphasis on the participation of various groups of antioxidants in the activity measured with different mechanisms of antioxidant action.