# The Effect of Type and Duration of Digestive Enzyme Treatment on Coffee Bean Composition
## 3 Results and Discussion
### Caffeine, Total Polyphenol and 3-CQA Contents in Coffee Beans  
The amount of caffeine in untreated green Robust beans was 1 g/100 g dm, while, in Arabica beans, it was 0.7 g/100 g dm (Table 2). The caffeine content in samples and controls was generally lower than that found in unmodified beans. Controls exhibited significantly higher caffeine content compared to the respective enzyme-treated ones (Table 3). Loosening of the beans' structure and the additional influence of the enzymes might have facilitated the extraction processes of the studied compound. The roasting process led to a reduction in caffeine content in controls and samples of both species; higher caffeine content in control beans was again observed. In the case of untreated beans, roasting resulted in a slight increase in caffeine amount (approximately 0.1 g/100 g dm regardless of bean type), which could be due to the loss of other bean components. In the case of modified green and roasted beans, a similar decreasing trend in caffeine content over time was observed (Tables 2 and 4). Data on caffeine content in kopi luwak are not straightforward. In the study of [PERSON] et al. [31], caffeine content in kopi luwak was approximately 1.2%, similar to the amount of caffeine determined in conventional Arabica beans from the same region. [PERSON] et al. [32] determined the caffeine content in kopi luwak beans (_C. canephora_) to be 0.361% dm, which was slightly lower than that found in other popular coffee beans. The results presented by [PERSON] and [PERSON] [33] showed a higher caffeine content in kopi luwak compared to conventional beans. Results presented in this study indicate a significant extraction of this compound during the digestion process. However, [PERSON] and [PERSON] [33] suggested that the accumulation of this alkaloid from the diet and biosynthesis in the palm civet's body might contribute to its higher content in green coffee beans. It is significant to note that several factors unrelated to the digestion process can affect caffeine content, which may explain the differences in data observed in the literature [24; 25]. Additionally, caffeine may, to a small extent, contribute to the bitterness of the brew, so reducing its quantity may enhance the overall quality of the beverage [31]. Various changes in caffeine content observed in beans after roasting in this study were previously reported [25; 34]. It is suggested that prolonged, more intense roasting might lead to a loss of caffeine due to dehydration or sublimation [31]. Total polyphenol content in untreated green Robust beans (2.04 g/100 g dm) was approximately 15% higher than in Arabica beans (1.74 g/100 g dm). The amount of 3-CQA in unmodified green beans was comparable, although slightly higher in Arabica beans (Table 2). Results presented by [PERSON] et al. [27] and [PERSON] et al. [21] confirm a higher polyphenol content in Robust beans. Authors also investigated the content of chlorogenic acid isomers in beans of various coffee species, demonstrating a higher overall amount in Robust beans. The differences observed here suggest the influence of other factors, not only related to botanical origin, on the content of polyphenols in coffee beans. When comparing untreated, control and modified samples of respective coffee species, it is noteworthy that the lowest total polyphenol and 3-CQA contents were observed in the modified samples. Robust controls exhibited significantly higher total polyphenol content and slightly higher 3-CQA content compared to untreated beans. In the case of Arabica beans, both control and modified samples showed lower total polyphenol and 3-CQA contents than those determined in unprocessed green beans of this species. In most samples, a negative impact of the extended modification time on the content of the investigated active compounds was observed. Only in Arabica and Robust samples modified with pepsin, a slight increasing trend was noted, mainly concerning changes in 3-CQA content (Tables 2 and 3).