# Improved Functions of Fermented Coffee by Lactic Acid Bacteria
###### Abstract
The concentration of these extracts depends upon the species of coffee plant and the method of extraction used (e.g., Coffee arabica, Arabica, Coffee canenbora, and Robusta); nevertheless, the bioactive properties, including antibacterial and antioxidative potential, of these coffee compounds are impacted by various factors such as coffee bean processing like fermentation, brewing techniques, and specific roasting conditions [16]. Chlorogenic acid, which is a recognized antioxidant, has been shown to possess anti-inflammatory, antibacterial, and antiviral properties [17], exhibit anticarcinogenic activity, and provide protective effects on neuronal cells is an important polyphenol in the human diet, and green coffee beans contain the largest amount of chlorogenic acid found in plants, ranging from 6% to 12% [18]. To harness the vast medicinal, unique qualities, and economic benefits of different types of coffee, blended varieties are commercially available as specialty coffee. For instance, Arabica (_Coffea arabica_ L.) and Robusta (_Coffea canenbora_) are two economically significant coffee species. Arabica is renowned for its aromatic and sweet characteristics, as well as its notable variations in acidity and flavor. In contrast, Robusta is known for its bitterness due to its higher caffeine content, and it has lower sweetness and acidity compared to Arabica [19]. Blends that combine both Arabica and Robusta have traditionally aimed to achieve a harmonious balance between aroma and flavor, integrating the desirable qualities of Arabica with the distinctive bitterness of Robusta [20]. Different concentrations of these two types of coffee can be mixed together to obtain different taste aromas and biological effects; however, 50% Arabica and 50% Robusta was favored in terms of brewing taste in a previous study [21]. One of the most important stages in the post-harvest processing of coffee is fermentation. It has been shown to increase the phenolic and flavonoid content as well as the antioxidant activity of fermented coffee [22]. Thus, fermentation improves the functionality of food [23]. Various studies have been performed on the fermentation of coffee beans, the use of different starter cultures in fermentation, and their impact on coffee quality and functionality [24; 25]. [PERSON] et al. [26] studied the effects of the coffee cherry sanitization method and fermentation times on coffee quality. In their study, the sanitization method influenced fermentation time because microbial loads were different according to the methods. Sanitization with a chemical disinfectant and prolonged fermentation times were favorable for coffee safety and quality. [PERSON] et al. [27] studied refermentation with yeast and lactic acid bacteria to improve the flavor of coffee beans. Co-inoculation of the two microorganisms after spontaneous coffee bean fermentation with dried coffee pulp as the substrate increased chlorogenic acid content significantly, and certain volatile compounds were found with higher concentrations in the inoculated samples. Fermentation depends on various factors including the type of starter culture [28]. The role of lactic acid bacteria (LAB) in fermentation in coffee is becoming more important as the improved quality of fermented products along with a reduction in fermentation time has been shown [29]. Lactic acid produced in coffee during fermentation can deliver a smoother, more rounded flavor profile, often featuring milky or yogurt-like notes that may add a creamy quality to the coffee [30]. In this study, however, we directly applied LAB to a coffee extract (50% Arabica + 50% Robusta) rather than coffee beans and finally selected three strains of LAB, including _Pediococcus pentosaceus_ KNUT 0384, _Lacticaseibacillus paracasei_ CJNU 1840, and _Lactiplantitobacillus plantarum_ CJNU 0441, which are resistant to the extract, for further functional evaluation.