Improving coffee quality through yeast addition in the fermentation process to support sustainable coffee production

Abstract

Indonesia is the fourth largest country in the world as a coffee producer. Coffee has complex chemical structure with volatile and non-volatile compounds, this composition has an important role in the distinctive coffee’s taste. Fermentation is an important stage in coffee processing, it has a direct effect on the coffee’s quality. So far, many people have done traditional fermentation relying on natural microbes in fresh coffee. The purpose of this study was to improve coffee’s quality by controlled fermentation using added yeast, thereby encouraging the sustainability of coffee production. The coffee cherries were taken from a coffee plantation in Merapi mountain area, Yogyakarta. Yeast isolates used were Saccharomyces cerevisiae and Pichia kudriavzevii. The experimental processes of fermentation were carried out on three different environmental variables, namely: fermentation in bioreactor with inoculum, fermentation in bioreactor without inoculum, and traditional fermentation in an open container. Coffee cherries were peeled by pulper machine then kept underwater for 72 hours, except for fermentation in an open container. Data logger was used to monitor the temperature changes, the moisture content, brix, PH, and color change were measured for each 24 hours during fermentation. From the data analyzed, the moisture content and brix were increased during fermentation. The result indicated that fermentation by yeast addition raised acidity in the final coffee result, this can be shown from the PH result that eventually decreased from 5.83 to 5.49 and 6.15 to 4.29, respectively. The maximum temperature for both yeast species addition was reached at a 24 to 48 hours period. The result showed that the color parameter (LAB) was elevated, except the lightness value from Pichia kudriavzevii fermentation. Result in this study revealed that the type of microorganism will determine the characteristics of the coffee produced, such as the acidity. The specific taste and aroma compound were generated during fermentation by different yeast species.

Physiochemical Characteristic of Fermented Coffee with yeast addition (Hanseniaspora uvarum and Candida parapsilosis)

“…This study is in line with that conducted by [18] which states that aerobic fermentation can produce temperatures reaching 40-45℃. This study is also in line with [19], which states that the temperature in anaerobic fermentation ranges from 28-31℃. According to [20], the optimum temperature for yeast growth ranged from 20-30 °C so that the temperatures during anaerobic fermentation, anaerobic with H. uvarum and anaerobic with C. parapsilosis obtained were suitable as conditions for yeast growth.…”

“…The analysis of variance carried out showed that the value of sig.> 0.05 so that it can be concluded that there was no significant difference between the fermentation treatment with TSS at the end of the fermentation. The results obtained are in line with research conducted by [19], which stated that the use of yeast had no significant effect on the total dissolved solids in the fermented water with an TSS value of approximately 2.5 at the end of fermentation.…”

Influence of Temperature-Controlled Fermentation on the Quality of Mild Coffee (Coffea arabica L.) Cultivated at Different Elevations

“…Controlling the fermentation temperature is necessary not only for the process development, but also to satisfy the demands of consumers regarding the improvement in coffee sensory profiles. In this sense, the main efforts with promising results have focused on achieving control of fermentation through the establishment of microbial starter cultures, the activity of which produces compounds that modify the chemistry of the coffee beans and highlight the attributes of the drink [11,16,27,61,[66][67][68]. Based on the results obtained in this research, temperature control is another mechanism by which the same effect can be achieved to determine the optimal conditions that can support the desired behaviors among native microbiota.…”

Characterization of yeast mutant strains for starter culture in Arabica coffee fermentation

“…Various reports have successfully improved the flavor quality of Arabica coffee by using starters such as Wickerhamomyces anomalus KNU18Y3 and Wickerhamomyces anomalus YWP1-3 9 , 10 . Moreover, yeast starters such as Saccharomyces cerevisiae and Pichia kudriavzevii were applied for Robusta coffee ( Coffea robusta ) fermentation under controlled fermentation in a bioreactor 39 .…”