UTILIZATION OF INDIGENOUS LACTIC ACID BACTERIA FROM COFFEE PULP TO ENHANCE ANTIOXIDANT ACTIVITY OF CASCARA

• Main Author: Oktaviani, Lina
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/46341
• Institution: Institut Teknologi Bandung

Cascara is herbal tea produced from dried coffee pulp. Cascara was known as a beverage with source of antioxidants. Nevertheless, production process of cascara didn’t have standard that results in a large variations of antioxidant activity of cascara. Antioxidant of cascara can be influenced by indigenous microbes present in the coffee pulp such as heterofermentative lactic acid bacteria. In this study, heterofermentative lactic acid bacteria that close with Leuconostoc pseudomesentoroides was found from fresh coffee pulp. This bacteria can increase the antioxidant activity because its ability to convert phenolic compounds into their derivative. Previous research about lactic acid bacteria utilization to increase the antioxidant activity of coffee pulp has been carried out by Lopez in 2013. The result showed that antioxidant can increase after the addition of bacterial inoculum. However, in the research, the unit of fermentation and drying of coffee pulp were separate so the production process was less efficient to be applied. Therefore, this study used simultaneous fermentation and drying to produce cascara. With using this system, cascara can be produced easily, efficiently, and cost effectively. This study used natural fermentation or fermentation without the addition of inoculum of microbes. The fermentation aims to increase the activity of indigenous bacteria such as heterofermentative lactic acid bacteria. The activity of lactic acid bacteria can increased by optimizing the temperature and time of incubation. Optimization process used the face centered central composite experimental design and the approach of quadratic non-linear regression model. The software used for this optimization is Design Expert® version 11. Independent variables in the optimization process include fermentation time (0 - 8 hours) and fermentation temperature (27 – 37 oC). The dependent variable consisted of the antioxidant activity of cascara, phenolic component of cascara, and the number of heterofermentative lactic acid bacteria. The target of the optimization is the optimum incubation time and incubation temperature that produce the highest value of dependent parameter. Fermented cascara under optimum conditions was then used for organoleptic test and the assay of phenolic components profile. Then, a controlled fermentation was carried out to determine the potential of heterofermentative lactic acid bacteria as a starter to increase the cascara antioxidant activity. The controlled fermentation is fermentation with the addition of heterofermentative lactic acid bacterial inoculums. The size of inoculum added to coffee pulp varied 5%, 10%, and 15% (v/w). To compare the result with natural fermentation, temperature and time of controlled fermentation was set the same as optimum conditions obtained from natural fermentation. The results of the regression model show that the fermentation time significantly influences the number of heterofermentative lactic acid bacteria. The increase of the number of bacteria can increase the concentration of phenolic components that act as antioxidants in cascara. The optimization results using software showed that the natural fermentation with incubation at 31.8 oC for 4.2 hours produced cascara with the highest antioxidant activity and phenolic components. The antioxidant activity increased by 56% of the fresh coffee pulp. The increase in antioxidant activity can be caused by the increased of phenolic component with a concentration of 5.79% after 4.2 hours of natural fermentation and 3.19% for fresh coffee pulp. The increase of phenolic components can occur due to the activity of the pectinase enzyme in the coffee pulp that can increase the yield of phenolic component. In addition, the increase can also occur due to the conversion of phenolic components into their derivative compounds by the metabolism of heterofermentative lactic acid bacteria. This can be determined through phenolic component profile, chlorogenic acid has decreased by 80% after fermentation for 4 hours. On the other hand, caffeic acid as a product from the hydrolysis of chlorogenic acid has increased up to 30%. Based on the organoleptic test, cascara with incubation for 4.2 hours at 31.8 oC has a more acidic aroma compared to cascara without the addition of natural fermentation time. Also based on testing the level of sweetness and acidity, cascara beverage with the addition of natural fermentation time has a lower sweetness value and higher acidity. Furthermore, based on the study of controlled fermentation, it was known that lactic acid bacteria as a starter can more increase the antioxidant activity of cascara. At an inoculum size of 10%, antioxidant activity increases to 68% of unfermented cascara. Based on this research, it can be concluded that simultaneous fermentation by drying can be used to produce cascara. The cascara antioxidant can increased by natural fermentation at 31.8 oC for 4 hours and can be further increased by the addition of an heterofermentative lactic acid bacteria inoculum with size of 10% at the same time and temperature. Controlled fermentation by reviewing indigenous microbes is a solution to solve the problem of the varied antioxidant activity of cascara.