This study was carried out to examine the physical characteristics of bacterial cellulose (BC) and its optimal culture condition using coffee by-products. Recently, recycling resources and employing eco-friendly materials have been raised as significant issues in the food industry. As the coffee industry develops, interests and efforts for recycling coffee wastes are also growing. This study attempted to confirm the production of BC by utilizing spent coffee grounds filtrate as a medium. In order to confirm the optimal culture conditions for BC production, different culture methods, initial pH, culture temperature, and culture period were examined. The optimal pH and temperature were 6.0 and 30oC, and the optimal culture period was 14 days. The cultivated BC was dried by hot air drying, freezedrying, and mold drying, respectively. Then, the properties of the BC films, such as tensile strength, elongation, water-solubility, thickness, and chromaticity were compared. The drying method affected the shape and structure of the final BC films. The production of BC film is expected to expand opportunities for recycling coffee by-products and contribute to solving environmental problems caused by food waste.

During the past few decades, significant increase in the consumption of coffee has led to rapid increase in the production of coffee waste in South Korea. Spent coffee waste is often treated as a general waste and is directly disposed without the necessary treatment. Spent Coffee Grounds (SCGs) can release several organic contaminants, including caffeine. In this study, leaching tests were conducted for SCGs and oxidative degradation of caffeine were also conducted. The tested SCGs contained approximately 4.4 mg caffeine per gram of coffee waste. Results from the leaching tests show that approximately 90% of the caffeine can be extracted at each step during sequential extraction. Advanced oxidation methods for the degradation of caffeine, such as UV/H2O2, photo-Fenton reaction, and UV/O3, were tested. UV radiation has a limited effect on the degradation of caffeine. In particular, UV-A and UV-B radiations present in sunlight cause marginal degradation, thereby indicating that natural degradation of caffeine is minimal. However, O3 can cause rapid degradation of caffeine, and the values of pseudo-first order rate constants were found to be ranging from 0.817min-1 to 1.506 min-1 when the ozone generation rate was 37.1 g/m3. Additionally, the degradation rate of caffeine is dependent on the wavelength of irradiation.