EVALUATION OF THE ANTIBACTERIAL ACTIVITY OF ARABICA COLD BREW AND ARABICA SPENT COFFEE GROUNDS ON STREPTOCOCCUS MITIS

Spent coffee grounds or coffee waste pose a growing environmental problem as it can harm the ecosystem by releasing greenhouse gases into the atmosphere during their decomposition process [1]. On the other hand, spent coffee ground extracts have been shown to contain polyphenols, trigonelline, phenolic acids, and melanoidins which show strong antibacterial activity toward Gram+ bacteria and yeast [2]. Given its activity towards Gram+ bacteria, this study seeks to find an alternative use of spent coffee grounds, aiming to mitigate their environmental impact. This research focuses on the investigation on whether arabica spent coffee grounds could be used as a natural alternative to iodine mouthwash solution, a commonly used product to kill dental plaque bacteria. Arabica coffee extract was prepared by a 24-hour cold brew procedure then spent coffee grounds extract was produced from the Arabica coffee waste. To obtain results, the antibacterial activity of both spent coffee grounds and coffee on S. mitis was analyzed using the well diffusion test and inhibition zones were measured and compared. The caffeine contents of the Arabica coffee grounds were quantified using HPLC. From our quantitative analysis, the spent arabica coffee grounds collected from the cold brew procedure consist of less caffeine, compared to that of the cold brew, but still showed antibacterial activity towards S. mitis. The inhibition zone of the spent coffee grounds was significantly lower than cold brew coffee but still comparable to iodine mouthwash solution. Our novel findings indicate that spent coffee grounds can be used as a natural antibacterial and an alternative to povidone-iodine mouthwash which leads to reduction of environmental harm from coffee waste.