Optimized Isolation Procedure for the Extraction of Bioactive Compounds from Spent Coffee Grounds

Due to the worldwide consumption of coffee, many tons of spent coffee grounds (SCGs) are discarded each year, as a by-product of coffee preparation. Not only their disposal is costly, but also it may cause the release of compounds that can endanger the environment. However, there are valuable chemical compounds that can be extracted from SCGs and used in the food industry. The aim of this study was to investigate the main parameters affecting the extraction of caffeine and polyphenols (i.e., chlorogenic acid, neochlorogenic acid, and caffeic acid) and to evaluate the antioxidant properties of the extracts. To this end, extraction solvent, temperature, time, and liquid-to-solid ratio were studied. A response surface methodology was used to optimize the extraction process. According to the results, the caffeine content of the optimum extract was found to be 6.14 mg/g in dry SCGs, the total polyphenol content was 19.85 mg gallic acid equivalents/g, while the ferric reducing antioxidant power and DPPH scavenging values were 136.69 mu moL ascorbic acid equivalents/g and 230.41 mu moL DPPH/g, respectively. The experimental values were in close agreement with the predicted ones, highlighting the potential of SCGs to be used for the isolation of bioactive compounds with the proposed extraction procedure.

Automated summary

Due to the worldwide consumption of coffee, a large amount of spent coffee grounds (SCGs) are discarded each year. This study aimed to investigate the extraction of valuable compounds from SCGs and evaluate their antioxidant properties. The main parameters studied included extraction solvent, temperature, time, and liquid-to-solid ratio. The results showed that the optimum extract had a caffeine content of 6.14 mg/g, total polyphenol content of 19.85 mg gallic acid equivalents/g, ferric reducing antioxidant power of 136.69 mu moL ascorbic acid equivalents/g, and DPPH scavenging value of 230.41 mu moL DPPH/g. The experimental values were in agreement with the predicted ones, demonstrating the potential of SCGs for bioactive compound extraction.