Valorization of spent coffee grounds by 2-methyloxolane as bio-based solvent extraction. Viable pathway towards bioeconomy for lipids and biomaterials

Abstract

This study attempts to shed light on the efficacy of the solvent 2-methyloxolane (2-MeOx) as an alternative for hexane in defatting spent coffee grounds (SCG). Higher lipid yields were obtained with the bio-based solvent dry 2-MeOx (13.67%) and water-saturated 2-MeOx (15.84%) compared to hexane oil yield, which is of petroleum origin and is a known neurotoxin. Palmitic acid and linoleic acid were the principal fatty acids identified. The fatty acid profile of coffee oils obtained with hexane, dry 2-MeOx and aqueous 2-MeOx were similar. Lipid hydrolysis was observed in oils extracted with 2-MeOx, which warrants further investigation. The residual caffeine content in the defatted SCG was highest when hexane was used highlighting better solubility of methylxanthine compounds in the solvent 2-MeOx.

Spent Coffee Grounds Valorization in Biorefinery Context to Obtain Valuable Products Using Different Extraction Approaches and Solvents

“…Comparing the results with the works of the other authors, for example, n-hexane and 95% ethanol extracts obtained in a batch process from Arabica spent coffee grounds obtained 14.5% and 11.2% yields, respectively, while for the CO sample the n-hexane yield reaches 14.82% (see Figure 3 B), which is basically very similar, while the CK sample 96% ethanol extract is obtained with a yield of 12.71% (see Figure 4 B), which is slightly more [ 26 ]. While performing conventional Soxhlet extraction with n-hexane for 6 h, Chemat et al showed that spent coffee ground from a cafeteria (CROUS, Agroparc, Avignon) is able to obtain n-hexane extract with a yield of 12.47%, which is comparable to the results obtained in this work [ 27 ]. The increased yield of 96% ethanol can be explained by the fact that lipophilic compounds are also extracted from the spent coffee grounds with a solution of this concentration, which is part of coffee oil and is usually extracted with n-hexane, because the obtained extract has an oily consistency compared to the lower concentration of ethanol solutions.…”

Integrated Approach to Spent Coffee Grounds Valorization in Biodiesel Biorefinery

“…The most represented compound was caffeine, whose presence in the SCGO have not been mentioned yet in the published articles. On the contrary, an article [58] published that using hexane as an extraction agent, less caffeine was extracted compared to 2-methyloxane (or most of the caffeine amount remained in the delipidized SCG), despite the lower oil yield when extracted with hexane [58]. The presence of phytosterols and tocopherol were identified in the study SCGO (Tables 4 and 5).…”

Valorization of Coffee Silverskin Using Extraction Cycles and Water as a Solvent: Design of Process

“…The typical method for the disposal of this waste is to incinerate or discard it, which releases caffeine and CO 2 into the environment, causing serious environmental issues [ 1 , 12 ]. Due to the recent growing interest in sustainability and environmentally friendly actions, numerous researchers and producers are investing in developing novel approaches to valorize coffee-making-related byproducts.…”

“…Due to the recent growing interest in sustainability and environmentally friendly actions, numerous researchers and producers are investing in developing novel approaches to valorize coffee-making-related byproducts. The latter copious waste can be used for animal feed [ 1 , 3 , 8 ], developing new materials [ 1 , 3 , 12 ], producing biofuels [ 1 , 3 , 6 , 8 ], formulating natural aromas [ 7 , 8 ], or isolating active compounds, which can further be used as ingredients for the food, cosmetic, nutraceutical, or pharmaceutical industries [ 1 , 7 , 13 ]. Such practices can significantly contribute to increasing the profitability of the coffee industry and establish the concept of a circular economy.…”