Environmental optimization of dietary fiber extraction from spent coffee grounds derived from coffee shop waste: A life cycle assessment approach

Spent coffee grounds (SCGs) are an abundant source of organic waste with significant potential for valorization, including dietary fiber extraction. The objective of this study was to evaluate and optimize the environmental performance of producing dietary fiber from SCGs using diluted acid hydrolysis, emphasizing the influence of key process variables on environmental impacts. In this sense, a life cycle assessment (LCA) was conducted according to ISO 14040 guidelines using a gate-to-gate approach with inventories based on material and energy balances derived from Aspen Plus V.12 from experimental results. A two-factor interaction (2FI) statistical model was used to identify significant process variables during the hydrolysis stage and was optimized using a genetic algorithm (GA). The results revealed that the fiber purification and solvent recovery stages had the highest environmental impact across all evaluated scenarios. Climate Change (CC) associated with producing dietary fiber from SCGs was comparable to emissions from alternative valorization routes studied in the literature. Furthermore, human toxicity (HT) impacts were equivalent to or lower than those of dietary fibers derived from other agro-industrial residues. Terrestrial Acidification (TA) impacts were not significantly affected by acid concentration. The 2FI model identified the solid:liquid ratio as the critical factor affecting environmental outcomes. Optimization showed that the best environmental performance is achieved at high temperatures and low solid-to-liquid ratios. This study demonstrated that combining the life cycle assessment method, statistical modeling, and artificial intelligence is an effective strategy for optimizing SCG valorization in fiber production in environmental terms. • LCA + Aspen Plus inventories assessed SCG-to-dietary fiber via dilute acid hydrolysis. • Downstream purification and ethanol recovery drive most impacts across scenarios. • 2FI model shows solid:liquid ratio and temperature dominate environmental outcomes. • Genetic algorithm optimization favors high T (184–189 °C) and low L/S (4.9–7.3). • CC and HT impacts are comparable to or lower than other agro-residue dietary fibers.