Environmental life cycle assessment of early-stage development of ergosterol extraction from mushroom bio-residues

Abstract

Mushroom farming has been rising to respond to consumers’ demand. Due to food market requirements, a substantial share of fresh mushrooms is annually wasted. Nevertheless, such bio-residues are a natural source of high added-value ingredients, namely ergosterol, a bioactive with cholesterol-reducing properties. Thus, mushroom residues can be valorised through ergosterol extraction. Despite the growing interest for natural food bioactive additives, their environmental impacts have seldom been addressed. Yet, supporting bioactive extraction procedures at an early stage of development, allows for the identification of critical factors that can be mitigated before scaling up. This work presents the environmental life cycle assessment (LCA) of an early-stage development of ergosterol enriched extract, obtained from mushroom bio-residues. It aims to identify the extraction process steps with the highest environmental impact and to assess improvement measures to reduce the overall impact of the extraction process. Results showed that electricity is responsible for a significant share of the environmental impacts, with lyophilization and evaporation being the processes with the highest contribution. Three alternative improvement scenarios were assessed, including the adoption of an on-site renewable energy (photovoltaic) system sourcing the processes (A), an osmotic pre-treatment to decrease lyophilization energy (B), and both renewable electricity and the osmotic pre-treatment together (C). Since electricity consumption affects most of the process steps, the lowest environmental impact was achieved using electricity sourced by local renewable production (A), corresponding to a reduction of up to 50%. The osmotic pre-treatment (B) achieved a reduction of around 9% when compared with the base case scenario. Moreover, a sensitivity analysis was performed to assess the influence of two critical input parameters (electricity and ethanol use). Overall, the analysis showed the robustness of the results, and that the electricity requirements have higher influence in most environmental impact categories than ethanol.