Accounting for circular economy principles in Life Cycle Assessments of extra-virgin olive oil supply chains – Findings from a systematic literature review

This study was conceived with the aim of exploring applications of the circular economy (CE) principles in the olive oil sector, with the lens of Life Cycle Assessment (LCA). To that end, the authors performed a systematic literature review (SLR), from a pre-determined set of keywords that were searched for in the two most comprehensive databases of peer-reviewed journals, namely Scopus and Web-of-Science. From the screening process provided by the PRISMA model, a total of fifteen papers were selected that formed the final review sample, most of which included research on production systems in the Mediterranean region. To facilitate a comparative analysis of the findings from those studies, the latter were grouped into clusters, considering their characteristics and methodological approaches. Five articles were classified as dealing with ‘closed-loop’ systems wherein the resources from the valorisation of by-products were reintegrated into the same production system. The remaining articles were categorised as related to ‘open loop’ systems since by-products were utilised in processes and systems outside olive oil production. Notably, the ‘closed-loop’ systems showed the best LCA outcomes. Identified hotspots within the sector included the agricultural and packaging phases. Although comparing LCA applications is challenging due to the inherent nature of the method and researcher autonomy in selecting basic characteristics, valuable best practices emerged from the analysis of the current state of the art. These practices included valorisation of olive pomace (OP) by converting it into biogas to meet the energy needs of the system processes themselves, the collection of waste cooking oil to convert it into biodiesel, and the use of organic farming techniques in olive production. OP oil extraction emerged as a widespread practice enhancing system sustainability. Moreover, increasing industrial symbiosis by promoting proximity amongst plants was documented by this SLR to be a key factor in strengthening system sustainability.