Carbon and water footprints of the revalorisation of glucosinolates from broccoli by-products: case study from Spain

Assessing the costs, benefits, and externalities of circular economy measures from a life cycle perspective is increasingly important for developing sustainable agro-food strategies. This study evaluates the carbon and water implications of revalorising glucosinolates from broccoli by-products through two distinct life-cycle scenarios in a case study conducted in Navarra, Spain. In the first scenario, glucosinolates are obtained from conventional broccoli production, where they are naturally present in the edible inflorescences. The second scenario introduces an innovative step: extracting glucosinolates from otherwise discarded broccoli by-products, such as stalks and inflorescence detachments. Carbon and water footprints were analysed for both scenarios based on the production of 1000 grams of glucosinolates. The results reveal that while the second scenario enhances resource efficiency by utilizing agricultural waste, the environmental costs of the extraction process outweigh the benefits, leading to a 37.6 % increase in greenhouse gas emissions and a 4.6 % rise in water usage compared to the first scenario. To address this, an improvement scenario is proposed, featuring a more efficient use of solvents during extraction, which significantly reduces both emissions and water use. This study underscores that circular economy strategies in agro-food systems do not always translate into environmental benefits accross all resources. A detailed analysis of various carbon and water indicators has provided valuable insights to enhance the environmental performance of such strategies, reinforcing the importance of life-cycle assessments in shaping more effective agro-food policies.