Environmental impacts of Scottish faba bean-based beer in an integrated beer and animal feed value chain

Beer is one of the most popular drinks globally and production methods clearly need to become more sustainable. The brewing of legume grains could contribute to improved sustainability through encouraging the diversification of cropped systems and by providing more nutritious local co-products as animal feed. The aim of this study was to assess the potential environmental effect of partially substituting malted barley with grain legumes as an option to mitigate the environmental impact of beer. A Life Cycle Assessment (LCA) was performed to compare a novel Scottish beer produced with malted barley and UK-grown faba beans with a traditional malted barley beer. We considered beer production as part of a multi-functional beer and animal feed value chain, where co-products are used as a high-protein UK-grown animal feed. The environmental performances of the different beers were highly dependent on the system boundaries adopted. The simple attributional LCA indicated that a barley-bean beer could offer environmental savings when alcohol yields are optimised, with environmental burdens that were significantly smaller than those of the barley beer across 6 categories. When boundaries were expanded to include both feed substitution and agricultural rotations, the barley-bean beer with current alcohol yields outperformed the barley beer across 8 impact categories, with a 15 %–17 % smaller climate change burden, mainly due to higher feed substitution achieved from a larger volume of brewing co-products with higher protein concentrations. Therefore, brewers should consider the use of legumes in their brewing recipes to lower their environmental footprint, increasing the availability of more nutritious beer co-products as a local source of animal feed, and diversifying cropping systems while adding novelty to their product range. Different boundaries settings and scenarios should be assessed in a beer LCA, and entire cropping rotations should be integrated to capture a more accurate picture of the agricultural stage.