Life cycle energy and carbon emissions of colorants extraction from Hibiscus sabdariffa

The food industry is interested in new plant-based, non-toxic, food additives to substitute synthetic ones. Aiming to support the development of H. sabdariffa bio-colorant extracts at an early stage, a cradle-to-gate life cycle assessment (LCA) approach was used to evaluate the primary energy (CED) and the global warming potential (GWP) of three extraction processes: maceration (A), ultrasound-assisted extraction (UAE) during 36.5 min (B), and UAE during 11.5 min (C). Impacts of feedstock production were not included since the goal was to focus on the extraction methods developed. Results showed that the electricity consumption, and consequently, the local electric mix, are the factors that influence the most the CED and GWP. Spray-drying is the unit process with highest impacts in all scenarios (representing more than 80% of CED and GWP). Overall, from CED and GWP results, the same trend is identified: the extraction of H. sabdariffa by UAE within 36.5 min (B) has the best environmental performance, presenting the lowest primary energy (109 MJ), and carbon emissions (5 kg of CO2-eq) to obtain 1 g of colorant extract. On average, scenario B has a 30.5% lower CED and CO2-eq emissions than maceration extraction (A) and a 71.5% lower CED and GWP than UAE for 11.5 min (C).