A Comparative Life Cycle Assessment of Drying Strategies for the Valorization of Pea Byproducts

The valorization of food industry byproducts is crucial for reducing the agri-food supply chain's environmental impact and ensuring food security. Substandard peas alone generate 0.135 million tons/year of waste in the EU. Innovative technologies like Supercritical CO2 Drying (SCD) offer a promising approach to valorizing food waste with a zero-waste strategy. This study aims to apply Life Cycle Assessment (LCA) methodology to comparing the environmental impact of Solvent Exchange + Supercritical Drying (SE+SCD) with traditional Air-Drying (AD) and Freeze-Drying (FD). This work focused on the carbon footprint derived from the pea drying process using the climate change (CC) indicator.

The preliminary study was conducted based on preliminary results achieved at the pilot scale [2], projecting the results at a bigger scale. For the LCA study, the functional unit was set to1 kg of substandard peas. The system boundaries were set from suboptimal pea discharge to the obtainment of dried peas. Primary data was derived from the project in [2], and secondary data was acquired from the Italian energy mix and Ecoinvent 3.10.

Among the technologies, AD showed the lowest environmental impact at both scales (0.037 and 0.429 kg CO₂ eq, respectively). At the pilot scale, SCD and FD had comparable emissions; however, at the industrial scale, SCD showed the highest emissions. A total of 35% of the impact at the industrial scale from SE+SCD was derived from solvent consumption.

These findings highlight the potential of SE+SCD as an innovative drying technology; however, future improvements in the solvent and CO₂ recovery systems could be crucial for minimizing the environmental impact and leveraging this technology for food waste valorization.

1. Upcycling pea waste side streams for developing future food ingredients-UPea; PRIN Bando 2022; Prot. 20222P5C3E, funded by EU-NextGenerationEU.
2. L. Manzocco, L. Barozzi, S. Plazzotta, Y. Sun, S. Miao, S. Calligaris; LWT, 194 (2024), 115778.