Microwave-Assisted Valorization of Tomato Pomace for Pectin Recovery: Improving Yields and Environmental Footprint

Rising industrial demands emphasize the need for exploring other non-traditional sources for obtaining pectin. As efforts to enhance circular economy practices and reduce reliance on primary resources intensify; the focus has shifted towards utilizing various types of agricultural and food industry waste; including tomato pomace waste (TPW). In this work; the microwave-assisted extraction (MAE) and TPW pretreatment methods were optimized to improve pectin yields and decrease the environmental impact of the extraction process; compared to conventional solvent extraction (CSE). The response surface methodology was used to model the optimization process. The physico-chemical properties of pectin were determined using titrimetric methods and FTIR spectroscopy. A life cycle assessment (LCA) was applied to assess the environmental impact of MAE and CSE. Optimal microwave conditions (11.66 min/600 W/pH 1) yielded two times more pectin than CSE (2 h/85 °C/pH 1.5). Pre-processing treatments (mechanical ball milling and defatting) showed marginal effects on pectin yields and properties; and; therefore; can be omitted in order to reduce the energy consumption of the process. The LCA showed that single conventional extraction treatment had two times higher values of the ecological footprint compared to MAE; for all indicators. The results suggest that MAE can be used as an efficient green method for pectin extraction from TPW.