Optimising Fig Peel Waste Phenolic Extraction through a Life Cycle and Cost-Analysis

Fig (Ficus carica L.) is an important Mediterranean fruit crop valued for its nutritional and health-promoting properties. Fig production generates substantial by-products, particularly peels, which are rich in phenolic compounds, such as flavonoids, phenolic acids, and anthocyanins. These bioactives exhibit antioxidant, anti-inflammatory, and cardioprotective effects, with Black Mission dark-skinned cultivars showing especially high levels. Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) Analysis offer a holistic valorisation supporting decision making in complicated systems depending on the compound of interest.
Fig peel waste was dried, milled, and subjected to solid-liquid extraction under varying time, temperature, and pH conditions. Extracts were evaluated for yield, total phenolics, antioxidant activity, and phenolic profile, with process optimisation via Response Surface Methodology (RSM) and sustainability assessed using LCA/LCC. The RSM successfully optimised the aqueous extraction of phenolics from fig peel, identifying pH as the most influential parameter, followed by extraction time and temperature. Maximum total phenolic content (12.28 mgGAE/gDW) was predicted at 37.5 °C, 38 min, and pH 7, with antioxidant capacity generally increasing alongside TPC.
However, extraction yield did not consistently correlate with phenolic enrichment or bioactivity. HPLC analysis revealed compound-specific behaviour. Chlorogenic acid was favoured at pH 5, lower temperature, and longer time; quercetin benefited from mildly acidic conditions and rutin was abundant at neutral pH but less directly linked to antioxidant activity. Integrating RSM with LCA-LCC demonstrated that high-yield conditions are not necessarily sustainable. Medium extraction time at pH 7 and room temperature minimised environmental impact and cost per mgGAE while maintaining acceptable bioactivity, representing the best compromise between performance and sustainability for fig peel valorisation.