Effect of Blanching Pretreatment on Polyphenol Extraction Efficiency from Pea Pod Industrial Waste

Abstract

The increasing interest in the valorisation of agro-industrial by-products has led to the development of strategies for the recovery of bioactive compounds while contributing to sustainability and the circular economy. In this study, pea pod waste has been evaluated as a potential source of bioactive compounds with antioxidant properties. The effect of blanching pretreatment on the recovery of phenolic compounds has been evaluated together with the influence of temperature and blanching time and extraction solvent composition using a full factorial design. The obtained extracts have been characterized by Total Phenolic content (TPC), Ferric Reducing Antioxidant Power (FRAP) and HPLC total peak area analysis in order to assess phenolic recovery and antioxidant capacity. Since the optimal processing conditions may vary depending on the perspective considered, the process has been assessed from analytical, energetic and economic points of view. While the analytical optimum represents the conditions that maximise the recovery of bioactive compounds, the economic optimum also takes into account energy consumption and processing costs. Considering all these aspects, the economic criterion has provided the most suitable overall solution. The optimal conditions identified in this study have been found to be 86 ºC, 1 min and 20% ethanol-water (v/v). Furthermore, HPLC-MS/MS analysis has been carried out to characterise the chemical composition of the extracts. The results have allowed the tentative identification of several phenolic compounds: cinnamic acid derivatives, benzoic acid derivatives and flavonoids; it has been detected a non flavonoid compound compatible with citric acid too. Summarizing, the results demonstrate that blanching is an effective pretreatment for improving the recovery of bioactive compounds from pea pod waste and support the potential valorisation of this agro-industrial by-product as a suitable source of natural antioxidant compounds.