Optimizing enzymatic processing of apple pomace: a strategy for modifying techno-functional properties and dietary fiber

Abstract

Apple pomace (AP) holds significant nutritional and health-promoting potential due to its dietary fiber (DF) content. However, integrating AP into food formulations requires addressing its highly insoluble nature, which limits its functionality. This study investigates the efficacy of enzymatic treatment as a sustainable and cost-effective approach to modify the insoluble fraction and enhance DF techno-functional properties. The effects of a carbohydrase complex on AP functionality and its soluble uronic acid (SUA) and soluble neutral sugar (SNS) contents were assessed by optimizing enzyme concentration (0.5–5 mL/kg dry weight (DW)), hydrolysis time (1–4 h), and temperature (40–60 °C) using response-surface methodology with a central composite design. The optimization process identified the ideal conditions to be 3.31 h of hydrolysis at an enzyme concentration of 4.1 mL/kg DW and a temperature of 48 °C, which significantly improved treatment efficiency and maximized all evaluated responses simultaneously. Under these conditions, the solubility of AP, soluble uronic acid content and soluble neutral sugar content increased by 1.70, 3.60 and 2.48 times, respectively, compared to untreated AP. The water and oil retention capacities decreased by 16% and 15%. Furthermore, a 35% increase in soluble DF and a 39% decrease in insoluble DF were observed under optimal conditions. This research highlights the potential of optimizing enzymatic processing to transform fruit by-products into novel food ingredients with enhanced solubility.

The authors acknowledge the project RTI 2018-095560-B-I00 funded by MICIU/AEI /10.13039/501100011033/ and by FEDER A way to make Europe and the project TED2021-131828B-100 funded by MICIU/AEI /10.13039/501100011033 and by the European Union NextGenerationEU/ PRTR. Díaz-Núñez, A. also thanks the University of Lleida for the predoctoral grant (BOU201-220/2020 UdL). We would like to acknowledge Dolors Esqué for her technical assistance.