Phenolic compounds and pectin-rich extracts recovered from peach pomace by sequential pressurized liquid extractions

Abstract

Peach pomace is a by-product from the peach industrial processing, rich in high-value bioactive compounds and pectin. This study aimed to conduct a sequential pressurized liquid extraction (PLE) for the fractionation of peach pomace, recovering phenolics and pectin extracts. These separated fractions were evaluated, and novel functional properties were determined. The alternative high-pressure method (PLE) was compared to low-pressure sequential extractions conducted by Soxhlet (SOX) and heat-stirred extraction (HSE), as standard procedures. The results indicate that PLE at 40 °C provided highest phenolics yield (10.31 mgGAE.g-1), exhibiting antioxidant potential, by DPPH, ABTS and FRAP, of 20.01, 37.57 and 155.15 µmol TE. g-1, respectively. The pectin yield was 20% by HSE, while PLE achieved maximum yield of 14%. Nevertheless, the quality of the pectin fraction indicated higher content of galacturonic acid from the PLE pectin (47 % with 31 % of degree of esterification), compared to the HSE sample (10.90 % galacturonic acid with 22.15 % degree of esterification). Besides, the functional properties of the pectin fraction show high water solubility (96.47%) without significant difference between PLE and HSE samples. The PLE-pectin exhibited low water-holding capacity (0.03 g water/g) but higher oil-holding capacity than HSE-pectin. Both samples showed good emulsification and foaming ability and stability, with a higher value for the HSE sample. The present results suggest peach pomace as a promising by-product for the recovery of phenolic-rich and pectin-rich fractions. This study introduces innovations for the peach pomace fractionation and sheds light on the techno-functional properties of the pectin-rich fraction, which have proven promising attributes for future applications in food formulations.