Ultrasonic depolymerization of pomegranate peel pectin: Effect of sonication time on antioxidant, α-amylase inhibitory, and prebiotic properties

This study aimed to investigate the effects of ultrasonic treatment time (5-30 min) on the structural characteristics, antioxidant, α-amylase inhibitory, and prebiotic properties of pomegranate peel pectin (PPP). The extracted PPP was rich in galacturonic acid (64.27 %) and exhibited a high degree of esterification (DE, 61.7 %), with an average molecular weight (<i>Mw</i>) of 135.6 kDa. The <i>Mw</i>, particle size, and DE of ultrasonic-treated PPPs (U-PPPs) significantly decreased compared to the PPP. FTIR analysis revealed that the intensity of the peak at ∼1730-1720 cm^-1 weakened with prolonged treatment time. The total phenol content, antioxidant activity, and α-amylase inhibition of U-PPPs were enhanced compared to PPP. Both PPP and U-PPP treated for 30 min promoted the growth of <i>Bifidobacterium longum</i> and <i>Lactobacillus casei</i>, with U-PPP-30 showing a greater preference over PPP and inulin. In conclusion, ultrasonic treatment represents a promising approach to depolymerization aimed at enhancing the biological activities of pectin.