Abstract
This study aimed to investigate the effects of ultrasound-assisted extraction (UAE) on the physicochemical properties, biological activities, and intestinal flora regulatory capacity of jackfruit polysaccharides (JPs). Under optimized UAE conditions (liquid-to-solid ratio 30 mL/g, extraction time 30 min, power 90 W), the yield of JP reached 8.70 ± 0.11%. Compared with hot-water-extracted jackfruit polysaccharides (HAE-JPs), ultrasonic-assisted extracted jackfruit polysaccharides (UAE-JPs) exhibited a lower molecular weight, a smaller particle size, and a significant 11.5-fold increase in galacturonic acid content. Structural analyses confirmed that UAE-JPs retained a triple-helix and highly branched conformation but with enhanced exposure of acidic monosaccharides. These structural modifications contributed to superior antioxidant activity and enzyme inhibition ability, demonstrated by its lower IC(50) values against DPPH, ABTS radicals, and α-glucosidase. Crucially, in vitro fecal fermentation revealed that UAE-JPs and HAE-JPs differentially modulated the gut microbiota. UAE-JPs preferentially promoted the proliferation of Lactobacillus (an increase of 27.04%) and Bifidobacterium, facilitating short-term acidification. In contrast, HAE-JPs enriched butyrate-producing bacteria like Clostridium (increase of 18.56%). Both polysaccharides significantly inhibited the growth of Fusobacterium (a decrease of 5.23%) related to cancer. Consequently, this study establishes UAE as a green and efficient technique capable of not only modifying the structure of JPs but also precisely tailoring their prebiotic functionality, which ultimately demonstrates the potential of UAE-JPs as a functional food ingredient with enhanced bioactivity.