Resistant starch from yam (Dioscorea alata L.) as a potential prebiotic and microencapsulation matrix for enhancing the viability of Lacticaseibacillus paracasei D4

Abstract

Resistant starch (RS) derived from tubers is a functional food ingredient with potential as a prebiotic and a matrix for probiotic microencapsulation. However, the exploration of resistant starch from Indonesian tuber sources remains limited. This study aimed to characterize starch and resistant starch type-3 (RS3) from yam (Dioscorea alata L.), sweet potato (Ipomoea batatas L.), and taro (Colocasia esculenta L.), evaluate their prebiotic activity toward Lacticaseibacillus paracasei D4, and assess probiotic viability under simulated gastrointestinal conditions. Starch was extracted and physically modified through autoclaving–cooling cycles to produce RS3. Prebiotic activity was evaluated using the prebiotic activity score (PAS) and the prebiotic index (PI). Microencapsulation was prepared by extrusion using a sodium alginate–chitosan–RS matrix, and viability was assessed through a three-phase gastrointestinal simulation (GIS). Yam starch (YS) showed the highest amylose (41.92 ± 0.77%) and RS content (6.12 ± 0.03%), as well as the highest prebiotic activity at a 2% concentration (PAS: 7.58 ± 4.97; PI: 1.19 ± 0.04). Yam RS microcapsule (YRSM) demonstrated the lowest viability decrease during GIS (1.45 log CFU/g), compared to the control microcapsule (3.15 log CFU/g). Scanning electron microscopy (SEM) analysis confirmed that YRSM maintained the best structural integrity post-GIS, as evidenced by minimal pore formation. These findings position YRS as an effective prebiotic and encapsulation matrix for synbiotic functional food development.