Synthesis and Characterization of Ulvan-Alginate Hydrogel Beads as a Scaffold for Probiotic Immobilization

¹ Department of Aquatic Product Technology, Faculty of Fisheries and Marine Sciences, IPB University, Bogor, West Java, 16680, Indonesia
² Center of Coastal and Marine Resources Studies (PKSPL), IPB University, Bogor, 16127, Indonesia

^* Corresponding author: wahyu.ramadhan@apps.ipb.ac.id

Abstract

Probiotic drinks have various benefits for the digestive tract. However, there is a problem with ensuring the viability of probiotics and their functionality while passing through the digestive tract to the large intestine, thus an alternative strategy is needed to maintain the viability of probiotics, namely hydrogel encapsulation of natural biopolymers such as ulvan and alginate. Hydrogels constructed from ulvan and alginate were predicted to be suitable for the challenge as a probiotic bioreactor that could stimulate human digestive health because its porosity and retention capacity could be chemically controlled. The aims of the study were to evaluate the characteristics of the selected ulvan concentrations and to determine the resistance of encapsulated probiotic bacteria in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). The research involved characterizing the hydrogel using different concentrations of ulvan (1%, 2%, 3%, and 4%) along with 2% alginate. Ulvan-alginate hydrogel produced the highest gel fraction and swelling ratio of 98.8% and 19.7%. The hydrogel system composed of 1% ulvan and 2% alginate effectively preserved the viability of probiotic bacteria in both SGF and SIF environments, with survival rates of 3.41 × 10⁷ and 0.14 × 10⁷ log CFU/g, respectively.