Alginate/PVA beads for levan production by Zymomonas mobilis

Abstract

The levan is a biopolymer of great importance to the food industry since it is capable of defining and modifying the structure of one food, acting as stabilizer, thickener, gelling agent and being largely responsible for the texture of processed foods. The levan production by bacterial cell immobilization may potentialize the results of these studies, having advantages such as: high cell concentrations inside the reactor, increase the substrate absorption rate, improve the performance and reduce the risk of microbial contamination. Thus, this study aims to evaluate the levan production by immobilized Zymomonas mobilis in hybrid system of alginate/polyvinyl alcohol (PVA) when submitted to different sucrose concentrations (5, 10, 25 and 30%), pH (5.7 and 7.0) and incubation temperature of 30C for 12, 18 and 24h. The results showed that the best levan production rate was 18.66g/L at 30% sucrose concentration, with productivity 1.55g/L/h at pH7.0. Practical ApplicationsThe biopolymer called levan is a nontoxic, nonmutagenic, odorless, tasteless and soluble dietary fiber; it has physiological effects that depend on its size and linkage type, and its fermentability. It can be produced by bacterial fermentation like Zymomonas mobilis. The administration of levan in human diet (5.5-6g, twice a day) for 2-3 months reduced body weight and body fat mass. The input of levan showed in some studies an increase of divalent cation (Zn, Mg and Fe) and calcium absorption in rats. In the food industry, levan improves the rheological properties and functional characteristics of dairy products, such as yogurt. Its application includes use as a stabilizer, emulsifier, surface agent, encapsulating agent and flavor and fragrances carrier.