In Situ β-Glucan Fortification of Cereal-Based Matrices by Pediococcus parvulus 2.6: Technological Aspects and Prebiotic Potential.

Adrián Pérez-Ramos,Daniela Fiocco,Paloma López,Giuseppe Spano,Vittorio Capozzi,Pasquale Russo,María Luz Mohedano

doi:10.3390/ijms18071588

Abstract

Bacterial exopolysaccharides produced by lactic acid bacteria are of increasing interest in the food industry, since they might enhance the technological and functional properties of some edible matrices. In this work, Pediococcus parvulus 2.6, which produces an O2-substituted (1,3)-β-d-glucan exopolysaccharide only synthesised by bacteria, was proposed as a starter culture for the production of three cereal-based fermented foods. The obtained fermented matrices were naturally bio-fortified in microbial β-glucans, and used to investigate the prebiotic potential of the bacterial exopolysaccharide by analysing the impact on the survival of a probiotic Lactobacillus plantarum strain under starvation and gastrointestinal simulated conditions. All of the assays were performed by using as control of the P. parvulus 2.6’s performance, the isogenic β-glucan non-producing 2.6NR strain. Our results showed a differential capability of P. parvulus to ferment the cereal flours. During the fermentation step, the β-glucans produced were specifically quantified and their concentration correlated with an increased viscosity of the products. The survival of the model probiotic L. plantarum WCFS1 was improved by the presence of the bacterial β-glucans in oat and rice fermented foods under starvation conditions. The probiotic bacteria showed a significantly higher viability when submitted to a simulated intestinal stress in the oat matrix fermented by the 2.6 strain. Therefore, the cereal flours were a suitable substrate for in situ bio-fortification with the bacterial β-glucan, and these matrices could be used as carriers to enhance the beneficial properties of probiotic bacteria.

Highlights

Bacterial exopolysaccharides (EPS) are extracellular polymers which can be tightly adhered, loosely associated to the microbial cell surface, or released into the environment [1,2,3,4]
A β-glucan producing strain of P. parvulus was tested for its potential use in the development of novel cereal-based functional foods
The occurrence of P. parvulus 2.6 β-glucan seems to increase the tolerance of a model probiotic strain to starvation stress conditions, typical of the food fermentation environment, and to confer survival advantages in the host’s intestinal tract

Summary

Introduction

Bacterial exopolysaccharides (EPS) are extracellular polymers which can be tightly adhered (i.e., capsular), loosely associated to the microbial cell surface, or released into the environment [1,2,3,4]. It is well known that EPS can act as natural viscosifiers and thickening agents, suggesting the use of EPS-producing LAB as starter cultures to enhance the texture and mouthfeel properties of some foods [9,10,11]. These biopolymers have been related with the mechanisms of cellular recognition and biofilm formation, modulating the probiotic colonization of the gut ecosystem [12,13]. EPS-produced by LAB can protect the producing organisms against the conditions associated with food processing and help with passage through the oro-gastrointestinal tract, encouraging the colonization of the gut environment [19]

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Results

Discussion

Conclusion