Bioactive Films Containing Alginate-Pectin Composite Microbeads with Lactococcus lactis subsp. lactis: Physicochemical Characterization and Antilisterial Activity.

Mariam Bekhit,Solenne Fleutot,Elmira Arab-Tehrany,Stephane Desobry,Cyril Kahn,Franck Cleymand,Laura Sánchez-González

doi:10.3390/ijms19020574

Abstract

Novel bioactive films were developed from the incorporation of Lactococcus lactis into polysaccharide films. Two different biopolymers were tested: cellulose derivative (hydroxylpropylmethylcellulose (HPMC)) and corn starch. Lactic acid bacteria (LAB) free or previously encapsulated in alginate-pectin composite hydrogel microbeads were added directly to the film forming solution and films were obtained by casting. In order to study the impact of the incorporation of the protective culture into the biopolymer matrix, the water vapour permeability, oxygen permeability, optical and mechanical properties of the dry films were evaluated. Furthermore, the antimicrobial effect of bioactive films against Listeria monocytogenes was studied in synthetic medium. Results showed that the addition of LAB or alginate-pectin microbeads modified slightly films optical properties. In comparison with HPMC films, starch matrix proves to be more sensitive to the addition of bacterial cells or beads. Indeed, mechanical resistance of corn starch films was lower but barrier properties were improved, certainly related to the possible establishment of interactions between alginate-pectin beads and starch. HPMC and starch films containing encapsulated bioactive culture showed a complete inhibition of listerial growth during the first five days of storage at 5 °C and a reduction of 5 logs after 12 days.

Highlights

Lactic acid bacteria (LAB) were traditionally used for a technological purpose
Among biopolymers used as support for LAB, cellulose derivatives appear as remarkable film forming compounds
In comparison with HPMC films, starch matrix proves to be more sensitive to the addition of bacterial cells or alginate-pectin microbeads

Summary

Introduction

Lactic acid bacteria (LAB) were traditionally used for a technological purpose. These bacteria provide taste, texture and increase the nutritional value of fermented foods such as dairy products (yoghurt, cheese), meat products, as well as some vegetables. Among biopolymers used as support for LAB, cellulose derivatives appear as remarkable film forming compounds. Are they biodegradable, odourless and tasteless [5] but they exhibit good barrier properties against lipids, oxygen and carbon dioxide at low and intermediate relative humidity [6]. Hydroxypropylmethylcellulose has been used for instance for their good film forming properties and mechanical resistance Another interesting polysaccharide used in active packaging is starch. This biopolymer is a renewable resource, inexpensive (compared with other compounds) and widely available [7]

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