Investigation on the film-forming properties of lab fermenter scale produced scleroglucans from Sclerotium rolfsii ATCC 201126

Abstract

The film-forming capacity of the biopolymer scleroglucan produced on the lab fermenter scale by Sclerotium rolfsii ATCC 201126 was studied. The effect of a freeze–thawing process on the physical properties of scleroglucan films was investigated with hydrogels of three different scleroglucan samples. Films were made from 1% (w/w) scleroglucan hydrogels using 2% (w/w) glycerol as plasticizer by applying two different protocols: (1) a room-temperature drying method and, (2) a freeze–thawing cyclic process (prior to the application of room-temperature drying). The obtained materials were characterized by physical studies including swelling, water vapor transmission, and environmental scanning electron microscopy. Based on the results obtained, when eight freezing–thawing cycles were applied during scleroglucan film preparation, a reinforcement of the structure was achieved pointing to an increase in the number of crosslinking points by H-bonding. All exopolysaccharides produced by S. rolfsii ATCC 201126 at lab fermenter scale showed a general promising behavior for the preparation of reinforced films, opening new perspectives for their potential use in either controlled release systems or the formulation of additive-complemented films for specific applications.